CATCHMENT CHARACTERIZATION FOR RAINWATER HARVESTING SUITABILITY ANALYSIS: CASE STUDY IN THE HIGHLANDS OF ETHIOPIA

In many respects rainwater is the most crucial element in the lives of Ethiopian people, but its uneven distribution and climatic uncertainty, resulting the lives of the people enormously precarious. As a result, rainwater harvesting (RWH) has become an increasingly important practice in Tigray. The main objective of this study was suitability analysis for RWH practices and its feasibility studies at catchment scale. The suitability analysis was a scoring system using primarily on biophysical criteria of precipitation, slope, soil, geology, drainage network and land use/land cover, hydrology (rainfall-runoff relationship) of catchment. The multicriteria evaluation method using weighted overlay analysis tool was applied to identify suitable areas for RWH systems. For continuous variables (slope and precipitation), the fuzzy membership sigmoid function scoring system was performed in a GIS system. Six in-situ RWH systems in terms of three crop groups (Crop, Grazing and Tree) using Boolean approach and one generalized macro-catchment system using SCS-CN method. The results of the suitability analysis are presented as a set of 11 maps, in which 10 for micro and 1 for macro-catchment RWH systems. The weighted overlay analysis model generated five categories of suitability: Highly suitable, Suitable, Moderately suitable, Marginally suitable and Not suitable. The results from the analysis indicated that in general 70% of the Mayleba catchment had overall suitable potential for in-situ RWH systems except with tree crops. Similarly, the weighted overlay analysis showed that 10–20% of the catchment was highly suitable. Yet, the catchment suitability evaluation as a macro-catchment RWH potential is considered as low due to low runoff yield from its catchment areas. This suitability analysis at the catchment could be used to develop methods for upscaling of RWH practices for building resilience against climatic shocks in the highlands of Ethiopia.