Integrated Watershed Management Towards Sustainable Solutions in Africa

Transcription

1 Integrated Watershed Management Towards Sustainable Solutions in Africa A. Bahri, H. Sally, R.E. Namara, M. McCartney, S.B. Awulachew, B. van Koppen, and D. van Rooijen International Water Management Institute 6th Biennial Rosenberg International Forum on Water Policy June 23-27, 2008 Zaragoza, Spain

2 OUTLINE D LAND, WATER & LIVELIHOODS CHALLENGES IN SUB-SAHARAN AFRICA D INTEGRATED APPROACH TO WATERSHED MANAGEMENT D CASE STUDIES D CONCLUSIONS AND POLICY IMPLICATIONS

3 LAND, WATER & LIVELIHOODS CHALLENGES IN SUB-SAHARAN AFRICA The percentage of the population living on less than $1 a day SSA is the poorest region in the world and getting poorer percentage (Source: NEPAD 2005, based on WB data) 0 SSA SA EAP LAC ECA MNA GDP, Ag GDP and Population growth % Population growth in SSA has exceeded the growth of both overall and agricultural GDP, so that the population has become poorer GDP grow th (annual %) Ag value added (annual grow th %) Population grow th % (Source: World Bank) 0 East Asia & Pacif ic Sout h Asia Middle East & Nor th Afr ica Lat in Amer ica & Car ibbean Sub-Saharan Afr ica

4 Water storage mitigates variability Low per capita storage (m 3 /capita) 7,000 6,000 5,000 4,000 3,000 2,000 1, Very little water storage has been built in Africa. Increased storage could reduce poverty and improve health Kenya Ethiopia South Africa Thailand Laos China Brazil Australia North America World Bank (2003)

5 Agricultural Water Management D 3.8% water withdrawals for agriculture (3.6%), water supply and energy. D 183 million ha (Mha) (6%) of the total area under cultivation: D 97% of total cultivated area under rainfed. Over 90% of the agricultural population dependent on green water. D 21% (39.4 Mha) of total cultivated area potentially irrigable. 9 Mha (5%) under water management. 7 Mha under irrigation. D Considerable scope for improved agricultural production and food security through irrigation and rainfed agriculture

6 Transboundary River Basins in Africa Water resources management means transboundary management Very high water interdependence: 53 sovereign states sharing 63 transboundary river basins Containing 93% of the total water Covering 61% of the surface area In which 77% of the human population live

7 Trends and challenges of integrated watershed management 1. Development and operation of water systems and structures, largely for irrigation. 2. Mid 1990s, water management placed into the context of river basins. 3. IWRM, IRBM, INRM, IWM, ICM, : D D Holistic, integrated, and participatory approaches Based on hydrological and bio-geophysical units D Link land and water development D Link social and economic development with protection of natural ecosystems

8 The Catchment Perspective Virtual water flow Return water flow (Adapted from Falkenmark, 2002)

9 CONCEPTUAL MODEL OF UPSTREAM-DOWNSTREAM INTERACTIONS (after Kirkby, In CPWF, 2003)

10 Historical evolution of integrated watershed management in Africa

11 Integrated watershed management in Africa D Most African countries engaged in WM and in IWRM. D Some have however moved to a state-wide approach. D How much water should be allocated to agriculture, other uses, and for environmental uses still a subject of debate. D There are major differences in countries needs and development stages: focus on how to attain the MDGs vs environmental protection and restoration. D Most African international basin organizations ineffective (AfDB, 2007). Issues of treaties unresolved and national interests prevailing.

