Groundwater Flow Modeling of A Microwatershed using Visual Modflow Flex

Abstract

The present study attempts to make a simulation of groundwater flow modeling in Chikkodi micro-watershed Belagavi (District), Karnataka. A two-layer conceptualization and the three-dimensional groundwater flow model are primarily underlain by weathered basalt and fractured basalt. The first layer weathered zone is 30m from the ground surface and the second layer fractured zone is 80m below the ground surface spread over 20 rows and 20 columns. The cell height is 674m and the cell width is 440m. The work described here built a groundwater flow model in the micro-watershed using Visual MODFLOW Flex. The steady-state groundwater flow model was then numerically projected in April 2020 using seventeen observation wells using the present stress levels. The model aims to quantify input and output stresses and pinpoint the basin's overstressed regions. The water budget analysis estimates that evapotranspiration loss makes up 56.54% of the basin's total groundwater recharge while overall groundwater leaks from river systems are 28.72%. The findings indicated that the southern section of the basin is undergoing severe aquifer stress as a result of river overflow and evapotranspiration. To improve groundwater levels, it is suggested that artificial recharge structures should be developed in and near Chikkodi village at appropriate sites. The trial-and-error approach was used to assess the sensitivity of the calibrated model, and it was discovered that the model is extremely sensitive to changes in hydraulic conductivity and recharge levels. Model performance is excellent, with R2, RMSE, and NRMSE values of 0.97, 5.34, and 13.23% of the assessing criteria.