Technical Manual no. 6 Mapping the Potential of Rainwater Harvesting Technologies in Africa A GIS overview on development domains for the continent and ten selected countries Bancy Mati, Tanguy De Bock, Maimbo Malesu, Elizabeth Khaka, Alex Oduor, Meshack Nyabenge & Vincent Oduor Mapping the Potential of Rainwater Harvesting Technologies in Africa: A GIS overview and atlas of development domains for the continent and ten selected countries ICRAF Technical Manuals series 1. Mbaria, J. 2006.Linking Research to Extension for Watershed Management: the Nyando experience. -- Nairobi , Kenya : World Agroforestry Centre (ICRAF) ICRAF technical manual No. 1, 61p.. [B14288 B14305] 556.51 MBA ICRAFP 2. Wightman, K.E. 2006. Bonnes pratiques de culture en pépinière forestière : Directives pratiques pour les pépinières communautaires. -- Nairobi , Kenya : World Agroforestry Centre (ICRAF) ICRAF Manuel Technique No. 2, 95p.. [B14473] ICRAF 3. Jaenicke, H. 2006. Bonnes pratiques de culture en pépinière forestière: directives pratiques pour les pépinières de recherche. -- Nairobi , Kenya : World Agroforestry Centre (ICRAF) ICRAF Manuel Technique no. 3, 93p.. [B14474] ICRAFP 4. Wightman, K.E.; Cornelius, J.P.; Ugarte-Guerra, L.J. 2006. Plantemos madera : manual sobre el establecimiento, manejoy aprovechamiento de plantaciones maderables para productores de la Amazonía peruana. -- Lima , Peru : World Agroforestry Centre – Amazon Regional Programme, ICRAF Technical Manual no.4, 204p.. [B14518] 630*26 WIG ICRAF 5. Maimbo M. Malesu, Joseph K. Sang, Alex R. Oduor, Orodi J. Odhiambo & Meshack Nyabenge. Rainwater harvesting innovations in response to water scarcity: The Lare experience. Nairobi, Kenya: Regional Land Management Unit (RELMA-in-ICRAF), Netherlands Ministry of Foreign Affairs and Swedish International Development Cooperation Agency (Sida). ICRAF Manuel Technique No. 5, 41p + xii includes bibliography. ISBN: 92 9059 197 8 Mapping the Potential of Rainwater Harvesting Technologies in Africa: A GIS overview and atlas of development domains for the continent and ten selected countries Bancy Mati, Tanguy De Bock, Maimbo Malesu, Elizabeth Khaka, Alex Oduor, Meshack Nyabenge, and Vincent Oduor United Nations Environmental Programme (UNEP) World Agroforestry Centre (ICRAF) Published by The SearNet Secretariat, Global Water Partnership Associated Programme of RELMA- in-ICRAF. World Agroforestry Centre, ICRAF House, United Nations Avenue, Gigiri. P.O. Box 30677 – 00100, Nairobi, Kenya. 2007 World Agroforestry Centre (ICRAF), Netherlands Ministry of Foreign Affairs and Swedish International Development Cooperation Agency (Sida). Editor of GWP-AP Series of ICRAF publications Alex R. Oduor, Programme officer - Information George Obanyi, Infomation officer ICRAF Eastern Africa region. Design and Layout Logitech Ltd P.O. Box 1003 00100 Nairobi, Kenya Cataloguing in publication data Bancy Mati, Tanguy De Bock, Maimbo Malesu, Elizabeth Khaka, Alex Oduor, Meshack Nyabenge, and Vincent Oduor. 2006. Mapping the potentials for Rainwater Harvesting technologies in Africa: A GIS overview on development domains for the continent and ten selected countries. Technical Manual No. 6 Nairobi, Kenya: World Agroforestry Centre (ICRAF), Netherlands Ministry of Foreign Affairs. 116 p. + x p; includes bibliography. ISBN: 92 9059 2117 The contents of this book may be reproduced without special permission. However, acknowledgement of the source is requested. Views expressed in the World Agroforestry Centre (ICRAF) series of publication are those of the authors and do not necessarily reflect the views of World Agroforestry Centre (ICRAF). iv Contents Part One: Developing the GIS Database Chapter 1 Background and database for the mappable RWH technologies ..........1 Introduction .............................................................................................................................1 1.1 Why focus on rainwater harvesting ..............................................................................2 1.2 Responding to demands for thematic geo-spatial data in Africa ...............................3 1.3 Project scope .................................................................................................................3 Chapter 2 Developing the GIS database .....................................................................5 2.1 Consultative meetings & decision on what to map .....................................................5 2.2 Identifying mappable RWH technologies .....................................................................5 2.3 Developing criteria for mapping attributes ..................................................................9 2.4 Creating the GIS Database .........................................................................................13 Chapter 3 GIS Database on Potential for Rainwater Harvesting in Africa ............14 3.1 GIS database for Africa ...............................................................................................14 3.2 Available formats of the GIS database.......................................................................15 3.3 Contents of the GIS Database ....................................................................................15 3.4 Country-Specific GIS Databases .................................................................................15 Chapter 4 Conclusions ................................................................................................20 Part Two: The Atlas of RWH potentials for Africa and ten selected countries Africa and ten selected countries ...............................................................................22 Bibliography ...............................................................................................................111 7. ANNEXES ...............................................................................................................113 Annex 1. Sources of spatial data .......................................................................................113 Annex 2. Types of GIS Data for mapping of RWH potential in Africa ...............................114 Annex 3. Types of GIS Data for GIS mapping of RWH potential for countries .................115 Annex 4. Available GIS Input data for country Case studies ............................................116 ANNEX 5: Project Team .......................................................................................................116 v List of Maps Africa basemaps and development Domains ...........................................................22 Slope map ...........................................................................................................................................23 Landuse /farming system map .........................................................................................................24 Sand dams based on availability of Ephemeral rivers ....................................................................25 Runoff rainwater harvesting ..............................................................................................................26 Rooftop rainwater harvesting ............................................................................................................28 In situ rain water harvesting ..............................................................................................................30 Botswana basemaps and development