Identifying suitable sites for underground dams using GIS: a case study in North-East Brazil

In arid and semi-arid areas, where rainfall tends to be erratic and unpredictable, concentrated in a few intense storms, water scarcity is a looming threat to water security. Water security is turning into a priority and it can be achieved only through the collection, conservation and wise use of the available water resources. Water harvesting, defined as the concentration and collection of floodwater or rainwater runoff for multi-purpose use, can ensure water availability for domestic and agricultural use. In water scarce areas, the selection of the best sites for the construction of water harvesting structures is often based on farmers’ traditional knowledge. Starting from the necessity of strengthening and complementing traditional knowledge in the definition of the best sites, a methodology for the assessment of suitable sites for underground dams construction using spatial multi-criteria analysis is proposed. Spatial data, as slope, rainfall, soil texture and curve number were used. As weighting technique, the analytic hierarchy process (AHP) has been used. The proposed methodology shows promising preliminary results for an early planning to identify suitable sites for underground dam construction.