Estimating Hydraulic Connectivity between River Tamsa (Tons) and Underlying Aquifer Using Multi-Proxy Data in Ambedkar Nagar, India

Comprehending the connection between groundwater and surface water is essential for their cohesive management. In this research, the connectivity of surface water with groundwater along the river Tamsa, India is estimated using multiple methods such as river and water table elevation, connectivity index model (CIM), river stage and groundwater piezometry, hydrochemistry, linear mixing model (LMM), and statistical analysis. River stage, water table, and hydraulic heads in piezometers were monitored at upstream and downstream sites of the studied five kilometers reaches of the Tamsa river and it was found that the river stage was higher than the groundwater level in both reaches, suggesting surface water recharging to groundwater. The similar dynamic changes in the river and piezometer water levels indicated the hydrological connectivity between the river and aquifer. Based on the CIM, medium connectivity is seen in both reaches of the Tamsa river. LMM shows “strong,” “moderate,” and “weak” hydraulic connectivity of river Tamsa with riparian groundwater (RGW), left bank groundwater (LBGW), and right bank groundwater (RBGW), respectively. Major ionic trends, Piper diagram, some tracers (pH, EC/TDS, Cl, silica), principal component analysis, and cluster analysis were all used to highlight the river and aquifer connectivity. The non-conformable ionic trends in river and groundwater, TDS, EC, Cl, and silica content plot with downstream river showed no significant groundwater contribution. The study concluded that the connectivity of river Tamsa with groundwater decreases as the distance between them increases. This study demonstrated the effectiveness of multi-proxy data for estimating river-aquifer connectivity.