Development and Testing of Environmental Flow Prescriptions for Kafue River

Transcription

1 The Hydropower Sustainability Assessment Forum (HSAF) Kafue Gorge, Zambia, 4-7 th September 2008 Development and Testing of Environmental Flow Prescriptions for Kafue River Dora Kamweneshe WWF Zambia Coordination Office

2 Outline of the Presentation Overview Environmental flows in the Kafue Flats Development of tools Results so far Lessons learnt Challenges Way forward

3 Overview The Kafue River Basin Central Zambia, area 150,000 km 2 Has two major wetlands, the Lukanga swamps and the Kafue Flats Most Zambia s economic activity 20% of the Zambia s population The Kafue Flats Located between Itezhi-tezhi and Kafue Gorge dams Wetlands with diverse ecosystem with an area of 6,500km 2

4 The Kafue River Basin Map of Zambia Upper catchment Solwezi ITEZHI-TEZHI DAM Lower catchment Kasempa Lufupa River BUSANGA SWAMP Hook Lunga River Chifumpa Lubungu KAFUE FLATS Chilenga Kafue River Nyimba 19 Luswishi River Machiya 2 2 KAFUE GORGE DAM LUKANGA SWAMPS 1 0 Kasaka Ndola Zambezi River Zimbabwe International boundary Sub-catchment boundary Rivers Hydrological Stations Marsh Towns Kafue River Basin

5 Importance of the Kafue Flats Endemic Kafue lechwe People Tourism Farming Fishing Hydropower Fishing Ramsar site Cattle rearing Ramsar site

6 Positive Impacts of the Dams Perceived impacts of ITT and KG Dams Electricity supply mostly for urban populations Commercial farming due to steady supply of water due to river regulation Negative Impacts Reduction of the available surface area of grazing lands Reduction of available lands for crop production as a result of loss of moisture retention that would have followed floods Increases in cattle disease have been observed and linked to increased presence of ticks, as they are no longer washed away during floods on a yearly basis Reductions in fisheries, partly caused by loss of fish breeding grounds The population of Kafue Lechwe, an endemic species of antelope, has declined

7 Natural reference situation Dam Operation Rules SWECO Operation rules ( ) Upon dam construction Rigid freshet of 300m3/sec to be released in March included, but never implemented SADC Operation rules (1994- ) Developed when Zambia was hit by drought Freshet never explicitly implemented Better for flood dynamics than SWECO rules No clearly defined strategy for creating a managmed flood, resulting in the unt-timed and fragmented releaseof surplus waters from ITT

8 Background Issues Restoration of Environment Improving flooding regime Improving recession regime Efficient water storage to try and meet ever rising demand

9 Environmental flows in the Kafue Flats Overall Objective Restore natural flooding regime in the Kafue Flats to restore the productivity of the wetlands for the benefit of nature Mimic the natural flooding pattern in the Kafue Flats, without compromising energy production and agricultural water demands Increase the productivity of the wetland by restoring the natural pattern of flooding through changes to the operating procedures of the Itezhi-tezhi and Kafue Gorge dams Specific Objectives

10 Environmental flows in the Kafue Flats One principle used to mimic the natural flooding pattern in the Kafue Flats, is management of environmental flows, specifically managed flood release from reservoirs. Acreman (2000) defines an environmental flow as a controlled release of water from a reservoir to inundate a specific area of floodplain or river delta downstream to restore and maintain ecological processes. WWF instigated multi-stakeholder dialogue to identify win-win solutions and engaged in building working relationships at all levels leading to an agreement to restore a more natural flow pattern to water releases from the ITT Dam, for ecological processes downstream without significantly diminishing hydro electricity production.

11 Environmental flows in the Kafue Flats The Partners GRZ Ministry of Energy and Water Development

12 Improved Operation Rules Freshet 1 Reach maximum flooded area Freshet 2 Follow rising and declining curve Smaller flooded area Freshet 3 Follow rising curve Larger flooded area Freshet 4 Follow declining curve Larger flooded area m3/s m3/s Release from Itezi-Itezi Release from Itezi-Itezi Oct Nov Dec Jan Feb Mar Apr Oct Nov Dec Jan Feb Mar Apr Natural Natural Freshet 1 Freshet 1 Freshet Freshet 2 2 Freshet 33 Freshet 4

13 Improved Operation Rules Freshet 1 Freshet 2 Freshet 3 Freshet 3 Birdlife Wildlife Water plants Fish

14 PITMAN Model Tools for Environmental flow management Rainfall Runoff Correlation Analysis Forecasting of inflows KAFRIBA Model Predicts water levels in the reservoirs and the hydrodynamic flooding patterns in the Flats for various release scenarios. when Zambia was hit by drought With an accurate forecasting, potential for an additional release from ITT Dam can be assessed. This potential can be used as a managed flood, in order to create an effective and maximised freshet. Useful tool in deciding the extent, duration and timing of the flooding.

15 Tools for Environmental flow management Output from KAFRIBA shows: Extent of flooding Depth of each segment

16 Tools for Environmental flow management Satellite image of Kafue flats, can be compared with the results from KAFRIBA

17 Tools for Environmental flow management Village Y Village Z Village X KAFRIBA output superimposed on Satellite Image

18 Results so far Review, design and implementation of the hydro-meteorological network KAFRIBA model was extended to include forecasts on the inflows into Itezhi-tezhi and Kafue Gorge Dam Improving dam operation rules in order to mimic the natural flooding pattern A freshet mimicking the natural rising and declining curve was found to be best suited to ecological requirements Study found that for mimicking the natural situation, more water should be released from Itezhi-tezhi during the months of January and February

19 Lessons learnt From the outset, the programme should be designed to allow it to be taken over and run by local stakeholders who have a lasting presence and interest in the area Keep explaining the strategic role of an organization like WWF To avoid misunderstandings that may hamper securing programme goals, the role of an organization like WWF (as a catalyst and intermediary, not as an owner or long-term donor) must be explained continually to the project partners and other stakeholders The partnership approach is highly challenging, but once established can work very well Key challenges are how to identify and contact partners, how to build relationships with them, how to overcome cultural differences with non-conservation oriented parties, and how to reach agreement. Start small and scale up For Kafue Flats, it was decided not to initiate a complex, fully integrated process from the beginning, but to start with simple, small-scale activities. From this ground level approach, a more integrated programme was gradually built up. The process of improving dam operating rules to benefit livelihoods and the environment is a long one and requires commitment of resources over a period of time.

20 Challenges The new flow regime is now in operation but the performance of the models is still low Remote sensing method needs to be ground-truthed via GPS measurement in the field to recalibrate the remote sensing-based images/maps The need to revisit the rule curve for Kafue Gorge reservoir Raising reservoir level to 977m seem to be a problem for other stakeholders (e.g. Fish Farms) Dropping the Reservoir to 974.4m also seem to be a problem for other stakeholders (e.g.sugar plantations) Dropping the reservoir by spilling from beginning of May to October is considered risky for some stakeholders(e.g. ZESCO).

21 Way Forward Current phase of the Project is focusing on two aspects which have been attributed to this low performance: Revamping and collection of good quality hydro-meteorological data from all the twenty seven stations and, Further comparisons of the KAFRIBA simulations against coincidently acquired satellite images of Kafue Flats. Work also has to continue through a detailed monitoring programme to ensure that a clear picture of the costs and benefits emerges. Designing to allow it to be taken over and run by local stakeholders who have a lasting presence and interest in the area.

22 Thank You