06b 2014 wp 4 hydrology report

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[Hydrology Report] 1

Gräfenberg, Germany, 21 April 2015

Hydrology Report



Nigerian Energy Support Programme

Hydrology Report

Published by:Deutsche Gesellschaft fürInternationale Zusammenarbeit (GIZ) GmbH

Nigerian Energy Support Programme (NESP)4 Julius Nyerere Crescent, Asokoro

Abuja/NigeriaContact: Daniel Werner ([email protected])T 00234 (0)8057601986

Federal Ministry of PowerFederal Secretariat ComplexShehu Shagari Way, Maitama

Abuja / NigeriaContact: Engr. Faruk Yusuf Yabo ([email protected])

This project is funded by the European Union& the German Federal Ministry for Economic Cooperation and Development (BMZ)

Author/Responsible/Editor etc.:Oliver J. Haas, Karl Tiller, Jakob Schmidt Reindahl

Photo credits-

Maps-The geographical maps are for informational purposes only and do not constitute recognition ofinternational boundaries or regions; GIZ makes no claims concerning the validity, accuracy orcompleteness of the maps nor assumes any liability resulting from the use of the information therein.

Printed and distributed by:

Place and date of publication

This document was produced with the financial assistance of the European Union. The views expressedherein can in no way be taken to reflect the official opinion of the European Union.




Hydrology Report

Contents

1. Acronyms ........................................................................................................... 1

2. Executive Summary ........................................................................................... 2

3. Report Background.......................................................................................... 10

4. Available Data .................................................................................................. 11

Hydrological Data ................................................................................................................... 11

Meteorological Data ............................................................................................................... 13

5. Surface Water Resources ................................................................................ 16

Overview ................................................................................................................................ 16

Sokoto .................................................................................................................................... 22

Plateau ................................................................................................................................... 23

Niger ....................................................................................................................................... 23

Ogun....................................................................................................................................... 27

Cross River ............................................................................................................................. 29

6. Site Specific Hydrological Assessment ......................................................... 33

Overview ................................................................................................................................ 33

Source Gauging Stations ....................................................................................................... 34

Cross River sites: Egaga Fall and Busi II ........................................................................... 34

Niger site: Tapa .................................................................................................................. 36

Egaga Fall .............................................................................................................................. 40

Location and general features ............................................................................................ 40

Flow Assessment ................................................................................................................ 41

Flow Duration Curve ........................................................................................................... 44

Ecological Flow ................................................................................................................... 45

Busi II ..................................................................................................................................... 45


Flow Assessment ................................................................................................................ 46


Ecological Flow ................................................................................................................... 49

Tapa ....................................................................................................................................... 50


Flow Assessment ................................................................................................................ 51




Hydrology Report


Ecological Flow ................................................................................................................... 54

7. Conclusions ..................................................................................................... 55

Annexes...................................................................................................................... I Annexe 1 ................................................................................................................................... I

Annexe 2 ................................................................................................................................... I

Annexe 3 ................................................................................................................................... I

Annexe 4 .................................................................................................................................. II

Annexe 5 ................................................................................................................................ IV

Annexe 6 ............................................................................................................................... XII

Annexe 7 .............................................................................................................................. XIII Annexe 8 ............................................................................................................................ XVIII

Annexe 9 ............................................................................................................................... XX

Annexe 10 ......................................................................................................................... XXIV

Annexe 11 ......................................................................................................................... XXVI

Annexe 12 ........................................................................................................................ XXVII

Annexe 13 ......................................................................................................................... XXIX

Annexe 14 .......................................................................................................................... XXX Annexe 15 ....................................................................................................................... XXXIV




Hydrology Report

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1. Acronyms

AFD Agence Française de Développement

BP Business processDISCOs Power Distribution Companies

DLR Deutschen Zentrums für Luft- und Raumfahrt []),

EoI Expression of interest

FMP Federal Ministry of Power

GIS Geospatial information systems

GIS-DMS GIS-based data management system

GIZ Deutsche Gesellschaft für Internationale Zusammenarbeit, GmbH

GSDI Geospatial data infrastructure

ISO International Standard Organisation

KPI Key performance indicatorkW kilo Watt

LCCA Life-cycle cost analysis

MW Mega Watt

NEPA National Electric Power Authority

NERC Nigerian Electricity Regulatory Commission

NESP Nigerian Energy Support Programme (implemented by GIZ)

OGC Open Geospatial Consortium

OLURN Operation Light Up Rural Nigeria

OP Operational plan

PV Photovoltaics

R/ESCOS (Renewable) Energy service company

RE Renewable energy

REA Rural Electrification Agency

RLI Rainer Lemonie Institute

RrE Rural electrification

RrE-Plan Rural electrification plan

SE4All Sustainable Energy For All

SEL The Sustainable Engineering Lap (Earth Institute - Columbia University)

SHP Small hydro power

SLD Standard layer descriptor

ToR Terms of Reference

WG Working group

WP Work package




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2. Executive Summary

Nigeria Hydrological Service Agency (NIHSA) is the responsible agency for hydrological monitoring

in Nigeria. The Japan International Cooperation Agency (JICA), in collaboration with NIHSA,

delineated at the National Water Resources Master Plan 2013, Hydrological Areas (HA) and Sub

Hydrological Areas (SHA). As a result eight HA and 168 SHAs were defined (Figure 2.1).

Figure 2.1 – Map with Hydrological Areas (HA) and Sub Hydrological Areas (SHA) of Nigeria (source: JICA1).

The National Water Resources Master Plan 2013 compiled flow records for 101 gauging stations.Figure 4.3 shows a map with the spatial distribution of the hydrological stations with available data.

Figure 2.2 – Location of Hydrological Stations with Available data (source: JICA1).




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The spatial distribution of hydrological variables in Nigeria can be observed in Figure 2.3 and Figure

2.4. Figure 2.3 presents maps of annual average precipitation and potential evapotranspiration, while

Figure 2.4 is a map of the mean annual runoff.

Figure 2.3 – Spatial Patterns of Mean Annual Precipitation and Mean Annual Potential Evapotranspiration (PET)(source: JICA1).

Figure 2.4 – Spatial Distribution of Average Annual Runoff Yield (source: JICA1).




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The availability of surface water resources in Nigeria is highly dependent on the climate conditions,

with rainfall averages over 2000 mm/year in the south, 1000 mm in the centre of the country and 500

mm in the northeast (Figure 2.3).

Like the precipitation, the runoff yield decreases from south to north. In southern hydrological areas

like HA-6 and HA-7, the average annual runoff yield is 359 mm/year and 978 mm/year respectively,while in HA-2, in the centre of the country, it decreases to 205 mm/year. In HA-1 and HA-8, in the

north, it achieves only 62 mm/year and 40 mm/year respectively (Figure 2.4 and Table 5.1).

A review of the flow data available for each of the partner states shows that there are two gauging

stations available for Sokoto, eight for Niger, one for Ogun, and five for Cross River. There are no

gaugin stations with available records for Plateau state. Figure 2.5 shows maps with the location of

the gauging stations for each state.

Sokoto Niger

Ogun Cross River

Figure 2.5 – Maps with available gauging stations at Sokoto, Niger, Ogun and Cross River state.




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An analysis of the flow records for the available gauging stations, at each of the mentioned states,

confirms the already identified pattern (Figure 2.4) of a progressive runoff yield decrease from south

to north (Figure 2.6).

Sokoto Niger

Ogun Cross River

Figure 2.6 – Average monthly flow and runoff at gauging stations at Sokoto, Niger, Ogun and Cross River state.

It is also possible to clearly identify the influence of a rainfall pattern are marked by distinct wet and

dry seasons, on the flows and runoff yield (Figure 2.6). This is effect is further confirmed in the flow

duration curves (FDC) presented in Figure 2.7.

Sokoto Niger

0

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R u n o f f ( m m )

Q ( m 3 / s )

Wamako

Average R un of f A ve rag e Flow

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Badeggi

Average Ru no ff Av er ag e Flow

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Average Ru no ff A ve ra ge Flow

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Average Ru noff Av er ag e Flow

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0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

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( m 3 / s )

% of exceedance

Wamako

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0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

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Badeggi




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Ogun Cross River

Figure 2.7 – Flow duration curves (FDC) at gauging stations at Sokoto, Niger, Ogun and Cross River state.

After the field mission in March 2015, three sites were identified has having potential for Micro/Mini

Hydropower, Tapa in Niger, and Egaga Fall and Busi II in Cross River (Table 2.1 and ).

Table 2.1 – Location of identified sites with micro/mini hydropower potential.

Site State Latitude LongitudeCatchmentArea (km2)

Egaga Fall Cross River 6.38259889 9.36074139 10.9

Busi II Cross River 6.54288889 9.26477778 7.9

Tapa Niger 9.31473361 7.02030861 694

Figure 2.8 – Map with location of selected sites for the hydrological assessment.

0

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0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

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( m 3

/ s )

% of exceedance

Apoje

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2750

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0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Q

( m 3

/ s )

% of exceedance

lkom




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Using the available data, a flow transposition method by catchment area ratio was computed to each

of the mentioned sites. The average monthly flows and runoff for each of the sites are presented

from Table 2.2 and Figure 2.9 to Table 2.4 and Figure 2.11.

Table 2.2 – Average monthly flow and runoff at Egaga Fall.

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual

Flow(m3 /s)

0.08 0.04 0.05 0.12 0.26 0.49 0.79 0.79 1.17 1.26 0.50 0.20 0.48

Runoff(mm)

18.6 8.6 12.9 29.5 64.7 116.2 194.4 194.7 277.0 309.1 119.7 49.8 1395.3

Figure 2.9 - Average monthly flows and runoff, and FDC at Egaga Fall.

Table 2.3 – Average monthly flow and runoff at Busi II.


Flow(m3 /s)

0.05 0.03 0.04 0.09 0.19 0.35 0.57 0.57 0.84 0.91 0.36 0.15 0.35

Runoff(mm)

13.5 6.2 9.3 21.4 46.9 84.2 140.9 141.1 200.8 224.0 86.8 36.1 1011.3

Figure 2.10 – Average monthly flows and runoff, and FDC at Busi II.

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2400.0

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R u n o f f ( m m )

Q ( m 3 / s )

Egaga Fall

S er ie s2 A ve ra ge Flow

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( m 3 / s )

% of exceedance

Egaga Fall

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80100

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R u n o f f ( m m )

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( m 3 / s )

Busi II

Average Ru noff Se ri es 1

0.0

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0.91.0

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0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Q ( m 3 / s )

% of exceedance

Busi II




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Table 2.4 – Average monthly flow and runoff at Tapa.


Flow(m3 /s)

0.29 0.19 0.15 0.18 0.31 0.67 2.68 10.93 24.07 12.95 2.75 0.70 4.67

Runoff(mm)

1.1 0.7 0.6 0.7 1.2 2.5 10.4 42.2 89.9 50.0 10.3 2.7 212.1

Figure 2.11 – Average monthly flows and runoff, and FDC at Tapa.

A common hydrology-based methodology was applied for determining environmental flows in the

three sites. Resumes the environmental flows for each of the project locations.

Table 2.5 – Location of identified sites with micro/mini hydropower potential.

Site Qα Environmental

Flow (m3 /s)

Egaga Fall Q90 0.04

Busi II Q90 0.03

Tapa Q85 0.14

Regarding the hydropower potential, it can be stated that the northern areas of Nigeria are not

suitable for any kind of run-off hydropower scheme due to flow scarcity during low flow season. This

is even more relevant for micro/mini hydropower as these schemes are usually located in small

catchment areas, which, in general, have lower specific yields than bigger watersheds.

In the case of Tapa site in Niger state, the highest average monthly flow is 161 times bigger than thelowest average monthly flow (24.07 m3/s vs 0.15 m3/s), and the flow is low, when compared to the

month with higher flows, for around half of the year (Figure 2.11).

For both sites in Cross River (southeast of Nigeria), it is clear that a low flow season with extremely

low flow values (under 100 l/s) lasts for four months (January to April) (Table 2.2 and Table 2.3, and

Figure 2.9 and Figure 2.10). The flow measurements at the sites in March 2015, 0.08 m3/s at Egaga

Fall and 0.035 m3/s at Busi II, also confirm the issues with flow scarcity. Moreover, regarding the

flow regime, the ratio between the higher and lower average monthly flows being stands at 33.

It is clear that, for the three sites considered to have potential for Micro/Mini Hydropower (Tapa,

Egaga Fall and Busi II), low flow season will be an issue regarding all year round production, and itis reasonable to consider that a shutdown period will be mandatory.

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Tapa


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40

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Q

( m 3 / s )

% of exceedance

Tapa




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Environmental flows have to be considered, as they will impose a limitation on operation at low flow

conditions.

Operation ranges of electromechanical equipment can be adapted to flow conditions, and operation

with extremely low levels of flow is not impossible (however, with a significant reduction of the

equipment’s efficiency and lifetime).It will be the economical sustainability of the projects to limit their feasibility.




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3. Report Background

The framework for this report is the ToR for Work-Package 4: Hydrological Assessment and Small

Hydropower Site Identification (ToR No. 06-2014-WP-4 (update 1)).

The current report makes a general assessment of the hydrology and hydrological data available in

Nigeria, with a focus on the five partner states of the NESP: Sokoto, Plateau, Niger, Ogun and Cross

River. Furthermore, it develops to a hydrological assessment on the sites visited during the field

mission in March 2015 and considered to have a minimum potential. This assessment focus on

computing flow data at the sites using a transposition method (catchment area ratio), flow duration

curves (FDC) and assessment of environmental flows.

This report supports the remaining tasks/objectives in ToR No. 06-2014-WP-4 (update 1), and will

be used as a reference document providing the necessary inputs for activities, such as the site-

specific reports for the sites identified during the field mission as having potential for Micro/Mini

Hydropower.




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4. Available Data

Hydrological Data

Nigeria Hydrological Service Agency (NIHSA) is the responsible agency for hydrological monitoring

in Nigeria. The Japan International Cooperation Agency (JICA), in collaboration with NIHSA,established for the National Water Resources Master Plan 2013, criteria for delineation of

Hydrological Areas (HA) and Sub Hydrological Areas (SHA). As a result eight HA and 168 SHAs

were defined (Table 4.1). The mentioned HA and SHA are presented in Figure 4.1, and in Annexe

1, maps with the detailed delineation of the SHAs for each HA can be found.

Table 4.1 – Summary of HA and SHA (source: JICA1)

HA 1 2 3 4 5 6 7 8 Total

Area (km2) 135,128 154,616 156,546 74,519 53,914 99,333 57,440 178,483 909,979

Num. of related SHAs 27 36 30 11 6 22 10 26 168

Number ofSHAs

divided byNational

Boundary

Total 36 38 34 12 6 24 11 33 194

InsideNigeria

28 36 29 11 6 22 10 26 168

Figure 4.1 – Map with Hydrological Areas (HA) and Sub Hydrological Areas (SHA) of Nigeria (source JICA1).

Besides the NIHSA, there are also other agencies and authorities collecting hydrological data.

According to the National Water Resources Master Plan from JICA1 above, the available hydrological

data and the agency/authority responsible for its collection is as follows:

1 National Water Resources Master Plan 2013 – Volume 5 – SR2: Evaluation of Water Resources Potential.




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Data available in NIHSA

Daily, monthly discharge

Daily water level for last a few years for selected stations

Data from Niger Basin Authority (NBA) (via. NIHSA)

Daily, monthly discharge for some of Niger-HYCOS stations

Data from NBA (via. World Bank Report for Hydrology in Niger Basin)

Monthly Discharge for Niger-HYCOS stations in other countries

Data in M/P1995

Monthly discharge

Database prepared by WSSSRP (EU supported project) for HA-8

Daily, monthly discharge in HY-8

Hydrological Yearbook in BORBDA

Daily, monthly water level and discharge in BORBDA

Reservoir operation data for selected large storage dams

Daily, monthly release, reservoir water level, etc. (only limited dams)

After analysing the mentioned data sources JICA1 compiled flow records for 101 gauging stations.

The list of gauging stations with indication of available years of records (complete and incomplete)

can be found in Annexe 2.

In Figure 4.2, it is also possible to observe the availability of monthly and daily hydrological data for

each year of records, while in Figure 4.3 a map with the spatial distribution of the mentioned 101hydrological stations with available data is presented.

Figure 4.2 – Change in Number of Hydrological Stations with Available Monthly and Daily Data (JICA1).




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Figure 4.3 – Location of Hydrological Stations with Available data (source: JICA1).

Meteorological Data

The Nigerian Meteorological Agency (NIMET) is the agency responsible for meteorological

observations and data collection in Nigeria. According to JICA1, NIMET operates 48 synoptic stations

covering the entire Nigeria. These stations are listed in Annexe 3.

In order to assess the spatial pattern of precipitation and potential evapotranspiration in Nigeria, for

the National Water Resources Master Plan 2013, the data from the mentioned meteorological

stations operated by NIMET was merged with data from the following international meteorological

databases:

CRU-TS3.12

Worldclim3

GSMaP4

As a result, maps of mean annual rainfall and evapotranspiration were obtained. These maps are

shown in Figure 4.4.

Figure 4.4 shows the clear existence of a precipitation pattern where average annual rainfall

decreases from south to north. Regarding the average annual evapotranspiration, the mentioned

pattern can also be identified, but it is not so clear.

2 University of East Anglia Climatic Research Unit (CRU)

3 Very high resolution interpolated climate surfaces for global land areas, http://www.worldclim.org/ 4 http://sharaku.eorc.jaxa.jp/GSMaP_crest/index.html




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Table 4.2 presents the mean annual precipitation and PET, as well as the annual mean temperature

for each of the eight Hydrological Areas.

Table 4.2 – Average annual precipitation, temperature and potential evapotranspiration for each HA, and for the

entire country (source: JICA

1

).

Entirecountry

HA-1 HA-2 HA-3 HA-4 HA-5 HA-6 HA-7 HA-8

AnnualPrecipitation(mm/year)

1148 767 1170 1055 1341 2132 1541 2106 610

Annual MeanTemperature (° C)

26.6 27.4 26.5 26 26.8 26.7 26.5 26.9 26.5

Annual PET(mm/year)

1337 1419 1318 1290 1338 1325 1314 1338 1347




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Figure 4.4 – Spatial Patterns of Mean Annual Precipitation and Mean Annual Potential Evapotranspiration (PET)(source: JICA1).




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5. Surface Water Resources

Overview

Climate characterizes the generally prevailing weather conditions of a region and represents an

average pattern of variation of meteorological variables such as temperature, air pressure, humidity,precipitation, sunshine, cloudiness, and winds. It has a significant influence over the hydrology of an

area or region, in conjunction with other factors such as the geology, soil type and soil cover.

The climate in Nigeria is semi-arid in the north and humid in the south. Except for an ultra-humid

strip along the coast with rainfall averages of over 2000 mm/year, where it rains almost all year

round, rainfall patterns are marked by distinct wet and dry seasons. Rainfall is concentrated in the

period June-September. Deficiency in total annual precipitation is a problem in parts of the country,

particularly in the northern parts. In most other areas, however, the major problems are the

distribution in time and space and the low dependability of rainfall. Mean annual rainfall over the

whole country is estimated at 1150 mm. It is about 1000 mm in the centre of the country and 500mm in the northeast. Mean annual pan evaporation is 2450 mm in the southeast, 2620 mm in the

center and 5220 mm in the north of the country5.

