usaid ethiopia attachment j1.1 - health centers ground water … · 2018-07-09 · study document...

USAID ETHIOPIA FROM THE AMERICAN PEOPLE HEALTH INFRASTRUCTURE PROGRAM

Ethiopia Health Infrastructure Program (EHIP)

ealth Centers Groundwater Investigation inal Report

ebruary 2016

HF

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This publication was produced for review by the United States Agency for International Development. It was prepared by Tetra Tech, Inc.

STUDY DOCUMENT OF POTENTIAL WATER SOURCES ASSESSMENT FOR 17 HEALTH CENTERS

Table of Contents ACKNOWLEDGMENTS ..................................................................................................8 EXECUTIVE SUMMARY ................................................................................................9 PART I. .......................................................................................................................................11 GENERAL OVERVIEW AND VERIFICATIONS OF THE STUDY......................................11 I. INTRODUCTION ...............................................................................................................12 1.1. Background.................................................................................................................................... 12

1.2. Objectives of the study ............................................................................................................. 14

1.3. Approach and Methodology of the study ...................................................................................... 15

1.3.1. Desk study......................................................................................................................... 15

1.3.2. Field investigation............................................................................................................. 15

1.4. Discussion with local residents, office staffs and Experts ........................................................ 17

1.5. Location and accessibility of the Project Areas ........................................................................ 20

II. EXISTING WATER SUPPLY SYSTEMS, POPULATION AND INFRASTRUCTURE .. 24

2.1. Existing situation and management of water Supply schemes ...................................................... 24

2.2. Population...................................................................................................................................... 26

2.3. Economic activity .......................................................................................................................... 27

2.4. Infrastructure ................................................................................................................................. 27

III. CLIMATE AND PHYSIOGRAPHY ..................................................................................28 3.1. Climate .......................................................................................................................................... 28

3.2. Physiography of the study areas .................................................................................................... 30

IV. GEOLOGY ..........................................................................................................................32 4.1. Regional Geology .......................................................................................................................... 32

4.2. Local Geology of the Study Areas................................................................................................. 35

4.2.1. Volcanic Rocks....................................................................................................................... 36

4.2.2. Quaternary Sediments............................................................................................................. 38

V. HYDRO-GEOLOGICAL INVESTIGATION ....................................................................39 5.1. General .......................................................................................................................................... 39

5.2. Hydro stratigraphic Units .............................................................................................................. 39

5.3. Recharge and Discharge Conditions.............................................................................................. 40

5.4. Aquifer characteristic................................................................................................................ 41

5.5. Groundwater Flow and Occurrence............................................................................................... 42

5.6. Feasible Hydro-geological site identification ........................................................................... 42

VI. GEOPHYSICAL SURVEYING..........................................................................................44 6.1. General .......................................................................................................................................... 44

6.2. Methodology of Geophysical survey............................................................................................. 45

6.3. Data Interpretation .................................................................................................................... 46

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VII. WATER QUALITY.............................................................................................................48 7.1. General ........................................................................................................................................ 48

7.2. In situ water quality test .............................................................................................................. 49

7.3. Water Type Classifications.............................................................................................................. 51

7.4. Water quality for drinking ............................................................................................................... 53

7.5. Overview of water pollution ............................................................................................................ 55

VIII. ENVIRONMENTAL ASSESSMENTS AND RECOMMENDED MANAGEMENT OPTIONS....................................................................................................................................57 PART II. ..................................................................................................................................... 59 VERIFICATIONS AND STUDY FINDINGS FOR EACH PROJECT AREA ........................ 59 1. Gerbicho Health center ................................................................................................................... 59

1.1. General......................................................................................................................................... 59

1.2. Geology and Hydro-geology........................................................................................................ 62

1.3. Geophysical data collection and Interpretation Result............................................................ 64

1.4. Conclusion and Recommendation ............................................................................................... 67

II. Wechemo Health Center............................................................................................................ 68

1.6. General......................................................................................................................................... 68




III. Haro Health center..................................................................................................................... 75

3.1. General......................................................................................................................................... 75




IV. Kedida Health center ................................................................................................................. 85

4.1. General......................................................................................................................................... 85


4.3. Geophysical data collection and Interpretation Result ................................................................ 88


V. Wodito Health Center ..................................................................................................................... 91

5.1. General......................................................................................................................................... 91




VI. Agumamit Health Center........................................................................................................... 99

6.1. General......................................................................................................................................... 99

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6.2. Geology and Hydro-geology ...................................................................................................101

6.3. Geophysical data collection and Interpretation Result............................................................103

6.4. Conclusion and Recommendations .........................................................................................105

VII. Kuni Sankistak Health Center ................................................................................................105

7.1. General.................................................................................................................................105

7.2. Geology and Hydro-geology ....................................................................................................107

7.3. Geophysical data collection and Interpretation Result ........................................................108

7.4. Conclusion and Recommendations ..........................................................................................111

VIII. Gulem Denjin Health Center ..................................................................................................111

8.1. General.................................................................................................................................111




IX. Lideta Health Center ..............................................................................................................116

9.1. General .....................................................................................................................................116




X. Kachana Gudie Health Center .....................................................................................................122

10.1. General.............................................................................................................................122

10.2. Geology and Hydro-geology............................................................................................122

10.3. Geophysical data collection and Interpretation Result.....................................................124

10.4. Conclusion and Recommendations..................................................................................126

XI. Addis Betechristian Health Center .........................................................................................127

11.1. General.............................................................................................................................127




XII. Gult Health Center..................................................................................................................135

12.1. General.............................................................................................................................135




XIII. Maksegnit Health Center........................................................................................................142

13.1. General.............................................................................................................................142


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13.3. Geophysical data collection and Interpretation Result......................................................144

13.4. Conclusion and Recommendations ...................................................................................145

XIV. Angot Health center .............................................................................................................145

14.1. General ..............................................................................................................................145

14.2. Geology and Hydro-geology.............................................................................................148


14.4. Conclusion and Recommendation.....................................................................................151

XV. Beta Health Center ....................................................................................................................151

15.1. General ..............................................................................................................................151


15.3. Conclusion and Recommendations ...................................................................................152

XVI. Gelsha Health center............................................................................................................153

16.1. General ..............................................................................................................................153




XVII. Zerit Health center ...............................................................................................................159

17.1. General ..............................................................................................................................159




PART III................................................................................................................................... 169 GENERAL CONCLUSIONS AND RECOMMENDATIONS................................................169 GENERAL CONCLUSIONS AND RECOMMENDATIONS................................................170

List of Tables

Table 1. Main informants from the respective project areas ...................................................................... 18

Table 2. Studied Project areas .................................................................................................................... 20

Table 3. Population Growth computed for Urban and Rural areas............................................................ .25

Table 4. Population size of the project areas .............................................................................................. 26

Table 5. Classification of Climate zone on the basis of altitude................................................................. 29

Table 6. VES Survey points at the respective project areas ....................................................................... 44

Table 7. Measured Physical parameters ..................................................................................................... 50

Table 8. Chemistry of representative samples/anions and cations (mg/l)................................................... 51

Table 9. Drinking Water Quality for different Countries ........................................................................... 54

