Groundwater Potential Mapping at Highly Populated Sub-districts of Thimphu District Using Fuzzy Analytic Hierarchy Process

Groundwater is important when there is an insufficient spring water supply for daily needs. The population growth and expansion of the cities demand more water. Thimphu is the capital city of Bhutan and facing water shortage in recent times due to urban expansion and population growth. This study aims to find the potential area for groundwater using the Fuzzy Analytic Hierarchy Process. The factors used for this study are elevation, slope, curvature, topographic wetness index, drainage density, normalized difference vegetation index, distance from fault density, rainfall distribution map, soil texture map, and drainage density. The rating for the factors and classes of the factors were carried out with the help of field experts. As per the fuzzy weight, the highest contributing factor for the groundwater is rainfall with a fuzzy weight of 0.215. Only 1.19% of the study area falls under very high potential zone for groundwater and the area under the curve of the groundwater potential map is 70.37%. The groundwater potential map will help concerned officials to explore the subsurface groundwater using geophysical investigation using test drilling and borehole geophysical logging techniques.