The hydrology of Nigeria6 is dominated by two great river systems, the Niger-Benue and the Chad

systems. With the exception of a few rivers that empty directly into the Atlantic Ocean (Cross River,

Ogun, Oshun, Imo, Qua Iboe and a few others), all other flowing waters ultimately find their way into

the Chad Basin or down the lower Niger to the sea. Figure 5.1 shows the eight hydrological areas of

Nigeria and the main rivers.

Figure 5.1 – Hydrological Areas of Nigeria and Main Rivers.

5 Aquasat – FAO, Nigeria – Geography, Climate and Population. http://www.fao.org/nr/water/aquastat/countries_regions/nga/index.stm6 Hydrology and Inland Water Resources of Nigeria – FAO. www.fao.org/docrep/005/t1230e/t1230e02.htm




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The Nigeria National Water Resources Master Plan 2013 developed a water balance methodology,

based on the Thornthwaite monthly water balance model, in order to assess the surface water

resources at a country level.

Some of the available hydrological stations (previously mentioned in chapter 4) were selected and

used to calibrate the model. These stations are identified in the map of Figure 5.2.

Figure 5.2 – Selected hydrological stations for calibration of water balance model (source: JICA1).

The results of the application the water balance model are presented in Table 5.1, Figure 5.3 and

Figure 5.4.

It must be noted that the results of the model can be assumed as representing quasi-natural

conditions, this meaning that the effect of large storage dams is excluded.

Table 5.1 – Annual Runoff Yields by Hydrological Area (source: JICA1).

HA-1 HA-2 HA-3 HA-4 HA-5 HA-6 HA-7 HA-8Entire

Country

Area (km2) 135128 154616 156546 74519 53914 99333 57440 178483 909979

Average AnnualPrecipitation(mm/year)

767 1170 1055 1341 2132 1541 2106 610 1148

Average AnnualRunoff Yield(mm/year)

62 205 218 415 744 359 978 40 268

Average Specific

Discharge(l/s/km2)

2.0 6.5 6.9 13.2 23.6 11.4 31.0 1.3 8.5




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HA-1 HA-2 HA-3 HA-4 HA-5 HA-6 HA-7 HA-8Entire

Country

Average Runoffrate (%)

8.1 17.5 20.7 30.9 34.9 23.3 46.4 6.6 23.4

Average Annual

Runoff Volume(BMC/year) 8.4 31.7 34.2 30.8 40.1 35.6 56.3 7.2 244.3

Figure 5.3 – Spatial Distribution of Average Annual Runoff Yield (source: JICA1).




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Figure 5.4 – Spatial Distribution of Average Runoff Rate (source: JICA1).

Figure 5.5 presents several hydrographs at representative points in quasi-natural conditions. From

their observation, the seasonal flow patterns, in an average year, are clearly identified, evidencing

the existence of dry and wet seasons. It can also be understood that the usable water in dry season

with stable manner is much smaller than the annual average discharge in quasi-natural condition.




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Figure 5.5 – Seasonal Flow Pattern at Representative Points in Quasi-Natural Condition (source: JICA1).

The average annual flow by itself does not give any information about the flow distribution during the

year, and it is not an indicator of the real availability of water resources. The use of potential surface

water resource depends, in fact, on their availability thorough the year.

At the National Water Resources Master Plan 2013, the flows were also analysed in terms of their

availability at low flow season. Therefore, two indicators were considered:

Q80M – 80 percentile monthly discharge for 40years [suffix M represents monthly], which may

represent low flow condition.

Q97DS90%Y – 90% yearly dependable Q97DS (Q97DS: 97 percentile daily discharge for asingle year, which is usually called as drought discharge, [suffix D represents daily, suffix S

represents single year]).

In Figure 5.6 is presented a map indicating, at representative, points the average annual discharge,

as well as Q80M and Q97DS90%Y.




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Figure 5.6 - Average annual discharge, Q80M and Q97DS90%Y, at representative points (source: JICA1).

The Q80M is larger in southern and central areas (mainly in the Benue Basin), than in the northern

areas where it reaches values of zero or close to it. This is a clear indicator of water availability during

low flow season, meaning that northern areas of Nigeria face water scarcity during low flow season.

This is also supported by analysing the pattern of Q97DS90%Y, which is zero or practically zero in all

of the northern areas.

It can be concluded that the northern areas are not suitable for any kind of run-off hydropower

scheme due to lack or absence of flow during low flow season. This is even more significant for

micro/mini hydropower as these schemes are usually located in small catchment areas, which, in

general, have lower specific yields than bigger watersheds.

As it would be expected, the availability of surface water resources in Nigeria is highly dependent on

the climate conditions previously described at the beginning of this chapter (with rainfall averages

over 2000 mm/year in the south, 1000 mm in the centre of the country and 500 mm in the northeast).

Like the precipitation, the runoff yield decreases from south to north. In southern hydrological areas

(HA) like HA-6 and HA-7 the average annual runoff yield is 359 mm/year and 978 mm/year

respectively, while in HA-2, in the centre of the country, it decreases to205 mm/year, and in HA-1

and HA-8, in the north, it achieves only 62 mm/year and 40 mm/year respectively (Table 5.1).




Hydrology Report

22

Sokoto

Sokoto state is located in the Northwest of Nigeria, on the border to Niger, and has an area of 27825

km2. Of the 101 hydrological stations mentioned in chapter 4, two are located in the state (Figure

5.7).

Figure 5.7 – Hydrological stations in Sokoto state.

In Table 5.2, the mean monthly flows and runoff are presented, while in Figure 5.8 the same data is

presented in a chart. The complete data, for the gauging stations, with monthly flows resumed in

Annexe 4.

Table 5.2 – Average flow and runoff for available gauging stations in Sokoto state.

Average Flow (m3 /s)

Gauging

Station

Area

(km2

)


Wamako 137219 0.6 0.3 0.3 0.3 0.9 18.2 63.8 184.1 161.9 32.3 1.7 0.6 39.0

GoronyoDam

30547 0.1 0.1 0.1 0.1 0.0 10.1 34.8 103.2 96.5 18.5 1.0 0.3 22.2

Average Runoff (mm)

GaugingStation

Area(km2)


Wamako 137219 0.01 0.01 0.01 0.01 0.02 0.34 1.25 3.59 3.06 0.63 0.03 0.01 9

GoronyoDam

30547 0.01 0.01 0.01 0.01 0.00 0.86 3.05 9.05 8.19 1.62 0.09 0.03 23




Hydrology Report

23

Figure 5.8 – Average flow and runoff for available gauging stations in Sokoto state.

Figure 5.9 presents Flow Duration Curves (FDC) for each of the gauging stations.

Figure 5.9 – Flow duration curves for gauging stations in Sokoto state.

Plateau

Plateau state is located in the East Central area of Nigeria, bordering the states of Bauchi, Taraba,

Nassarawa and Kaduna, and has an area of 27147 km2. Of the 101 hydrological stations mentioned

in chapter 4, none of them is located in the state.

A possible hydrological characterization of Plateau state can be made assuming the characteristics

of Lower Benue hydrological area (HA-4) (Figure 4.1 and Figure 5.1).

The average annual runoff for the area is 415 mm and the average runoff rate 30.9% (Table 5.1).

Niger

Niger state is located in the West Central area of Nigeria, having a border with Benin and borders

with the federal states of Kebbi, Zamafra, Kaduna, Federal Capital Territory, Kogi and Kwara. It has

an area of 68925 km2.

Of the 101 hydrological stations mentioned in chapter 4, eight are located in the state (Figure 5.10).

0

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9

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R u n o f f ( m

m )

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s )

Wamako


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Goronyo Dam

Average R un of f Av er ag e Flow

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28

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F l o w

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% of exceedance

Wamako

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18

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

F l o w

( m 3 / s )

% of exceedance

Goronyo Dam




Hydrology Report

24

Figure 5.10 – Gauging Stations located in Niger state.

In Table 5.3, mean monthly flows and runoff are presented for each of the available gauging stations,

while in Figure 5.8 the same data is presented in a chart. The complete data, for each gauging

station, with monthly flows in each year of available records is in Annexe 5.

Table 5.3 – Average flow and runoff for available gauging stations in Niger state.


GaugingStation

Area(km2)


Jebba 1629481 1392.0 1402.6 1210.5 953.9 738.2 687.6 780.5 1168.7 1986.5 1886.5 1308.6 1268.9 1230.6

Baro 1726856 1342.5 1389.6 1223.8 1099.2 949.7 1039.1 1517.1 2701.4 4534.9 3828.7 1789.7 1337.6 1897.9

Wuya 64726 37.3 24.0 22.0 21.9 66.0 147.5 671.9 1723.5 3312.9 1320.7 209.1 37.8 634.7

Shiroro 34702 36.1 29.6 28.2 29.9 92.1 181.6 405.5 872.0 1046.9 446.4 83.0 41.6 275.8

Komi 2326 2.9 2.6 2.5 3.7 3.9 8.1 9.7 20.4 31.5 13.3 5.0 3.7 9.0

Izom 6203 11.3 7.1 7.7 14.7 52.8 89.5 213.7 375.3 488.2 267.1 53.2 16.1 133.8

Ebba 1896 0.8 0.5 0.4 0.5 0.8 1.8 7.3 29.9 65.8 35.4 7.5 1.9 12.7

Badeggi 5850 3.3 2.7 2.5 2.8 4.2 9.6 28.8 93.6 177.7 109.2 27.6 6.5 39.2




Hydrology Report

25

Average Runoff (mm)

GaugingStation

Area(km2)


Jebba 1629481 2.29 2.08 1.99 1.52 1.21 1.09 1.28 1.92 3.16 3.10 2.08 2.09 24

Baro 1726856 2.08 1.95 1.90 1.65 1.47 1.56 2.35 4.19 6.81 5.94 2.69 2.07 35

Wuya 64726 1.54 0.90 0.91 0.88 2.73 5.91 27.80 71.32 132.67 54.65 8.37 1.56 309

Shiroro 34702 2.79 2.06 2.18 2.23 7.11 13.57 31.30 67.31 78.19 34.45 6.20 3.21 251

Komi 2326 3.36 2.73 2.87 4.09 4.53 9.03 11.13 23.47 35.12 15.30 5.61 4.25 121

Izom 6203 4.89 2.76 3.34 6.13 22.80 37.39 92.25 162.03 203.99 115.33 22.25 6.96 680

Ebba 1896 1.10 0.66 0.58 0.67 1.20 2.49 10.36 42.19 89.90 49.96 10.26 2.69 212

Badeggi 5850 1.52 1.13 1.16 1.25 1.91 4.26 13.20 42.87 78.72 49.98 12.22 2.99 211

0

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R u n o f f ( m m )

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Jebba

Average Run of f Av er age Flow

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Baro

Average R un off Av er ag e Flow

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Wuya


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R u n o f f ( m m )

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Shiroro





Hydrology Report

26

Figure 5.11 – Average flow and runoff for available gauging stations in Niger state.


0

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R u n o f f (

m m )

Q ( m 3

/ s )

Komi


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m m )

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/ s )

Izom


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R u n o f f ( m m )

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Ebba


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Badeggi


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Jebba

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0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Q

( m 3 / s )

% of exceedance

Baro




Hydrology Report

27

Figure 5.12 – Flow duration curves for gauging stations in Niger state.

Ogun

Ogun state is the Southwest of Nigeria, having a border with Benin and borders with the federal

states of Oyo, Osun, Ondo and Lagos. It has an area of 16400 km2.

Of the 101 hydrological stations mentioned in chapter 4, only one is located in the state (Figure 5.13).

0

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40004500

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6500

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0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Q

( m 3

/ s )

% of exceedance

Wuya

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( m 3

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% of exceedance

Shiroro

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( m 3 / s )

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Komi

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Izom

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0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

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% of exceedance

Ebba

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700

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Q

( m 3 / s )

% of exceedance

Badeggi




Hydrology Report

28

Figure 5.13 – Gauging Stations located in Ogun state.

In Table 5.3 mean monthly flows and runoff are presented for each of the available gauging stations,

while in Figure 5.8 the same data is presented in a chart. The complete data, of each gauging station,

with monthly flows in each year of available records is in Annexe 6.

Table 5.4 – Average flow and runoff for available gauging stations in Ogun state.


GaugingStation

Area(km2)


Apoje 8517 65.9 75.5 78.0 76.1 88.1 111.8 147.2 127.5 154.2 185.1 123.5 80.3 109.6

Average Runoff (mm)

GaugingStation

Area(km2)


Apoje 8517 20.72 21.43 24.52 23.16 27.69 34.03 46.28 40.11 46.94 58.21 37.60 25.24 406




Hydrology Report

29

Figure 5.14 – Average flow and runoff for available gauging stations in Niger state.

In Figure 5.9, a Flow Duration Curve (FDC) for the available gauging station is presented.

Figure 5.15 – Flow duration curves for gauging stations in Niger state.

Cross River

Cross River state is located in the Southeast of Nigeria, having a border at East with Cameroon and

borders with the federal states of Benue, Ebony, Abia and Akwa Ibom. It has an area of 21787 km2.

Among the 101 hydrological stations mentioned in chapter 4, five are located in the state (Figure

5.16).

0

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650

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R u n o f f ( m m )

Q ( m 3 / s )

Apoje

Average Runoff Average Flow

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0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Q

( m 3 / s )

% of exceedance

Apoje




Hydrology Report

30

Figure 5.16 – Gauging Stations located in Cross River state.

In Table 5.5, mean monthly flows and runoff are presented for each of the available gauging stations,

while in Figure 5.17 the same data is presented in a chart. The complete data, for each gauging

station, with monthly flows in every year of available records is in Annexe 4.

Table 5.5 – Average flow and runoff for available gauging stations in Niger state.


GaugingStation Area(km2) Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual

lkom 16900 148.1 103.2 139.5 177.4 348.6 819.2 1407.2 2059.6 2272.8 1904.9 675.8 247.8 863.5

Adonatarn 18900 348.3 306.4 330.3 430.6 750.2 1068.1 1664.7 2344.6 2557.0 1996.3 1096.7 500.8 1120.9

Obubra 35800 162.6 99.2 117.7 219.9 456.5 1168.7 2039.4 2998.6 3878.5 3313.8 1235.3 423.9 1350.0

Afikpo 46200 251.6 178.0 188.6 298.8 690.1 1449.0 2558.3 3444.9 4373.8 3598.9 1319.3 440.1 1574.1

IkotOkpara

48300 235.1 166.3 159.2 274.2 638.0 1439.8 2548.5 3559.6 4708.6 4125.9 1462.8 431.1 1654.4




Hydrology Report

31

Average Runoff (mm)

GaugingStation

Area(km2)


lkom 16900 23.48 14.77 22.11 27.20 55.26 125.65 223.02 326.41 348.59 301.90 103.65 39.28 1611

Adonatarn 18900 49.36 39.22 46.81 59.05 106.32 146.49 235.90 332.26 350.67 282.90 150.41 70.97 1870

Obubra 35800 12.17 6.71 8.81 15.92 34.15 84.61 152.58 224.35 280.81 247.93 89.44 31.71 1189

Afikpo 46200 14.59 9.32 10.94 16.76 40.01 81.29 148.32 199.71 245.39 208.64 74.02 25.51 1075

IkotOkpara

48300 13.04 8.33 8.83 14.71 35.38 77.27 141.33 197.39 252.69 228.80 78.50 23.91 1080

Figure 5.17 – Average flow and runoff for available gauging stations in Cross River state.

0

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3600

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R u n o f f ( m m )

Q ( m 3 / s )

Ikom

Average Run off Av er age Flow

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R u n o f f ( m m )

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Adonatarn

Average R un of f Av er age Flow

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R u n o f f ( m m )

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Obubra

Average Ru nof f Av er ag e Flow

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R u n o f f ( m m )

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Afikpo


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R u n o f f ( m m )

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Ikot Okpara

Average R un of f Av er age Flow




Hydrology Report

32


Figure 5.18 – Flow duration curves for gauging stations in Cross River state.

0

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0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Q

( m 3 / s )

% of exceedance

lkom

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Adonatarn

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Obubra

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( m 3 / s )

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Ikot Okpara




Hydrology Report

33

6. Site Specific Hydrological Assessment

Overview

The site-specific hydrological assessment hereafter presented is for the three selected sites – Tapa,

Egaga Fall and Busi II – among the nine sites visited during the field mission in March 2015. Fromthese three sites, one is located in Niger state and Hydrological Area (HA) HA-2 and two in Cross

River, HA-7 (Egaga Fall) and HA-4 (Busi II) (Figure 6.1).

Figure 6.1 – Map with location of selected sites for the hydrological assessment.

Table 6.1 resumes the location and catchment areas of the sites.

Table 6.1 – Location and catchment area of assessed sites with potential for Micro/Mini Hydropower.

Site State

Location CatchmentArea

Lat. Long.Hydrological Area

(HA)(km2)

Egaga FallCrossRiver

6.38748333 9.36092361 HA-7 10.9

Busi IICrossRiver

6.54288889 9.26477778 HA-7 7.9

Tapa Niger 9.30311889 7.13363194 HA-2 694

The assessment includes an analysis of nearby gauging stations, simple test for the quality of the

series, transformation of flows by catchment area ratio method, computing of flow duration curve

and estimation of ecological flows.




Hydrology Report

34

It has to be noted that the catchment areas of the sites located in Cross River are quite small when

compared to the catchment areas of the available nearby gauging stations. This result in a reduced

accuracy of the obtained results, given the usual differences in the hydrological behaviour between

small and large catchment areas. Larger catchment areas tend to have higher specific yields, thus

higher low flow season flows per unit of area of the watershed.

Source Gauging Stations

Cross River sites: Egaga Fall and Busi II

Among the nearby gauging stations to Egaga Fall and Busi II sites, two of them where selected to

be analysed regarding its suitability to be used as source for a flow transposition method by

catchment area ratio. It has to be noted that, the nearby stations to consider where not restricted to

Ogun state, and one gauging station in Benue state was considered (Figure 6.2).

Figure 6.2 – On the left: Gauging Stations nearby Egaga Fall and Busi II sites; on the right: gauging stationsselected to be used for catchment area ratio method.

The selected gauging stations are presented in Table 6.2, resuming their main features are resumed.

The criteria for selecting the gauging stations were:

Dimension of record period

Distance to site location

Catchment area size.

Hydrological behaviour/Flow pattern




Hydrology Report

35

Table 6.2 – Average flow and runoff for Ikom and Katsina-Ala gauging stations.


GaugingStation

Area(km2)


Ikom 16900 148.1 103.2 139.5 177.4 348.6 819.2 1407.2 2059.6 2272.8 1904.9 675.8 247.8 863.5

Katsina-Ala

16789 116.8 59.4 80.7 191.2 405.8 752.8 1218.7 1220.2 1794.4 1937.4 775.5 312.3 742.8

Average Runoff (mm)

GaugingStation

Area(km2)


Ikom 16900 23.48 14.77 22.11 27.20 55.26 125.65 223.02 326.41 348.59 301.90 103.65 39.28 1611

Katsina-Ala

16789 18.64 8.56 12.87 29.52 64.74 116.23 194.42 194.66 277.04 309.07 119.72 49.82 1395

The complete set of monthly flow records is in Annexe 8, while Figure 6.3 presents in charts the

average monthly flows and runoff.

Figure 6.3 – Average flow and runoff for Ikom and Katsina-Ala.

Figure 6.4 shows the flow duration curves (FDC) for the Ikom and Katsina-Ala gauging stations.

Figure 6.4 – Flow duration curve for Ikom and Katsina-Ala gauging stations.