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Table 10. Interpretation Result of VES 1 of Gerbicho................................……………………………………..65

Table 20. Interpretation Result of VES 1, Agumamit................................……………………………………104

Table 21. Interpretation Result of VES 1, Kuni................................................................……………………………………109

Table 22. Interpretation Result of VES 2, Kuni................................................................……………………………………110

Table 23. Interpretation Result of VES 1, Guluem Denjen ................................……………………………………114

Table 24. Interpretation Result of VES 2, Gulem Denjin ................................……………………………………115

Table 25. Interpretation Result of VES 1, Lideta ................................……………………………………120

Table 26. Interpretation Result of VES 2, Lideta ................................……………………………………121

Table 27. Interpretation Result of VES 1, Kuchana Gudie................................……………………………………125

Table 28. Interpretation Result of VES2Kachana, Gudie ................................……………………………………126

Table 29. Interpretation Result of VES1, Adis Betechrstian ................................……………………………………133

Table 30. Interpretation Result of VES2, Adis Betechrstian ................................……………………………………134

Table 31. Interpretation Result of VES1, Gult................................................................……………………………………140

Table 32. Interpretation Result of VES 2, Gult................................................................……………………………………141

Table 33. Interpretation Result of , VES1, Maksegnit ................................……………………………………144

Table 34. Interpretation Result of VES1, Angot................................……………………………………151

Table 35. Interpretation Result of VES1, Gelsha................................……………………………………159

Table 36. Interpretation Result of VES 1, Zerit ................................................................……………………………………165



Table 39. Revised Recommended Sites ................................................................…………………………………172

Table 11. Interpretation Result of VES 2, Gerbicho................................……………………………………..66

Table 12. Interpretation Result of VES 3, Gerbicho................................……………………………………..67

Table 13. Interpretation Result of VES 1, Wechemo................................……………………………………..73

Table 14. Interpretation Result of Haro VES 1................................................................……………………………………..81

Table 15. Interpretation Result of VES2, Haro................................................................……………………………………..82

Table 16. Interpretation Result of VES 3, Haro................................................................…………………………………….83

Table 17. Interpretation Result of VES 1, Kedida ................................…………………………………….90

Table 18. Interpretation Result of VES 1, Wadito ................................…………………………………….97

Table 19. Interpretation Result of VES 2, Wadito ................................…………………………………….98

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List of Pictures

Picture 1. Discussion with community members and officials..................................................... 18

Picture 2. Discussion with the local people on selection of suitable water sources .................... 18

Picture 3. Traditional hand dug well, poorly constructed spring and hand dug wells ................. 26

Picture 4. Ignimbrite rock ............................................................................................................ 37

Picture 5. Fractured basalt............................................................................................................ 37

Picture 6. Coarse deposit close to foot of mountain along river Valley ...................................... 38

Picture 7. Geophysical VES survey in the compound of Health center ...................................... 47

Picture 8. Geophysical VES survey at the surrounding of Health center .................................... 48

Picture 9. In situ Water sample collection and Quality Testing .................................................. 50

Picture 10. Deep well in Haro town............................................................................................. 76

Picture 11. Haro Health center and excavated pipe line very close to the Health center ............ 84

Picture 12. Kedida poorly constructed spring.............................................................................. 86

Picture 13. Agumamit Health center............................................................................................ 99

List of Figures

Figure 1 . Location map of study areas in Amhara National Regional State (ANRS)................................ 22

Figure 2. Location map of study areas in SNNPR...................................................................................... 23

Figure 3. Main physiographic classification of Ethiopia ............................................................................ 34

Figure 4. Location map of Aleta Wondo, Dilla zuria and Yergachefe woredas in which four of the sites

are located in SNNPR ................................................................................................................................. 60

Figure 5. DEM enhanced map for Aleta wondo, Dilla Zuria and Yerga chefe woredas in SNNPR .......... 61

Figure 6. Geological map of Gerbicho area in Aleta wondo woreda of SNNPR ....................................... 63

Figure 7. Hydro-geological map of Gerbicho area in Aleta wondo woreda ............................................... 64

Figure 8. Geological map of Wachema area in Dilla Zuria woreda of SNNPRS....................................... 71

Figure 9. Hydro-geological map of Wachamo area in Dilla Zuria of SNNPRS......................................... 72

Figure 10. Location map of Haro and Kedida areas in Yergacheife woreda of SNNPR............................ 75

Figure 11. Geological map of Haro in Yergachefe woreda of SNNPR...................................................... 78

Figure 12. Hydro-geological map of Haro area in Yergachefe woreda of SNNPR.................................... 79

Figure 13. Geological map of Kedida area in Yergachefe woreda of SNNPRS......................................... 87

Figure 14. Hydro geological map of Kedida area ....................................................................................... 88

Figure 15. Location map of Wodito area in Cheha woreda of SNNPR...................................................... 92

Figure 16. DEM enhanced location map of Wodito area in Cheha woreda of SNNPR ............................. 93

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Figure 17. Geological Map of Wodito area ................................................................................................ 94

Figure 19. Location map of Agumamit and Kuni in Jabi Tahinan woreda, Gulem Denjin in Bure Woreda,

Lideta in Banja woreda, Kachana Gude in Dangla woreda of West Gojjam and Awi zone of Amhara

Figure 35. DEM enhanced location map of Gult and Maksegnit areas in Andabet woreda of South Gonder

Figure 18. Hydro-geological map of Wodito area. ..................................................................................... 95

national Regional State ............................................................................................................................. 100

Figure 20. Geological map for Agumamit area in West Gojjam of ANRS .............................................. 102

Figure 21. Hydro-geological map of Agumamait area ............................................................................. 103

Figure 22. Geological map of Kuni area................................................................................................... 107

Figure 23. Hydrogeological map of Kuni area ......................................................................................... 108

Figure 24. Geological map of Gulem Dejen ............................................................................................. 112

Figure 25. Hydrogeological map of Gulem Dejen.................................................................................... 113

Figure 26. DEM enhanced map of Lideta area in Awi Zone of ANRS .................................................... 117

Figure 27. Geological map of Lideta area................................................................................................. 118

Figure 28. Hydrogeological map of Lideta area ....................................................................................... 119

Figure 29. Geological map of Kachana Gude........................................................................................... 123

Figure 30. Hydrogeological map of Kachana Gudi .................................................................................. 124

Figure 31. Location map of Study woredas in South Gonder................................................................... 128

Figure 32. DEM enhanced location map of Adis Betechristian area. ....................................................... 129

Figure 33. Geological map of Addis Betechristian area in Fogera woreda of ANRS .............................. 131

Figure 34. Hydro-geological map of Adis Betechristian area................................................................... 132

zone of ANRS ........................................................................................................................................... 136

Figure 36. Geological map of Gult and Maksegnit area in South Gonder zone of ANRS ....................... 138

Figure 37. Hydro-geological map of Gult and Maksegnit areas in South Gonder of ANRS.................... 139

Figure 38. Location map of woredas in North wollo of ANRS ................................................................ 146

Figure 39. DEM enhanced location map of Angot (Sokolo) and Ayichal Boniya ................................... 147

