Contract number: 031A249A Work package number 4 December 2014 Deliverable 4.4.1 Drainage Basin Water Resources Development and Attributed Causes in Eastern and Southern Africa Literature review report in frames of the Trans-SEC project study on water resources development in the Wami-Ruvu river basin, Tanzania Meike Pendo Schaefer, Ottfried Dietrich Institute of Landscape Hydrology Leibniz Centre for Agricultural Landscape Research (ZALF) Müncheberg, Germany Public use Yes Confidenal use --- “Drainage Basin Water Resources Development and Attributed Causes in Eastern and Southern Africa” Literature review report in frames of the Trans-SEC project study on water resources development in the Wami-Ruvu river basin, Tanzania December 2014 Meike Pendo Schaefer, Ottfried Dietrich Institute of Landscape Hydrology Leibniz Centre for Agricultural Landscape Research (ZALF) Müncheberg, Germany gefördert Table of Content 1. INTRODUCTION ............................................................................................................................................ 6 2. METHODICAL APPROACH ............................................................................................................................. 9 2.1 Study selection criteria ...................................................................................................................... 9 2.2 Database structure .......................................................................................................................... 10 2.3 Definition of terminology ................................................................................................................ 11 2.4 Analysis approach ............................................................................................................................ 14 3. DEFINITION OF TERMINOLOGY AND DESCRPTION OF MAIN FACTORS ..................................................... 16 3.1 Hydrologic parameters employed to determine changes in drainage basins ................................ 16 3.1.1 Hydrologic parameters in rivers ............................................................................................. 17 3.1.2 Hydrologic parameters in lakes .............................................................................................. 20 3.2 Main causes of hydrological change in Eastern and Southern African drainage basins ................. 21 3.2.1 Climate variability and climate change .................................................................................. 21 3.2.2 Land use and land cover change ............................................................................................ 24 3.2.2.1 LULCC - Farming and grazing activities ...................................................................... 26 3.2.2.2 LULCC – Deforestation and afforestation .................................................................. 27 3.2.2.3 LULCC – Fire ............................................................................................................... 28 3.2.3.4 LULCC - Soil-water management practices ............................................................... 29 3.2.3 Water withdrawal ................................................................................................................... 31 3.2.4 Dams and reservoirs ............................................................................................................... 32 3.2.5 Tectonic activity ...................................................................................................................... 34 4. OVERVIEW OF AGGREGATED ANNUAL WATER RESOURCES TRENDS IN EASTERN AND SOUTHERN ........... AFRICA FROM 1900-2010 ........................................................................................................................... 34 4.1 Background and composition of reviewed references ................................................................... 35 4.2 Synopsis of findings from entirety of river drainage basin studies ................................................. 39 4.3 Synopsis of findings from entirety of lake drainage basin studies .................................................. 46 5. REVIEW OF REPORTED CHANGES IN BASIN WATER PARAMETERS AND ATTRIBUTED PRESSURES IN ......... EASTERN AND SOUTHERN AFRICA FROM 1970-2010 ................................................................................ 50 5.1 Composition of references covering 1970-2010 period ................................................................. 50 5.2 Discussion of changes in and pressures attributed to selected hydrologic parameters ................ 52 5.2.1 Increased annual streamflow / lake water levels .................................................................. 52 5.2.2 Decreased annual streamflow / lake water levels ................................................................. 54 5.2.3 Changes in seasonal composition of streamflow / lake water levels .................................... 57 5.2.4 Changes in frequency / intensity of floods and basin response time .................................... 61 5.2.5 Changes in frequency and duration of no flow ...................................................................... 64 5.3 Regional relevance of hydrologic parameter development and attributed pressures ................... 67 5.4 Temporal relevance of hydrologic parameter development and attributed pressures ................. 72 5.5 Relation of basin size to reported hydrologic parameters and attributed pressures ..................... 80 6. SUMMARY AND OUTLOOK ......................................................................................................................... 82 6.1 Summary of review findings ............................................................................................................ 82 6.2 Outlook on expected future development...................................................................................... 87 6.3 Relevance and scope for Trans-SEC project .................................................................................... 91 List of Annexes Annex 1: Reference Background and Drainage Basin Information for All Reviewed References .............. 94 Annex 2: Described Hydrological Developments and Attributed Pressures for All Reviewed References.…………………………………………………………………………………………………………………..……… . 101 Annex 3: Overview of Selected Developments in Hydrological Parameters and Associated Drainage Basins (1970-2010 subset) ..................................................................................................................... 111 Annex 4.1: Temporal Distribution of Pressures Attributed to Increased Annual Flow / Water Levels (1970-2010 subset) ..................................................................................................................... 113 Annex 4.2: Spatial Distribution of Pressures Attributed to Increased Annual Flow / Water Levels (1970-2010 subset) ..................................................................................................................... 114 Annex 5.1: Temporal Distribution of Pressures Attributed to Decreased Annual Flow / Water Levels (1970-2010 subset) ..................................................................................................................... 115 Annex 5.2: Spatial Distribution of Pressures Attributed to Decreased Annual Flow / Water Levels (1970-2010 subset) .................................................................................................................... 116 Annex 6: Temporal Distribution of Pressures Attributed to Changes in Seasonal Flow / Water Levels (1970-2010 subset) ................................................................................................................... 117 Annex 7: Temporal Distribution of Pressures Attributed to Increased Frequency / Intensity of Floods (1970-2010 subset) ..................................................................................................................... 119 Annex 8: Temporal Distribution of Pressures Attributed to Increased Frequency and Duration of No Flow (1970-2010 subset) .................................................................................................................... 120 References ............................................................................................................................................... 121 List of Figures Fig. 1: Tanzania Locator Map ........................................................................................................................... 6 Fig. 2: Map of Tanzania with Trans-SEC study sites and Wami-Ruvu basin ..................................................... 6 Fig. 3: Overview of information collected in literature review database ...................................................... 10 Fig. 4: Hydrologic changes at drainage basin scale structured in terms of a modified DPSIR model ….……….12 Fig. 5: Components of runoff, featuring streamflow and discharge .............................................................. 17 Fig. 6: River water level gauge at the seasonal Ngerengere river, Tanzania ................................................. 18 Fig. 7: Variation of Lake Victoria water level over time ................................................................................. 20 Fig. 8: Surface temperature curve for the 20th century in Africa .................................................................. 24 Fig. 9: Evidence of recent