Both of the gauging stations have identical catchment areas – 16900 km2 for Ikom and 16789 km2 for Katsina-Ala – however, as it can be observed in Table 6.2 and Figure 6.3, Ikom gauging station

has higher average flows and as a result higher average runoff values. Considering the annual

0

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3600

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R u n o f f ( m m )

Q ( m 3 / s )

Ikom

Average R un of f Av er ag e Flow

0

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320

3600

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R u n o f f ( m m )

Q ( m 3 / s )

Katsina‐Ala

Average R un of f Av era ge Flow

0

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0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

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lkom

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Katsina‐Ala




Hydrology Report

36

average flow, Ikom has 863.5 m3/s, resulting in an average annual runoff of 1611 mm, while Katsina-

Ala has an annual average flow of 742.8 m3/s, equivalent to an average annual runoff of 1395 mm.

In order to check the quality of the series, a chart with simple accumulated flows was plotted for both

the gauging stations (Figure 6.5).

Figure 6.5 – Simply accumulated flows for Ikom and Katsina-Ala gauging stations.

For each of the charts (Figure 6.5), a line with a constant slope can be fitted to each of the series of

plotted points, showing that the records are consistent and have the required quality for a hydrologic

assessment.

Niger site: Tapa

Several gauging stations are available nearby Tapa site in Niger state (Figure 6.6).

In order to select the gauging stations to compute flows for Tapa site by a catchment area ratio

method, the following criteria was applied:

Dimension of record period

Distance to site location

Catchment area size.

Hydrological behaviour/Flow pattern

Four gauging stations were selected. They can be observed on the map in Figure 6.6, while its flow

data is resumed in Table 6.4.

0

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0 10 20 30 40 50 60 70 80 90 100

A c c u m l a t e d f l o w

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Acummulated months

Ikom

0

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100000

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0 25 50 75 100 125 150 175 200 225 250 275 300 325

A c c u m l a t e d f l o w

( m 3 / s )

Acummulated months

Katsina‐Ala




Hydrology Report

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Figure 6.6 – On the top: gauging stations nearby Tapa site, on the bottom: selected gauging stations nearbyTapa site for catchment area ratio analysis.




Hydrology Report

38

Table 6.3 – Average flow and runoff for Izom, Ebba, Kachia and Kaeia gauging stations.


GaugingStation

Area(km2)


Izom 6203 11.3 7.1 7.7 14.7 52.8 89.5 213.7 375.3 488.2 267.1 53.2 16.1 133.8

Ebba 1896 0.8 0.5 0.4 0.5 0.8 1.8 7.3 29.9 65.8 35.4 7.5 1.9 12.7

Kachia 124 0.4 0.3 0.3 0.4 1.2 1.7 3.6 4.2 3.5 1.8 0.7 0.5 1.6

Kaeia 559 0.8 0.6 0.7 1.8 3.9 5.0 14.9 19.8 24.9 11.0 2.7 1.2 7.3

Average Runoff (mm)

GaugingStation

Area(km2)


Izom 6203 4.89 2.76 3.34 6.13 22.80 37.39 92.25 162.03 203.99 115.33 22.25 6.96 680

Ebba 1896 1.10 0.66 0.58 0.67 1.20 2.49 10.36 42.19 89.90 49.96 10.26 2.69 212

Kachia 124 8.37 6.09 5.54 8.77 26.71 35.38 78.83 90.02 73.99 39.82 15.52 10.08 399

Kaeia 559 4.03 2.64 3.15 8.28 18.58 22.99 71.24 95.01 115.68 52.84 12.43 5.86 413

The complete set of monthly flow records is in Annexe 9, while in Figure 6.7 the average monthly

flows and runoff are presented as charts.

Figure 6.7 – Average flow and runoff for Izom, Ebba, Kachia and Kaeia gauging stations.

0

20

40

60

80

100

120

140

160

180

200

2200

50

100

150

200

250

300

350

400

450

500

550


R u n o f f ( m m )

Q ( m 3 / s )

Izom


0

20

40

60

80

100

120

140

160

180

200

2200

5

10

15

20

25

30

35

40

45

50

55

60

65

70


R u n o f f ( m m )

Q ( m 3 / s )

Ebba


0

20

40

60

80

100

120

140

160

180

200

2200.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5


R u n o f f ( m m )

Q ( m 3 / s )

Kachia


0

20

40

60

80

100

120

140

160

180

200

2200

5

10

15

20

25

30


R u n o f f ( m m )

Q ( m 3 / s )

Kaeia





Hydrology Report

39

Figure 6.8 shows the flow duration curves (FDC) for Izom, Ebba, Kachia and Kaeia gauging stations.

Figure 6.8 – Flow duration curve for Izom, Ebba, Kachia and Kaeia gauging stations.

Regarding the quality of the data series, a simple accumulated flow technique was applied for each

of the gauging stations. In Figure 6.9,charts with the plotted accumulated series are presented.

0

200

400

600

800

1000

1200

1400

1600

1800

2000

2200

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Q

( m 3 / s )

% of exceedance

Izom

0

20

40

60

80

100

120

140

160

180

200

220

240

260

280

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Q

( m 3 / s )

% of exceedance

Ebba

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Q

( m 3 / s )

% of exceedance

Kachia

0

5

10

15

20

25

30

35

40

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Q

( m 3 / s )

% of exceedance

Kaeia

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

0 10 20 30 40 50 60 70 80 90 100 110 120 130

A c c u m u l a t e d f l o w

( m 3 / s )

Accumulated months

Izom

0

200

400

600

800

1000

1200

1400

1600

1800

0 10 20 30 40 50 60 70 80 90 100 110 120 1 30 1 40

A c c u m u l a t

e d f l o w

( m 3 / s )

Accumulated months

Ebba




Hydrology Report

40

Figure 6.9 – Simply accumulated flows for Izom, Ebba, Kachia and Kaeia gauging stations.

By observing the charts of the accumulated flows, for each of the gauging stations (Figure 6.9), it is

possible to conclude that, for each of them, a line with a constant slope can be fitted to the series of

plotted points. This shows that the records are consistent and have the required quality for ahydrologic assessment.

Egaga Fall

Location and general features

Egaga Fall is located close to the Obudu Cattle Ranch in the Obanliku local government area (LGA).

Table 6.4 resumes the location, administrative and basic hydrological data of the site.

Table 6.4 – Location and basic hydrological features of Egaga Fall site.

Site Name Egaga Fall

State Cross River

Local Government Area Obanliku

Latitude 6.38259889

Longitude 9.36074139

Hydrological Area (HA) Eastern Litoral (HA-7)

Catchment Area (km2) 10.9

In Figure 6.10, it can be observed the location of Egaga Fall site, as well as the available nearby

gauging stations, and a satellite view of the watershed.

0

20

40

60

80

100

120

140

0 10 20 30 40 50 60 70 80 90 100

A c c u m u l a t e d f

l o w

( m 3 / s )

Accumulated months

Kachia

0

100

200

300

400

500

600

700

0 10 20 30 40 50 60 70 80 90 100

A c c u m u l a t e d f

l o w

( m 3 / s )

Accumulated months

Kaeia




Hydrology Report

41

Figure 6.10 – On the left: location of Egaga Fall site in Cross River State and nearby gauging stations, on theright: Satellite view of Egaga Fall site catchment area (source: Google Earth).

Flow Assessment

A brief analysis on the previously presented data for the gauging stations of Ikom and Katsina-Ala

(page Error! Bookmark not defined.) points out that:

In terms of distance to the sites (Egaga and Busi II) location, Katsina-Ala is the closest

gauging station. However, the distance from the sites to Ikom gauging station is not

significantly bigger.

The difference between Ikom and Katsina-Ala catchment areas is neglectable (16900 km2 vs

16789 km2)

In terms of average runoff, Kastina-Ala has the lowest annual average value with 1395 mm,against 1611 mm for Ikom.

To compare the available data transposed to the site location, in Figure 6.11, two charts resuming

the transposed flow data are presented. One presents the average monthly flows for Egaga site

computed from each of the source gauging stations, while the second one presents adimensional

flow duration curves (FDC) (this meaning each flow value has been divided by the average flow, Qm)

for the Egaga site, also obtained from Ikom and Katsina-Ala gauging stations.

Table 6.5 presents the average monthly flows at Egaga Fall, obtained by catchment area ratio

transposition from Ikom and Katsina-Ala.

All the monthly flows for Egaga Fall obtained by transposition from each of the source gaugingstations are compiled in Annexe 10.




Hydrology Report

42

Table 6.5 – Average monthly flows at Egaga Fall in m3 /s, obtained by catchment area ratio transposition fromIkom and Katsina-Ala gauging stations.

SourceGauging

Station

AreaRatio


(m3

/s)

Ikom 0.0007 0.10 0.07 0.10 0.13 0.24 0.56 1.00 1.46 1.55 1.26 0.48 0.17 0.60

Katsina-Ala 0.0006 0.08 0.04 0.05 0.12 0.26 0.49 0.79 0.79 1.17 1.26 0.50 0.20 0.48

Figure 6.11 – On the top: Average monthly flows for Egaga Fall obtained by transposition by catchment arearatio method from Ikom and Katsina-Ala gauging stations; on the bottom: Adimensional FDC for Egaga Fall

using flow transposition from both source gauging stations.

The observation of Figure 6.11and Table 6.5 tells that:

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6


A v e r a g e f l o w

( m 3 /

s )

Ikom Katsina‐Ala

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Q / Q m

% of exceedance

Ikom Katsina‐Ala




Hydrology Report

43

Flow transposition from Katsina-Ala gauging station generates the lowest average monthly

flows in the period from January to April (low flow season).

Between June and September (which covers rain season), transposition from Ikom clearly

generates the highest average monthly flows.

Flows generated from Ikom gauging station show an extremer distribution of flows, having

the highest values of Q/Qm until an exceedance percentage of 40%. From and exceedance

percentage of 40% onwards both gauging stations have similar values of Q/Qm.

Additionally to the computed flow data at Egaga Fall by flow transposition, a flow measurement was

made at the site during the site visit in March 2015. At this occasion it was recorded a flow of 0.08

m3/s.

Comparing with the recorded flow at the site, 0.08 m3/s, the average flow obtained using Ikom

gauging station, 0.1 m3/s, is the closest one. However, the difference between the measured value

at the site and the average obtained using Katsina-Ala is not significantly bigger (0.05 m3/s vs 0.08

m3/s).

Considering the low flow conditions observed at Egaga Fall during the site visit, the average monthly

flows, the flows at low flow season, and the shape of the FDC (Table 6.5 and Figure 6.11), the flows

obtained by transposition from Katsina-Ala gauging station will be onwards used to proceed the

studies for Egaga Fall.

As already pointed out at the Mission Report, conditions at site were not ideal for flow measurements

due to the low flow and stepped nature of the river profile. It is assumed the measured flow is an

overestimation of the real flow at Egaga Fall during the site visit.

To use the flows obtained by transposition from Katsina-Ala is a cautious and conservative approach,

reasonable to consider due to the uncertainty on the accuracy of the flow data analysis and theimportance of low flow season for a Micro/Mini Hydropower Project.

In Figure 6.12 and Table 6.6, the average monthly flows adopted at Egaga Fall are presented, and

in Annexe 11, the complete set of flows is compiled.

Figure 6.12 – Average monthly flow and runoff at Egaga Fall.

0

20

40

60

80

100

120

140

160

180

200

220

2400.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1.1

1.2

1.3

1.4


R u n o f f ( m m )

Q ( m 3 / s )

Egaga Fall

Series2 Average Flow




Hydrology Report

44

Table 6.6 – Average monthly flow and runoff at Egaga Fall.


Flow(m3 /s)

0.08 0.04 0.05 0.12 0.26 0.49 0.79 0.79 1.17 1.26 0.50 0.20 0.48

Runoff(mm)

18.6 8.6 12.9 29.5 64.7 116.2 194.4 194.7 277.0 309.1 119.7 49.8 1395.3

Flow Duration Curve

Figure 6.21 shows the flow duration curve at Tapa, while in Table 6.15 the flows corresponding to

several percentages of exceedance are presented.

Figure 6.13 – Flow Duration Curve at Egaga Fall.

Table 6.7 – Flow values for several percentages of exceedance for Egaga Fall.

% of exceedance 5% 10% 20% 30% 40% 50% 60% 70% 80% 85% 90% 95% 100%

Q (m3 /s) 1.32 1.14 0.93 0.70 0.52 0.36 0.22 0.12 0.07 0.05 0.04 0.03 0.01

It can be observed in Figure 6.13 and Table 6.7 that the flow regime at Egaga steadily decreases,

at an approximately constant rate, for flows corresponding to a percentage of exceedance between

10% and 70%. It can also be observed that, however, the flow values get extremely low during low

flow season, the stream will not dry.

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Q ( m 3 / s )

% of exceedance

Egaga Fall




Hydrology Report

45

Ecological Flow

A common hydrology-based methodology applied for determining environmental flows in a river

reach is the Flow Duration Curve Analysis (FDCA) method. Smakhtin7 indicated that the design low-

flow range of an FDC ranges between 70% and 99% (meaning the flow corresponding to a

percentage of exceedance of 70% and 99%, Q70 and Q99 respectively). Pyrce8

mentions that Q90and Q95 are frequently used as indicator of low flow and have been widely used to set minimum

environmental flows.

For Egaga Fall, the environmental flow will be set at Q90, which equals a flow of 0.04 m3/s (Table

6.7).

Busi II


Busi II site is located at the north of Ogun state in the Obanliku LGA close to the the village Busi II

which gives this site its name. Table 6.8 resumes the location, administrative and basic hydrological

data about the site.

Table 6.8 – Location and basic hydrological features resume for Egaga Fall site.

Site Name Busi II

State Cross River

Local Government Area Obanliku

Latitude 6.54288889


Hydrological Area (HA) Lower Benue (HA-4)

Catchment Area (km2) 7.9

In Figure 6.14 it can be observed the location of Busi II site, as well as the available nearby gauging

stations, and a satellite view of the watershed.

7 Smakhtin VU (2001) low flow hydrology: a review. J Hydrol 240(3-4):147-186.8 Pyrce R (2004) Hydrological low flow indices and their uses. Watershed Science Centre. WSC Report N0. 04, trent University,Peterborough, Ontario.




Hydrology Report

46

Figure 6.14 – On the left: location of Busi II site in Cross River State and nearby gauging stations, on the right:Satellite view of Busi II site catchment area (source: Google Earth).

Flow Assessment

It was previously mentioned in page Error! Bookmark not defined. (Source Gauging Stations:

Error! Reference source not found.), that for Busi II and Egaga Fall sites, the nearby gauging

tations of Ikom and Katsina-Ala where selected to perform the flow analysis and assessment by

transposition method.

The brief analysis already presented in page 41 (Egaga Fall: Flow Assessment), will not be repeated

as it refers to the same data for the gauging stations of Ikom and Katsina-Ala.

In order to compare the flow data resulting from the flow transposition from Ikom and Katsina-Ala to

Busi II, two charts resuming the transposed flow data are presented in Figure 6.15. One shows theaverage monthly flows for Busi II site computed from each of the source gauging stations, while the

second one presents adimensional flow duration curves (FDC) (this meaning each flow value has

been divided by the average flow, Qm) for Busi II site, obtained, as well, from Ikom and Katsina-Ala

gauging stations.

Table 6.9 presents the average monthly flows at Busi II, obtained by catchment area ratio

transposition from Ikom and Katsina-Ala.

All the monthly flows for Busi II, obtained by transposition from both source gauging stations, are

compiled in Annexe 12.




Hydrology Report

47

Table 6.9 – Average monthly flows at Busi II in m3 /s, obtained by catchment area ratio transposition from Ikomand Katsina-Ala gauging stations.

SourceGaugingStation

AreaRatio


(m3 /s)

Ikom 0.0005 0.07 0.05 0.07 0.09 0.17 0.40 0.73 1.06 1.12 0.91 0.34 0.12 0.43

Katsina-Ala 0.0005 0.05 0.03 0.04 0.09 0.19 0.35 0.57 0.57 0.84 0.91 0.36 0.15 0.35

Figure 6.15 – On the top: Average monthly flows for Busi II obtained by transposition by catchment area ratiomethod from Ikom and Katsina-Ala gauging stations; on the bottom: Adimensional FDC for Busi II site using

flow transposition from both source gauging stations.

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1.1

1.2



( m 3 / s )

Ikom Katsina‐Ala

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

2.2

2.4

2.6

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Q / Q m

% of exceedance

Ikom Katsina‐Ala




Hydrology Report

48

The observation of Figure 6.15 and Table 6.9 tells that:

Flow transposition from Katsina-Ala gauging station generates the lowest average monthly

flows in the period from January to April (low flow season).

Between June and September (which covers rain season), transposition from Ikom clearly

generates the highest average monthly flows. Flows generated from Ikom gauging station show an extremer distribution of flows, having

the highest values of Q/Qm until an exceedance percentage of 40%. From and exceedance

percentage of 40% onwards both gauging stations have similar values of Q/Qm.

Additionally to the computed flow data at Busi II by flow transposition, during the site visit in March

2015 a flow was measured at the site. At this occasion it was recorded a flow of 0.035 m3/s.

Comparing with the recorded flow at the site, 0.035 m3/s, the average flow obtained using Katsina-

Ala gauging station, 0.04 m3/s, is the closest one.

Considering the low flow conditions observed at Busi II during the site visit, the average monthly

flows, the flows at low flow season, and the shape of the FDC (Table 6.9 and Figure 6.11), the flows

obtained by transposition from Katsina-Ala gauging station will be onwards used to proceed the

studies for Busi II.

To use the flows obtained by transposition from Katsina-Ala is a cautious and conservative approach,

which is reasonable to consider due to the uncertainty on the accuracy of the flow data analysis and

the importance of low flow season for a Micro/Mini Hydropower Project.

In Figure 6.16 and Table 6.10, the average monthly flows adopted at Busi II are presented, and in

Annexe 11, the complete set of flows is compiled.

Figure 6.16 – Average monthly flow and runoff at Busi II.

0

20

40

60

80

100

120

140

160

180

200

220

240

260

280

300

320

3400.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0


R u n o f f ( m m )

Q ( m 3 / s )

Busi II

Average Runoff Series1




Hydrology Report

49

Table 6.10 – Average monthly flow and runoff at Busi II.


Flow(m3 /s)

0.05 0.03 0.04 0.09 0.19 0.35 0.57 0.57 0.84 0.91 0.36 0.15 0.35

Runoff(mm)

13.5 6.2 9.3 21.4 46.9 84.2 140.9 141.1 200.8 224.0 86.8 36.1 1011.3

Flow Duration Curve

Figure 6.17 shows the flow duration curve at Busi II, while in Table 6.11 the flows corresponding to


Figure 6.17 – Flow Duration Curve at Busi II.

Table 6.11 – Flow values for several percentages of exceedance for Busi II.

% of exceedance 5% 10% 20% 30% 40% 50% 60% 70% 80% 85% 90% 95% 100%

Q (m3 /s) 0.96 0.82 0.67 0.51 0.38 0.26 0.16 0.08 0.05 0.04 0.03 0.02 0.01

It can be observed in Figure 6.17 and Table 6.11 that the flow regime at Busi II steadily decreases,

at an approximately constant rate, for flows corresponding to a percentage of exceedance between

10% and 70%. It can also be observed that, however the flow values get extremely low during low

flow season, the stream will not dry.

Ecological Flow

For Egaga Fall, the environmental flow will be set at Q90, which equals a flow of 0.03 m3/s (Table

6.11).

