Predicting non-point source of pollution in Maithon reservoir using a semi-distributed hydrological model

Area of Science:

• Environmental Hydrology
• Water Quality Management
• Ecosystem Assessment

Background:

• Non-point source (NPS) pollution is a primary driver of lake water quality decline.
• Increased human activities and catchment disturbances exacerbate NPS pollution, particularly during monsoon seasons with high surface runoff.

Purpose of the Study:

• To predict seasonal (monsoon) NPS pollutant loading, including sediment, nitrogen, and phosphorus, in the Maithon reservoir.
• To identify critical NPS pollution hotspots within the reservoir's catchment area for targeted mitigation efforts.

Main Methods:

• Utilized the Soil and Water Assessment Tool (SWAT) hydrologic model for NPS loading prediction.
• Calibrated and validated the SWAT model using monthly runoff and sediment yield data from 1998-2005.
• Employed observed data from Rajdhanwar, Giridih, and Santrabad stations for model calibration and validation.

Main Results:

• Average sediment yield from micro-watersheds ranged from 0.231 to 7.458 ton/ha during monsoon.
• Average monthly nitrogen and phosphorus yields varied from 0.224 to 1.377 kg/ha and 0.073 to 0.363 kg/ha, respectively.
• Net monthly average yields in the reservoir were 1.53 M tons of sediment, 1834.2 kg of nitrogen, and 191.1 kg of phosphorus.

Conclusions:

• Substantial influxes of nutrients and sediments into Maithon reservoir were confirmed.
• The study provides crucial insights into NPS pollutant loading and identifies priority areas for pollution control measures.