Groundwater flow modelling of Yamuna-Krishni interstream, a part of central Ganga Plain Uttar Pradesh

Groundwater is a major source of water for agricultural and domestic requirements in western Uttar Pradesh. Due to increasing agricultural requirements the abstraction of groundwater has increased manifold in the last two-to-three decades. The quaternary alluvium hosts the aquifer in the region. The study area forms a part of Yamuna-Krishni interfluve. Although the area hosts potential aquifers these have been adversely affected by poor management. For effective groundwater management of a basin it is essential that a careful water balance study should be carried out. Keeping this in mind groundwater flow modelling was attempted to simulate the behaviour of the flow system and evaluate the water balance. The groundwater flow modelling was carried out. The horizontal flows, seepage losses from unlined canals, recharge from rainfall and irrigation return flows were applied using different boundary packages available in Visual MODFLOW, Pro 4.1. The river-aquifer interaction was simulated using the river boundary package. Hydraulic conductivity values were applied to specific zones and these ranged from 9.8 to 26.6 m/day. Recharge due to rainfall and irrigation returns were assigned to respective zones. Pumping rates of 500 m(3)/day, 1000 m(3)/day, 1500 m(3)/day, 2000 m(3)/day and 2500 m(3)/day were applied to appropriate areas of the model to simulate areas of stress. The zone budget shows a water balance deficit for the period June 2006 to June 2007. The total recharge to the study area is 160.21 million m(3) (Mcum). The groundwater draft through pumping is of the order of 233.56 Mcum, thus leaving a deficit balance of -73.35 Mcum. The sensitivity of the model to input parameters was tested by varying the parameters of interest over a range of values, monitoring the response of the model and determining the root mean square error of the simulated groundwater heads to the measured heads. These analyses showed that the model is most sensitive to hydraulic conductivity and recharge parameters. Three scenarios were considered to predict aquifer responses under varied conditions of groundwater bstraction.