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1.1

1.2

1.3

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Q ( m 3 / s )

% of exceedance

Busi II




Hydrology Report

50

Tapa


The Tapa site is located in Niger state in the Gurara LGA, close to the border with Federal Capital

Territory. Table 6.12 resumes the location, administrative and basic hydrological data about the site.Table 6.12 – Location and basic hydrological features resume for Tapa site.

Site Name Tapa

State Niger

Local Government Area Gurara

Latitude 9.31473361


Hydrological Area (HA) Niger Central (HA-2)

Catchment Area (km2) 694

In Figure 6.18, it can be observed the location of Tapa site, as well as the available nearby gauging

stations, and a satellite view of the watershed.




Hydrology Report

51

Figure 6.18 – On the top: location of Tapa site and catchment area and nearby gauging stations, on the right:Satellite view of Tapa catchment area (source: Google Earth).

Flow Assessment

A brief analysis on the previously presented data for the gauging stations of Izom, Ebba, Kachia,

Kaeia (page Error! Bookmark not defined.) points out that:

In terms of distance to the site location, Izom is the closest gauging station, but on the other

hand, it has the largest catchment area (6203 km2)

Kaeia is the gauging station with the closest catchment area to the one of Tapa (599 km2

versus 694 km2)

Kachia has the smallest catchment area (124 km2).

In terms of average runoff, Ebba has the lowest annual average value with 212 mm, which

is about 3 times lower than the one of Izom (680 mm), while Kachia and Kaeia have

respectively 399 mm and 413 mm.

The similarity of average annual runoff values from Kachia and Kaeia gauging stations is

consistent with their location, as they are located quite close to each other. Thus, similar

hydrological conditions can be expected, even if the catchment areas differ.

To compare the available data transposed to the site location, in Figure 6.19, two charts resuming

the transposed flow data are presented. One presents the average monthly flows for Tapa site

computed from each of the source gauging stations, while the second one presents adimensional

flow duration curves (FDC) (this meaning each flow value has been divided by the average flow, Qm)

for the Tapa site, also obtained from the four source gauging stations.

Table 6.13 presents the average monthly flows at Tapa, obtained by catchment area ratio

transposition from Izom, Ebba, Kaeia and Kachia gauging stations.

All the monthly flows for Tapa obtained by transposition from each of the source gauging station

area complied in Annexe 14.

.




Hydrology Report

52

Table 6.13 – Average monthly flows at Tapa in m3 /s, obtained by catchment area ratio transposition from Izom,Ebba, Kaeia and Kachia gauging stations.

SourceGaugingStation

AreaRatio


Izom 0.11 1.24 0.78 0.58 1.83 6.02 10.49 24.52 41.56 53.39 31.12 6.19 1.87 15.05

Ebba 0.37 0.29 0.19 0.15 0.18 0.31 0.67 2.68 10.93 24.07 12.95 2.75 0.70 4.67

Kaeia 1.24 1.01 0.73 0.59 2.49 4.46 6.89 20.80 23.73 31.17 14.28 3.44 1.54 9.31

Kachia 5.60 2.21 1.77 1.43 2.65 6.90 9.13 19.08 20.12 20.45 10.69 4.29 2.75 8.50

Figure 6.19 – On the top: Average monthly flows for Tapa obtained by transposition by catchment area ratiomethod from each of the four source gauging stations; on the bottom: Adimensional FDC for Tapa site using

flow transposition from each of the four source gauging stations.

0

5

10

15

20

25

30

35

40

45

50

55



( m 3 / s )

Izom Ebba Kaeia Kachia

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

6.5

7.0

7.5

8.0

8.5

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Q

/ Q

m

% of exceedance

Izom Ebba Kaeia Kachia




Hydrology Report

53

The observation of Figure 6.19 and Table 6.13 tells that:

Flow transposition from Ebba gauging station generates the lowest average monthly flows in

all months except September and October.

Between May and November (which covers all rain season), transposition from Izom clearly

generates the highest average monthly flows. Transposition from Kachia generates the highest monthly average monthly flows between

January and May (which covers all low flow season).

Flows generated from Ebba gauging station show an extremer distribution of flows, having

the highest values of Q/Qm and having lower values of Q/Qm when compared to the values

obtained from the other three gauging stations (Izom, Kaeia and Kachia) from an exceedance

period of about 20%.

Additionally to the obtained flow data at tapa by flow transposition, during the site visit in March 2015

a flow measurement was made at the site. At this occasion it was recorded a flow of 0.095 m3/s.

Comparing with the recorded flow at the site, 0.095 m3/s, the average flow obtained using Ebbagauging station, 0.15 m3/s, is clearly the closest one. Besides this, the shape of the FDC obtained

from Ebba.

Considering the low flow conditions observed at Tapa during the site visit, the average monthly flows,

the flows at low flow season, and the shape of the FDC (Table 6.13 and Figure 6.19), the flows

obtained by transposition from Ebba gauging station will be onwards used to proceed the studies for

Tapa. To use the flows obtained by transposition from Ebba is a cautious and conservative approach,

which is reasonable considering the uncertainty on the accuracy of the flow data analysis and the

importance of low flow season for a Micro/Mini Hydropower Project.

In Figure 6.20 and Table 6.14, the average monthly flows adopted at Tapa are presented, and in Annexe 15 the complete set of flows is compiled.

Figure 6.20 – Average monthly flow and runoff at Tapa.

0

10

20

30

40

50

60

70

80

90

1000

2

4

6

8

10

12

14

16

18

20

22

24

26


R u n o f f

( m m )

Q ( m

3 / s )

Tapa

Average Runoff Average Flow




Hydrology Report

54

Table 6.14 – Average monthly flow and runoff at Tapa.


Flow(m3 /s)

0.29 0.19 0.15 0.18 0.31 0.67 2.68 10.93 24.07 12.95 2.75 0.70 4.67

Runoff(mm)

1.1 0.7 0.6 0.7 1.2 2.5 10.4 42.2 89.9 50.0 10.3 2.7 212.1

Flow Duration Curve

Figure 6.21 shows the flow duration curve at Tapa, while in Table 6.15 the flows corresponding to


Figure 6.21 – Flow Duration Curve at Tapa.

Table 6.15 – Flow values for several percentages of exceedance for Tapa.

% of exceedance 5% 10% 20% 30% 40% 50% 60% 70% 80% 85% 90% 95% 100%

Q (m3 /s) 24.57 18.36 7.93 3.55 1.09 0.56 0.41 0.28 0.27 0.14 0.00 0.00 0.00

It can be observed in Figure 6.21 and Table 6.14 that the flow regime at Tapa has huge variations

between rain season and low flow season. For about 60% of the period of available records, the

flows at the site are lower than 1 m3/s, and for 10% of that period there is no flow. This is an indicator

that in dry years, periods with absence of flow are likely.

Ecological Flow

For Tapa, the environmental flow will be set at Q85, which equals a flow of 0.14 m3/s (Table 6.15).

0

5

10

15

20

25

30

35

40

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Q ( m 3 / s )

% of exceedance

Tapa




Hydrology Report

55

7. Conclusions

The climate in Nigeria is semi-arid in the north and humid in the south. Rainfall patterns are marked

by distinct wet and dry seasons, with rainfall concentrating in the period from June to September.

The mentioned climate features heavily influence the country’s hydrology.

Mean annual runoff decreases from south, where in hydrological areas (HA) HA-5 and HA-7 it can

achieve values around 1000 mm, to north, where in some areas of HA-1 and HA-8, the mean annual

runoff can be as low as less than 20 mm (Figure 7.1 and Figure 7.2).

Figure 7.1 – Map of mean annual runoff in Nogeria (source: JICA1).

The rainfall pattern has a direct influence in the flow distribution through the year, resulting in a clear

low flow season and significant differences between maximum and low flows (Figure 7.2).

0

1

2

3

4

5

6

7

8

9

100

20

40

60

80

100

120

140

160

180

200


R u n o f f ( m m )

Q ( m 3 / s )

Wamako


0

20

40

60

80

100

120

140

160

180

200

2200

500

1000

1500

2000

2500

3000

3500


R u n o f f ( m m )

Q ( m 3 / s )

Wuya





Hydrology Report

56

Figure 7.2 – Average monthly flows and runoff for gauging stations in Sokoto, Niger, Ogun and Niger states.

The northern areas of Nigeria are not suitable for any kind of run-off hydropower scheme due to

severe flow scarcity during low flow season. This is even more relevant for micro/mini hydropower

as these schemes are usually located in small catchment areas, which, in general, have lowerspecific yields than bigger watersheds. However, even in central and southern areas of the country,

the flow pattern and low flow season can be threat to the viability of a run-off hydropower project.

In the case of Tapa site in Niger state (Figure 7.3), the highest average monthly flow is 161 times

bigger than the lowest average monthly flow (24.07 m3/s vs 0.15 m3/s), and the flow is at reduced

levels, when compared to the month with higher flows, for around half of the year.

Figure 7.3 – Average monthly flow and runoff, and FDC at Tapa.

The sites located in the south of the country (Egaga Fall and Busi II) are located in areas that, onaverage, have reasonable mean annual runoff yield. However, the fact that their catchment areas

are small (10.9 km2 for Egaga and 7.9 km2 for Busi II) is a concern regarding flow scarcity during low

flow season (Figure 7.4).

0

5

10

15

20

25

30

35

40

45

50

55

60

650

20

40

60

80

100

120

140

160

180

200


R u n o f f ( m m )

Q ( m 3 / s )

Apoje


0

40

80

120

160

200

240

280

320

3600

200

400

600

800

1000

1200

1400

1600

1800

2000

2200

2400


R u n o f f ( m m )

Q

( m 3 / s )

Ikom


0

10

20

30

40

50

60

70

80

90

1000

2

4

6

8

10

12

14

16

18

20

22

24

26


R u n o f f ( m m )

Q ( m 3 / s )

Tapa


0

2

4

6

8

10

12

14

16

18

20

22

24

26

2830

32

34

36

38

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Q ( m 3 / s )

% of exceedance

Tapa




Hydrology Report

57

Figure 7.4 – Average monthly flow and runoff, and FDC at Egaga Fall and Busi II.

For both of the sites it is clear that a low flow season with extremely low flow values (under 100 l/s)

lasts for four months (January to April). The flow measurements at the sites 0.08 m3/s at Egaga Fall

and 0.035 m3/s at Busi II, in March 2015, also confirm the issues with flow scarcity. Moreover,

regarding the flow regime, the ratio between the higher and lower average monthly flows being

stands at 33.

It is clear that, for the three sites considered to have potential for Micro/Mini Hydropower (Tapa,

Egaga Fall and Busi II), low flow season will be an issue regarding all year round production, and it

is reasonable to consider that a shutdown period will be mandatory.

Environmental flows have to be considered, as they will also impose a limitation on operation at low

flow conditions.

Operation ranges of electromechanical equipment can be adapted to flow conditions, and operation

with extremely low levels of flow is not impossible (however, with a significant reduction of the

equipment’s efficiency and lifetime).

It will be the economical sustainability to limit the feasibility of the projects.

0

20

40

60

80

100

120

140

160180

200

220

240

260

280

300

320

3400.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1.1

1.2

1.3

1.4


R u n o f f (

m m )

Q ( m 3

/ s )

Egaga

Average R uno ff A ve ra ge Flow

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Q ( m 3 / s )

% of exceedance

Egaga Fall

0

20

40

60

80

100120

140

160

180

200

220

240

260

280

300

320

3400.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0


R u n o f f ( m m )

Q ( m 3 / s )

Busi II

Average R un of f S er ies 1

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1.1

1.2

1.3

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Q ( m 3 / s )

% of exceedance

Busi II




Hydrology Report

Annexes




Hydrology Report

I

Annexe 1

SHA boundaries (source: JICA1)




Hydrology Report

II




Hydrology Report

III




Hydrology Report

IV




Hydrology Report

Annexe 2

List of Available Hydrological Stations




Hydrology Report




Hydrology Report

I

Annexe 3

List of Meteorological Stations Operated by NIMET.




Hydrology Report

II

Annexe 4

Monthly flows for gauging stations in Sokoto State.

Wamako 1 2 3 4 5 6 7 8 9 10 11 12

137219 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual

1960

1961

1962

1963

1964

1965

1966

1967

1968

1969

1970 1.49 1.24 1.12 0.00 0.37 4.24 43.68 288.61 309.03 159.42 3.47 1.87 68.30

1971 1.49 1.24 1.12 0.77 0.75 6.17 63.84 215.05 253.86 38.46 3.47 1.87 49.21

1972 0.00 0.00 0.00 1.16 1.49 23.53 33.60 101.93 74.85 6.35 1.16 0.75 20.52

1973 4.11 0.41 0.37 0.39 0.37 7.72 56.00 117.61 52.85 1.87 0.39 0.37 20.42

1974 0.37 0.41 0.37 0.39 0.37 3.09 73.18 267.70 255.40 92.59 2.31 1.12 58.50

1975 0.37 0.41 0.37 0.39 1.87 19.68 64.59 189.67 219.14 57.12 4.24 1.12 46.801976 1.12 0.40 0.37 0.39 0.37 15.05 44.80 93.71 45.91 29.12 6.94 1.12 20.13

1977 0.37 0.41 0.37 0.00 0.00 1.54 36.59 132.17 220.29 23.15 0.77 0.37 34.72

1978 0.00 0.00 0.00 1.16 6.72 35.49 106.78 161.29 187.11 54.14 0.39 0.00 46.36

1979 0.37 0.00 0.00 0.00 1.12 2.31 26.88 195.27 235.73 1.87 1.16 0.00 38.81

1980 0.00 0.00 0.00 0.00 0.00 5.02 33.98 225.88 131.17 2.61 0.77 0.00 33.55

1981

1982 0.00 0.00 0.00 0.00 0.00 27.39 45.18 173.61 114.58 3.73 0.00 0.00 30.57

1983 0.00 0.00 0.00 0.00 0.00 49.38 72.80 164.65 103.01 0.75 0.00 0.00 32.76

1984 0.00 0.00 0.00 0.00 0.00 12.73 78.41 128.06 62.11 13.44 0.00 0.00 24.83

1985 0.00 0.00 0.00 0.00 0.00 59.03 177.34 305.78 162.81 0.00 0.00 0.00 59.27

1986

1987

1988

1989

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

20042005

2006

2007

2008

2009

Average Flow 0.65 0.30 0.27 0.31 0.90 18.16 63.84 184.07 161.86 32.31 1.67 0.57 39.0

Average Runoff 0.0 0.0 0.0 0.0 0.0 0.3 1.2 3.6 3.1 0.6 0.0 0.0 9.0




Hydrology Report

III

Goronyo Dam 1 2 3 4 5 6 7 8 9 10 11 12


1960

1961

1962

19631964

1965

1966

1967

1968

1969

1970 0.37 0.41 0.37 0.39 0.00 0.00 13.07 129.18 209.10 89.61 1.93 0.00 37.16

1971 0.75 0.83 0.75 0.39 0.37 0.77 23.89 93.34 139.66 22.03 1.93 1.12 23.88

1972 0.75 0.80 0.75 0.77 0.00 4.63 11.57 77.28 68.67 5.97 0.77 0.37 14.43

1973 0.00 0.00 0.00 0.00 0.00 5.79 37.71 78.78 35.49 1.12 0.77 0.37 13.48

1974 0.00 0.00 0.00 0.00 0.00 1.93 39.95 146.36 139.27 50.40 1.54 1.12 31.93

1975 0.00 0.00 0.00 0.00 0.00 12.35 36.22 106.41 123.07 32.11 2.70 1.49 26.32

1976 0.00 0.00 0.00 0.00 0.00 10.80 30.24 63.10 30.86 19.41 4.63 0.75 13.44

1977 0.00 0.00 0.00 0.00 0.00 1.16 21.65 78.03 130.40 13.81 0.00 0.00 20.45

1978 0.00 0.00 0.00 0.00 0.00 24.69 60.48 91.10 105.32 29.87 0.00 0.00 26.10

1979 0.00 0.00 0.00 0.00 0.00 2.31 15.31 113.13 136.57 1.12 0.77 0.00 22.48

1980 0.00 0.00 0.00 0.00 0.00 2.70 20.16 134.41 77.93 1.87 0.39 0.00 19.95

1981

1982 0.00 0.00 0.00 0.00 0.00 15.82 25.76 99.31 65.59 1.87 0.00 0.00 17.47

1983 0.00 0.00 0.00 0.00 0.00 28.16 41.44 93.71 58.64 0.37 0.00 0.00 18.65

1984 0.00 0.00 0.00 0.00 0.00 7.33 45.55 74.30 35.88 7.47 0.00 0.00 14.36

1985 0.00 0.00 0.00 0.00 0.00 32.79 98.57 170.25 90.66 0.00 0.00 0.00 32.98

1986

1987

1988

1989

1990

1991

19921993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

2008

2009

Average Flow 0.12 0.14 0.12 0.10 0.02 10.08 34.77 103.25 96.48 18.47 1.03 0.35 22.2

Average Runoff 0.0 0.0 0.0 0.0 0.0 0.9 3.0 9.1 8.2 1.6 0.1 0.0 22.9




Hydrology Report

IV

Annexe 5

Monthly flows for gauging stations in Niger State.

