Application of GIS/RS for identification of suitable sites for rainwater harvesting structures in Kaabong district.

Abstract

Arid and semi-arid areas such as Karamoja suffer not only from limited precipitation but also from poor management of rainwater for animal, human and agricultural use. One such solution is rainwater harvesting (RWH) (collect excess runoff water during the rainy season and store it during dry spells). Identification of potential sites for rainwater harvesting (RWH) is an important step towards maximizing harvesting of this runoff using different RWH technologies. However, selection of appropriate sites for different RWH technologies on a large scale presents a great challenge. The main objective of this study was to apply a geographic information system(GIS) that uses remote sensing (RS), to identify potential sites for RWH technologies. The input into the GIS include generated thematic maps of. The thematic layers such as (rainfall, slope, soil texture, drainage, runoff depth and land use/cover) were assigned suitable weights and then integrated in a GIS to generate an RWH potential map of the study area. Validation of the RWH potential map with existing RWH structures was carried out and finally sensitivity analysis was performed to determine the importance of a factor or group of factors in the site selection process for RWH. The study area can be classified into five RWH potential zones; Not Suitable zone (102.23km Or 1.4%), Marginally Suitable zone (1306.9km2 or17.9%), Moderately Suitable zone (3696.3km or 50.6%) Suitable zone (1910.5km2 or 26.1%) and Highly Suitable zone (291 km or 4. 0%).Validation test showed that out of 19 different existing RWH technologies, 0% fall within not suitable and marginally suitable zones and 32%, 53% and 16% fall within moderately suitable, suitable and highly suitable zones respectively. The integrated RS, GIS and MCDA techniques were found to be a cost-effective, faster and environmentally friendly method to select suitable RWH sites as compared to field surveys Keywords: Rainwater harvesting, remote sensing and geographic information system, multicriteria decision analysis, Thematic maps/layers.