Figure 40. Geological map of Angot in North Wollo zone of ANRS....................................................... 148

Figure 41. Hydro-geological map of Angot in North Wollo zone............................................................ 149

Figure 42. Location of woredas in South Wollo zone of ANRS .............................................................. 154

Figure 43. Geological map of Gelsha area in South Wollo of ANRS ...................................................... 156

Figure 44. Hydro-geological map Gelsha area in South Wollo of ANRS ................................................ 157

Figure 45. DEM enhanced Location map of Zerit area ............................................................................ 160

Figure 46. Geological map of Zerit area in North Shewa Zone of ANRS................................................ 162

Figure 47. Hydro-geological map of Zerit area in North Shewa zone of ANRS...................................... 163

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Acknowledgments

Shumet Kebede Water Works consultant is deeply indebted to TETRA TECH for inviting us to

conduct the work and facilitating the execution process in the shortest time possible. The all-

rounded support of Mr. Jim Rogers, Tt, Deputy COP (Design)-ESCO is highly appreciated. I

appreciate staff members of TETRA TECH. Without the help and cooperation of community

members named in this report, this work would have been very difficult; I deeply would like to

forward my deepest gratitude for all of them found in all health center project areas. For valuable

comments, I appreciate Mr. Thomas Keeffe Tt, Marlborough MA. All organizations and

individuals who provided reports and vital verbal information are highly appreciated

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Executive Summary

The United States Agency for International Development (USAID) Ethiopia will be implementing

the “Engineering Services and Construction Oversight” (ESCO) project which will provide

architectural and engineering (A&E) services in support of infrastructure projects in Ethiopia.

The project will involve supporting USAID/Ethiopia with its implementation of infrastructure

projects by providing management services, design services, pre-construction services, and

construction phase services. ESCO is a three year project intended to improve the quality of

USAID/Ethiopia infrastructure projects while controlling costs and schedules. ESCO will provide

these services for new health centers, a National Blood Center in Addis Ababa, and multi-drug

resistant tuberculosis (MDR TB) Treatment Centers.

Subcontractor, Tetra Tech, will provide the design for a groundwater well at 17 health centers,

including the necessary hydrogeological investigations, pump sizing, and other engineering.

Accordingly, Tetra Tech entered contractual agreement with Shumet Kebede Water Works

Consultant to carry out potential water sources assessment as per the standard and terms of

reference given by the employer, Tetra Tech at 17 Health Centers. The study was conducted in

South Nation Nationality Peoples Region (SNNPR) in five health centers and in Amhara National

Regional State (ANRS) in 12 health centers.

The principal objective of the study was to identify potential water sources and the mechanism of

supply to the 17 health centers under construction by USAID. The focus area of the study included

the health center compounds and its vicinity and the surrounding environs from technical,

economical and social point of view. During this study, conventional investigation methodologies

were deployed systematically one after the other.

Finally, based on detail Geological, Hydrogeological and Geophysical investigations, with other

supporting investigation inputs the consulting team selected potential water resource sites for all

projected Health Centers. Selection of water source sites considered evaluation of surface water

and groundwater sources. As a general truth groundwater sources are more preferable than surface

water sources. Hence, in this report an emphasis is given for groundwater sources. Groundwater

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abstraction could be done from spring, Shallow wells (excavated hand dug wells and tube wells)

and deep wells. Hand dug wells usually are 15-20 meters and Shallow tube wells are 60-80 meters

deep drilled by drilling rigs, supposed to install hand pumps. Deep wells are below 80 m depth,

usually installed with motorized pumps.

Based on these local classifications of sources priority is given for deep wells in the compound of

the health center and its vicinity then spring development at the vicinity of health centers and at

last shallow wells drilling and constructions in or its vicinity.

For understanding of the subsurface situations of the study areas a total of 29 VES surveys were

conducted in 16 out of the 17 project sites to ascertain the depth of occurrence of ground water,

aquifer type identification and determination of anticipated drilling depth. Finally the study team

recommended;-

Borehole Drilling in and around the health center compound is proposed for 14 project

sites namely; Haro, Kedida, Wodito, Agumamit, Kuni, Gulem Denjin, Lideta, Kachana

Gudie, Addis Betechristian, Gult, Maksegnit, Angot, Gelsha, and Zerit sites

Spring construction and improvement is primarily recommended for 3 sites named;

Gerbicho, Wechema, and Beta sites

This report including three parts:

Part I. General Overview and verifications of the study that includes Introduction,

objectives of the study, methodologies, Climate and Physiography, Geology,

Hydrogeology, Geophysical survey, Water quality and Environmental Impact assessments.

Part II. Verifications and Findings for each project area, which also includes local geology,

hydrogeology and geophysical survey result with possible recommended primary and

optional water sources.

Part III. Conclusions and Recommendations.

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PART I.

General Overview and verifications of the study

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I. Introduction

1.1. Background

Potable water supply is one of the least developed sectors in Ethiopia. Especially, the rural

community and innumerable small and medium towns are suffering for lack of safe and adequate

drinking water. The majority of the population depends on unprotected water sources like hand-

dug wells, springs, streams, rivers and seasonal ponds which are often polluted. Such unprotected

water sources are the major causes of water-borne and water related diseases, which results in high

mortality rate of infants and partly adults in the rural community every year. Understanding of

these situations Tetra Tech made an agreement with USAID to provide Architectural and

Engineering services as required by USAID/Ethiopia to include management services, design

services, pre-construction services and construction phase services. In the course of action,

provision of safe water for drinking and for sanitary purposes to the new health centers under

construction in 17 kebeles of Amhara National Regional State (ANRS) and South Nation

Nationalities Peoples Region (SNNPR) and/or forthcoming health centers with some

complementary works to the nearby communities becomes evident.

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The projects are to be designed to provide safe and adequate potable water and improve sanitation

facilities for the health centers in general and the beneficiary communities in the respective project

areas. Accordingly, Tetra Tech entered contractual agreement with Shumet Kebede Water

Works Consultant to carry out potential water sources assessment as per the standard and terms

of reference given by the employer Tetra Tech. Accordingly Shumet Kebede water works

consultant established a team consisting of specialized disciplines (Shumet Kebede,

Hydrogeologist and Geophysicist, Nuru Mohammed, Hydrogeologist and Kefyalew Girma,

Geologist) for water source investigation.

Whenever the assessment for water supply projects is undertaken, site investigation has to be

employed in line with desk studies. Pre-construction evaluation includes site investigation which

encompasses assessment of the Hydrological, Geological, Hydro-geological, Geophysical and

Hydro-chemical conditions in general and site specific studies. Site investigations are helpful in

determining the pros and cons in projects ahead of time before significant resources are committed

to the project. Parallel to it, opportunities and risks are determined and all necessary adjustments

enforced.

Before the field investigation was launched, the consultant has set up a clear methodology and

checklist of the study mainly divided in two sections;

The Desk study included; planning of the site investigation works, use of primary and

secondary sources of information, literature review, and technical maps. Accordingly, the

project areas were categorized into two groups basing their geographic orientation and

accessibility. A team consisting of a Hydrogeologist, Geophysicist, Geologist and a driver

travelled to the sites in SNNPR and spend two weeks time for the surveillance and then to

project sites in Amhara National Regional State that has taken about three weeks. Upon

completion of the field work, the study team was committed in producing the technical

report and associated maps based on the desk study and field investigation findings.