12 CASE STUDIES 1. Balancing inter-sectoral water demands in the Rufiji Basin in Tanzania 2. Water management in urban watersheds 3. The Nile an example of multi-national water management

13 Target flows in rivers and allowable abstractions to meet Ruaha goal Great Ruaha River

14 The Problem: severe impacts on Ruaha National Park and failure of hydropower production Area under rice (ha) Comparison of the dry season inflow to the Ihefu wetland and irrigated area in the Usangu catchment Since the mid-1990s, the Great Ruaha River has ceased flowing in the dry season every year because: water levels in the Usangu wetland have dropped below a critical level and outflows from the wetland have ceased y = x R 2 = of diversions to rice irrigation 0 0 5,000 10,000 15,000 20,000 25,000 30,000 35,000 40,000 45,000 50,000 upstream of the wetland. Dry season Flow (Mm Irrigated Area (ha)

15 Value of water across sectors Should water be allocated to the highest economic benefits or to secure the livelihood of the poor? Paddy irrigation Hydropower Water consumed (Mm 3 ) 542 1,094 (4,096) Net Real Value ($m -3 ) (0.06) If based simply on criteria of economic efficiency, water would be allocated away from irrigation to the downstream hydropower schemes. Rice: D 14-24% national paddy production D 60% exported out of basin D 30,000 households ($ 912/year) Hydropower: D 50% of national power (284 MW) D Only 1% rural population connected Ultimately, water allocation is a difficult political choice

16 Wetland Hydrology Q in Wetland water levels P E Water level at exit Storage Q out Great Ruaha NG iriama exit River Natural annual water budget Inflow: 3,390 Mm 3 Rainfall: 490 Mm 3 Evapotranspiration: 835 Mm 3 Outflow: 3,045 Mm 3 (78% of total input) Human withdrawals from the rivers: 834 Mm 3 Environmental flow (Desktop Reserve Model): Mean annual flow: 2,933 Mm 3 (93 m 3 s -1 ) Annual environment flow: 635 Mm to maintain the absolute basic ecological condition (21.6% of MAF) Min dry season outflow: 0.5 m 3 s -1 Min dry season inflow: 7.0 m 3 s -1 3

17 The African Urban Challenges D World s most rapid rate of urbanization (~ 5% / year) D African urban population will nearly quadruple (138 million in million in 2020) D Several large African cities share at least one international river basin: the Nile, Niger, Congo, Limpopo, Volta and Zambezi. D Growing water demand and discharge of wastewater from the cities pose a special challenge for river basins water resources management. D Water authorities manage their water supply, sewerage and stormwater drainage systems as separate entities. D Sharing of common water bodies by several African cities poses a special threat to freshwater quality and aquatic ecosystems (ex: Lake Victoria).

18 Spatial context of urban water flows in Accra Watershed Approach to Urban WRM: manage both catchment (pollution control) and urban water cycle elements (water, wastewater, stormwater and water reuse) in an integrated way Volta Lake Akosombo Dam Linking Urban ~ Rural water management: Agriculture ~ land treatment system and nutrient recycling part of the loop Domestic ~ Agricultural water use Hydrologic Cycle /Water and Nutrient Cycle Kpong-Akuse Treatment Plant Official urban boundary!(!(!(!( Wejia Lake Tanker waste disposal!( Piped outflow Korle Lagoon Ocean

19 Water production at Weija Treatment Plant in Accra Wastewater disposal into Ocean at Lavendel Hill

20 Wastewater reuse in Ghana

21 Addis Ababa (after Awulachew, 2006) Access to sanitary facilities: 74% <10% provided with sewer system Kaliti WSP treats <3.6% 11 unions with 957 households and 7450 family members 262 ha cultivated by the unions, 134 ha by the private

22 Spatial context of urban water flows (after van Rooijen) Water supply Water collection, storage, conveyance and treatment Flood protection Urban unit Water supply, storage and distribution Sewage collection and treatment (MDG, EcoSan, etc.) Water reuse /disposal (Waste)Water quantity & quality Reuse for irrigation purposes and others Environmental services

23 Economic value of water and nutrients D Conserves water and reduces freshwater demand D Provides a reliable water supply to farmers Trade-offs Environmental and public health risks D Health risks for the irrigators and communities in contact with wastewater D Low-cost method for disposal of municipal wastewater D Reduces pollution of rivers, canals and other surface waters D Conserves nutrients, reducing the need for artificial fertilizers D Increases crop yields D Health risks for the consumers of vegetables irrigated with wastewater D Contamination of groundwater D Build-up of chemical pollutants in the soil D Creation of habitats for disease vectors in peri-urban areas D Has direct positive income effect for farmers

