Groundwater flow modeling and prognostics of Kandivalasa river sub-basin, Andhra Pradesh, India

The Kandivalasa river sub-basin (KRSB) of northern parts of Eastern Ghats of India is mainly underlain by the Khondalitic suit of rocks. A groundwater flow model for the KRSB with two conceptual layers is developed under steady as well as transient conditions using Visual MODFLOW for the period 2013-2016. Based on intense hydrogeophysical studies and borehole lithologs of the region, the top layer is considered as highly weathered layer (kaolinized layer) followed by the weathered and fractured layer as bottom layer. Lower hydraulic conductivities are assigned to kaolinized layer than fractured khondalitic layer since the kaolinized layer is less permeable than fractured khondalitic rocks. The results of groundwater flow model indicating that, under transient state conditions, the balance of groundwater is almost zero in every year for the present abstraction rate and the recharge conditions. According to the prediction scenario of the water levels in the study area for the next 20 years (2017-2036), if the rate of extraction increases 2% per year in the basin continued, there will be considerable dry cells developing from the year 2021 in the study area. The extent of dry cells has considerably increased by the year 2036. Hence, there has to be reduction in groundwater pumping where the dry cells are observed by using the surface water more wisely through revival of ponds and canal system and by application of micro-irrigation systems in the basin.

Automated summary

The Kandivalasa river sub-basin in the Northern Eastern Ghats of India is mainly composed of Khondalitic rocks. A groundwater flow model with two conceptual layers was developed using Visual MODFLOW for the period 2013-2016. The model predicts that if the extraction rate continues to increase by 2% per year, significant dry cells will develop in the study area starting from 2021, with an even greater extent by 2036. Mitigation measures such as reducing groundwater pumping and using surface water more efficiently are recommended.