Jebba 1 2 3 4 5 6 7 8 9 10 11 12


1960 1982.26 2054.48 1991.29 1242.00 534.13 412.67 856.39 1681.61 4044.67 3892.90 2211.33 1918.06 1899.73

1961 1960.32 2033.93 1961.29 1389.73 597.35 359.33 660.03 1475.48 3403.00 2984.84 1785.67 1705.81 1689.81

1962 1791.94 1852.14 1583.55 769.93 367.52 307.37 677.42 1735.71 4659.67 4859.35 2579.00 2066.45 1936.65

1963 2055.48 2131.79 2168.06 1745.67 882.29 529.00 846.10 2395.48 3306.33 3490.32 2076.67 1733.55 1945.56

1964 1816.13 1931.03 1894.52 1199.43 479.32 395.23 490.74 1857.13 3271.33 3483.55 2075.33 1733.55 1717.02

1965 2018.06 2154.64 2133.23 1704.33 796.52 517.97 621.65 1780.13 3943.00 3250.65 1990.00 1850.65 1893.06

1966 1943.87 2033.93 1900.00 1031.00 476.77 442.80 558.77 815.19 2873.33 3005.16 1874.00 1736.45 1553.72

1967 1868.71 1988.93 1940.65 1005.37 386.81 305.97 366.68 1419.94 3972.67 3901.94 2129.67 1928.06 1765.19

1968 2104.19 2279.31 2316.13 1855.33 890.10 696.53 1465.48 1647.74 1941.33 1418.90 1624.63 1715.81 1659.36

1969 1719.35 1861.79 1501.16 1147.33 1145.61 778.40 1075.68 1162.26 2376.33 1348.06 2156.33 1775.81 1499.86

1970 1992.58 2224.64 2255.81 1891.33 1097.74 1016.27 1183.77 1849.81 2265.00 1760.65 1404.33 1416.45 1692.76

1971 1520.32 1659.29 1229.03 883.63 895.29 1001.63 1244.84 1643.55 1625.33 1343.55 995.27 1038.84 1254.83

1972 1607.10 1587.59 1065.13 1045.27 1013.16 1022.43 869.23 613.45 693.27 652.03 541.50 1236.58 992.56

1973 1226. 19 1090. 25 641. 16 532. 70 600. 32 638. 57 641. 52 777. 13 1298. 67 952. 26 719. 73 923. 48 835.18

1974 1144.16 793.18 594.39 422.20 542.26 583.30 597.30 1316.73 2836.33 1751.29 1278.67 1504.52 1114.50

1975 1760.00 1652.50 971.74 913.27 835.32 831.87 1185.42 1250.68 1045.27 1154.39 1328.33 1552.90 1205.08

1976 1768.71 1835.86 1208.06 939.23 989.65 1116.23 1173.65 1026.94 939.47 985.45 919.67 688.71 1128.54

1977 755.81 1430.29 1539.03 1176.43 947.58 919.40 1028.35 1262.48 1315.33 1369.03 813.73 656.90 1098.99

1978 657. 10 647. 11 642. 39 633. 27 646. 52 948. 03 965. 81 720. 06 826. 77 1158. 39 953. 73 926. 13 811.45

1979 1170.26 1246.79 823.19 702.37 767.32 891.00 1139.03 1949.68 2395.33 1850.97 1224.80 1324.52 1290.65

1980 1438.06 1640.00 941.93 970.33

1981 921.32 951.67 1002.19 1006.61 1632.63 1526.13 1004.30 948.48

1982 1219.68 1183.21 879.42 1091.87 1104.00 934.53 909.16 1133.55 1064.00 994.48 874.90 862.68 1019.95

1983

1984 392. 32 425. 25 438. 66 523. 45 623. 46 792. 64 868. 43 795. 52 800. 48 457. 56 514. 49

1985 585. 42 540. 26 483. 12 464. 51 451. 39 361. 88 328. 18 561. 16 1500. 77 1343. 71 717. 59 1061. 45 700.60

1986 1025. 61 647. 32 653. 38 638. 50 773. 60 766. 59 794. 50 950. 90 687. 47 333. 42 764. 60 828. 97 739.76

1987 1102. 16 803. 89 944. 00 746. 57 848. 48 973. 90 839. 42 828. 68 838. 00 682. 00 863. 53 809. 65

857.141988 1028. 68 706. 79 659. 45 930. 37 564. 52 457. 80 462. 22 813. 55 2489. 20 1819. 00 998. 07 1142. 85 1006.17

1989 991. 64 613. 01 574. 22 743. 44 836. 32 716. 44 363. 65 1160. 97 1613. 33 1849. 45 814. 87 1112. 84 951.69

1990 1048. 48 937. 11 894. 74 221. 40 504. 68 448. 97 149. 45 332. 13 856. 00 454. 81

1991 392.13 386.73

1992 604.58 411.16 209.20 364.40 1106.77

1993 1161.00 1143.00 1290.17 1115.89 770.23 612.40 522.58 537.58 1124.27 918.06 530.10 349.61 837.01

1994 434. 77 470. 57 494. 61 529. 11 319. 30 146. 90 153. 13 589. 27 2311. 67 3908. 71 1785. 67 1540. 97 1060.38

1995 1710.97 2068.93 1758.39 1432.00 1518.71 1623.67 1494.58 1660.00

1996 903. 45 823. 14 746. 16 500. 00 557. 22 358. 27 665. 45 702. 23 1243. 93 1125. 32 1072. 37 893. 03 799.08

1997 1211.45 1231.00 872.42 946.57 513.23

1998

1999

2000

2001

20022003

2004

2005

2006

2007

2008

2009

Average 1392.02 1402.65 1210.55 953.88 738.18 687.59 780.48 1168.69 1986.47 1886.54 1308.58 1268.91 1230.6

Average Runoff 2.3 2.1 2.0 1.5 1.2 1.1 1.3 1.9 3.2 3.1 2.1 2.1 23.8




Hydrology Report

V

Baro 1 2 3 4 5 6 7 8 9 10 11 12


1960

1961 1329.09 417.04 246.91 1115.96 2597.82 4609.95 4746.12 2011.96 1594.98

1962 1656.96 1732.80 1531.14 641.98 181.08 354.94 1214.16 2579.90 7248.07 7548.16 3815.97 2075.87 2550.01

1963 1861.93 1943.20 1988.87 1837.96 813.17 513.89 1478.12 4118.13 5792.05 5996.12 3250.00 1829.82 2621.641964 1789.87 1843.07 1810.04 1194.83 474.16 679.01 779.94 3002.17 6809.03 6058.84 2560.96 1854.84 2404.89

1965 1804.06 1932.04 2001.94 1623.07 744.10 709.88 1133.14 3110.07 5508.10 5185.93 2415.90 1833.93 2334.28

1966 1844.01 1824.16 1762.99 998.84 510.01 964.12 1263.81 2940.93 6172.84 5813.17 2537.81 1805.93 2371.10

1967 1823.85 1943.20 1904.12 1104.17 442.05 190.97 1080.12 2544.06 5991.90 6600.96 2839.89 1995.97 2373.54

1968 2071.01 2234.20 2296.89 1944.06 990.89 1060.19 2535.84 5766.13 5520.83 2993.95 2006.94 1767.10 2601.63

1969 1676.00 1992.81 1512.84 1153.94 1163.01 787.81 2069.15 3493.13 5998.84 4121.12 3158.18 2006.05 2427.51

1970 2046.37 2246.61 2276.36 2023.53 1159.65 1197.15 1755.15 3632.02 5734.57 3881.42 1750.77 1468.79 2429.86

1971 1502.02 1719.58 1272.77 820.22 910.62 1117.28 1898.15 3994.55 5356.87 3332.96 1261.96 1072.66 2022.83

1972 1409.80 1578.07 1069.67 970.29 1058.47 1413.19 1487.83 2351.40 3564.43 1842.14 606.48 1121.57 1538.04

1973 1246.64 1124.34 598.49 425.54 509.26 640.43 894.56 2381.27 3414.35 2501.49 911.27 939.74 1299.85

1974 1112.60 814.32 526.43 423.61 636.20 660.49 1101.78 2486.56 5376.93 4742.76 1817.52 1620.00 1781.30

1975 1668.91 1763.39 1030.47 923.23 973.72 1024.31 2030.32 2459.30 4451.39 3725.36 1786.65 1646.88 1957.60

1976 1777.93 1802.36 1312.72 936.34 1100.66 1485.73 1883.96 1903.00 2251.16 3739.17 2359.18 858.35 1784.35

1977 751.57 1323.58 1559.89 1163.19 1108.50 1493.83 1286.59 1599.09 3540.12 3387.10 931.33 694.44 1569.63

1978 608.20 589.04 568.25 602.62 715.35 1261.96 1910.10 2523.52 4576.39 3462.14 1838.73 949.45 1637.62

1979 1122.69 1129.30 775.46 693.29 817.65 1141.20 2135.23 4160.32 5855.32 3864.25 1724.54 1421.00 2074.64

1980 1365.81 1636.55 948.84 916.57 901.71 1078.40 1508.32 2657.42 4024.00 2681.29 1522.33 957.71 1681.41

1981 818.24 835.46 786.35 796.27 997.90 1107.23 1837.74 2934.52 4704.67 3124.19 1232.50 871.84 1674.27

1982 1058.35 1041.86 745.29 934.67 990.68 967.83 1435.81 2157.10 2651.00 2237.10 1093.30 814.06 1345.66

1983 605.84 581.89 776.68 753.53 811.23 857.93 1069.97 1430.68 1786.67 881.77 467.70 373.32 867.68

1984 391.03 432.86 379.06 424.20 523.61 769.83 1109.81 1438.06 1573.00 1509.32 604.47 490.00 806.39

1985 540.19 528.61 450.39 428.93 472.84 528.67 850.52 2699.23 5348.67 4226.77 1308.83 1295.48 1561.24

1986 1504.52 901.50 673.65 699.47 781.42 971.27 1062.42 1377.10 2864.67 2395.81 1211.57 815.74 1272.82

1987 868.97 800.14 961.65 1236.87 1248.00 1061.00 936.97 1376.45 3397.00 2449.03 959.93 980.06 1357.54

1988 919.95 762.69 704.90 1641.98 1193.90 969.70 898.42 1382.23 4879.67 4342.90 1317.23 1358.39 1699.82

1989 1158.90 770.09 660.10 896.55 1533.77 998.90 1289.35 2697.74 3932.67 3400.00 1082.13 1165.48 1638.18

1990 1223.42 1137.86 1071.81 1041.23 1530.97 1423.00 1406.77 1915.81 3540.33 2435.81 1534.67 1296.87 1631.13

1991 1009.29 1265.00 1044.90 1158.03 1190.87 1966.67 3449.35 4518.06 4868.00 2976.45 1521.33 1250.00 2190.27

19921993

1994

1995 2095.00 1989.03 1626.33 1863.87 2201.33 2210.65 2880.32 3570.67 3223.55 2181.00 1521.94

1996 908.65 912.40 972.00 913.71

1997

1998

1999 1838.00 1661.29 1792.33 2395.16 3792.26 5405.00 6918.71 3436.67 2392.58

2000 2378.06 2142.41 2170.97 2169.67 1902.26 1819.67 1609.68 2735.16 3866.00

2001

2002

2003

2004

2005

2006

20072008

2009

Average 1342.48 1389.62 1223.84 1099.18 949.67 1039.13 1517.05 2701.41 4534.86 3828.66 1789.69 1337.60 1897.9

Average Runoff 2.1 1.9 1.9 1.6 1.5 1.6 2.4 4.2 6.8 5.9 2.7 2.1 34.7




Hydrology Report

VI

Wuya 1 2 3 4 5 6 7 8 9 10 11 12


1960

1961

1962

19631964

1965

1966

1967

1968

1969

1970 179.01 401.73 2246.49 3705.63 738.87 119.85

1971

1972 98.19 34.34 94.46 200.62 340.13 1848.49 1875.39 622.01 152.39 49.66

1973 39.27 30.62 39.58 68.67 222.89 1268.29 1358.80 541.74 102.62 36.96

1974 126.57 288.98 152.01

1975 39.95 37.20 31.36 32. 02 127.31 140. 43 659.35 1326.54 3639.27 1170. 85 206.40 92. 22 625.92

1976 56.00 39.35 122.09 246.53 461.10 1512.47 472.99

1977 43.68 35.55 26.88 23.92 45.55 259.26 1824.22 4594.91 2756.50 154.71

1978 44.80 41.34 41.07 2219.24 7852.62 3145.91 1011.96

1979 98. 57 66. 96 49. 66 45. 91 155. 32 343. 36 2662. 04 5220. 65 6187. 11 3107. 83 319. 44

1980 52.27 9.98 44.06 42. 44 112.38 232. 64 1536. 36 3452.43 3724.15 1261. 57 186.73 46. 67 897.36

1981 6. 56 101. 18 189. 43 585. 05 1340. 35 2410. 88 691. 46

1982 11.99 8.96 7.72 5.23 8.10 511.50 1311.60 1534.34 871.79 24.69

1983 9.33 9.92 7.84 6.94 11.95 51.31 29.87 697.43 1310.96 257.99 3.86 13.07 200.88

1984 9.33 9.58 8.59 8.10 7.47 10.45

1985 8.59 7.44 7.47 8.87 11.20 30.86 46.30 1816.76 2701.39 1754.41 376.54 17.92 567.89

1986 8.96 13.64 12.32 11.96 13.07 25.08 2868.83 687.35 74.46 23.52

1987 23.52 24.80 11.95 57.87 192.65 2315.97 1044.65 19.68 13.44

1988 12.32 11.57 11.20 274.69 60.86 600.36 4965.66 1054.36 28.55 20.16

1989 17.17 16.53 16.05 16.59 16.05 52.08 52.64 983.05 1961.03 1232.45 59.03 9.71 370.59

1990

1991

19921993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

20072008

2009

Average 37.34 23.98 22.00 21. 90 65.96 147. 50 671.87 1723.52 3 312.93 1 320. 72 209. 13 37. 80 634.7

Average Runoff 1.5 0.9 0.9 0.9 2.7 5.9 27.8 71.3 132.7 54.7 8.4 1.6 309.2




Hydrology Report

VII

Shiroro 1 2 3 4 5 6 7 8 9 10 11 12


1960

1961

1962

19631964

1965

1966

1967

1968

1969

1970

1971

1972

1973

1974

1975

1976

1977

1978

1979

1980

1981

1982

1983

1984 22.40 109. 18 149.34 315.11 428. 24 268.82 70.60 13.07

1985 12.69 6.20 15.31 36.27 116.49 263.50 323.70 1018.89 1169.37 287.49 49.38 4.85 276.41

1986 3.36 2.89 24.27 33.95 145.98 88.35 281.88 667.56 1308.26 413.31 59.80 6.35 253.74

1987 7.47 8.27 9.33 34.72 81.02 167.05 246.42 586.92 855.71 322.58 57.10 9.33 199.52

1988 5.60 5.19 3.36 38.97 232.60 130.79 121.71 749.33 1567.13 363.28 8.49 17.55 270.69

1989 7.84 9.09 14.56 22.38 274.79 109.18 297.57 848.27 987.65 385.30 26.23 24.27 252.19

1990 46.10 62.61 70.74 63.93 96.97 119.43 397.10 772.42 1074.63 335.48 84.50 38.87 264.43

1991 60.68 42.75 29.23 17.00 246.00 318.80 559.94 911.35 777.80 255.03 46.90 30.35 276.39

1992 21.48 36.54 78.42 76.60 49.10 146.80 410.58 857.84 1356.40 352.61 64.33 39.87 291.651993 50.45 40.43 43.16 18.57 26.90 187.93 655.19 875.74 1013.37 280.94 54.00 28.45 274.34

1994 53.26 60.29 36.13 20.00 59.68 224.70 258.94 845.19 934.00 860.90 129.60 26.35 293.95

1995 18.87 23.75 28.00 46.57 84.42 126.77 284.32 747.16 766.10 316.03 56.70 44.35 213.06

1996 38.16 18.24 23.77 11.93 103.35 276.37 526.00 873.00 874.30 509.39 70.47 59.32 283.91

1997 73.42 33.71 38.52 38. 53 103.06 235. 03 348.55 833.42 1091.90 522.32 178.23 66.68 298.14

1998 49.19 44.46 31.58 37.47 60.26 180.10 375.32 887.84 988.80 692.32 118.80 64.68 295.88

1999 54.13 44.39 33.61 31.97 46.23 217.57 662.52 772.90 1079.83 725.13 96.10 38.71 318.73

2000 52.94 34.21 45.06 20.83 55.19 244.10 275.16 1009.03 1081.83 565.65 74.20 62.90 294.88

2001 57.32 39.32 24.77 27.63 88.90 154.37 550.48 901.10 1246.53 364.74 130.43 79.68 306.70

2002 23.23 12.54 11.06 28.87 21.97 237.37 649.42 930.84 926.10 599.42 107.43 59.61 302.76

2003 48.77 38.61 19.84 15. 57 22.52 244. 00 576.58 1327.68 1752.50 492.55 102.03 39.55 391.39

2004 32.97 33.07 40.55 26.47 72.23 199.57 588.23 1011.10 922.10 334.23 73.20 38.87 282.82

2005 21.55 17.79 19.00 15.57 81.16 166.00 423.81 680.48 627.07 372.71 46.50 38.23 210.68

2006 40.77 37.96 28.23 20.33 81.26 97.73 469.35 747.19 1265.63 878.16 119.13 87.29 324.52

2007 51.39 27.93 13.19 34.93 69.19 201.03 528.74 1048.90 951.50 249.39 95.73 38.84 277.442008 30.42 26.03 10.84 9.87 88.61 168.13 303.61 1022.29 1042.20 357.71 89.00 61.42 268.84

2009 41.35 33.79 13.45 17. 97 65.10 108. 40 279.74 1431.29 1130.00 500.58 147.80 61.71 321.26

Average 36.14 29.60 28.24 29.88 92.13 181.63 405.55 872.03 1046.88 446.39 82.95 41.58 275.8

Average Runoff 2.8 2.1 2.2 2.2 7.1 13.6 31.3 67.3 78.2 34.5 6.2 3.2 250.6




Hydrology Report

VIII

Komi 1 2 3 4 5 6 7 8 9 10 11 12


1960

1961

1962

19631964

1965

1966

1967

1968

1969

1970

1971

1972

1973

1974

1975

1976

1977

1978

1979

1980

1981

1982

1983

1984 1.01 0.96 1.01 6.60 6.20 11.69 13.81 8.66 16.20 5.86 2.51 2.02 6.39

1985 2.50 2.40 3.51 2.58 4.22 3.70 8.33 41.26 22.92 11.46 4.13 3.25 9.25

1986 2.61 2.73 2.43 4.90 5.19 6.33 11.20 13.55 50.31 17.36 7.37 4.14 10.67

1987 3.88 3.14 2.80 2.39 2.80 15.28 13.07 20.68 26.31 11.69 5.02 3.99 9.27

1988 3.70 2.99 2.28 2.74 2.50 4.40 5.49 9.89 42.40 12.47 4.71 4.22 8.13

1989 3.81 3.51 2.91 2.82 2.69 7.21 6.09 28.23 30.98 20.87 6.48 4.52 10.04

1990

1991

19921993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

20072008

2009

Average 2.92 2.62 2.49 3.67 3.93 8.10 9.66 20.38 31.52 13.29 5.03 3.69 9.0

Average Runoff 3.4 2.7 2.9 4.1 4.5 9.0 11.1 23.5 35.1 15.3 5.6 4.2 121.5




Hydrology Report

IX

Izom 1 2 3 4 5 6 7 8 9 10 11 12


1960

1961

1962

19631964

1965

1966

1967

1968

1969

1970 5.79 33.98 60.19 156.06 439.07 597.99 156.44 34.34 10.83

1971 6.35 2.89 1.87 13.12 28.38 68.67 175.10 488.35 515.05 231.11 45.91 10.83 133.05

1972 5.60 2.39 3.36 9.26 60.48 166.67 257.24 614.17 314.04 166.89 32.79 13.44 138.37

1973 8.21 3.72 1.49 8.87 19.04 46.68 97.45 420.77 394.68 165.40 47.45 17.55 103.18

1974 7.84 3.31 1.12 9.65 61.23 63.27 232.97 323.33 674.38 232.60 48.61 18.29 140.19

1975 9.33 4.55 2.99 13.12 38.08 71.37 221.77 420.40 538.19 398.75 43.98 6.35 148.37

1976 3.36 3.99 2.99 4.24 47.04 99.15 192.65 276.28 260.80 379.70 112.27

1977 39.58 35.96 25.76 54.78 104.17 86.03 185.56 213.19 378.09 279.64 33.56 7.84 120.85

1978 3.36 1.24 6.35 28.16 54.51 126.54 259.86 288.98 799.00 370.00 26.88

1979 15.31 10.33 6.35 16.98 98.57 104.55 260.23 355.44 484.18 334.90 71.76 25.76 149.61

1980 11.57 1.60 0.00 5.40 26.14 104.55 308.39 313.62 413.58 222.52 61.73 23.52 125.15

1981 14.19 7.85 32.86 6.56 61.98 76.00 216.55 349.46

1982

1983

1984

1985

1986

1987

1988

1989

1990

1991

19921993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

20072008

2009

Average 11.34 7.08 7.74 14.66 52.80 89.47 213.65 375.26 488.18 267.09 53.24 16.13 133.8

