INTER BASIN WATER TRANSFERS. Susantha Mediwaka. Department of Irrigation, Sri Lanka

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1 INTER BASIN WATER TRANSFERS Susantha Mediwaka Department of Irrigation, Sri Lanka

2 Land darea Wet Zone 30% Dry & Intermediate Zone 70% Annual Rain fall Wet zone 1900mm Dry zone 800mm Dry & Intermediate zone Wet zone

3 103 river basins most basins are smaal only 17 exceeds 1000 km 2

4 Mahaweli river Basin Inter basin water transfer was imminent to augment the water shortage dry zone from water abundance wet zone.

5 Out of all 103 river basins Mahaweli river basin covers 16% of the land area Which has 10,327 km2, benefit from both monsoons. and is the most beneficial river starting from the Central hills and running through a dry fertile plateau

6 Adjacent river basins benefited by Mahaweli river diversion Malwathu Oya Yan Oya Maduru Oya & Kala Oya The land area under above 30% Hence Mahaweli is the principal source of water for Dry zone.

7 Polgolla Barage

8 Inter Basin Diversion 2010 Kothmale Mahaweli River Kalawewa System 77% Polgolla Baragea Bowathenna Elahera Hurulu Poshitha System Elahera/Minneriya Victoria Res. Angamedilla anicut System Parakrama Samudra Res. Randenigala Res. Ambanganga Rantambe Res. RB Minipe LB Mahaweli River 55% System C Maduruoya 54% System B Sorabora/Mapakada/Dambarawa Ulhitiya Rathkinda

9 Management Strategies Mahaweli Authority of Sri Lanka Overall responsibility Water Management Secretariat (WMS) WATER MANAGEMENT PANEL With the involvement of other agencies and Ministries concerned,

10 Members Water Management Panel Ministry of Agriculture Ministry of Irrigation & Water Resources Planning Irrigation Department t Ceylon Electricity Board Agriculture Department District Secretaries The Director functions as the Secretary to the Panel.

11 FUNCTIONS OF WATER MANAGEMENT PANEL (WMP) Govern the management of water resources of the Mahaweli diversion system Achieve optimum benefits from irrigation as well as from hydro power. formulation of operation policy and setting of overall cultivation. programs for the irrigated area served by Mahaweli program.

12 Data Base WMS maintains a data base Irrigation scheme/system performance Main system reservoir/power station performance Thermal station generation Main system diversions Cropped area Hydrological data ( rainfall, runoff etc.)

13 Allocation/ Distribution of water SOP is prepared prior to the each season through a consultative process IEE & RPMM provide cultivation data as; first and last date of water issues Irrigation demand based on crop data CEB availability of power plants, energy & peak demand

14 Other inputs for SOP past p hydrological data, system status at the beginning of the season, Diversion capacities of structures, maintenance programs of power plants & other structures t

15 SOP provides the following details for all irrigation schemes connected with Mahaweli network. * projected reservoir releases * energy generation ( hydro ) * projected diversions * reservoir behavior * allocation of water for each irrigation scheme * sluice issues * expected rainfalls.

16 Feasibility of the Operational Plan Feasibility of the Proposals are examined using a Computer Program ( ACRES Reservoir Simulation Program)

17 Conflicts while implementing the approved plans Hydro power requirement during off season when maintenance works are in progress. Restrictions in Generation Capacity. (Water releases are too much when generated at full capacity.)

18 Over the diversion i volumes main barrage. Limitation on capacities of diversion tunnels and canals New demands for domestic & industrial water supply Non adherence to SOP More extents are cultivated Dl Delayed cultivation Overuse of water etc.

19 Pre seasonal Water Panel Meeting SOP Prepared is discussed at the Pre seasonal Water Panel meeting that will be held with all concerned Parties and Farmer Reps. Main tool to resolve the most of above Main tool to resolve the most of above conflicts raised and for the smooth season.

20 W t M t P l Water Management Panal held at 1 st October 2010 in Kandy Peradeniya for 2010/11 Cultivation Season

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22 Monthly meetings (PMC ) To finalize the cultivation data Monitor M the SOP implemented Water Duty Water Allocation Rehabilitations.etc with FO reps, Govt officers, other related organizations.

23 WEEKLY PLANNING MEETINGS Seasonal Operational plan need to be reviewed Weekly meetings with the participation p of MASL, ID, CEB & NWS&DB in Colombo for; Variations from the operational plan Any A updates dt with new dt data if the variation iti are significant

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