Trends and Sustainability of Groundwater in Highly Stressed Aquifers (Proc. of Symposium JS.2 at the Joint IAHS & IAH Convention, Hyderabad, India, September 2009). IAHS Publ. 329, 2009. 103 Sustainability of a shallow aquifer in Yamuna-Krishni interstream region, Western Uttar Pradesh, India: a quantitative assessment RASHID UMAR & IZRAR AHMED Department of Geology, Aligarh Muslim University, Aligarh, Uttar Pradesh, India rashidumar@rediffmail.com Abstract The Yamuna-Krishni interstream is part of the Central Ganga Plain, which is very fertile and is famous for sugarcane cultivation. Due to increasing demand to meet agriculture requirements the abstraction of groundwater has increased manifold in the last few decades. Although the area hosts potential aquifers, due to uncontrolled pumping the shallow aquifer is adversely affected. For proper management of any basin it is essential that careful water balance studies should be carried out. Keeping this in view, an attempt has been made to evaluate groundwater balance of the area. The Groundwater Resource Estimation Committee 1997 (GEC, 1997) methodology, with a few additions, is applied to compute the ground- water resources. Since subsurface horizontal flows significantly affect the input and output components in an alluvial aquifer, emphases have been given to precisely estimate various inflows and outflows. The river– aquifer interaction and other boundary flows were estimated using Visual MODFLOW Pro 4.1. The results of water balance show that the net recharge into the interstream region is 413.08 million m 3 and discharge is 477.33 million m 3 , leaving a deficit balance of 64.25 million m 3 . Therefore, the status of groundwater development is 116%, which puts it in the over-exploited category. This is also reflected by the continuously falling water level situation in the basin. Thus, the hydrogeological and water balance studies shows that the groundwater development has attained a critical state in the region. Key words hydrogeology; groundwater budget; river-aquifer interaction; Yamuna-Krishni; interstream; India INTRODUCTION Quantification of the groundwater resource is a basic prerequisite for efficient groundwater resource development (Sophocleous, 1991) and this is particularly vital for India, with a widely prevalent semi-arid climate. Due to increasing demand to meet agriculture requirements the abstraction of groundwater has increased manifold in the last few decades. The heavy demand for groundwater sometimes leads to excessive withdrawal, which is often reflected in serious imbal- ance of hydrogeological situations at a later date. The indiscriminate utilization of groundwater in the last few decades has reached a state termed over-exploitation. The situation in the study area is no exception. Groundwater is the main source for agricultural, domestic and industrial uses, and its utilization has increased manifold in previous years. The increasing agricultural activities and other anthropogenic influences have detrimentally affected the groundwater regime, which is envisaged by depletion of dynamic groundwater resource in the area. Previous hydrogeological investigations in the area were mainly carried out by the Central Ground Water Board (CGWB) and Groundwater Department of Uttar Pradesh (UP) government. Khan (1992) and Kumar (1994) carried out systematic hydrogeological investigations in Muzaffarnagar district and studied the first group of aquifers. They identified numbers of blocks under the over-exploited category. The blocks are small administrative units of a district, in order to carry out the developmental plan at the micro level. A water balance study using water table fluctuation and tritium method was carried out in parts of the Yamuna-Krishni interstream area by Ahmed & Umar (2008). The result of water balance studies show a negative balance and place the area under over-exploited category basin of groundwater balance. The effective groundwater budgets of an alluvial area require proper understanding of the hydrodynamics of the basin. It is therefore imperative to identify various recharge and discharge components of the groundwater regime and their effect on its variation with time. This paper attempts to precisely present the groundwater budget estimates of an alluvial aquifer, including all variable components of groundwater recharge and discharge. The study area was divided into two zones for assessment purpose, i.e. canal command area and non-command Copyright © 2009 IAHS Press