Identification of potential sites for rainwater storage to enhance agricultural practices in kirthar mountain range

Rainwater harvesting is an ancient technique to irrigate agriculture land in arid and semi-arid regions. Kirthar mountain range, Sindh Pakistan, receives an average annual rainfall of 250 mm, mainly during monsoon season from June to September, which is used to irrigate the agricultural land. Rainwater is also stored by local farmers in the form of small ponds which is not sufficient to fulfill agricultural requirements throughout the year. Rainwater storage structures like irrigation dams can be used to augment water supplies in the agricultural areas. Therefore, the objective of this study is to identify potential sites for rainwater storage. For this, the understanding of spatial and temporal patterns of rainfall is important factor for annual run off estimation. Due to scarcity of weather station in the county, both the gauge data of Dadu station and satellite estimates were used to determine annual rainfall runoff using soil conservation service curve number (SCS-CN) method. Analytic Hierarchy Process (AHP) was employed to calculate the relative importance of different spatially varying parameters like geology, runoff potential, landuse/ land cover, stream network, settlement and slope. Then the relative percentage weights of each influencing factors were processed using weighted overlay analysis to identify potential sites. The analysis identified five, the most suitable sites for rainwater storage structure. Out of these five sites, site-3 is already under construction which validates the findings. The study showed strong potential of building water storage structure to store rainwater during intense rainfall events in monsoon. Subsequently these structures can help to increase gross productivity of agriculture as well as to enhance the socio-economic status of the local community and farmers living in nearby villages.