The field investigation part included; collection of all necessary social and technical

information from respondents in the woredas and kebeles, assessment of existing water

sources, hydrological and hydro-geological investigation, study of local geology assisted

with transect walk and geophysical survey, sampling and in-situ testing of water chemistry

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from different water sources, proposition of potential water source sites, scheme type with

consideration of proximity and economic analysis.

During this study, conventional investigation methodologies were deployed systematically one

after the other. Data collection, interpretation and confirmation of supporting documents, maps,

evaluation of remote sensing materials; interview and discussion with the local community and

concerned officials; measuring yields of springs and understanding mode of emerge; conducting

geo-traverse surveys, surface water impoundments and general Hydro-geological features of the

area, conducting Geophysical investigation, and in-situ testing of hydro-chemistry from different

sources.

This report encompasses brief hydro-geological evaluation and results of desk and field

investigations for the water supply of 17 identified Health Centers under construction by USAID.

The health centers covered by this study document are; Gerbicho/Seda, Wochema, Haro, Kedida

and Wodito health centers in SNNPR and; Kuni, Agumamit, Gulem Denjin, Lideta, Kachana

Gudie, Addis Betechristian, Gult, Maksegnit, Angot, Gelsha, Beta, and Zeret health centers in

Amhara Region. As a result; potential, economical and sustainable water sources with the type of

schemes are identified correlating the data collected on desk study and field investigation.

1.2. Objectives of the study

The principal objective of the study was to identify potential water sources and the mechanism of

supply to the 17 health centers under construction by TETRA TECH/USAID. The focus area of

the study included the health center compounds and its vicinity, and the surrounding environs from

technical, economical and social point of view.

The specific objectives includes (but is not limited to):

Groundwater assessment and mechanism of abstraction

Proposition of appropriate scheme types and sitting of wells

Determination of the type of drilling methodology to be employed

Proposition of optional water sources other than water well drilling, when water well

drilling is not feasible

Recommendation of Pumping system

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Engineering estimates of drilling and construction

Water well design and tender document preparation for water well drilling

1.3. Approach and Methodology of the study

The methodologies adopted and applied in the project areas are widely accepted standards and

definitely improves the success rates significantly. The work at this inception stage consists of:

Data collection and analysis in the office (Desk Study), and Field investigations.

1.3.1. Desk study

Water Resources investigation at this phase started through examining all relevant works and

available information in and around each project area that includes:-

Assessment of existing published and unpublished reports and maps.

Assessment of existing hydro-meteorological data

Evaluation of Regional and Sub-regional hydro-geological maps.

Usage of Shuttle Radar Terrain Mission (SRTM) data generating for Digital Elevation

Model (DEM) with 30 * 30 meters resolution and identify regional structures and drainage

patterns.

Evaluation of regional geological and hydro-geological features using Enhanced Thematic

Mapper satellite images at a resolution of 30 * 30 meters.

1.3.2. Field investigation

The field investigation works were conducted from November 15, 2015 to November 30, 2015 in

SNNPR and from December 3rd to December 21st in ANRS. The field work lasted from November

to December. The ground water condition during the time of investigation was expected to be

below the seasonal average since Ethiopia has experienced its worst drought in decades by 2015

caused by El-Nino and associated low precipitation during the long Ethiopian rainy season (June

to September). Under normal circumstances, November is the last month of spring and December

is the start of the dry season. Slightly higher ground water levels from the seasonal average were

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expected from November to December, if not preceded by bad weather and a weak rainy season.

Higher ground water levels are anticipated in August and least water levels are in May. There was

no considerable precipitation recorded in the study areas (except untimed precipitation in few areas

of southern highlands) from November to December that could hamper ground water levels or

storage. Well recorded and documented data of ground water levels was unavailable on yearly or

seasonal basis during the survey for the purpose of water level comparison.

The major activities covered by the field work include:

Reaching the project areas and visit the status of construction of the health centers with the

aid of GPS and local informants

Interview with local elders and leaders, most often women, woreda health and water

resources officials

Transect walk in conformity with remote sensing data interpretations and other relevant

documents analyzed on desk

Detailed assessment of structural and Geological setup of target areas and their relation

with regional geological structures and hydro-geological importance

Measuring the yield of unprotected and protected springs and consistency of the yield in

dry and wet seasons, evaluation of hand dug wells and drilled tube wells

Evaluation of recharge and discharge conditions, catchment area and hydrometeorology.

Geophysical investigations in and around the health centers

Discussion with relevant professionals, project coordinators and community leaders at

woreda level in connection with continuity of existing water supply systems for alternative

options

Identification of potential, economical and sustainable water sources in and around the

Health Centers

Collection of water samples and conduct in situ measurements

The most important equipment used included:

Earth Resistivity Meter (ABEM 4000, Swedish made digital resistivity meter)

pH and TDS meter

EC meter

Depth meter

Bucket for discharge measurement of spring

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Stopwatch

Lap top computer

High resolution GPS (The UTM coordinates, i.e. Easting and Northing, obtained with the

help of a GARMIN II GPS receiver in Adindan datum)

Thematic Mapper satellite images and DEM (Digital Elevation Model 30X30m resolution)

Topographic maps (1:50000) and Hydro-geological map of Ethiopia (1:50000)

1.4. Discussion with local residents, office staffs and Experts The working team has collected relevant data through direct interviews with experts from different

offices, community leaders, elders, women and children. Some were working with the team in the

course of selection of water source sites.

Prior to conducting groundwater investigation, the study team explained and started up with:

Introducing organizational set up and qualifications of the study team

Purposes of the visit

About the Client and its initiations on the project

Explaining about the study methodology and request volunteers to participate on the study.

In all areas, the community participants show keen interest on the importance of the project and

its implementation coming into being. One of the major problems in the country and in particular

such small towns and villages are absence of published documents about the existing water sources

and construction history. The main data sources taken into consideration are the semi-annual and

annual reports prepared by woreda and zonal experts and regional water bureau staffs. Water

Quality analysis results of representative sources are collected from regional water bureau.

As a result, community members were considered as important informants in directing the study

team: the location of existing water sources and seasonal fluctuation, year of construction and

implementing body, surface water sources and related explanation, rock exposures, history of the

study area, beneficiaries’ situations, etc. Active participation of the community supported the

study team broadly to obtain detailed information about the project area and minimized

investigation period.

