ShodhPatra: International Journal of Science and Humanities

Hydrogeochemical Assessment of the Asan River, Uttarakhand, India

The present study investigates the hydrogeochemical characteristics and water quality status of the Asan River in Dehradun, Uttarakhand, India. Water samples were collected from selected locations along the river and analyzed for major physicochemical parameters, including pH, temperature, turbidity, total dissolved solids (TDS), total suspended solids (TSS), dissolved oxygen (DO), biological oxygen demand (BOD), chemical oxygen demand (COD), calcium, magnesium, and total hardness. The results revealed that pH values ranged from 7.30 to 7.98, indicating slightly alkaline conditions and compliance with national and international drinking water standards. Water temperature varied between 17.0°C and 22.2°C, reflecting favourable environmental conditions for aquatic ecosystems. Turbidity values ranged from 11 to 29 NTU, exceeding recommended drinking water limits and indicating elevated suspended sediment loads. TDS concentrations varied between 750 and 850 mg/L, suggesting moderate mineralization of river water. Dissolved oxygen levels ranged from 3.8 to 6.2 mg/L, while BOD and COD values varied from 2.8–5.6 mg/L and 3.2–5.4 mg/L, respectively, indicating moderate organic pollution at certain locations. Calcium and magnesium concentrations ranged from 189.5–354.1 mg/L and 108.0–136.6 mg/L, respectively, resulting in total hardness values between 917.8 and 1446.8 mg/L as CaCO₃. The elevated hardness indicates strong rock–water interaction and the influence of carbonate weathering processes within the catchment. Comparison with BIS, WHO, and CPCB standards revealed that although the river maintained acceptable pH conditions, elevated turbidity, hardness, calcium, and magnesium concentrations may limit its direct suitability for domestic consumption without treatment. The study highlights the combined influence of natural geogenic processes and anthropogenic activities on river water chemistry and emphasizes the need for regular monitoring and sustainable watershed management for the conservation of the Asan River ecosystem.