Inference of hydrological modelling and field-based monitoring on dynamics of heavy metals in water of Hindon Basin

The Hindon basin, crucial for agriculture, faces pollution from industry and farming, affecting the water quality and ecosystems. This research unravels heavy metal dynamics in uncertain pathways, varying hydrological conditions, and data-restricted basins by integrating a hydrological model with heavy metal mass budgeting. Initially, spatiotemporal meteorological data and landscape properties were utilized to develop a monthly-scale hydrological model for 12 years (2010–2022). Subsequently, heavy metal concentrations were measured in 2023 from rivers, canals, and wastewater drains across the basin. The river flows predicted by the hydrological model were then used to estimate seasonal heavy metal loads based on observed concentrations. The hydrological activity in the region displayed drier conditions from 2010 to 2023, with declining post-monsoon water balance components in the lower and middle regions. However, in 2023, enhanced monsoon rainfall reversed this trend, improving surface water availability, increasing flow rates, and altering heavy metal dynamics during the post-monsoon season. This shift underscores the role of hydrological uncertainty in heavy metal loads across all surface water bodies. River water contributed the largest share of heavy metal loads (52 %) in both seasons, followed by wastewater (26 %) and canal water (22 %). These findings emphasize the influence of changing hydrological conditions on heavy metal contributions from surface water sources, reducing reliance on direct flow measurements in challenging field environments. • Developed a monthly-scale hydrological model to simulate hydrology in a data-restricted basin. • Established a heavy metal budget for rivers including tributaries, minor irrigation canals, and wastewater drains. • Estimated water availability declined by 34.2 %, with surface runoff fluctuating between 4.05 % and 14.87 %. • Accumulated river flows in the lower Hindon region carry high heavy metal loads from upstream areas. • Kali river, due to intense industrial discharge, contributes higher heavy metal loads to the Hindon than Krishni.