Evaluation of parameter sensitivity for groundwater potential mapping in the mountainous region of Nepal Himalaya

Abstract

Groundwater potential (GWP) mapping of an area is the initial stage of assessing groundwater for further investigation leading towards exploitation of the resources to meet the water demand for various sectors. Groundwater availability is explicitly important especially in the mountainous area in the Himalayan region. In practice, different combinations of parameters are used to prepare GWP map, however, the sensitivity of parameters are poorly assessed. This paper aims to evaluate the sensitivity of parameter for delineating groundwater potential using GIS and remote sensing. Multi-Criteria Decision Analysis (MCDA) technique is used to prepare groundwater potential map of Khadadevi-Manthali area, Ramechhap district, of Bagmati Province, Nepal. Nine influencing parameters are considered in the present analysis, which were integrated through assigning normalized weight to the thematic layers and their classes using Analytical Hierarchical Process (AHP). Further, groundwater potential maps have been prepared for 7 different cases using different combination of parameters and for each case, the results were successively validated with 21 springs and 3 tube wells spatially distributed within the study area. The results show that the GWP maps prepared using the lineament and hydro-geomorphic maps yield better result. The ROC/AUC Curve (Receiver operating characteristic curve/Area under curve) for GWP map prepared using 9 parameters shows higher prediction accuracy (72.4%) as compared to other cases\\. Thus, we conclude that lineament and hydro-geomorphology of an area are most influencing factors in delineating GWP zones in mountainous area of Himalayan region and the nine parameters considered in the present study can be applied in also other areas of the region for preparing GWP map.