Integrated Analysis of the Water Quality Index and Dissolved Oxygen Modeling for Managing Surface Water Quality of the Banas River in Rajasthan

Degradation of surface water quality is a serious environmental issue in semi-arid regions of India, especially in Rajasthan. Limited water availability makes pollution effects worse. This study looks at the surface water quality of the Banas River using the Water Quality Index (WQI) and dissolved oxygen (DO) modeling methods. Monthly water quality data, collected from January 2023 to May 2025 under the National Water Monitoring Programme (NWMP), were analyzed from five main monitoring stations in the Banas River basin. We examined thirty-three physicochemical and biological parameters, following guidelines from CPCB, BIS, and WHO. We calculated WQI using the weighted arithmetic method based on CPCB Class B standards. We assessed dissolved oxygen dynamics using the Streeter Phelps model. The results show clear spatial and seasonal changes in water quality, with higher pollution levels at upstream stations like Guwardi Reservoir and better conditions at downstream locations such as Bisalpur Dam. We found a strong inverse relationship between BOD and dissolved oxygen. The combined WQI and DO modeling approach offers a useful tool for assessing river water quality and aids in managing water resources for the Banas River.