This document summarizes different methods for identifying suitable areas for water harvesting in the Upper Blue Nile Basin of Ethiopia. It discusses various water harvesting techniques that can bridge dry spells, droughts, and flooding while improving soil fertility and sustaining stream flows. Suitability analysis is performed using factors like precipitation, slope, land cover, and soil type to produce maps showing moderate to highly suitable areas, with the largest potential being 6-24% of the region. The results are sensitive to the precipitation data and land use assignments used.

1. WELCOME Identifying suitable areas for water harvesting in the Upper Blue Nile Basin, Ethiopa Authors: Yihun Dile Taddele , Louise Karlberg, Johan Rockström Stockholm Environment Institute

2. What are they? Pitting Strip catchment tillage Meskat-type system Contour bunds Semi-circular bunds Floodwater harvesting within the stream bed Ephemeral Stream Diversion Hillside sheet/rill runoff utilization

4. Why Water Harvesting Dry spells Flooding Drought Land degradiation

6. BUT?

8. Precipitation DEM Land Cover Soil Surface Analysis Slope map Land cover rastar map Land cover rastar map Vector to grid conversion Reclassified Precipitation Reclassified slop map Reclassified land cover Reclassified Soil Reclassifying into 5 classes WH suitability maps Weighted Overlay Analysis

10. Suitability Criteria Suitability values 1 2 3 4 5 Precipitation(mm) <200 >1200 200-400 800-1200 400-800 Slope(%) >20 12-20 8-12 2-8 <2 Land cover Bushland, forest N.A N.A plantations cultivated land woodland, grassland irrigated land swamp, shurbland Soil Leptosols Arenosols Vertisols Luvisols, Cambisols Regosols Acrisols, Alisols Fluvisols, Nitisols

11. Percent Influence Assignment Percent Influence Parameter Precipitation Slope Land use Soil Condition - 1 25 25 25 25 Condition - 2 30 30 20 20 Condition - 3 35 25 20 20 Condition - 4 25 35 20 20 Condition - 5 35 30 20 15 S = ∑w i *x i S = final suitability score; w i is weight of factor i and x i is the criterion score of factor i Suitability Analysis

12. Equal inflience assignment for precipitation, slope, land use and soil 30% influence assignment for Precipitation & slope, and 20% for land use & soil Results

13. 35%, 25%, 20% and 20% influence assignment For precipitation, slope, land use & soil resp. 25%, 35%, 20% and 20% influence assignment For precipitation, slope, land use & soil resp. Results

14. Results % precipitation slope 0 1 0 1 0 1 29 23 28 23 16 2 61 62 61 61 57 3 6 10 8 11 23 4 0 0 0 0 0 5 Condition-5 Condition-4 Condition-3 Condition-2 Condition-1 Suitability level

16. Thank You Questions?