Regional-scale planning of water harvesting interventions in Somali arid areas: A multicriteria approach

Somalia is one of the most arid countries in the world. In its northern part, Water Harvesting (WH) - the collection and storage of runoff water for productive use - can represent a viable solution for combating the effects of limited and erratic rainfall, and subsequent water shortages. A major barrier to WH implementation is the difficulty of selecting suitable sites, especially for large areas where this approach has never been implemented. This study presents a multi-criteria analysis for selecting the best sites for WH Ponds and Sand Dams for seven regions of northern Somalia. Criteria and weights for the analysis were based on existing literature and expert consultation with FAO-SWALIM officers. The Analytical Hierarchy Process (AHP) was used to minimize uncertainty in weights selection, and the analysis was validated using over 100 existing WH structures. Finally, the biophysical suitability of different catchments in the study area was evaluated, showing good potential in the north-western side along the eastern coast. This approach, covering half of the country, represents a baseline and a starting point for any lower-scale investigation, and can be replicated in any similar context.