The Volta River Basin Comprehensive Assessment of Water Management in Agriculture Comparative study of river basin development and management Boubacar BARRY Emmanuel OBUOBIE Marc ANDREINI Winston ANDAH Mathilde PLUQUET January, 2005 Draft 1 TABLE OF CONTENT List of Tables......................................................................................................................................... 7 List of Figures....................................................................................................................................... 9 I. INTRODUCTION ...................................................................................................................... 11 I.1 The Volta River Basin.................................................................................................................. 11 I.2 Methodology and presentation of the study ................................................................................ 14 II.THE VOLTA RIVER BASIN: HUMAN AND PHYSICAL SETTING............................... 16 II.1 Climatic features....................................................................................................................... 16 II.1.1 Distribution of Rainfall....................................................................................................... 16 II.1.2 Distribution of Evaporation and Evapotranspiration (ETP) compared to rainfall . 22 II.1.3 Temperature and humidity.................................................................................................. 26 II.2 Human Context ............................................................................................................................ 29 II.3 Economic Sector and Policies...................................................................................................... 37 II.4 Agro-ecological Zoning .............................................................................................................. 41 II.4.1 Drainage network and sub-basins ........................................................................................... 41 II.4.2 Relief ........................................................................................................................................ 43 II.4.4 Geology of the Basin............................................................................................................... 47 II.4.5 Land use, land ownership and land degradation ...................................................................... 49 i. BENIN ........................................................................................................................................ 52 ii. BURKINA FASO....................................................................................................................... 53 iii. CÔTE D’IVOIRE.................................................................................................................... 55 iv. GHANA .................................................................................................................................. 56 White Volta Basin............................................................................................................................... 57 Black Volta Basin ............................................................................................................................... 58 Lower Volta Basin .............................................................................................................................. 58 Oti Basin ............................................................................................................................................. 59 Daka Basin.......................................................................................................................................... 59 v. MALI ....................................................................................................................................... 59 vi. TOGO ...................................................................................................................................... 59 II.4.6 Agriculture ............................................................................................................................... 61 i. Crop production ....................................................................................................................... 61 ii. Livestock..................................................................................................................................... 65 iii. Fisheries .................................................................................................................................. 66 iv. Forestry ................................................................................................................................... 67 II.5 Water resources........................................................................................................................... 67 II.5.1 Surface Water Resources in the Volta River System.......................................................... 67 i. GHANA.................................................................................................................................... 67 • The White Volta Basin............................................................................................................... 69 • The Black Volta Basin................................................................................................................ 69 • The Lower Volta......................................................................................................................... 70 • Oti Basin..................................................................................................................................... 72 • Daka basin................................................................................................................................... 72 ii. BURKINA FASO....................................................................................................................... 73 iii. MALI ...................................................................................................................................... 77 iv. TOGO ..................................................................................................................................... 78 v. CÔTE D’IVOIRE .................................................................................................................... 78 vi. BENIN .................................................................................................................................... 78 II.5.2 Groundwater Resources, Recharge, and Quality ..................................................................... 78 2 i. GHANA ...................................................................................................................................... 79 (b) Aquifers found in Ghana......................................................................................................... 84 (c) Borehole Yields...................................................................................................................... 84 (d) Groundwater abstraction and distribution............................................................................... 87 (e) Aquifer recharge..................................................................................................................... 88 (f) Groundwater quality............................................................................................................... 89 ii. Burkina Faso............................................................................................................................... 90 (a) Aquifers in Burkina Faso........................................................................................................ 90 (b) Groundwater availability........................................................................................................ 91 (c) Aquifer yield........................................................................................................................... 92 (d) Recharge Mechanisms ............................................................................................................ 94 (e) Groundwater Abstraction and Distribution............................................................................. 94 (f) Quality of aquifers in Burkina Faso........................................................................................ 95 • Nitrogen species.......................................................................................................................... 96 • Salinity ........................................................................................................................................ 96 • Fluoride....................................................................................................................................... 96 • Arsenic ........................................................................................................................................ 97 • Iodine .......................................................................................................................................... 97 II.4.2 A geographical triptych............................................................................................................. 97 A. Agro-Ecological Zones in the Volta Basin of Ghana