Micro-watershed Delineation and Potential Site Selection for Runoff Water Harvesting Using Remote Sensing and GIS in a Hilly Area of Bangladesh

The dry-season water scarcity is a problem of crop intensification in many hilly areas of the world. The rainwater or runoff water harvesting (RWH) could be a potential solution for those areas. The methodologies and the criteria for selecting the site for RWH structure are available for macro-watershed but not for micro-watershed. This study aims at selecting a suitable location of RWH structure for micro-watershed through all possible combinations of methodologies and criteria. For this, we developed a conceptual framework where a participatory approach, field and questionnaire surveys with remote sensing and GIS techniques were adopted. After preliminary selection of the watershed site through field surveys, four micro-watersheds were delineated using ArcGIS hydrological tools. Watershed delineation was carried out using SRTM DEM (automatic-delineation) and Google Earth (manual-delineation). Integrated approaches involving both biophysical and socioeconomic factors were followed for identifying the potential site for the RWH structure. In regards to biophysical assessment, various thematic maps, such as stream networks, slope, soil and land use were developed to describe the characteristics of each micro-watershed. The socioeconomic considerations were the number of population to be benefited, possibilities of expanding farming, and accessibility to the watershed reservoir in each micro-watershed. Thus, the results obtained from biophysical and socioeconomic determinants reveal that the micro-watershed (MWS)-2 and MWS-3 are most suitable for the same scores and recommended for constructing the RWH structure. However, various attempts need to consider regarding the choice of crops on hill slopes, conservation of soil, and management of the structure for getting full potential benefits from the watershed reservoir.