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Picture 1. Discussion with community members and officials

Picture 2. Discussion with the local people on selection of suitable water sources

Table 1. Main informants from the respective project areas

No Health Name of interviewed Responsibility Telephone No

Center person

1 Gerbicho/Seda -Abayneh Dogisso -Head of health center -0921453327

-Lamma Lamisso -Expert in cooperative -0916373082

sector of the town

2 Wochema -Fikru Woressa -Agri. Office head -0924646513

-Tariku Memeru -community leader -0926032248

3 Haro -Alemayehu Waqo -head/town water -0949029468

-Mihret Jillo service -0913187411

-kebele chairman

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4

5

6

7

8

9

10

11

12

13

14

15

16

Kedida

Wodito

Kuni

Agumamit

Kachana

Gudie

Gulem Denjin

Lideta

Addis

Betechristian

Gult

Maksegnit

Angot

Beta

Gelsha

-Abera Tegenu

-Dergu Beyene

-Bedru Delil

-Muzemil Kheyru

-Getaneh Addis

-Yeneneh Zeleke

-Kies Geremew Anagaw

-Tiruneh Mengist

-Azmeraw Aregu

-Tilahun Kebede

-Yaregal Engide

-Abraham Mossie

-Tefera Esubalew

-Birhanu Bitew

-Wendim Fetene

-Miskir Shiferaw

-Getachew Mengistie

-S/r Tirualem Eskemayzen

-Ayalew Wubante

-Mulatie Mihretu

-Tsega Mellesse

-Simegnat Abreham

-Kasaye Sitote

-Asfaw Melaku

-Megenagna Lulseged

-Mekibib Ewunetu

-Wubetu Alebachewu

-Ahmed Ali

-Seid Ibrahim

-Miftah Hassen

-head, agri. Office

-vice chairman of kebele

-kebele manager

-Agri. office

-Clinic guard

-resident

-kebele chairman

-kebele chairman

-Water committee

-kebele manager

-cabinet member

-Militia

-resident

-kebele manager

-police

-resident

-Supervisor

-clinical nurse

-kebele manager

-water expert

-kebele chairman

-health extension

-kebele chairman

-Amhara water wo.

-health worker

-Agri. Office

-School Director

-Resident

-kebele manager

-Clinic head

-0916170677

-0916800862

-0911935495

-0921311397

-0925300710

-0940276521

-0946975829

-0960337568

-0931833551

-0928425319

-0921292959

-0912724051

-0920502875

-0918134607

-0918194530

-0924272885

-0923419906

-0918435832

-0928528209

-0910582525

-0918027618

-0919476247

-0921536782

-0914649523

-0945699470

-0928396623

-0914330448

-0914333022

-0915549615

Page 19 of 174


-Mohammmed Yimer -Guard and resident

17 Zeret -Getaw Wondimu -Clinical nurse -0923165128

-Meseret Asfaw -Resident -0937609367/25

1.5. Location and accessibility of the Project Areas

The project areas are located in 14 woredas of Amhara National Regional State (ANRS) and South

Nations and Nationalities Peoples Regional State (SNNPR). Location map of geographically

related woredas are presented in the figures below

Table 2. Studied Project areas

No Region Zone Woreda Village/ Town UTM Coordinates

and Elevation of

Health center *****

1 SNNPR Sidama Aleta Wondo Gerbicho/Seda 0438207E, 0723746N

Elev. 1989m.

2 SNNPR Gedeo Dilla Zuria Wochema 0427438E, 0694170N

Elev. 2060m.

3 SNNPR Gedeo Yirga Chiefe Haro 0405641E, 0678230N

Elev. 1984m.

4 SNNPR Gedeo Yirga Chiefe Kedida 0402511E, 0675128N

Elev. 2212m.

5 SNNPR Guragie Cheha Wodito 358559E, 906441N

Elev. 1864m

6 ANRS West Jabi Thahnan Agumamit 296324E, 1179555N

Gojjam Elev. 1878m

7 ANRS West Jabi Thahnan Kuni Sankistak 303984E, 1193888N

Gojjam Elev. 2252m

Distance and accessibility

3km South on the Asphalt road

from Aleta wondo and 8km west

along all weather gravel road

8km South on the asphalt road

from Dilla and 12km North East

on the all weather gravel road and

7km East on dry weather road.

During the survey the team

travelled on foot

8km North west of Yerga chefe

town on all weather road

15km, North west of Yerga

chefe town. 8km to Haro is

accessible but the rest 7 km is

only dry weather road.

During the survey the team

travelled on foot.

11km from Welkite to Indibir

road and turn right at Zabidar

beer factory before Gubri and

another 11km on all weather

road to wodito

10kms from Finoteselam town to

Bahir Dar Direction and turns

left for 5kms on an all weather

road. A total of 15kms from

Finote selam town

15kms from Finote selam town

North on a dry weather road

which needs major maintenance

Page 20 of 174


8 ANRS West

Gojjam

Burie Gulem Denjin 292440E, 1170729N

Elev. 1982m

15kms from Burie town of

Gojjam on an all weather gravel

road

9 ANRS Awi Banja Lideta 267415E, 1210039N

Elev. 2502m

8kms away from Injibara town

on all weather road

10 ANRS Awi Dangla Kachana Gude 241267E, 1234484N

Elev. 1811m

A total of 30kms from Dangila

town on an all weather road

11 ANRS South

Gondar

Fogera Addis

Betechristian

373812E, 1324487N

Elev. 1876m

18km From Wereta town to

weldia road and turns North to

an all weather gravel road for

7kms

12 ANRS South

Gondar

Andabet Gult 373538E, 1257472N

Elev. 2410m

10kms from Jara Gedo town, all

weather gravel road

13 ANRS South Andabet Maksegnit 378311E, 1250044N 13kms from Jara Gedo town on

Gondar Elev. 2276m a dry weather road

14 ANRS North Gubalafto Angot 538676E, 1302244N 70kms from Wegel Tena town

Wollo Elev. 3474m on an all weather road. The other

road from Ahun Tegegn rural

town very steep and difficult

15 ANRS South Borena Ayichal 461720E, 1178632N Very difficult steep and bad road

Wollo Boniya/Beta/ Elev. 2198m even for small vehicles. 13kms

from Mekane selam town and

turn left and more 16kms via

Segno Gebeya.

16 ANRS South Dessie Zuria Gelsha 560086E, 1215384N 26kms from Dessie to

Wollo Elev. 2971m Mekaneselam asphalt road

17 ANRS North Menz Keya Zeret 0532032E, -48 kms from Mehal Meda to

Shewa 1122880N Zerit

Elev. 2665m

Page 21 of 174

-- - -- --

-- -- - --

--1[ _., .... ,...,. ~-z-.. A ..... Regiaa o ...... si-a111 .. .- - -•Doru., D EmlG--D N11IIGinl• D N11IIS

D N11II_ ..

D 0nmioo -Ga-• - -.-0 1111!,llllj.,.


