Comparative Assessment 0f Water Quality in the Bagmati River Basin, Nepal

Abstract

Kathmandu, the capital city of Nepal is one of the most populated destinations of the country. The water pollution remains a challenging issue for the sustainable development in the valley despite several pollution control devices, awareness-raising and policy measures. During monsoon period 2018, surface water samples were collected from 10 sites of the Bagmati River and its tributaries within the valley to evaluate the water quality. The different physico-chemical parameters were determined to assess pollution along a 26.5 km stretch between Sundarijal Dam to Balkhu Bridge of the Bagmati River and its selected tributaries. The Electrical Conductivity (EC) ranged from 33-816μS/cm while turbidity ranged from 0.3- 981 NTU and Total Dissolved Solids (TDS) ranged from 16 to 612 mg/l. The ionic concentrations were higher in the lower sections where the population density is high compared to the head waters. The high value of TDS and low value of Dissolved Oxygen (DO) in the lower belts of rivers were due to large inputs of waste water, uncoordinated rapid urban expansion, inadequate waste water treatment facilities and organic loads caused by anthropogenic activities. A comparative study for the water quality variables in the urban areas showed that the main river and its tributaries were equally polluted. From water analysis, downstream sites showed contamination and comparatively polluted among the tributaries and Bagmati River. There is a need to take action plan against polluted site for sustainability of aquatic health of the riverine environment and to address the river for its longer life both by public and government sectors.

Imprints of COVID-19 lockdown on the surface water quality of Bagmati river basin, Nepal

“…The results indicated that variations in the hydrochemical parameters in the BRB were mainly controlled by the extent of anthropic activities which were also consistent with the previous studies ( Paudyal et al, 2016 ; Pal et al, 2019 ). It has clearly revealed that the relatively low concentrations of hydrochemical parameters during the post lockdown ( Table 1 ) indicate the imprints of lockdown in the core urban area.…”

“…Comparing to the global average i.e., 120 mg/L ( Gaillardet et al, 1999 ), the TDS values were 4.69 and 1.89 times higher during pre-lockdown and post-lockdown periods, respectively ( Table 1 ). Generally, the TDS values were found to be < 120 mg/L in most of the freshwater rivers, but the higher values observed even in post lockdown could be due to municipal wastes and agricultural runoff in the BRB ( Pal et al, 2019 ; Paudyal et al, 2016 ). Also, the EC dropped from 956 μS/cm to 431 μS/cm, indicating substantially less dissolved materials in the river water during post-lockdown.…”

“…1 ). The Hindu cremation sites are located in the vicinity, which could also be the major input sources of NO 3 − in the river water ( Thakur et al, 2017 ; Pal et al, 2019 ). Also, the famous Hindu Temple named Pashupatinath is another major source of anthropic contamination in the river segment ( Fig.…”

“…SO 4 2− was measured by the Gravimetric method using BaCl 2 crystals whereas, the EDTA titration was used for the Ca 2+ , Mg 2+ , HCO 3 − and TH. Additionally, Cl − was determined by the Argentometric method using K 2 CrO 4 as an indicator ( Pal et al, 2019 ). Likewise, the open-air reflux method and 5-day BOD-test were performed to determine the level of COD and BOD, respectively.…”

Application of Multivariate Approaches to the Hydro-chemical Assessment of the Ghodaghodi Lake, Sudurpaschim Province, Nepal

“…The contamination of freshwater bodies can result in low drinking and irrigation water quality and cause potential human and ecological health problems. In general, the fluctuation in the parameters, including ionic constituents in water beyond the permissible level due to various natural and anthropogenic processes (Pal et al 2019;Pant et al 2021a) Although Nepal is rich in freshwater resources, the Ramsar sites and other freshwater lakes are under high pressure due to various anthropogenic activities and global climate change (Zhang et al 2019). Overdependence on the water to meet the ever-increasing demands of domestic, agricultural, industrial, and haphazard developmental activities has resulted in the overexploitation of water resources and deteriorated lake water quality in Nepal (Rupakheti et al 2017).…”