Delineation of Ground Water Potential Zoning Using GIS and Remote Sensing by AHP of Sunsari District (Koshi Basin) Area of Nepal

Abstract

This study assesses the groundwater potential in Sunsari district of Nepal by using a multi-criteria decision analysis tool along with remote sensing and geographic information system (GIS).The study has taken precipitation, Land use/cover (LULC), slope, geology, drainage density, lineament density, soil, and canal density as key influencing factors for determining the groundwater potential of the study area. The Analytical Hierarchical Process (AHP) technique was adopted in deriving the relative weights of these criteria and sub-criteria based on a review of the literature according to their relative importance in recharging the groundwater. The final thematic map of groundwater potential zones was prepared based on a groundwater potential index computed by aggregating the selected thematic layer with appropriate weights. The groundwater potential zones are classified into three zones based on the score of the groundwater potential index. The generated groundwater potential zones were further validated with ground truth data using a confusion matrix with a kappa coefficient and analysis of the receiver operating curve (ROC). The validation indicated fair predictability of groundwater potential zone with the AHP and GIS model. The areas under “Poor”, “Moderate” and “Good” are 13.6%, 36.0%, and 50.4% of the study area, respectively. The areas under the “Good” potential category are concentrated in the lower southern and western parts of the study area, while the east central part with highly dense built-up area falls under the “Poor” potential category. Also, the area just north of the central part is under the “Moderate” zone. There is a good coherence of precipitation and LULC with groundwater potential zones and less coherence of other factors.