Shallow aquifer potential mapping in the foothills of Churia in Eastern Gangetic Plain of Saptari District, Nepal

Abstract The population living in the foothills of Churia, the study area, faces severe water scarcity due to limited access to surface water. The only alternative is groundwater, and there is extensive use of groundwater for domestic and agricultural purposes. Groundwater in some areas is limited and very limited information pertaining to the aquifer. In this context, this research tries to answer the pertinent questions concerning the aquifer properties, depth and thickness of the groundwater aquifer layer and groundwater prospects for irrigation. The objective of this research is to identify the aquifer properties and groundwater prospects using two-dimensional electrical resistivity tomography methods (2D-ERT). Five 2D-ERT profiles were used to collect information to a depth of around 40 m, with minimum electrode spacing of 5 m over a profile length of 240 m. The survey was carried out using Wenner electrode configurations. The resistivity tomogram sections were interpreted using RES2DINV software, which provides output in the form of resistivity contours that are used to draw up the lithological and geological information. The result of the survey indicates that the areas with good potential for groundwater access exist mostly along the southeast to central east parts of the study area, where there is gravel and sand with resistivity values between 100 and 500 Ω m. Areas along the northwest with clay and silty clay formations have low resistivity values (< 70 Ω m) and low groundwater potential. While the northeast has high resistivity values (> 2000 Ω m) due to sand formation underlain by boulder and cobbles, it also has limited groundwater potential due to the limited depth (< 6 m) of sand and low storage capacity. The study reveals a variation in lithological formation, including a patchwork of clay, silty clay, sand, gravel and boulder materials, with varying groundwater potentials. When developing shallow tube wells in the study area, spatial variation in the productive aquifer, hydraulic conductivity of groundwater flow within and near the tapped aquifer and geological and lithological material need to be considered.

Abstract licence: CC BY-NC-ND

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