Average Runoff 4.9 2.8 3.3 6.1 22.8 37.4 92.3 162.0 204.0 115.3 22.2 7.0 680.1




Hydrology Report

X

Ebba 1 2 3 4 5 6 7 8 9 10 11 12


1960

1961

1962

19631964

1965

1966

1967

1968

1969

1970 1.49 1.24 1.12 0.77 1.12 1.54 2.99 17.55 91.82 32.86 5.79 2.24 13.35

1971 1.12 0.83 0.75 0.77 1.87 1.54 13.44 48.54 86.81 25.76 5.02 2.24 15.76

1972 1.49 0.80 0.37 1.16 1.12 1.93 10.83 27.26 50.15 18.67 2.70 0.75 9.80

1973 0.37 0.00 0.00 0.00 0.00 0.39 1.12 17.55 27.01 17.17 3.09 0.75 5.64

1974 0.00 0.00 0.00 0.00 0.37 2.31 3.73 16.43 62.50 53.39 6.56 1.49 12.27

1975 0.75 0.41 0.37 0.77 0.75 0.77 17.55 21.65 69.83 56.75 8.49 1.12 15.00

1976 0.00 0.00 0.00 0.00 0.00 3.86 7.47 9.71 25.46 39.58 17.75 1.49 8.82

1977 0.75 0.41 0.00 0.00 1.12 1.54 1.49 36.59 93.36 59.74 7.33 2.61 17.12

1978 0.75 0.41 0.37 0.39 0.37 1.93 5.97 51.52 101.47 34.72 10.80 2.99 17.66

1979 0.75 0.83 0.75 0.77 1.49 2.70 13.07 57.50 47.84 18.67 6.94 2.99 12.94

1980 1.12 0.80 0.75 0.77 1.12 1.54 2.99 24.27 67.13 31.74 8.10 2.24 11.89

1981

1982

1983

1984

1985

1986

1987

1988

1989

1990

1991

19921993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

2008

2009

Average 0.78 0.52 0.41 0.49 0.85 1.82 7.33 29.87 65.76 35.37 7.51 1.90 12.7

Average Runoff 1.1 0.7 0.6 0.7 1.2 2.5 10.4 42.2 89.9 50.0 10.3 2.7 212.1




Hydrology Report

XI

Badeggi 1 2 3 4 5 6 7 8 9 10 11 12


1960

1961

1962

19631964

1965

1966

1967

1968

1969

1970 5.23 3.31 2.61 2.31 3.73 5.02 8.59 98.94 260.80 115.37 18.90 11.57 44.74

1971 4.85 4.13 5.23 5.02 9.33 13.12 50.78 135.53 233.41 88.11 30.09 8.59 49.15

1972 6.35 5.19 4.48 4.24 7.84 11.96 47.42 124.33 176.31 64.22 15.43 5.97 39.62

1973 4.85 4.13 3.36 3.09 2.99 5.79 21.65 75.42 127.31 78.78 13.89 2.24 28.73

1974 1.49 1.24 1.12 1.16 2.61 8.87 16.43 60.48 173.61 119.10 19.29 4.48 34.25

1975 1.87 1.65 1.49 2.31 2.99 3.47 52.27 53.76 171.30 172.86 19.29 5.97 41.00

1976 2.61 2.39 1.87 1.54 2.24 14.66 20.91 38.46 56.71 101.55 75.23 9.71 27.42

1977 1.87 1.65 1.49 1.54 2.61 5.02 11.20 86.99 178.24 146.36 23.53 4.11 38.88

1978 1.87 1.65 1.49 5.40 5.23 10.80 32.48 125.45 219.52 117.23 40.51 7.84 47.60

1979 2.24 2.07 2.24 1.54 2.24 17.36 26.51 137.02 179.40 88.11 19.68 4.85 40.43

1980

1981

1982

1983

1984

1985

1986

1987

1988

1989

1990

1991

19921993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

20072008

2009

Average 3.32 2.74 2.54 2.82 4.18 9.61 28.82 93.64 177.66 109.17 27.58 6.53 39.2

Average Runoff 1.5 1.1 1.2 1.2 1.9 4.3 13.2 42.9 78.7 50.0 12.2 3.0 211.2




Hydrology Report

XII

Annexe 6

Monthly flows for gauging stations in Ogun State.

Apoje 1 2 3 4 5 6 7 8 9 10 11 12


1960

1961

1962

1963

1964

1965

1966

1967

1968

1969

1970

1971

1972

1973

1974

1975

1976

1977

1978

1979

1980

1981

1982 81.02 74.82 73.18 75.23 100.43 138.50 139.64 94.46 118.83 211.69 118.06 81.02 109.15

1983 72.06 71.92 72.06 73.69 116.86 73.30 109.77 93.71 175.54 130.68 82.18 68.32 95.13

1984 72.06 71.84 72.06 76.54 126.93 156.06 177.34 170.14 180.33 109.95 81.39

1985 63.10 66.83 80.27 111.88 201.61 137.40 146.22 217.67 153.55 90.35

1986 36.59 86.81 111.63 83.33 80.65 108.41 128.81 134.78 160.49 153.94

1987 70.56 71.92 72.06 72.15 73.55

1988

1989

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

2008

2009

Average 65.90 75.46 77.97 76.10 88.05 111.81 147.18 127.54 154.24 185.09 123.53 80.27 109.6

Average Runoff 20.7 21.4 24.5 23.2 27.7 34.0 46.3 40.1 46.9 58.2 37.6 25.2 405.9




Hydrology Report

XIII

Annexe 7

Monthly flows for gauging stations in Cross River State.

lkom 1 2 3 4 5 6 7 8 9 10 11 12


1960

1961

1962

1963

1964

1965

1966

1967

1968

1969

1970 1842.59 2211.39 1168.60 172.49

1971 21.65 20.25 173.61 182.10 266.20 965.28 2381.65 3091.40 2764.27 1547.57 594.91 311.01 1033.83

1972 158.68 118.53 326.31 266.20 404.72 1018.52 1416.14 2323.03 2966.82 1860.44 528.55 228.49 972.53

1973 133. 66 90. 11 112. 01 207. 56 404. 35 538. 97 993. 13 1404. 94 830. 25 1467. 29 629. 63 242. 68 592.371974 103.05 45.06 84.75 256.56 441.31 1070.60 1098.42 1837.66 2642.75 2144.56 444.44 317.73 878.20

1975 153.82 103.34 99.69 189.04 370.74 477.62 397.63 1745.82 2280.09 2763.22 1601.85 209.08 869.29

1976 274.04 228.69 167.82 131.05 2592.21 2459.68

1977 72. 06 119. 60 255. 00 1867. 16 2101. 25 2577.93 1967. 22

1978 1606.87 2054.96 668.60 199.00

1979 1390.38 2491.41 2236.11 1395.61 654.71 232.23

1980 101.18 81.02 116.86 109.18 317.35 900.46 1393.37 2231.93 2683.64 2004.55 891.59 298.31 932.01

1981 177.72 97.55 296.45 195.99 616.79 725.69 2011.65 2351.40 2485.73 1387.77 723.38 263.96 950.50

1982 177.72 131.04 151.58 221.45 509.63 1161.65 1823.10 2663.53 2658.95 1870.52 786.27 308.02 1044.24

1983 171.74 99.62 42.56 117.67 237.08 769.68 1848.12 2504.85 2254.24 1176.82 125.39 259.11 806.16

1984 141.88 80.62 113.50 201.00 266.95 624.23 1180.56 1218.26 1942.90 1670.77 318.29

1985

1986 186.68 171.13 204.97 172.84 404.72 1418.21 1730.88 1936.98 2408.18 2190.11 738.04 257.62 989.54

1987 173.98 171.96 179.96 175.93 405.09 654.32 858.35 1449.75 2092.21 1852.23 471.45 218.04 728.47

1988 126.19 55.08 75.04 118.06 234.09 532.41 1059.59 1628.96 2013.50 2149.42 576.39 244.18 739.161989 120.22 54.15 42.94 136.96 313.25 611.50 1064.81 1972.07 2304.40 2019.12 566.74 203.11 788.78

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

20032004

2005

2006

2007

2008

2009

Average 148.15 103.21 139.49 177.37 348.65 819.22 1407.18 2059.58 2272.82 1904.91 675.81 247.82 863.5

Average Runoff 23.5 14.8 22.1 27.2 55.3 125.6 223.0 326.4 348.6 301.9 103.7 39.3 1611.3




Hydrology Report

XIV

Adonatarn 1 2 3 4 5 6 7 8 9 10 11 12


1960

1961

1962

19631964

1965

1966

1967

1968

1969

1970

1971

1972

1973

1974

1975 252. 76 229. 41 238. 20 249. 61 353. 57 428. 24 477. 15 652. 63 787. 42 841. 17 557. 48 462. 22 462.23

1976 386. 42 345. 63 390. 16 603. 78 1277. 63 1148. 53 2881. 94 2083. 72

1977 721.33 1790.90 2562.72 2464.90 2987.27 2335.72 1089.51 586.54

1978 353.20 2524.27 1458.72 215.43

1979 545.91 539.13 937.89 2172.19 2656.81 2047.45 1469.91 1099.15 576.84

1980 284.50 98.98 128.43 143.52 375.22 994.21 1636.05 2733.35 3028.16 2663.90 1792.05 382.69 1194.08

1981 431.55 421.52 605.71 1184.29 1001.93 1411.29 2869.62 3028.16 2145.31 908.56 413.68

1982 337.51 272. 40 312.87 541.37 972.99 1501.27 2700.49 3028.16 1006.56 651.88

1983 475.28 419.15 393.89 486.11 757.92 983.41 1989.99 2918.53 3017.75 2396.21 1136.96 626.12 1306.19

1984 428.99 389.93 495.07 819.06 837.07 1174.00 1633.44 2431.68 2869.98 2142.70 587.58 312.50 1181.26

1985 226. 25 191. 91 307. 87 740. 74 1010. 42 1305. 26 1500. 90 2743. 06 1701. 02 939. 04 540. 99

1986 341. 62 337. 30 560. 78 924. 43 1307. 10 1957. 14 1979. 54 2505. 40 1742. 46 1488. 43 739. 62

1987 396.51 233.55 170.25 113.43

1988

1989

1990

1991

1992

19931994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

20082009

Average 348.30 306.43 330.31 430.56 750.24 1068.15 1664.65 2344.58 2556.96 1996.27 1096.73 500.77 1120.9

Average Runoff 49.4 39.2 46.8 59.0 106.3 146.5 235.9 332.3 350.7 282.9 150.4 71.0 1870.4




Hydrology Report

XV

Obubra 1 2 3 4 5 6 7 8 9 10 11 12 365


1960

1961

1962

19631964

1965

1966

1967

1968

1969

1970 849. 01 1893. 90 2340. 58 2937. 57 3966. 82 2747. 16 317. 73

1971 164.65 88.46 118.73 424.00 304.66 927.08 2435.78 3468.49 4004.63 3693.62 2392.75 1230.21 1613.24

1972 199.00 144.48 228.87 478.40 571.61 1592.59 1664.80 2228.57 3802.47 3080.20 814.43 297.94 1263.24

1973 179. 58 76. 47 81. 77 209. 10 457. 36 770. 06 977. 08 2057. 20 3193. 29 2561. 98 844. 91 330. 42 982.65

1974 146.73 66.14 85.87 275.85 603.35 1319.83 2074.00 3479.32 4440.20 4200.64 1372.30 362.53 1544.17

1975 157.18 105.41 101.55 184.80 499.55 704.48 1587.51 1725.66 2954.48 3810.11 1072.53 483.12 1122.59

1976 223.64 233.08 317.35 418.21 876.64 1727.24 2781.14 3227.67 3391.59 3882.17 2135.80 446.54 1646.91

1977 133. 93 65. 71 110. 34 258. 36 1101. 47 2049. 36 4237. 65 3164. 58

1978 3644.34

1979

1980 112.38 147.38 416.67 1409.72 2055.70 3613.72 4725.31 3865.37 1410.88

1981 2789. 35 3886. 65 4451. 39 2737. 83 315. 86

1982

1983 179.58 102. 10 56.75 86.03 254.26 2550.78 3425.18 3495.37

1984

1985 3505.79 2861.78 981.87 386.05

1986 170. 25 98. 79 153. 82 182. 10

1987 120.97 47.95 57.87 110.73 305.03 723.38 1453.85 2299.51 3974.92 3071.98 685.57 256.12 1097.82

1988 129.93 51.09 63.10 123.84 331.17 685.57 1752.91 3634.26 4154.71 3071.98 642.36 235.96 1247.74

1989 117. 23 42. 99 86. 25 108. 02 206. 84

1990

1991

1992

19931994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

20082009

Average 162.61 99.24 117.69 219.91 456.50 1168.67 2039.45 2998.65 3878.47 3313.84 1235.34 423.86 1350.0

Average Runoff 12.2 6.7 8.8 15.9 34.2 84.6 152.6 224.3 280.8 247.9 89.4 31.7 1189.2




Hydrology Report

XVI

Afikpo 1 2 3 4 5 6 7 8 9 10 11 12 365


1960

1961

1962

19631964

1965

1966

1967

1968

1969

1970

1971

1972 279.27 201.15 257.24 494.21 783.68 2039.35 1964.23 2841.62 4557.87 3952.36 997.30 389.78 1569.34

1973 279.64 183.12 190.79 311.73 585.05 1101.85 1213.04 2654.57 3999.61 3276.21 1016.98

1974 236.34 156.66 170.62 364.58 733.65 1615.35 2830.79 4173.39

1975 245.67 189.73 199.00 291.28 790.40 1047.84 2060.19 2436.90 3480.71 4325.72 1439.04 595.88 1433.82

1976 323.70 324. 07 433.47 514.66 1204.82 3179.51 3607.38 4058.26 2647.38 564.14

1977 332.29 218.67 148.97 184.03 367.01 1087.58 2772.18 3706.69 900.85 350.21

1978 216.17 158.32 198.25 450.62 781.81 2242.28 2162.49 3016.35 4570.22 4310.78 1571.76 433.84 1682.711979 233.72 211.23 230.73 331.40 841.55 1971.06 2763.22 3922.86 4392.36 2789.35 1216.44 421.15 1617.90

1980 242.68 154. 85 169.50 207.18 558.54 1696.76 2590.73 4095.73 1709.49 518.22

1981 276.28 181.46 163.16 287.81 1073.40 1130.79 3388.59 4540.02 5335.65 3607.75 1306.71 423.76 1820.74

1982 274.79 180.64 247.16 309.03 785.54 1912.42 3393.07 3983.72 5065.59 4640.83 1471.84 484.99 1906.68

1983 263. 96 172. 78 117. 98 157. 79 365. 52 1229. 94 3994. 92 4263. 12 1922. 04 663. 58 370. 00

1984 225.88 147.27 166.14 294.37 489.84 1335.65 1806.30 2570.19 3820.99 2986.11 1056.71 408.83 1281.12

1985 369.21 660.84 998.46

1986 183.69 118.22 169.88 214.12 523.45 876.16 3133.59 2683.69 4567.90 4177.87 1153.16 319.97 1519.47

1987 160. 54 104. 58 84. 01 122. 69

1988

1989 144. 68 71. 31 174. 77 496. 94

1990

1991

1992

19931994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

20082009

Average 251.64 177.96 188.64 298.79 690.13 1448.96 2558.30 3444.86 4373.84 3598.90 1319.33 440.06 1574.1

Average Runoff 14.6 9.3 10.9 16.8 40.0 81.3 148.3 199.7 245.4 208.6 74.0 25.5 1074.5




Hydrology Report

XVII

Ikot Okpara 1 2 3 4 5 6 7 8 9 10 11 12 365


1960

1961

1962

19631964

1965

1966

1967

1968

1969

1970

1971

1972

1973

1974

1975 306.90 311.67 165.40 302.08 710.50 1044.75 2154.64 2614.25 3565.59 4554.21 1630.02 610.44 1505.77

1976 285.99 318.49 365.89 481.48 1101.40 2115.74 3127.24 3690.26 4223.38 4566.91 2958.33 531.66 1989.14

1977 289.35 183.95 71.68 145.45 309.14 1182.48 2711.69 3837.74 5065.20 4831.24 1020.45 409.95 1681.76

1978 246.04 156.25 249.40 521.99 792.64 2265.05 2338.34 3225.81 4698.69 4543.01 1660.49 477.15 1772.071979 199.00 123.18 139.26 216.05 817.28 2180.17 2834.53 3918.38 4633.10 2932.35 1277.01 479.76 1653.63

1980 234. 47 127. 69 179. 01 547. 72 1792. 82 2630. 30 4557. 57 5516. 20 5026. 51 1890. 43

1981 275.16 186.01 161.66 266.98 1081.99 1224.15 3421.45 4768.89 5576.39 3881.42 1373.84 392.03 1895.64

1982 242.31 148.40 219.91 274.31 795.25 2000.39 3492.01 4124.85 5283.95 4800.63 1655.09 446.16 1968.00

1983 224.39 138.89 122.46 155.86 328.93 1209.49 2895.76 4223.42 4398.92 2144.56 849.92 304.29 1424.31

1984 204.97 127.71 143.00 274.69 504.78 1444.44 1974.31 2728.87 4266.59 3122.76 1120.76 390.53 1364.15

1985 198.25 121.53 97.07 391.20 729.91 1150.46 1899.64 3217.97 4197.53 3800.40 1304.40 379.70 1464.99

1986 212.07 135.17 215.43 318.67 641.05 1033.18 3266.13 3042.49 4629.63 4442.95 1538.97 389.04 1665.43

1987 219.16 140.13 117.98 218.75 268.07 796.30 1765.98 2771.80 5065.97 3729.09 905.48 316.23 1365.36

1988 187.05 148.87 143.00 179.78 349.09 883.49 1546.82 2740.82 4174.77 4398.52 1219.14 455.12 1376.21

1989 201.24 88.05 48.91 186.73 592.52 1273.92 2169.21 3931.45 5333.72 5113.87 1537.81 453.26 1754.12

1990

1991

1992

19931994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

20082009

Average 235.09 166.31 159.25 274.20 638.02 1439.79 2548.54 3559.64 4708.64 4125.90 1462.81 431.09 1654.4

Average Runoff 13.0 8.3 8.8 14.7 35.4 77.3 141.3 197.4 252.7 228.8 78.5 23.9 1080.2




Hydrology Report

XVIII

Annexe 8

Monthly flows for gauging stations used for Flow transposition by catchment area ratio method for

Egaga Fall and Busi II.

lkom 1 2 3 4 5 6 7 8 9 10 11 12


1960

1961

1962

1963

1964

1965

1966

1967

1968

1969

1970 1842.59 2211.39 1168.60 172.49

1971 21.65 20.25 173.61 182.10 266.20 965.28 2381.65 3091.40 2764.27 1547.57 594.91 311.01 1033.83

1972 158.68 118.53 326.31 266.20 404.72 1018.52 1416.14 2323.03 2966.82 1860.44 528.55 228.49 972.53

1973 133. 66 90. 11 112. 01 207. 56 404. 35 538. 97 993. 13 1404. 94 830. 25 1467. 29 629. 63 242. 68 592.37

1974 103.05 45.06 84.75 256.56 441.31 1070.60 1098.42 1837.66 2642.75 2144.56 444.44 317.73 878.20

1975 153.82 103.34 99.69 189.04 370.74 477.62 397.63 1745.82 2280.09 2763.22 1601.85 209.08 869.29

1976 274.04 228.69 167.82 131.05 2592.21 2459.68

1977 72. 06 119. 60 255. 00 1867. 16 2101. 25 2577.93 1967. 22

1978 1606.87 2054.96 668.60 199.00

1979 1390.38 2491.41 2236.11 1395.61 654.71 232.23

1980 101.18 81.02 116.86 109.18 317.35 900.46 1393.37 2231.93 2683.64 2004.55 891.59 298.31 932.01

1981 177.72 97.55 296.45 195.99 616.79 725.69 2011.65 2351.40 2485.73 1387.77 723.38 263.96 950.50