24 The Nile an example of multi-national water management D Unique in Africa for its long history, great technical complexity and its international scale. D 15 bilateral treaties and agreements dated from 1891 to 1993 (Adams, 2001). D The Nile Basin Initiative, established in 1999 with the support of the World Bank to facilitate cooperation among riparian countries. D NBI s Strategic Action Program: a basin wide Shared Vision Program and Subsidiary Action Programs (ENSAP, NELSAP)

25 Economic value of cooperation: status quo versus full cooperation Million USD Status quo Full cooperation Ethiopia Sudan Egypt Others Total Extra benefits of full cooperation is US$4.94 billion annually (Whittington et al., 2005).

26 Why multi-national water management is needed on the Blue Nile? D Watershed degradation D Flood damage along the Blue Nile in Sudan recently estimated at USD 527 million for a 1-in-100-year flood event (USD 52 million/year on average) (Cawood, 2005). D Significant impacts of sedimentation: D Loss of hydropower potential and of agricultural production D Sediment load of the Blue Nile at El Diem of 140 million tons per year (Ahmed, 2003) D Management difficulties of irrigation canals networks in the Gezira scheme: costs of the sediment clearance amounting at more than 60% of the total O&M costs.

27 The Blue Nile an example of multi-national water management D A research project, aiming at improving water and land management in the Ethiopian highlands and its impact on downstream stakeholders dependent on the Blue Nile is underway. D The work includes: D hydrological and water allocation modeling D watershed management D policy and institutional studies at various levels

28 Causes The Waters hed Prob lems Impacts: Local Impacts: DS Sediment Volume and Content of Roseires Dam

29 Khartoum Hawata 1,102 Rahad SUDAN Giwasi Border 6,246 Dabus 2,797 Dinder Sennar Roseires ETHIOPIA Lake Tana 3,809 Beles Outlet Lake Tana 4,345 North Gojam Wonbera South Gojam 3,874 5,012 4,389 2,355 Anger 1,719 2,187 5,673 Guder Didessa Finchaa Kessie 3,920 2,440 4,345 Bosheilo 2,072 4,798 Muger Welaka Jemma Flow gauging station Reservoir Mean annual discharge (Mm 3 ) Schematic showing proposed configuration of the water allocation model of the Blue Nile 1.40E E E E E E E E+00 Flow (cms) Runoff hrus1 SURQ_GENmm E E E E E E E+00 Sediment Export (t/ha) Sediment Yield hrus1 SYLDtha Schematization of Blue Nile for erosion and sediment modeling Modeling the Gumera watershed runoff and sediment yield, preliminary results

30 CONCLUSIONS D IWM is about decision making in a multiple-use and multiple-user context to improve water productivity and derive optimum benefits for all relevant stakeholders. D Different approaches are needed to address the critical development and management issues. D Still a range of challenges: D inter-sectoral competition for water D dealing with trade-offs related to developmental and economic objectives, and equity and conservation considerations/between ecosystems D integration across scales D reconciling hydrological boundaries with administrative and political boundaries

31 CONCLUSIONS D Decision-making can be enhanced using tools that promote stakeholder dialogue and take into account existing local-level traditional arrangements. D In urban watersheds, comprehensive understanding of the entire urban water system is required. Innovations and investment interventions in technological, institutional change and sociological learning are needed. D Transboundary coordination is needed to foster major win-win opportunities and overcome constraints to upscaling promising management practices and technologies.

32 D D D D D D D D D POLICY IMPLICATIONS The adoption of the ecosystem approach will ensure watershedwide perspectives to development and management and make for social equity. The MUS concept in IWDM may provide the most equitable option on which watershed-wide plans may be based. Think more in terms of AWM rather than about irrigated or rainfed agriculture. Manage water, wastewater, non-point source pollution, and water reuse in an integrated way. In water allocation decisions, consideration of equity, food security, poverty reduction and development needs should be taken into account. Both watershed and administrative or social/cultural boundaries need to be considered. Nested institutional structures should be set up to manage us-ds interactions. Include informal small-scale water users. Adoption of a pragmatic mix of new and existing management arrangements to improve services and reduce conflicts.