domains ....................................................32 Soils map ............................................................................................................................................32 Possibility of development domains for sand dams ........................................................................33 Development domains for rooftop rain water harvesting ...............................................................34 Annual rainfall map ...........................................................................................................................36 Protected areas map .........................................................................................................................38 Population density map .....................................................................................................................39 Elevation map .....................................................................................................................................40 Ethiopia basemaps and development domains .......................................................41 Possibility of development domains for sand and sub-surface dams ...........................................41 Development domains for runoff rainwater harvesting .................................................................41 Possibility of development domains for rooftop rainwater harvesting ...........................................43 Annual rainfall map ..........................................................................................................................45 Protected areas ..................................................................................................................................45 Population density map .....................................................................................................................46 Landuse map .....................................................................................................................................46 Development domains for insitu rain water harvesting .................................................................47 Elevation map .....................................................................................................................................49 Kenya Basemaps and development domains ..........................................................50 Possibility for development domains for sand and sub-surface dams ..........................................50 Possibility for runoff rain water harvesting .....................................................................................50 Development domains for rooftop rain water harvesting ...............................................................52 Annual rainfall map ..........................................................................................................................54 Protected areas map .........................................................................................................................54 Population density map ....................................................................................................................55 Landuse map .....................................................................................................................................55 Development domains for insitu rain water harvesting ..................................................................56 Elevation map .....................................................................................................................................58 Annual rainfall ...................................................................................................................................58 Malawi Basemaps and development domains .........................................................59 Development domains for rooftop rain water harvesting ...............................................................59 Development domains for runoff rain water harvesting .................................................................61 Annual rainfall map ..........................................................................................................................63 Protected areas map .........................................................................................................................64 Population ...........................................................................................................................................65 Elevation map .....................................................................................................................................66 Mozambique Basemaps and development domains ...............................................67 Soil map ..............................................................................................................................................67 Development domains for runoff rain water harvesting .................................................................68 Development domains for rooftop water harvesting .......................................................................70 Annual rainfall ....................................................................................................................................72 vi Protected areas map .........................................................................................................................73 Population map ..................................................................................................................................74 Elevation map .....................................................................................................................................75 Tanzania Basemaps and development domains ......................................................76 Soil map ..............................................................................................................................................76 Development domains for runoff rain water harvesting .................................................................77 Development domains for rooftop rain water harvesting ...............................................................79 Annual rainfall map ...........................................................................................................................81 Protected area map ...........................................................................................................................82 Population density map .....................................................................................................................83 Landuse map .....................................................................................................................................84 Development domains for in situ rain water harvesting .................................................................85 Elevation map .....................................................................................................................................87 Uganda Basemaps and development domains ........................................................88 Development domains for runoff rain water harvesting .................................................................88 Development domains for rooftop rain water harvesting ...............................................................90 