1982 177.72 131.04 151.58 221.45 509.63 1161.65 1823.10 2663.53 2658.95 1870.52 786.27 308.02 1044.24

1983 171.74 99.62 42.56 117.67 237.08 769.68 1848.12 2504.85 2254.24 1176.82 125.39 259.11 806.16

1984 141.88 80.62 113.50 201.00 266.95 624.23 1180.56 1218.26 1942.90 1670.77 318.29

1985

1986 186.68 171.13 204.97 172.84 404.72 1418.21 1730.88 1936.98 2408.18 2190.11 738.04 257.62 989.54

1987 173.98 171.96 179.96 175.93 405.09 654.32 858.35 1449.75 2092.21 1852.23 471.45 218.04 728.47

1988 126.19 55.08 75.04 118.06 234.09 532.41 1059.59 1628.96 2013.50 2149.42 576.39 244.18 739.16

1989 120.22 54.15 42.94 136.96 313.25 611.50 1064.81 1972.07 2304.40 2019.12 566.74 203.11 788.78

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

2008

2009

Average 148.15 103.21 139.49 177.37 348.65 819.22 1407.18 2059.58 2272.82 1904.91 675.81 247.82 863.5

Average Runoff 23.5 14.8 22.1 27.2 55.3 125.6 223.0 326.4 348.6 301.9 103.7 39.3 1611.3




Hydrology Report

XIX

Katsina‐Ala 1 2 3 4 5 6 7 8 9 10 11 12


1960 134. 77 48. 66 41. 48 228. 60 416. 23 727. 60 989. 26 1080. 84 1532. 33 1904. 03 775. 49 312. 27 686.38

1961

1962 58. 81 22. 18 129. 52 320. 53 455. 81 865. 30 1177. 26 984. 39 1561. 00 2037. 74 984. 39 508. 29 762.91

1963 178. 39 55. 89 52. 55 202. 60 649. 55 772. 87 985. 45 1168. 06 1566. 33 1649. 68 720. 97 263. 94 692.671964 122. 16 44. 31 47. 13 219. 10 366. 94 800. 60 959. 61 623. 26 1664. 00 2060. 65 1090. 30 440. 00 705.95

1965

1966 116.85 27.57 29.58 164.47 564.42 1250.37 1325.90 1336.88 2014.39 1885.81 782.03 281.00 818.80

1967 105. 00 34. 00 16. 00 56. 97 254. 26 740. 87 1315. 48 1108. 81 1693. 67 2280. 00 860. 40 297. 65 734.80

1968

1969

1970 122.46 74.82 129.18 359.95 577.58 1013.50 1306.38 1090.20 1646.60 1770.83 836.42 303.17 772.83

1971 125.82 74.82 106.48 447.90 305.13 529.87 1811.87 1387.87 2194.27 2470.48 505.63 454.75 873.86

1972 164.28 148.07 203.11 400.08 645.16 853.43 1377.10 1570.97 2167.33 2651.61 1150.08 190.41 964.81

1973 80. 65 46. 30 80. 66 70. 10 183. 03 471. 53 595. 71 903. 06 1610. 33 1808. 71 423. 87 77. 00 531.96

1974 127.00 76.21 76.29 154.00 344.42 459.88 1532.26 1274.27 2129.63 2192.26 1046.30 557.80 835.78

1975 77.28 46.30 60.74 106.30 298.47 572.70 1706.06 1 022.25 1 750.00 1 920.55 833.33 271.06 726.62

1976 157.93 120.53 153.68 301.73 441.77 869.00 1224.00 1536.00 1949.85 2019.12 956.79 377.46 846.31

1977 70. 94 42. 99 54. 88 160. 11 477. 52 836. 42 1132. 39 958. 03 1446. 37 1499. 78 709. 88 283. 75 642.69

1978 122.46 100.03 174.36 346.45 848.27 913.40 1075.61 1089.71 2096.33 2530.65 829.20 444.00 885.481979 208.00 55.79 57.65 57.70 357.77 1010.97 1363.74 1543.42 1700.00 1660.00 711.20 302.71 756.85

1980 126. 84 26. 17 25. 55 60. 23 290. 47 713. 35 1054. 73 1280. 62 1500. 00 1628. 96 673. 23 354. 69 648.64

1981 132.17 53.39 39.45 128.77 510.13 605.93 1145.68 1426.00 1951.67 1303.68 621.73 177.97 678.15

1982 68.19 33.04 97.26 111.97 342.58 662.45 1351.84 1 530.10 2 093.00 2 031.45 632.77 194.13 767.16

1983 96. 70 60. 76 61. 23 60. 19 96. 70 463. 35 1099. 91 1 590. 13 1 733. 41 1 767. 47 556. 71 277. 40 659.69

1984 57. 12 55. 08 57. 12 57. 10 95. 21 676. 31 1061. 45 1 118. 58 1 682. 87 1 611. 04 584. 49 188. 17 606.62

1985

1986

1987

1988

1989

1990

1991

1992

19931994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

20082009

Average 116.85 59.38 80.66 191.18 405.78 752.84 1218.65 1220.16 1794.45 1937.36 775.49 312.27 742.8

Average Runoff 18.6 8.6 12.9 29.5 64.7 116.2 194.4 194.7 277.0 309.1 119.7 49.8 1395.3




Hydrology Report

XX

Annexe 9

Monthly flows for gauging stations used for Flow transposition by catchment area ratio method for

Tapa.

31 28 31 30 31 30 31 31 30 31 30 31

Izom 1 2 3 4 5 6 7 8 9 10 11 12


1960

1961

1962

1963

1964

1965

1966

1967

1968

1969

1970 5. 79 33.98 60. 19 156. 06 439.07 597. 99 156. 44 34. 34 10. 83

1971 6.35 2.89 1.87 13.12 28.38 68.67 175.10 488.35 515.05 231.11 45.91 10.83 133.051972 5.60 2.39 3.36 9.26 60.48 166.67 257.24 614.17 314.04 166.89 32.79 13.44 138.37

1973 8.21 3.72 1.49 8.87 19.04 46.68 97.45 420.77 394.68 165.40 47.45 17.55 103.18

1974 7.84 3.31 1.12 9.65 61.23 63.27 232.97 323.33 674.38 232.60 48.61 18.29 140.19

1975 9.33 4.55 2.99 13.12 38.08 71.37 221.77 420.40 538.19 398.75 43.98 6.35 148.37

1976 3.36 3.99 2.99 4.24 47.04 99.15 192.65 276.28 260.80 379.70 112.27

1977 39.58 35.96 25.76 54.78 104.17 86.03 185.56 213.19 378.09 279.64 33.56 7.84 120.85

1978 3.36 1.24 6.35 28.16 54.51 126.54 259.86 288.98 799.00 370.00 26.88

1979 15.31 10.33 6.35 16.98 98.57 104.55 260.23 355.44 484.18 334.90 71.76 25.76 149.61

1980 11.57 1.60 0.00 5.40 26.14 104.55 308.39 313.62 413.58 222.52 61.73 23.52 125.15

1981 14.19 7.85 32.86 6.56 61.98 76.00 216.55 349.46

1982

1983

1984

1985

19861987

1988

1989

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

2008

2009

Average 11.34 7.08 7.74 14.66 52.80 89.47 213.65 375.26 488.18 267.09 53.24 16.13 133.8

Average Runoff 4.9 2.8 3.3 6.1 22.8 37.4 92.3 162.0 204.0 115.3 22.2 7.0 680.1




Hydrology Report

XXI

31 28 31 30 31 30 31 31 30 31 30 31

Ebba 1 2 3 4 5 6 7 8 9 10 11 12


1960

1961

19621963

1964

1965

1966

1967

1968

1969

1970 1.49 1.24 1.12 0.77 1.12 1.54 2.99 17.55 91.82 32.86 5.79 2.24 13.35

1971 1.12 0.83 0.75 0.77 1.87 1.54 13.44 48.54 86.81 25.76 5.02 2.24 15.76

1972 1.49 0.80 0.37 1.16 1.12 1.93 10.83 27.26 50.15 18.67 2.70 0.75 9.80

1973 0.37 0.00 0.00 0.00 0.00 0.39 1.12 17.55 27.01 17.17 3.09 0.75 5.64

1974 0.00 0.00 0.00 0.00 0.37 2.31 3.73 16.43 62.50 53.39 6.56 1.49 12.27

1975 0.75 0.41 0.37 0.77 0.75 0.77 17.55 21.65 69.83 56.75 8.49 1.12 15.00

1976 0.00 0.00 0.00 0.00 0.00 3.86 7.47 9.71 25.46 39.58 17.75 1.49 8.82

1977 0.75 0.41 0.00 0.00 1.12 1.54 1.49 36.59 93.36 59.74 7.33 2.61 17.121978 0.75 0.41 0.37 0.39 0.37 1.93 5.97 51.52 101.47 34.72 10.80 2.99 17.66

1979 0.75 0.83 0.75 0.77 1.49 2.70 13.07 57.50 47.84 18.67 6.94 2.99 12.94

1980 1.12 0.80 0.75 0.77 1.12 1.54 2.99 24.27 67.13 31.74 8.10 2.24 11.89

1981

1982

1983

1984

1985

1986

1987

1988

1989

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

2008

2009

Average 0.78 0.52 0.41 0.49 0.85 1.82 7.33 29.87 65.76 35.37 7.51 1.90 12.7

Average Runoff 1.1 0.7 0.6 0.7 1.2 2.5 10.4 42.2 89.9 50.0 10.3 2.7 212.1




Hydrology Report

XXII

31 28 31 30 31 30 31 31 30 31 30 31

Kachia 1 2 3 4 5 6 7 8 9 10 11 12


1960

1961

19621963

1964

1965

1966

1967

1968

1969

1970

1971

1972 0.04 1.27 2.12 5.34 8.18 2.74 1.38 0.58 0.30

1973 0.19 0.12 0.07 0.15 0.63 1.12 2.80 6.50 4.32 1.72 0.89 0.56 1.60

1974 0.41 0.25 0.15 0.96 2.05 1.39 5.86 3.77 5.71 1.64 0.81 0.56 1.98

1975 0.52 0.45 0.52 0.69 1.64 2.08 4.22 3.96 6.02 1.68 0.62 0.34 1.90

1976 0.26 0.20 0.11 0.27 0.78 0.73 2.95 2.65 2.85 3.55 0.96 0.56 1.33

1977 0.34 0.29 0.15 0.31 0.82 2.12 2.65 2.20 2.58 1.72 0.46 0.41 1.181978 0.34 0.29 0.26

1979 0.52 0.45 0.41 0.42 1.64 1.27 2.87 3.29 2.78 1.75 1.04 0.63 1.43

1980 0.52 0.44 0.37 0.50 1.05 2.70 2.50 2.80 1.31 1.31 0.58 0.37 1.21

1981

1982

1983

1984

1985

1986

1987

1988

1989

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

2008

2009

Average 0.39 0.31 0.26 0.42 1.24 1.69 3.65 4.17 3.54 1.84 0.74 0.47 1.6

Average Runoff 8.4 6.1 5.5 8.8 26.7 35.4 78.8 90.0 74.0 39.8 15.5 10.1 399.1




Hydrology Report

XXIII

31 28 31 30 31 30 31 31 30 31 30 31

Kaeia 1 2 3 4 5 6 7 8 9 10 11 12


1960

1961

19621963

1964

1965

1966

1967

1968

1969

1970

1971

1972 0.46 5.90 0.81 1.68 24.83 23.84 7.73 2.04 1.12

1973 0.78 0.62 0.71 1.54 1.64 4.86 9.00 25.09 31.21 10.04 1.66 0.41 7.32

1974 0.30 0.21 0.19 1.12 6.20 4.32 17.85 24.53 36.42 7.32 2.20 1.16 8.52

1975 0.78 0.58 0.56 1.43 4.67 5.52 22.81 20.80 29.55 8.06 2.12 1.23 8.22

1976 0.93 0.80 0.34 6.40 3.81 7.14 12.66 16.24 16.05 13.03 3.94 2.54 7.02

1977 2.09 1.49 1.27 1.08 2.46 7.41 9.56 11.20 16.98 11.39 2.35 1.46 5.751978 1.05 0.74 1.94

1979 0.37 0.25 0.19 0.46 3.17 1.47 25.61 14.45 21.53 16.13 3.51 0.86 7.40

1980 0.41 0.20 0.07 3.17 8.14 19.79 21.51 24.00 14.52 3.63 1.01

1981

1982

1983

1984

1985

1986

1987

1988

1989

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

2008

2009

Average 0.84 0.61 0.66 1.79 3.88 4.96 14.87 19.83 24.95 11.03 2.68 1.22 7.3

Average Runoff 4.0 2.6 3.2 8.3 18.6 23.0 71.2 95.0 115.7 52.8 12.4 5.9 412.7




Hydrology Report

XXIV

Annexe 10

Monthly flows at Egaga Fall obtained by flow transposition by catchment area ratio method, from the

source gauging stations Ikom and Katsina-Ala.

10.9 31 28 31 30 31 30 31 31 30 31 30 31 365

Source 1 2 3 4 5 6 7 8 9 10 11 12

Ikom Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual

1960

1961

1962

1963

1964

1965

1966

1967

1968

1969

1970 1.25 1.50 0.79 0.12

1971 0.01 0.01 0.12 0.12 0.18 0.65 1.61 2.09 1.87 1.05 0.40 0.21 0.701972 0.11 0.08 0.22 0.18 0.27 0.69 0.96 1.57 2.01 1.26 0.36 0.15 0.66

1973 0.09 0.06 0.08 0.14 0.27 0.36 0.67 0.95 0.56 0.99 0.43 0.16 0.40

1974 0.07 0.03 0.06 0.17 0.30 0.72 0.74 1.24 1.79 1.45 0.30 0.21 0.59

1975 0.10 0.07 0.07 0.13 0.25 0.32 0.27 1.18 1.54 1.87 1.08 0.14 0.59

1976 0.19 0.15 0.11 0.09 1.75 1.66

1977 0.05 0.08 0.17 1.26 1.42 1.74 1.33

1978 1.09 1.39 0.45 0.13

1979 0.94 1.69 1.51 0.94 0.44 0.16

1980 0.07 0.05 0.08 0.07 0.21 0.61 0.94 1.51 1.82 1.36 0.60 0.20 0.63

1981 0.12 0.07 0.20 0.13 0.42 0.49 1.36 1.59 1.68 0.94 0.49 0.18 0.64

1982 0.12 0.09 0.10 0.15 0.34 0.79 1.23 1.80 1.80 1.27 0.53 0.21 0.71

1983 0.12 0.07 0.03 0.08 0.16 0.52 1.25 1.69 1.53 0.80 0.08 0.18 0.55

1984 0.10 0.05 0.08 0.14 0.18 0.42 0.80 0.82 1.31 1.13 0.22

Average Flow (m3/s) 0.10 0.07 0.10 0.13 0.24 0.56 1.00 1.46 1.55 1.26 0.48 0.17 0.60

Average Runoff

(mm) 24.4 15.0 24.0 30.0 58.5 132.8 246.6 359.7 368.6 310.1 113.1 42.1 1724.8




Hydrology Report

XXV

7.9 31 28 31 30 31 30 31 31 30 31 30 31 365

Source 1 2 3 4 5 6 7 8 9 10 11 12

Katsina‐Ala Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual

1960 0.06 0.02 0.02 0.11 0.20 0.34 0.47 0.51 0.72 0.90 0.36 0.15 0.32

1961

1962 0.03 0.01 0.06 0.15 0.21 0.41 0.55 0.46 0.73 0.96 0.46 0.24 0.361963 0.08 0.03 0.02 0.10 0.31 0.36 0.46 0.55 0.74 0.78 0.34 0.12 0.33

1964 0.06 0.02 0.02 0.10 0.17 0.38 0.45 0.29 0.78 0.97 0.51 0.21 0.33

1965

1966 0.05 0.01 0.01 0.08 0.27 0.59 0.62 0.63 0.95 0.89 0.37 0.13 0.39

1967 0.05 0.02 0.01 0.03 0.12 0.35 0.62 0.52 0.80 1.07 0.40 0.14 0.35

1968

1969

1970 0.06 0.04 0.06 0.17 0.27 0.48 0.61 0.51 0.77 0.83 0.39 0.14 0.36

1971 0.06 0.04 0.05 0.21 0.14 0.25 0.85 0.65 1.03 1.16 0.24 0.21 0.41

1972 0.08 0.07 0.10 0.19 0.30 0.40 0.65 0.74 1.02 1.25 0.54 0.09 0.45

1973 0.04 0.02 0.04 0.03 0.09 0.22 0.28 0.42 0.76 0.85 0.20 0.04 0.25

1974 0.06 0.04 0.04 0.07 0.16 0.22 0.72 0.60 1.00 1.03 0.49 0.26 0.39

1975 0.04 0.02 0.03 0.05 0.14 0.27 0.80 0.48 0.82 0.90 0.39 0.13 0.34

1976 0.07 0.06 0.07 0.14 0.21 0.41 0.58 0.72 0.92 0.95 0.45 0.18 0.40

1977 0.03 0.02 0.03 0.08 0.22 0.39 0.53 0.45 0.68 0.71 0.33 0.13 0.301978 0.06 0.05 0.08 0.16 0.40 0.43 0.51 0.51 0.99 1.19 0.39 0.21 0.42

1979 0.10 0.03 0.03 0.03 0.17 0.48 0.64 0.73 0.80 0.78 0.33 0.14 0.36

1980 0.06 0.01 0.01 0.03 0.14 0.34 0.50 0.60 0.71 0.77 0.32 0.17 0.31

1981 0.06 0.03 0.02 0.06 0.24 0.29 0.54 0.67 0.92 0.61 0.29 0.08 0.32

1982 0.03 0.02 0.05 0.05 0.16 0.31 0.64 0.72 0.98 0.96 0.30 0.09 0.36

1983 0.05 0.03 0.03 0.03 0.05 0.22 0.52 0.75 0.82 0.83 0.26 0.13 0.31

1984 0.03 0.03 0.03 0.03 0.04 0.32 0.50 0.53 0.79 0.76 0.28 0.09 0.29

Average Flow (m3/s) 0.05 0.03 0.04 0.09 0.19 0.35 0.57 0.57 0.84 0.91 0.36 0.15 0.35

Average Runoff (mm) 13.5 6.2 9.3 21.4 46.9 84.2 140.9 141.1 200.8 224.0 86.8 36.1 1011.3




Hydrology Report

XXVI

Annexe 11

Monthly flows at Egaga Fall

Egaga 1 2 3 4 5 6 7 8 9 10 11 12

10.9 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual

1960 0.09 0.03 0.03 0.15 0.27 0.47 0.64 0.70 0.99 1.24 0.50 0.20 0.44

1961

1962 0.04 0.01 0.08 0.21 0.30 0.56 0.76 0.64 1.01 1.32 0.64 0.33 0.49

1963 0.12 0.04 0.03 0.13 0.42 0.50 0.64 0.76 1.02 1.07 0.47 0.17 0.45

1964 0.08 0.03 0.03 0.14 0.24 0.52 0.62 0.40 1.08 1.34 0.71 0.29 0.46

1965

1966 0.08 0.02 0.02 0.11 0.37 0.81 0.86 0.87 1.31 1.22 0.51 0.18 0.53

1967 0.07 0.02 0.01 0.04 0.17 0.48 0.85 0.72 1.10 1.48 0.56 0.19 0.47

1968

1969

1970 0.08 0.05 0.08 0.23 0.37 0.66 0.85 0.71 1.07 1.15 0.54 0.20 0.50

1971 0.08 0.05 0.07 0.29 0.20 0.34 1.18 0.90 1.42 1.60 0.33 0.30 0.56

1972 0.11 0.10 0.13 0.26 0.42 0.55 0.89 1.02 1.41 1.72 0.75 0.12 0.62

1973 0.05 0.03 0.05 0.05 0.12 0.31 0.39 0.59 1.05 1.17 0.28 0.05 0.34

1974 0.08 0.05 0.05 0.10 0.22 0.30 0.99 0.83 1.38 1.42 0.68 0.36 0.54

1975 0.05 0.03 0.04 0.07 0.19 0.37 1.11 0.66 1.14 1.25 0.54 0.18 0.47

1976 0.10 0.08 0.10 0.20 0.29 0.56 0.79 1.00 1.27 1.31 0.62 0.25 0.55

1977 0.05 0.03 0.04 0.10 0.31 0.54 0.74 0.62 0.94 0.97 0.46 0.18 0.42

1978 0.08 0.06 0.11 0.22 0.55 0.59 0.70 0.71 1.36 1.64 0.54 0.29 0.57

1979 0.14 0.04 0.04 0.04 0.23 0.66 0.89 1.00 1.10 1.08 0.46 0.20 0.49

1980 0.08 0.02 0.02 0.04 0.19 0.46 0.68 0.83 0.97 1.06 0.44 0.23 0.42

1981 0.09 0.03 0.03 0.08 0.33 0.39 0.74 0.93 1.27 0.85 0.40 0.12 0.44

1982 0.04 0.02 0.06 0.07 0.22 0.43 0.88 0.99 1.36 1.32 0.41 0.13 0.49

1983 0.06 0.04 0.04 0.04 0.06 0.30 0.71 1.03 1.13 1.15 0.36 0.18 0.43

1984 0.04 0.04 0.04 0.04 0.06 0.44 0.69 0.73 1.09 1.05 0.38 0.12 0.39

Average Flow (m3/s) 0.08 0.04 0.05 0.12 0.26 0.49 0.79 0.79 1.17 1.26 0.50 0.20 0.48




Hydrology Report

XXVII

Annexe 12

Monthly flows at Busi II obtained by flow transposition by catchment area ratio method, from the

source gauging stations Ikom and Katsina-Ala.