Figure 1 . Location map of study areas in Amhara National Regional State (ANRS)

Page 22 of 174

I

I

8

I I

I ff

I I

I I

8 00000 ••oooo ,00000 HOOOO 2,0000 1 0000 ... 0000 aooooa

0 1 2 15,>6 60 76 100 -=-=----===--• K110mo1ors


Figure 2. Location map of study areas in SNNPR

Page 23 of 174


II. Existing water Supply systems, Population and Infrastructure

2.1. Existing situation and management of water Supply schemes

The portion of community getting water from protected sources is 50 to 85% out of the total

population of the kebeles (the lowest registered is in Beta kebele and the highest percentage is in

Agumamit kebele). Access and coverage to protected water sources was found as a compiled report

at kebele and woreda level (source: woreda and kebele offices). The major parameters taken for

estimation of water coverage are daily consumption per day per person and distance to be travelled

to fetch water for different types of water sources. Regulations of water coverage were stated to

cover 100% in the country by Ministry of Water and Energy in 2006, on the Strategic Plan of

Millennium Development Goal (MDG) of Ethiopia that has to be completed in 2015(Report from

Ministry of Water and Energy). Ministry of Health produced National Drinking Water Quality

Monitoring and Surveillance Strategy in May 2011. The strategic intervention areas concentrated

on strengthening intersectional collaboration with defined roles and responsibilities at all levels

establish coordination mechanism and emphasize the importance of conducting multi-level

advocacy, promotion and communication to revitalize water quality monitoring and surveillance

activities to prevent contamination of drinking water from source to consumption in a sustainable

way. Hence, prevention strategy promoted to all level sectoral offices and communities to protect

water sources from contaminants. Although presently those who drinks unprotected water sources

are often utilizing disinfecting chemicals that kills harmful microorganisms.

In general daily water demand estimation has considered climatic conditions: such that for Arid,

Semi-Arid and hot sub-tropical areas is 35 lit/person/day. Whilst for Sub tropical and tropical areas

are 25 lit/person/day. The health centers have a defined water demand of 5,250 liters/day. For

sanitary purposes the required minimum offset distances for Hand dug wells is 0.5km, for shallow

wells 0.75km, for deep motorized wells kilometers and for springs 1.2-1.5 km. However, due to

different reasons the Strategic Plan of Millennium Development Goal is delayed against the

timeline (the delay to accomplish MDG is not the scope of this report).

In accordance with this National Standard design period of water schemes has been setup:

Page 24 of 174


Design period of hand dug well is 10 years

Design period of motorized scheme is 25 years

Well constructed springs is 40 years

In most cases the water coverage is based on temporary provisions from hand dug wells and tapped

springs. Such schemes have short life span and the coverage in another time is quite different from

these figures due to malfunctioning of hand pumps, lack of follow up and maintenance, and short

life span of such schemes as a result of poor workmanship and ground water depletion. Thus, the

community depends on unprotected surface sources like Rivers and natural springs in one or

another time to meet the demand. However, few areas have better water supply sources especially

in Amhara region.

The most abundant water sources are hand dug wells, springs and shallow wells (fitted with hand

pumps). Deep wells are not common except in Haro town. Shallow hand dug wells often with

depth ranges of 10 to 25 m are common. The shallow hand dug wells fitted with hand pumps are

not functional in many places. This is mainly due to breakage of pumps, shortage of pump

accessories and maintenance tools, and drying up of wells in dry seasons because of shallow depth

and depletion of ground water table.

The responsible body for water supply management is the village water committee consisting of

5-7 members; however, the committee lacks the necessary technical capacity for maintenance and

managerial skills. Management of the water sources is mainly left for the Woreda Water resources

office. The Woreda Water resources office experts have technical capacity to undertake

maintenance of schemes; budget for maintenance is reported as a major constraint.

Surveillance of existing water supply systems has been carried out during the survey. This has

given the study team the opportunity to observe the existing and real situation of the water supply

facilities in each project area. From the survey, it is evident that the water supply coverage is

relatively low in many project areas. In some areas in particular children and women are fetching

water from deep incised gorges and travel long distances. Existing water supply sources are

discussed solely for each project area.

Page 25 of 174


Picture 3. Traditional hand dug well, poorly constructed spring and hand dug wells

2.2. Population

According to information obtained from Woreda and kebele administration offices, the kebele

population for each project site where the health center is established is summarized below.

Table 3. Population size of the project areas

No Health Center/kebele/ Population size in number

1 Gerbicho/Seda 4600

2 Wochema 4800

3 Haro 13245

Page 26 of 174


4 Kedida 6740

5 Wodito 4015

6 Agumamit 5000

7 Kuni 6500

8 Gulem Denjin 10000

9 Lideta 5500

10 Kachana Gude 6485

11 Addis Betechristian 4959

12 Gult 6750

13 Maksegnit 6470

14 Angot 6032

15 Ayichal Boniya/Beta/ 5117

16 Gelsha 8192

17 Zeret 3879

2.3. Economic activity

SNNPR is one of the major coffee growing regions in Ethiopia with high population density and

extensively cultivated. According to data collected, the major economic activities of

Gerbicho/Seda, Wochema, Haro and Kedida areas are mainly growing and trading of coffee,

informal and retail trading in shops and services of small hotels. The coffee plantation is mainly

associated with indigenous trees and Enset (False Banana). Most of the area is highly vegetated;

only limited plain lands are covered with grass (grazing land). Economic activities of Wodito area

are mainly based on agriculture; the majority households are farmers engaged on mixed

agricultural activity with livestock rearing. The major agricultural products are sorghum and

Maize. Employment on agricultural works is also one basic economic main stay in all surveyed

areas.

The Amhara people are mainly agrarian and fully dependent on agricultural farming. The main

agricultural products include Teff, wheat, Barley, Sorghum and Maize. Livestock rearing in

homestead is considered as a means of subsistence and additional income generating activity. Petty

trade is another source of income in small rural towns.

2.4. Infrastructure

The common infrastructure types, services and institutions in the project areas include:

Page 27 of 174


Almost all project sites in SNNPR are supplied by 24 hours electricity from the main

hydropower grid system except Gerbicho town (supply of electricity for Gerbicho town is

under construction)

The project sites in Amhara region are partly supplied by electric power and the remaining

sites are yet to be supplied by the rural electrification program of the Government of

Ethiopia.

There are government institutions and services in all surveyed areas such as: first and

second cycle schools (First cycle are Grade 1-4, Second cycle are Grade 5-8), , Agriculture

offices, health posts, kebele offices, cable and mobile telephone services, mosques and

churches. There are also a number of shops and small restaurants.

Most of the houses are built with wood and mud plastering while very few are built with

hollow blocks. Most of the roofs are made with corrugated iron sheets. There are some

grass-thatched roofs with wooden walls plastered with mud.

III. Climate and Physiography

3.1. Climate

Surface and subsurface water potential is dependent on various factors. These factors include

climate, geology, vegetation topography, elevation, etc. Among the above listed factors, climate

plays a great role in influencing meteorological parameters such as rainfall, temperature, relative

humidity, evapo-transpiration and wind speed, which are very important parameters for water

resources evaluation.

In Ethiopia, rainfall has an uneven distribution both in time and in space. This is partly due to the

presence of one major and one small rainy season, in large parts of the country. A subsidiary effect

is that a large amount of rainfall on the highlands is concentrated as runoff in river valleys, which

drain into the low-lying areas where annual rainfall is low. In almost all river basins in Ethiopia,

some 80% of the runoff results from annual precipitation falling in four months from June to

October. Two groups of factors mainly determine the extent of flow in streams: climatic and

physical characteristics of the drainage basins.

Page 28 of 174


Based on altitude, the climate can be classified into five groups (Table 1.4): The table shows these

zones with their typical characteristics value of temperature and elevations.

