9th Session of the Forum on RegionalClimate Monitoring Assessment

and Prediction for ASIA (FOCRAII)

Beijing, China

08-10 April,2013

Planning and Management of Water Resources in a Climate Change

PerspectiveAnd

Comparison of results of Hydrological Models used by PAKISTAN

By

Muhammad Ajmal Shad

DirectorPakistan Meteorological DepartmentFlood Forecasting Division (FFD)Lahore-Pakistan.

SCHEME OF PRESENTATION Introduction

Features and Problems for the models in individual Rivers

Results of the Models Conclusion

Responsibilities of Flood Forecasting Division (FFD), Lahore

FFD of the Pakistan Meteorological Department plays a pivotal role in the entire flood mitigation process. Hydrometeorological data from the various national and international sources is received in this office which is then processed to produce flood forecasts and warnings to be disseminated outwards to various national organizations

Flood Forecasting Division (FFD) Lahore is a specialized unit of PMD for this purpose.

Responsibilities

i. Flood Forecasting

ii. River stream flow forecasting

iii Water availability Forecast for Dams

iii. Assisting Water Management at Dams specially during Monsoon

HYDROMETEOROLOGICAL SERVICES AND FLOOD FORECASTING

Burning of fossil fuels due to human activities has leads to increase in greenhouse gases Climate of the globe is warming Frequency of high floods are expected to increase Extreme climate events badly affect the economy of the world Pakistan’s economy highly depends on the water resources of Indus river system

The rivers in Pakistan are distinguished with complex topography, diverse climate and varied morphology which produces specific hydrological characteristics and highly variable discharge in rivers. Difficult orography in northern parts of the country has strong influence on the meteorological situation of the region which ultimately greatly affects river flow.

Floods In Pakistan•Summer Floods (Monsoon Season)

•Winter Floods (Due to strong westerly waves)

•Flash Flooding (High intensity of rainfall over mountainous region)

•Urban/Coastal Flooding etc

FLOOD MODELS

Flood forecasting system of Pakistan is based upon two major components i.e. computerized mathematical models and regression equations procedure of flood forecasting

MODELS BEING USED IN FFD FEWS MODEL

Sacramento Rainfall Runoff Model (SAMO)

SOBEK Routing Model

CLS constraint Model

Other Models

Sacramento Rainfall Runoff Model (SAMO)

+

SOBEK Routing Model

Flood Early Warning System(FEWS)

FIVE MODULES OF FEWS MODEL

Rainfall Measurement

River Gauge Measurements

Forecast Input Data

Simulation Inputs

Simulation Results

Discharge DataDischarge of Tarbela, Kabul, Khairabad, Soan, Warsak,

Chakdra

TELEMETRIC RAINFALLCHAKDARA,WARSAK,NOWSHERA,ATTOCK KHAIRABAD, DHOK PATHAN,RASHIDABAD(KALPANI), TANDA DAM, GHARIALA(Haro River)

FORECASTED RAINFALLAutomatically pickup from Ugrib

file, downloaded from www.ugrib.us

OrIf not available than feed manually

FEWS MODE

L

Forecast for Kalabagh

PMD RAINFALLCHITRAL SAIDUSHARIF, KALAM, DIR, PESHAHWAR, ISLAMABAD, MURREE, KOHAT, CHERAT, RISAL

PUR

KALABAGH

CHASHMA

TAUNSA

GUDDU

SUKKUR

KOTRI

COMPARISON OF FEWS Model & ACTUAL IN CURRENT FLOOD

SEASON

RIVER INDUS:

1.The FEWS Model was run day by day w.e.f 15.06.2010. The Catchments of Indus River and its tributaries received severe rainfall resulting flood peak of exceptionally high magnitude in River Indus and its tributaries was experienced..The Maximum discharge of 6,12,800 Cs on 30-07-2010 at 0500 and 5,50,000 Cs on 10-08-2010 at 0900 were released from Down stream of Tarbela. Rainfall runoff and routing model for Tarbela Upstream and Kabul River has not been developed and incorporated in the Fews Model. Therefore, Fews Model does not generate forecast of Upstream Tarbela and for Kabul River.

2.The gauge at Nowshera on River Kabul was washed away on 29/07/2010 at 18:00 hrs. and data was not received upto 05/08/2010 of 06:00 hrs.

Evaluation of FEWS Model Performance and Operational Real-Time Flood Forecasting

(Flood Season 2011)

Discrepancies:

1: The preprocessing Data requires enough time to run the Model.

2: The causing of crashing of the model are not fully defined.

3: The Catchments of FEWS model are not overlay with the radars Catchments.

4: The Grid display modules are not function able (Inundation Maps).

5: Some times U-grib gives negative values of forecasted rainfall which crashes the FEWS Model.

6: Incase of no rainfall, some times FEWS shows negative discharges at the rim stations .

7: The Help in the tool bar of FEWS Model is not functionable.

6. U-grib Negative Value Should be automatically filter.

7. The Source Code of the model should be provided to PMD.

8. As per NESPAK 30 days forecasted hydrograph value is required to obtain 30 days forecast, the forecasted days is minimized, up to 7 days. Because u-grib gives QPF for 7 days.

9. Help module may be activated

Constrained Linear System

(CLS)

Rainfall/runoff model for the catchment areas above the rim.

Stream flow routing model for the river basin, down steam, below the rim station.

Major Inputs of CLS modelMeteorological data Actual rainfall Quantitative Precipitation Forecast(QPF) Radar data(QPM)Hydrological data River base flow data for last 10 days Real time data

Evaluation of CLS Model Performance and Operational Real-Time Flood Forecasting

(Flood Season 2010-12)

LIMITATIONSThe catchments of all the rivers lies in the Indian Mountainous Region. The rainfall data of high altitude catchments are not available, due to which water availability at the RIM Stations can not be estimated. The discharge data of eastern rivers (Sutlej, Ravi & Chenab) is supplied by India through Pakistan Commissioner For Indus Water (PCIW) during the flood season only (10th July to 30th September)

PROBLEMS The Problems of Flood Forecast not

merely related to the models but also to the condition under which the models used

Every River has unique Flood Forecasting Problems in term of data availability ,Physiographic and Hydro Meteorological Conditions

The flood flows are extremely unsteady and the models do not readily adopt to the abrupt flow changes

Presently the flood forecasting Models are far from satisfactory .

There is dare need to improve the present system in term of data gap(dense Observational Network )

There is need for more reliable rainfall prediction model specially for the runoff forecast at the rim station. Since the available meteorological models are not accurate in temporal and spatial Rainfall prediction

Conclusion

CONFUSION CREATED BY DIFFERENCES IN THE OUTPUTS FROM THE MODELS . HOW TO DECIDE

AFTER TWO DAYS , HEAVY RAINFALL DISAPPEARED FROM MODEL .SUNNY WEATHER OR LIGHT RAIN OBSERVED INSTEAD OF HEAVY RAINFALL .WHAT ABOUT THE WARNING AND ABOUT THE PUBLIC & MEDIA COMMENTS