WATER QUALITY MONITORING OF BAGMATI RIVER BASIN, KATHMANDU VALLEY

Abstract

The Bagmati River in the Kathmandu Valley flows along the core urban areas. The main aim of the study was to estimate 14 parameters water pH (pH), total suspended solids (TSS), total dissolved solids (TDS), turbidity (Turb), biological oxygen demand (BOD), chemical oxygen demand (COD), dissolved oxygen (DO), total phosphorus (TP), faceal coliform (FC), iron (Fe), manganese (Mn), copper (Cu), chromium (Cr) and cadmium (Cd) to assess the water quality of the Bagmati River. The surface water samples were collected from 11 sites in the Bagmati River during the pre-monsoon season. The highest DO record was found at headwater Sundarijal (8 mg/L) where 50% of the samples had DO less than 3 mg/L. Meanwhile, turbidity, TSS, and TDS ranged from 3 to 600 NTU, 12 to 740 mg/L and 58 to 612 mg/L respectively. All the samples were contaminated from the faceal coliforms. High BOD and COD were observed in the much-populated core urban area due to wastewater and organic load. Similarly, among 5 heavy metals tested Fe and Cu were only detected in the samples. Fe exceeds the WHO limits while Cu is within the guidelines. Only 2 clusters were obtained from cluster analysis in which C2 had a high value of all parameters except DO indicating towards polluted station i.e BA09. Meanwhile, correlation analysis between BOD and COD with TP and Cu defined wastewater and organic loads are the main sources for the high concentration of these water quality parameters.