Table 4. Classification of Climate zone on the basis of altitude

No Altitude (m.a.s.l.) Temperature (0c) Climate Zone

1 Below500 ≥25 Arid (Berha)

2 600-1200 20-25 Semi arid (Kifle Berha)

3 1200-1900 18-20 Hot sub tropical (Kola)

4 1900-2200 14-18 Humid Sub Tropical (Weina Dega)

5 Above 2200 ≤14 Cold Humid sub tropical (Dega)

The rainfall, temperature, wind speed and humidity are highly variable with altitude and latitude.

Rainfall and temperature increases and decreases respectively with increasing altitude apart from

some that are more influenced by topography.

According to the above classification, the project areas located in SNNPR and Eastern Amhara

Region are dominantly classified as Humid Sub Tropical (Weina dega) and cold humid sub-

tropical, dominated by distinctly bi-modal (two peak) rainfall pattern. Rainfall is well received

from September to November and March to May. The mean annual rainfall of the project areas

and their surroundings are characterized by high mean annual rainfall ranging from 1000-1200mm.

The mean monthly minimum and maximum temperature of the study areas and its surrounding

area ranges from 10-14 0C and 16-20 0C respectively.

Project areas located in Western Amhara region receive uni-modal rainfall pattern that lasts from

June to September. The mean annual rainfall is characterized by high mean annual rainfall ranging

from 1100-1200mm. The mean monthly minimum and maximum temperature ranges from 10-14

0C and 16-20 0C respectively.

Rainfall intensity plays significant role for groundwater recharge system. The main source of

recharge for the vast groundwater systems is the rainfall in the highlands. The major recharge

zones regionally occurs mainly from Dilla and Gedeo highlands in the case of projects in Southern

Page 29 of 174


Ethiopia and Choke, Guna, Guguftu, Dessie zuria highlands for projects in Amhara region where

the annual rainfall is relatively high.

3.2. Physiography of the study areas

Physiography is the physical characteristics of an area, which includes Topography, Drainage,

Vegetation cover, Soil type, etc. The study of Physiographic features and identification of

geological structures and drainage patterns is done by interpretation of Enhanced Thematic

Mapper satellite images at a resolution of 30*30 meters.

The Satellite images and SRTM data were exhaustively used for tracing major lineaments and

identifying hydro-stratigraphic units and possible groundwater localization zones. Lineament

analysis using satellite images has been particularly valuable in determining regional and sub-

regional fracture patterns that reveal some of the tectonic events in the studied areas. Lineament

analysis (faults and fractures) has immense practical importance in groundwater exploration.

Lineament identification can be used in locating fracture patterns that could control groundwater

distribution and accumulation. The surface features enhanced in the imagery in contrast to the

surface expression of geological and geo-morphological features and land cover gives direct and

indirect hydro-geological information.

The project areas (Gerbicho/Seda, Wochema, Haro and Kedida) are part of South- Eastern plateau

located at the margin of the Rift valley Basin whilst Wodito is a part of Central and Northern high

lands of Ethiopia portrayed by mountaintop settlement characterized by undulated, highly

dissected landscape, entrenched valleys and erosion scarps.

The project areas in Amhara region lie fully in the North western highlands physiographic zone.

Five project sites in West Gojjam (Kuni, Agumamit, Lideta, Gulem denjin, and Kachana Gudie

are aligned in Choke mountains catchment. Addis Betechristian is sited in Tana basin. Gult and

Maksegnit lie in the lower catchment area of Guna Mountains. Angot and Zeret sites are located

on high grounds and separated by tectonic cliff zones and stands solely on the plateau. Gelsha and

Beta sites regionally divided by the Guguftu mountain ranges to north and South of the catchment

where Beta lies in poor hydro geologic zone in the upper catchments of Abbay Valley.

Page 30 of 174


The geomorphology of the areas is generally the outcome of repeated tectonism, with associated

volcanism and intrusion followed by denudational and erosion processes. Gerbicho, Wochema,

Haro and Kedida areas are endowed with quite substantial amount of seasonal and perennial rivers,

draining to Genale Dawa Basins. Wodito and its surroundings are part of the Omo-Gibe basin. The

available rivers are tectonically controlled and follow regional and sub-regional lineaments.

The drainage density is high and mainly dendritic and radial pattern. There are few perennial rivers.

Most of the streams are flashy type.

High rainfall and the resulting physical and chemical weathering has developed thick soil cover in

many places except on sloping landforms and is often with volcanic fragments. The soils are

dominantly reddish clay. Low grounds are wide plains and dominated by black cotton soil. The

type of soil is closely related to soil parent material and its degree of weathering. The main parent

materials are rhyolite, ignimbrite, volcanic ash and basalt.

The growth of vegetation, whether natural or cultivated depends on the availability of favorable

soil conditions and sufficient soil moisture to sustain their consumptive uses, however, the natural

vegetation cover in the study areas are dominantly ‘’coffee plantation’’ shaded by scarce

indigenous trees; and scarcely scattered scrubs, eucalyptus and acacia found around open grass

lands and highly incised river valleys. The elders living at the projected areas asserted “a few

years ago the area was covered by lush vegetation”. The main causes for destruction of forests are

mainly overgrazing and land demand for agricultural activities, and home and industrial use.

In this regard conservation of natural resources should be the prior motto of the corresponding

woreda administrators and other supporting NGOs. Otherwise land degradation, desertification

dryness of surface water and depletion of subsurface water manifests sooner.

Page 31 of 174


IV. Geology

4.1. Regional Geology Ethiopia can be divided into three major Physiographic regions widely known as the Central North

Western plateau, the South Eastern plateau, and the Main Ethiopian Rift together with the Afar

Depression. These Physiographic regions are determined by the geologic process and structural

settings. According to the Ethiopian Institute of Geological survey, 1996, Ethiopia has the

following major groups of rocks

Precambrian metamorphic rocks with associated intrusive forming the "Old Basement";

Late Paleozoic to Early Mesozoic Sediments;

Mesozoic Sedimentary Rocks;

Early Tertiary Sedimentary Rocks;

Tertiary Volcanic and Sedimentary Rocks;

Late Tertiary to Quaternary Volcanic and Sedimentary Rocks;

Quaternary Volcanic and Sedimentary Rocks.

The oldest rock in the country, which forms the basement, is of Precambrian age. Overlying this

basement rock is the late Paleozoic and the Mesozoic sedimentary succession and/or Cenozoic

Volcanics except where the basement rocks are overlain by Paleozoic sedimentary rocks,

quaternary deposits or simply exposed to the surface. The largest part of the county (about 32%)

is covered by volcanic rocks of different ages and types. One can categorize these volcanic rocks

based on various criteria such as age (tertiary and Quaternary Volcanics), and taking rift formation

as a reference (pre- rift & post- rift Volcanics). The volcanic rocks of the country can also be

described as the Trap series Volcanics and Aden Series Volcanics, also named post rift Volcanics.

The trap series represent the oldest volcanic rocks in the country compared to Aden series

Volcanics. The major uplifting followed by cracking of horn of Africa gave rise to the formation

of Trap series. It is comprised mainly of flood basalt with some trachytes and rhyolites, especially

on its upper part. The trap series forms the central and northwest and southeast plateau, reaching

its maximum development in central Ethiopia attaining a thickness of up to 3km, (Mengesha et. al

1996).