Annual rainfall map ...........................................................................................................................92 Protected areas map .........................................................................................................................93 Population density map .....................................................................................................................94 Landuse map .....................................................................................................................................95 Development domains for in situ rain water harvesting .................................................................96 Elevation map .....................................................................................................................................98 Zambia Basemaps and development domains ........................................................99 Soil map ..............................................................................................................................................99 Development domains for runoff rain water harvesting .................................................................99 Development domains for rooftop rain water harvesting .............................................................101 Annual rainfall map .........................................................................................................................103 Protected areas map .......................................................................................................................103 Population density map ...................................................................................................................104 Elevation map ...................................................................................................................................104 Zimbabwe Basemaps and development domains ................................................105 Soil map ............................................................................................................................................105 Development domains for runoff rain water harvesting ...............................................................105 Development domains for rooftop rain water harvesting .............................................................107 Annual rainfall map .........................................................................................................................109 Protected areas ................................................................................................................................109 Population density map ...................................................................................................................110 Elevation map ...................................................................................................................................110 vii List of Synonyms ACZ Agro-climatic zone AfDB African Development Bank AMCOW African Ministerial Council on Water AWTF African Water Task Force ASAL Arid and Semi-Arid Lands CAADP Comprehensive Africa Agriculture Programme ECA Economic Commission for Africa ET Evapotranspiration FAO Food and Agricultural Organization of the United Nations GIS Geographical Information System GPS Geographic Positioning System GWP Global Water Partnership GWP/AP Global Water Partnership-Associated Programme ICRAF International Centre for Research in Agroforestry / World Agroforestry Centre IWRM Integrated Water Resource Management MDG Millennium Development Goals NEPAD New Partnership for Africa’s Development NGO Non Governmental Organization RELMA Regional Land Management Unit RWH Rainwater Harvesting SEARNET South and East Africa Rainwater harvesting Network UNEP United Nations Environmental Programme WSSD World Summit for Sustainable Development SOTER viii Preface Water is at the heart of Millennium Development Goals (MDGs) numbers one (1), three (3) and Seven (7), and is indirectly associated with the success or otherwise of all the other Goals. But for Africa to meet the MDGs, bold and targeted actions will be obligatory in the water sector. Given that about 300 million people in Africa, a third of the continent’s population, are living under “water scarcity” circumstances, an urgent action is required to avoid 12 more African countries joining “water scarce” nations by 2025. To address this, the African Water Vision for 2025 has been set to develop the full potential of Africa’s water resources for sustainable growth in the region’s economic and social development, of which rainwater harvesting (RWH) and storage forms a major component. Among others, the Vision calls for “improving water wisdom”, which is to be achieved by establishing an elaborate system of data collection, management, dissemination, including standardization and harmonization of data and information. Towards this end, data sources have been developed such as FAOSTAT, AQUASTAT and Agriculture Towards 2015/30. However, continent-wide spatial information on rainwater harvesting potentials in Africa has been lacking. This information is necessary to raise world-wide awareness and guide policy decisions on the contribution of rainwater harvesting towards meeting; the MDGs, the African Water Vision and generally, the water needs of men and women in Africa, for improved ecosystems and livelihoods. In Part One, this captures the background and database for the mappable technologies both for the continent and ten selected countries. In addition, the report describes the mapping by GIS (Geo-referenced Information Systems), of the rainwater harvesting potential in Africa. The project provides an advocacy tool, which shows in spatial domains the expansive opportunities for RWH in Africa, including some ten selected countries; Botswana, Ethiopia, Kenya, Malawi, Mozambique, Rwanda, Tanzania, Uganda, Zambia and Zimbabwe. It produced a GIS database that captures the major factors associated with RWH which are; rainfall, topography, soils, population density, and landuse. These baseline thematic maps were further combined through spatial analyses to produce composite maps that show attributes or “development domains” that serve as indicators of suitability for targeted RWH interventions, grouped as; (i) rooftop RWH, (ii) surface runoff from open surfaces with storage in pans/ponds, (iii) flood-flow harvesting from watercourses with storages in sand/ subsurface dams and (iv) in-situ soil water storage systems. Consequently, the project produced a total of 73 maps comprising of 29 thematic basemaps, maps covering Africa and 44 composite thematic maps for the ten country case studies. All the maps are presented in Part Two. These maps provide a broad-brush, exploratory scale decision-support tool, since the GIS input data used was of low resolution, and either at country or continental scales. Noting that the major ingredient in rainwater harvesting is rainfall, and guided by the fact that if it rains, it can be harvested regardless of the quantities (too little or too much), the authors have therefore avoided labeling areas as either suitable or unsuitable for RWH. The decision of final prioritization is left to the user, after analyses of other factors beyond the GIS database, such as financial, cultural, political and local preferences. Henning Baur Regional Coordinator Eastern Africa ix