Assessment of Groundwater Potential in Appapuram Canal Command Area Using Water Balance Equation

Abstract

Groundwater is a critical source of irrigation and domestic water in regions where surface-water availability is seasonally variable. This study assessed groundwater potential in the Appapuram canal command area, Guntur district, Andhra Pradesh, India, for the period 2012–13 to 2021–22 using a groundwater-balance approach. The assessment quantified precipitation, irrigation supply, crop evapotranspiration, evaporation from uncultivated land, groundwater extraction, direct surface runoff, groundwater-storage change, and recharge from rainfall, canal seepage, storage tanks, and irrigation return flow. Reference evapotranspiration and crop evapotranspiration were estimated using CROPWAT 8.0, while direct runoff and recharge components were determined using the methods specified in the manuscript. The mean crop evapotranspiration, evaporation from uncultivated land, groundwater extraction, and direct runoff were 44,136.95, 19,827.73, 2,247.00, and 21,706.27 ha-m, respectively. Mean gross groundwater recharge was 29,971.27 ha-m, comprising mean recharge values of 8,799.86 ha-m from rainfall, 1,969.04 ha-m from canal seepage, 309.62 ha-m from tanks, and 18,892.74 ha-m from irrigation return flow. Net groundwater recharge varied across the study period, with positive values from 2012–13 to 2018–19 and negative values during 2019–20 to 2021–22. The results indicate substantial interannual variability in groundwater balance and provide a quantitative basis for groundwater-resource planning in the command area.