Temporal variability in groundwater-surface water interactions using hydraulic and hydrochemical observations in a segment of Kali Nadi, Aligarh, UP, India

Understanding the hydraulic relationships between groundwater (GW) and surface water (SW) is crucial for effective long-term water resource management in various scenarios. Through the intensive monitoring using a combination of aquifer hydraulic heads measurements, river stage observations, and hydrochemical analyses of piezometers GW and SW from the Kali River located in the plains of western Ganges, UP, the extent of temporal variation in GW-SW interaction was identified. Three piezometers (A, B, and C) were installed at the left bank of the Kali Nadi to observe the hydraulic head. The variation in hydraulic heads and river stages was recorded from February 2023 to January 2024. The similarity in the dynamic variation of hydraulic heads and river stage suggests a hydrological connection between GW and SW, with the river exhibiting a losing character. Twenty sediment samples were also collected during piezometer installation, revealing lithological units dominated by various grades of sand (fine, medium, and coarse) and silt. A total of 130 water samples were gathered from the piezometers and Kali Nadi from February 2023 to January 2024 and analyzed for the physical parameters and major ions. The hydrochemical data were interpreted using graphical methods, such as Piper and Schoeller plots. The temporal shift in Piper clustering of GW and river water (RW) samples shows the connectivity between the GW and SW, which is also supported by the Schoeller diagram. The conclusions of this study are important for developing effective conjunctive water resource management strategies, particularly for aquifer systems and floodplain habitats.