Identification of suitable sites for construction of rainwater harvesting systems using MCA-HM method in GIS environment (Case study: Ab Bahareh nomadic ecosystem in Kohgiluyeh and Boyerahmad province)

Rainwater harvesting is a management technique with many positive results that can be used to supply the water needed by livestock in rangelands. In this study, suitable sites for the construction of rainwater harvesting systems using multi-criteria analysis (MCE) and hydrological model (HM) in the GIS environment were identified in the nomadic ecology of Ab Bahareh at the interval of Bahmaei and Lendeh counties in Kohgiluyeh and Boyer-Ahmad province. For this purpose, appropriate criteria maps to identify sites of rainwater harvesting system including slope, rock type, land use and land cover, runoff depth, and drainage density were provided in the GIS environment. After classifying the suitability map of each criterion, the classified map of the criteria was overlaid into the geographic information system environment and the appropriate sites for the rainwater harvesting system were identified. The results showed that in terms of each of the selected parameters, except for the slope, about 30 to 50 percent of the Ab Bahareh area was very suitable for the construction of rainwater harvesting systems. Due to the mountainous nature of the region, the slope parameter is the main limitation for the construction of rainwater harvesting systems. Based on the combined analysis of all the criteria selected, about 25% of the nomadic ecosystem of Ab Bahareh is highly suitable for the construction of rainwater harvesting systems, especially pits and ponds, rock outcropping catchment, road catchment, and check dams that can be provided during the dry season between rains. In regard to the number of 4000 goats and sheep in 5 villages in the nomadic ecosystem of Ab Bahareh, assuming the daily requirement of each livestock to 4 liters of water and the dry period of 30 days between the main rains, the total catchment area for the 25 mm rainwater harvesting system to meet the needs of livestock in the region is about 2.4 hectares.