Page 32 of 174


Trap series is hardly distinguished from the Aden Volcanic series based on the petrographic

analysis, Mohr (1971). Even though not conclusive, morphological distribution may be employed

to distinguish them. The trap series predates the rift faulting and usually occupies great height of

the Ethiopian North western and South Eastern Plateaus, whereas the Aden volcanic series are

associated with well – preserved volcanic cones or lava flows, Mohr (1971).

The study areas are part of Southeastern and the Central and North Western plateau separated by

the rift floor (Zennettin and Justin – Visentine, 1974). The geological history of the area is an

integral part of the evolution/development of the Ethiopian plateau and the Rift system. According

to Mohr (1964), the present morphology, and geological setting of this part of Ethiopia are the

results of two major post-Paleozoic tectonic events, which were followed by important phases of

volcanic activity. The first tectonic event (the epierogenic uplift), which occurred in late Mesozoic

– Early Tertiary period, produced the Afro- Arabian Dome. As an immediate consequence of up

arched landmass under tension, gave rise to the extrusions of voluminous basaltic magma through

fissures (Mohr, 1983). The extrusion of the Trap series fissure basalt of Ethiopia during Eocene -

Oligocene was the major and widespread volcanic episode of the whole Cenozoic. According to

Kazmin (1975), contemporaneous eruption formed shield volcanoes mainly consisting of basaltic

lava and developed on both the southeastern & the Central Northern western plateau in the

Miocene.

Page 33 of 174

= c . •· ~ • .-0 ............... 1-« I L.,e Ttrti.il)'~~ D t.dyTuti,wyvdur.kt

S 3 J.iA,JOr Wet:1

tout~o~ r--- ftl.-.tt ,.. , i;i,,.,\11SiA!wo;.~

• 3 Tow ..

==""';;; ...


Figure 3. Main physiographic classification of Ethiopia

The second tectonic event resulted in development of rift and associated volcanic phenomena

during Tertiary – Quaternary period was superimposed on the long uplifted Afro – Arabian swell,

whose axis approximately runs north – south.

The Main Ethiopian Rift was the result of extensional tectonics that trends in NNE- SSW. It started

to develop in the Miocene. According to Zennettin et al., (1980), Rift related volcanic rocks were

outpoured when fissural volcanism in the adjacent plateau had died out.

Initial sagging of the Main Ethiopian Rift started about 14 to 15 Ma (Mega Annum) and was

followed by major episodes of rifting at 10, 5, 4 and 1.8 to 1.6 Ma. Each stage of rifting and down

faulting was accompanied by a bimodal (silicic-mafic) volcanism in the rift and formation of

basaltic and trachytic shield volcanoes on the rift shoulders & margins, (Kazmin et al., 1980).

There were wide spread basaltic cinder cones eruption as well as restricted local flows of olivine

Page 34 of 174


basalt and olivine trachy- basalt in study areas, contemporaneously with the emplacement of per

alkaline rhyolites, trachyte lavas and ignimbrites (Mohr, 1964).

Quaternary volcanism was not confined to Rift; it also took place on plateaus, Mohr (1971). These

Quaternary alkaline basalts and trachytes were erupted along the pre- existing structures on the

north - west and south - east plateaus. Their well - preserved structures and/or unmodified

geomorphologic features such as cinder cones and small collapse craters, especially in heavy

rainfall and perennial stream regions indicate their recent age, Mengesha et al (1996).

The major geological structures in the country mostly parallel the rift system, some faults run

transversally to it on North West Ethiopian plateau. These rocks have undergone through several

structural episodes since the Precambrian orogenic movements to produce the Rift valley with

fracturing along the cliff in the floor of the valley and faults trending NNE, NNW, and ESE,

corresponding to the southern, Red sea and Aden rift System respectively.

4.2. Local Geology of the Study Areas

Geological study is the foundation and cornerstone of Hydro-geological investigation. Any

hydrostratigraphic classification of water bearing formations should start from stratigraphic or

lithological classifications by accounting geological structures such as faults, joints, folds and

other tectonic features having hydrological importance. Therefore, before the establishment of the

Hydro-geological map of the area at appropriate scale, the geological characteristics of the area

was assessed. In the course of the geological investigation the following issues have been

considered.

Regional Geological map of Ethiopia scale 1:2,000,000;

Analysis and interpretation of DEM (Digital Elevation Model, Resolution of 30m).

Observation and interpretation of topographic map of the project area with a scale of

1:50,000

Conducting Geo-traverse, observation of geological formations, and identification and

mapping of geological structures along rock exposures and River banks

Determination of lateral and vertical extent of litho-strtaigraphic units

Page 35 of 174


Determination of attitude of major structures having important hydro-geological

implications (faults, folds, dykes, etc.)

Detailed analysis of the relation between geological units with the drainage pattern and the

occurrence of water points (springs, seepage zones, ponds and existing wells)

The litho-stratigraphic units of the study areas described as follows by referencing the above

important points. Most of the study areas are characterized by extensive outcrops of volcanic rocks

and Quaternary sediments.

4.2.1. Volcanic Rocks

The volcanic rocks of the study areas are the Tertiary volcanics consisting of four kinds formations;

the Tarmaber, Aiba , Alajie and Ashengie basalts. These Tertiary volcanics form elevated and

main mountainous areas with very rugged topography where many higher peaks of the country

occurs. The Tarma ber and Aiba Basalts outcrop at the top of ridges and rarely flat-topped hills.

These Aiba Basalts are part of the early flood basalts called Trap Series that were erupted from

fissures during the early and middle Tertiary. The Tarma ber and Aiba Basalts are typical

transitional basalts, very homogeneous in composition. They show a distinctive tholeiitic nature

with transitions to mildly alkaline varieties. They are generally aphyric, compact rocks, in places,

showing stratification and contain rare inter-bedded basic tuffs, the units are observed almost in

all parts of the study areas.

The Alagie and Asengie formation are located in some parts of the study areas, stratigraphically

located below the Aiba Basalts. The Alagie mostly Asengie formations are composed of pale

coloured, fine grained lavas and plugs which are of alkaline trachytic and phonolitic composition.

The rocks show trachytic texture. The alkaline plugs form a youthful and peaked topography with

flow structure, columnar jointing, and concentric exfoliation and commonly form mountains of

bare rock. The plateau from which they rise is 2,400 m above sea level, with the highest peaks

reaching 2500 m above sea level.

Page 36 of 174


Picture 4. Ignimbrite rock

Picture 5. Fractured basalt

Page 37 of 174


4.2.2. Quaternary Sediments

In the studied areas, Quaternary sediments are found in limited thickness and aerial extent mainly

in the terrain overlying volcanic rocks and as thin strips along the margins of seasonal and

perennial rivers. The sediments do not have the same thickness throughout the area in which they

are exposed.

Less extensive unconsolidated sediments occur along the margins of the seasonal and perennial

rivers of the study areas (See Geological Map). These sediments are formed by the processes of

weathering from the underlying volcanic rocks. The sediments are mainly reddish clay and in some

parts black cotton soil. The thickness ranges f

usaid ethiopia attachment j1.1 - health centers ground water … · 2018-07-09 · study document...

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