Rainwater-Smart Management Best Western Hotel, Nairobi, Kenya February

Transcription

1 Rainwater-Smart Management Best Western Hotel, Nairobi, Kenya February Technical challenges to implementing small-scale offseason rainwater harvesting irrigation technologies Stephen Ngigi, PhD Part-time Program Coordinator Kenya Rainwater Association

2 We cry for water and from water! Water Crisis in Africa: Floods and Droughts 1 of 18

3 Brief on KRA: Vision and Mission Vision: That all people have access to safe, reliable, and sustainable water supplies for productive uses Mission: To promote integrated RHM systems and complementary technologies for improving water supply, food & nutrition security, sanitation & hygiene, climate change adaptation and sustainable livelihoods 2 of 18

4 KRA Strategy: Integrated RHM Systems for Multiple Uses Rainwater Harvesting and Management (RHM) Schools Community Livestock production Crop production Roof catchment Sanitation Farm ponds Roof catchment Rock catchment Sand/surface dams Shallow wells Springs protection Earth dams/ Water pans In-situ SWC - soil storage Farm ponds Small reservoirs Low-head drip irrigation systems Hand-pumps/Treadle pumps Low-cost greenhouses Complementary Technologies for micro-irrigation 3 of 18

5 KRA Footprints in Kenya: Past and Present Projects Key Arid Turkana Marsabit Moyale Mandera Semi-arid High- and m potential West Pokot Wajir Baringo Samburu Isiolo Laikipia Garissa Mwingi Mbeere Turkana Marsabit Moyale Mandera Source: Ministry of Agriculture Key Arid Trans Mara Semi-arid High- and mediumpotential Narok Makueni Kajiado Kitui T/Taveta Tana River Kilifi Ijara Mombasa Baringo West Pokot Samburu Laikipia Isiolo Wajir Garissa Note: ASALs covers 80% of the country and hence huge potential for scaling up RHM systems as the most viable options! 4 of 18

6 Building Partnerships: Tripartite MoU, NDMA Consultancy & BDBP KRA have been involved in policy advocacy which has resulted in the following: 1. Signing of MoU with GoK (Ministry of Water & Irrigation and two Universities 2. NDMA Consultancy to review designs & BoQs Found out that Engineers overestimate cost of dams by 40-70% => times of actual cost! 3. Multi-partners development of Billion Dollar Business Plan (BDBP) for adopting business approach to promote farm pond technology in Africa 5 of 18

7 Technical challenges to implementing small-scale offseason rainwater harvesting irrigation technologies

8 Challenge: Low per capita water availability Source: UNEP 1999 Water scarcity in many countries is becoming a critical constraint to economic development Water resources endowment is limited by an annual renewable freshwater supply (e.g Kenya: 647 cubic meters per capita (2002) Now? <500m3! Many countries are classified as a chronically water-scarce country i.e. the renewable freshwater supplies are less than 1,000 cubic meters per capita (World Bank 2000). This means high demand for harvested rainwater for irrigation water is used for multiple uses due to lack of alternative sources 6 of 18

9 Challenges: Climate change and variability Predicted impacts of climate change and vulnerability areas in Africa => Low reliability of runoff storage structures due to rainfall variations 7 of 18

10 Rainfall, SIR, ETcrop (mm day -1 ) Challenges: Water Scarcity Crop growing period (90 days) Rainy season ODS ISDS Rainfall SIR ETcrop Day of the year Low water reliability hence inadequate irrigation water supply to bridge the offseason dry spell leading to crop stress, reduced yields or total crop failure 8 of 18

11 Challenge: Rainfall Dependent Economic Development in SSA The relationship between Development Index (GDP) and rainfall Note: There is a direct correlation between per capita water storage and per capita income! 9 of 18

12 Technical challenges: Potential options

13 Farm Pond Technology: Challenges and Mitigation Measures Risk/Challenge Stability risk: Collapsing of side walls Safety risk: Drowning for human and domestic animals Health risk: Mosquitoes breeding and prevalence of malaria Reliability risk: Water losses through seepage and evaporation Siltation risk: Runoff carries a lot of sediments and debris Mitigation Measures Adopting 40-60% side slopes Fencing with barbed wire and chain-link around the farm pond Covering/roofing the open reservoir with shade net (80% to allow direct precipitation to penetrate) Ultra-violet plastic lining enhanced by adoption of regular truncated pyramid shaped design Covering/roofing the open reservoir with shade net trade-off between bigger ponds with high losses and smaller ponds with evaporation control Planting passion fruit along chain-link perimeter fence Integrate biological soil conservation vegetation and stone pitching along the water way Incorporate double chamber masonry silt trap and screen filter to prevent silt and debris entering the pond Regular maintenance of water way, silt trap and screen filter 10 of 18

14 Farmers Interventions and Challenges: Low Performances Technical design: irregular shapes, steep side slopes, siltation, physical and health risks High water losses: High Seepage and Evaporation (40-60%) 11 of 18

15 Past Experiences: Attempts to Reduce Water Losses Seepage losses: Lining with either concrete, masonry, UV-resistance plastic Evaporation losses: Roofing with iron sheets, thatch, vegetation e.g. non-flowering passion fruit High investment costs: Need for cost-effective interventions 12 of 18

16 Technology challenge: High siltation of farm pond Lined farm pond in Bugesera, Rwanda harvesting silt? Addressing siltation challenge: Double chamber silt trap (adopted from Ethiopia) Screen filter Spillway Inlet 13 of 18

17 Evaporation water losses: Evolution of roofing design of Upgraded Farm Ponds 1 st Generation 2 nd Generation 4 th Generation 3 rd Generation 14 of 18

18 20 of 27 Technical Challenges: Poor water application and management Drip irrigation: low-head drip irrigation system whose water supply is matched with water storage Greenhouses: Low-cost greenhouses for weather sensitive crops Simple pumps: hand or solar pumps 15 of 18

19 Scaling up challenges: Land holding, Farm pond size, Livelihood status and Construction process Land size Farm pond size Livelihood status (Financing option) Construction approach Small size (½ - 1 acre) m 3 Safety net (grant-based) Manual labour Medium size (1-2 acre) m 3 Subsidy (grant/credit) Mechanization/ Manual labour Large size (>2 acres) m 3 Self-financing (credit) Mechanization 16 of 18

20 Scaling up challenge: Financing Mechanism for Smallholder Farmers Build, Manage & Transfer (BMT): Market-oriented business model financing mechanism for scaling up proven climatesmart cost-effective upgraded farm pond technology for smallholder drylands farming systems. Graduated smart subsidies that consider financial capability for different livelihood status (poverty levels) Build Manage A finance intuition provide credit/loan through a grantor, who will build the RHM system with the farmer/client The grantor and the farmer will manage (operate) the production and marketing system with the farmer Transfer The grantor will transfer the production system to the farmer after full repayment of the loan the farm has adequate capacity to sustain the system 17 of 18

21 Parting Shot: Conclusions Water storage is a prerequisite for off-season irrigation But we still have low per capita water storage? Inadequate standardization and quality control on RHM systems hence low cost-effectiveness (high cost/m 3 ) Different actors with various implementation approaches need for harmonization Technical challenges but cost effective options to address them that have been researched, developed, tested and proven Scaling up challenges relatively high investments for poor farmers aggravated by inadequate financing mechanisms Government subsidies (e.g. Duty and VAT exemption) and support for non-state actors like NGOs and CBOs 18 of 18