7.9 31 28 31 30 31 30 31 31 30 31 30 31 365

Source 1 2 3 4 5 6 7 8 9 10 11 12

Ikom Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual

1960

1961

1962

1963

1964

1965

1966

1967

1968

1969

1970 0.90 1.08 0.57 0.08

1971 0.01 0.01 0.09 0.09 0.13 0.47 1.17 1.52 1.36 0.76 0.29 0.15 0.511972 0.08 0.06 0.16 0.13 0.20 0.50 0.69 1.14 1.45 0.91 0.26 0.11 0.48

1973 0.07 0.04 0.05 0.10 0.20 0.26 0.49 0.69 0.41 0.72 0.31 0.12 0.29

1974 0.05 0.02 0.04 0.13 0.22 0.52 0.54 0.90 1.30 1.05 0.22 0.16 0.43

1975 0.08 0.05 0.05 0.09 0.18 0.23 0.19 0.86 1.12 1.35 0.79 0.10 0.43

1976 0.13 0.11 0.08 0.06 1.27 1.21

1977 0.04 0.06 0.13 0.92 1.03 1.26 0.96

1978 0.79 1.01 0.33 0.10

1979 0.68 1.22 1.10 0.68 0.32 0.11

1980 0.05 0.04 0.06 0.05 0.16 0.44 0.68 1.09 1.32 0.98 0.44 0.15 0.46

1981 0.09 0.05 0.15 0.10 0.30 0.36 0.99 1.15 1.22 0.68 0.35 0.13 0.47

1982 0.09 0.06 0.07 0.11 0.25 0.57 0.89 1.31 1.30 0.92 0.39 0.15 0.51

1983 0.08 0.05 0.02 0.06 0.12 0.38 0.91 1.23 1.11 0.58 0.06 0.13 0.40

1984 0.07 0.04 0.06 0.10 0.13 0.31 0.58 0.60 0.95 0.82 0.16

Average Flow (m3/s) 0.07 0.05 0.07 0.09 0.17 0.40 0.73 1.06 1.12 0.91 0.34 0.12 0.43

Average Runoff

(mm) 17.7 10.8 17.4 21.7 42.4 96.2 178.7 260.7 267.1 224.8 81.9 30.5 1250.1




Hydrology Report

XXVIII

7.9 31 28 31 30 31 30 31 31 30 31 30 31 365

Source 1 2 3 4 5 6 7 8 9 10 11 12

Katsina‐Ala Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual

1960 0.06 0.02 0.02 0.11 0.20 0.34 0.47 0.51 0.72 0.90 0.36 0.15 0.32

1961

1962 0.03 0.01 0.06 0.15 0.21 0.41 0.55 0.46 0.73 0.96 0.46 0.24 0.361963 0.08 0.03 0.02 0.10 0.31 0.36 0.46 0.55 0.74 0.78 0.34 0.12 0.33

1964 0.06 0.02 0.02 0.10 0.17 0.38 0.45 0.29 0.78 0.97 0.51 0.21 0.33

1965

1966 0.05 0.01 0.01 0.08 0.27 0.59 0.62 0.63 0.95 0.89 0.37 0.13 0.39

1967 0.05 0.02 0.01 0.03 0.12 0.35 0.62 0.52 0.80 1.07 0.40 0.14 0.35

1968

1969

1970 0.06 0.04 0.06 0.17 0.27 0.48 0.61 0.51 0.77 0.83 0.39 0.14 0.36

1971 0.06 0.04 0.05 0.21 0.14 0.25 0.85 0.65 1.03 1.16 0.24 0.21 0.41

1972 0.08 0.07 0.10 0.19 0.30 0.40 0.65 0.74 1.02 1.25 0.54 0.09 0.45

1973 0.04 0.02 0.04 0.03 0.09 0.22 0.28 0.42 0.76 0.85 0.20 0.04 0.25

1974 0.06 0.04 0.04 0.07 0.16 0.22 0.72 0.60 1.00 1.03 0.49 0.26 0.39

1975 0.04 0.02 0.03 0.05 0.14 0.27 0.80 0.48 0.82 0.90 0.39 0.13 0.34

1976 0.07 0.06 0.07 0.14 0.21 0.41 0.58 0.72 0.92 0.95 0.45 0.18 0.40

1977 0.03 0.02 0.03 0.08 0.22 0.39 0.53 0.45 0.68 0.71 0.33 0.13 0.301978 0.06 0.05 0.08 0.16 0.40 0.43 0.51 0.51 0.99 1.19 0.39 0.21 0.42

1979 0.10 0.03 0.03 0.03 0.17 0.48 0.64 0.73 0.80 0.78 0.33 0.14 0.36

1980 0.06 0.01 0.01 0.03 0.14 0.34 0.50 0.60 0.71 0.77 0.32 0.17 0.31

1981 0.06 0.03 0.02 0.06 0.24 0.29 0.54 0.67 0.92 0.61 0.29 0.08 0.32

1982 0.03 0.02 0.05 0.05 0.16 0.31 0.64 0.72 0.98 0.96 0.30 0.09 0.36

1983 0.05 0.03 0.03 0.03 0.05 0.22 0.52 0.75 0.82 0.83 0.26 0.13 0.31

1984 0.03 0.03 0.03 0.03 0.04 0.32 0.50 0.53 0.79 0.76 0.28 0.09 0.29

Average Flow (m3/s) 0.05 0.03 0.04 0.09 0.19 0.35 0.57 0.57 0.84 0.91 0.36 0.15 0.35

Average Runoff (mm) 13.5 6.2 9.3 21.4 46.9 84.2 140.9 141.1 200.8 224.0 86.8 36.1 1011.3




Hydrology Report

XXIX

Annexe 13

Monthly flows at Busi II.

Busi II 1 2 3 4 5 6 7 8 9 10 11 12

7.9 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual

1960 0.06 0.02 0.02 0.11 0.20 0.34 0.47 0.51 0.72 0.90 0.36 0.15 0.32

1961

1962 0.03 0.01 0.06 0.15 0.21 0.41 0.55 0.46 0.73 0.96 0.46 0.24 0.36

1963 0.08 0.03 0.02 0.10 0.31 0.36 0.46 0.55 0.74 0.78 0.34 0.12 0.33

1964 0.06 0.02 0.02 0.10 0.17 0.38 0.45 0.29 0.78 0.97 0.51 0.21 0.33

1965

1966 0.05 0.01 0.01 0.08 0.27 0.59 0.62 0.63 0.95 0.89 0.37 0.13 0.39

1967 0.05 0.02 0.01 0.03 0.12 0.35 0.62 0.52 0.80 1.07 0.40 0.14 0.35

1968

1969

1970 0.06 0.04 0.06 0.17 0.27 0.48 0.61 0.51 0.77 0.83 0.39 0.14 0.36

1971 0.06 0.04 0.05 0.21 0.14 0.25 0.85 0.65 1.03 1.16 0.24 0.21 0.41

1972 0.08 0.07 0.10 0.19 0.30 0.40 0.65 0.74 1.02 1.25 0.54 0.09 0.45

1973 0.04 0.02 0.04 0.03 0.09 0.22 0.28 0.42 0.76 0.85 0.20 0.04 0.25

1974 0.06 0.04 0.04 0.07 0.16 0.22 0.72 0.60 1.00 1.03 0.49 0.26 0.39

1975 0.04 0.02 0.03 0.05 0.14 0.27 0.80 0.48 0.82 0.90 0.39 0.13 0.34

1976 0.07 0.06 0.07 0.14 0.21 0.41 0.58 0.72 0.92 0.95 0.45 0.18 0.40

1977 0.03 0.02 0.03 0.08 0.22 0.39 0.53 0.45 0.68 0.71 0.33 0.13 0.30

1978 0.06 0.05 0.08 0.16 0.40 0.43 0.51 0.51 0.99 1.19 0.39 0.21 0.42

1979 0.10 0.03 0.03 0.03 0.17 0.48 0.64 0.73 0.80 0.78 0.33 0.14 0.36

1980 0.06 0.01 0.01 0.03 0.14 0.34 0.50 0.60 0.71 0.77 0.32 0.17 0.31

1981 0.06 0.03 0.02 0.06 0.24 0.29 0.54 0.67 0.92 0.61 0.29 0.08 0.32

1982 0.03 0.02 0.05 0.05 0.16 0.31 0.64 0.72 0.98 0.96 0.30 0.09 0.36

1983 0.05 0.03 0.03 0.03 0.05 0.22 0.52 0.75 0.82 0.83 0.26 0.13 0.31

1984 0.03 0.03 0.03 0.03 0.04 0.32 0.50 0.53 0.79 0.76 0.28 0.09 0.29

Average Flow (m3/s) 0.05 0.03 0.04 0.09 0.19 0.35 0.57 0.57 0.84 0.91 0.36 0.15 0.35




Hydrology Report

XXX

Annexe 14

Monthly flows at Tapa obtained by flow transposition by catchment area ratio method, from each of

the source gauging stations (Izom, Ebba, Kaeia, Kachia).

31 28 31 30 31 30 31 31 30 31 30 31 365

Source 1 2 3 4 5 6 7 8 9 10 11 12

Izom Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual

1960

1961

1962

1963

1964

1965

1966

1967

1968

1969

1970

1971 0.71 0.32 0.21 1.47 3.17 7.68 19.59 54.64 57.62 25.86 5.14 1.21 14.89

1972 0.63 0.27 0.38 1.04 6.77 18.65 28.78 68.71 35.14 18.67 3.67 1.50 15.48

1973 0.92 0.42 0.17 0.99 2.13 5.22 10.90 47.08 44.16 18.50 5.31 1.96 11.54

1974 0.88 0.37 0.13 1.08 6.85 7.08 26.07 36.17 75.45 26.02 5.44 2.05 15.68

1975 1.04 0.51 0.33 1.47 4.26 7.99 24.81 47.03 60.21 44.61 4.92 0.71 16.60

1976 0.38 0.45 0.33 0.47 5.26 11.09 21.55 30.91 29.18 42.48 12.56 1.87 13.15

1977 4.43 4.02 2.88 6.13 11.65 9.63 20.76 23.85 42.30 31.29 3.76 0.88 13.52

1978 0.38 0.14 0.71 3.15 6.10 14.16 29.07 32.33 89.39 41.40 6.19 3.01 18.89

1979 1.71 1.16 0.71 1.90 11.03 11.70 29.11 39.77 54.17 37.47 8.03 2.88 16.74

1980 1.29 0.18 0.00 0.60 2.92 11.70 34.50 35.09 46.27 24.90 6.91 2.63 14.00

1981

1982

1983

1984

Average

(m

3

/s) 1.24 0.78 0.58 1.83 6.02 10.49 24.52 41.56 53.39 31.12 6.19 1.87 15.05




Hydrology Report

XXXI

31 28 31 30 31 30 31 31 30 31 30 31 365

Source 1 2 3 4 5 6 7 8 9 10 11 12

Ebba Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual

1960

1961

19621963

1964

1965

1966

1967

1968

1969

1970 0.55 0.45 0.41 0.28 0.41 0.56 1.09 6.42 33.61 12.03 2.12 0.82 4.89

1971 0.41 0.30 0.27 0.28 0.68 0.56 4.92 17.77 31.77 9.43 1.84 0.82 5.77

1972 0.55 0.29 0.14 0.42 0.41 0.71 3.96 9.98 18.36 6.83 0.99 0.27 3.59

1973 0.14 0.00 0.00 0.00 0.00 0.14 0.41 6.42 9.89 6.29 1.13 0.27 2.07

1974 0.00 0.00 0.00 0.00 0.14 0.85 1.37 6.01 22.88 19.54 2.40 0.55 4.49

1975 0.27 0.15 0.14 0.28 0.27 0.28 6.42 7.93 25.56 20.77 3.11 0.41 5.49

1976 0.00 0.00 0.00 0.00 0.00 1.41 2.73 3.55 9.32 14.49 6.50 0.55 3.23

1977 0.27 0.15 0.00 0.00 0.41 0.56 0.55 13.39 34.17 21.87 2.68 0.96 6.27

1978 0.27 0.15 0.14 0.14 0.14 0.71 2.19 18.86 37.14 12.71 3.95 1.09 6.47

1979 0.27 0.30 0.27 0.28 0.55 0.99 4.78 21.05 17.51 6.83 2.54 1.09 4.74

1980 0.41 0.29 0.27 0.28 0.41 0.56 1.09 8.88 24.57 11.62 2.97 0.82 4.35

1981

1982

1983

1984

Average (m3/s) 0.29 0.19 0.15 0.18 0.31 0.67 2.68 10.93 24.07 12.95 2.75 0.70 4.67




Hydrology Report

XXXII

31 28 31 30 31 30 31 31 30 31 30 31 365

Source 1 2 3 4 5 6 7 8 9 10 11 12

Kaeia Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual

1960

1961

19621963

1964

1965

1966

1967

1968

1969

1970

1971

1972

1973 0.97 0.77 0.88 1.92 2.04 6.04 11.17 31.15 38.75 12.47 2.06 0.51 9.09

1974 0.37 0.26 0.23 1.39 7.69 5.36 22.16 30.45 45.22 9.09 2.73 1.44 10.58

1975 0.97 0.72 0.70 1.77 5.79 6.85 28.32 25.82 36.69 10.01 2.63 1.53 10.21

1976 1.16 0.99 0.42 7.95 4.73 8.86 15.71 20.16 19.93 16.18 4.89 3.15 8.72

1977 2.60 1.85 1.58 1.34 3.06 9.20 11.87 13.91 21.07 14.14 2.92 1.81 7.14

1978

1979 0.46 0.31 0.23 0.57 3.94 1.82 31.80 17.94 26.73 20.02 4.36 1.07 9.18

1980 0.51 0.25 0.09 2.49 3.94 10.11 24.57 26.70 29.79 18.03 4.50 1.25 10.25

1981

1982

1983

1984

Average (m3/s) 1.01 0.73 0.59 2.49 4.46 6.89 20.80 23.73 31.17 14.28 3.44 1.54 9.31




Hydrology Report

XXXIII

31 28 31 30 31 30 31 31 30 31 30 31 365

Source 1 2 3 4 5 6 7 8 9 10 11 12

Kachia Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual

1960

1961

19621963

1964

1965

1966

1967

1968

1969

1970

1971

1972

1973 1.04 0.69 0.42 0.86 3.55 6.26 15.67 36.36 24.18 9.61 4.97 3.13 8.96

1974 2.30 1.39 0.84 5.40 11.49 7.77 32.81 21.10 31.96 9.19 4.53 3.13 11.06

1975 2.93 2.54 2.93 3.89 9.19 11.66 23.61 22.15 33.68 9.40 3.45 1.88 10.65

1976 1.46 1.12 0.63 1.51 4.39 4.10 16.51 14.84 15.98 19.85 5.40 3.13 7.47

1977 1.88 1.62 0.84 1.73 4.60 11.88 14.84 12.33 14.47 9.61 2.59 2.30 6.58

1978

1979 2.93 2.54 2.30 2.38 9.19 7.13 16.09 18.39 15.55 9.82 5.83 3.55 8.02

1980 2.93 2.46 2.09 2.81 5.85 15.11 14.00 15.67 7.34 7.31 3.24 2.09 6.77

1981

1982

1983

1984

Average (m3/s) 2.21 1.77 1.43 2.65 6.90 9.13 19.08 20.12 20.45 10.69 4.29 2.75 8.50




Hydrology Report

Annexe 15

Monthly flows at Tapa

Tapa 1 2 3 4 5 6 7 8 9 10 11 12


1960

1961

1962

1963

1964

1965

1966

1967

1968

1969

1970 0.55 0.45 0.41 0.28 0.41 0.56 1.09 6.42 33.61 12.03 2.12 0.82 4.89

1971 0.41 0.30 0.27 0.28 0.68 0.56 4.92 17.77 31.77 9.43 1.84 0.82 5.77

1972 0.55 0.29 0.14 0.42 0.41 0.71 3.96 9.98 18.36 6.83 0.99 0.27 3.59

1973 0.14 0.00 0.00 0.00 0.00 0.14 0.41 6.42 9.89 6.29 1.13 0.27 2.07

1974 0.00 0.00 0.00 0.00 0.14 0.85 1.37 6.01 22.88 19.54 2.40 0.55 4.49

1975 0.27 0.15 0.14 0.28 0.27 0.28 6.42 7.93 25.56 20.77 3.11 0.41 5.49

1976 0.00 0.00 0.00 0.00 0.00 1.41 2.73 3.55 9.32 14.49 6.50 0.55 3.23

1977 0.27 0.15 0.00 0.00 0.41 0.56 0.55 13.39 34.17 21.87 2.68 0.96 6.27

1978 0.27 0.15 0.14 0.14 0.14 0.71 2.19 18.86 37.14 12.71 3.95 1.09 6.47

1979 0.27 0.30 0.27 0.28 0.55 0.99 4.78 21.05 17.51 6.83 2.54 1.09 4.74

1980 0.41 0.29 0.27 0.28 0.41 0.56 1.09 8.88 24.57 11.62 2.97 0.82 4.35

1981

1982

1983

1984

Average Flow (m3/s) 0.29 0.19 0.15 0.18 0.31 0.67 2.68 10.93 24.07 12.95 2.75 0.70 4.67

06b 2014 wp 4 hydrology report

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