Water Quality Assessment of the Betkot Lake, Sudurpaschim Province, Nepal

Abstract Wetlands are the most productive ecosystems in the world, and are also considered as the kidney of nature. The lentic environments i.e., lake, and ponds are the inland water bodies, not only provides the water but also supports the livelihood, habitat of plants and animals, regulates the hydrological cycle, and aesthetic values including other environmental services. The study on the hydrochemistry of the lentic ecosystems will have immense significance in updating the existing environmental and chemical database and also support to maintain their ecological health. The Betkot Lake, located in the Kanchanpur district, of Sudurpaschim Province, Nepal plays a key role in the ecology of the lowland Terai region and the present study emphasized on the hydrochemical assessment of its water quality. Besides ecological importance, the water body have a significant role in irrigation, fisheries, power generation and domestic water use. Recently, the lake has been witnessing severe deterioration in water quality mainly due to anthropogenic activities. For further assessment we had collected altogether 13 water samples in winter season, 2018, and the parameters of water temperature, pH, EC, TDS, DO, turbidity, free CO2, major cations, and anions including alkalinity, phosphate, ammonia, hardness, BOD and COD were analyzed. The results revealed that the water quality meets the guideline of Nepal’s Drinking Water Quality; however, some parameters like concentrations of DO, BOD, COD and ammonia didn’t meet the Nepal Water Quality Guidelines for Aqua Culture in some of the sampling locations. In addition to the usual interactions of Lake Environment with the fragile local land topography, the lake is subjected to anthropogenic interference due to its proximity to the increasing settlements and mobility of people around the lake. Multivariate statistical methods i.e., Hierarchical Cluster Analysis (CA) and Principal Component Analysis (PCA) were applied to assess the influence of pollutants disposal and their controlling mechanism. Particularly, the PCA results demonstrated that both natural and anthropogenic factors contributing to the contamination in the lake with 87.37 % cumulative variance. On the other hand, the CA results differentiate the sampling locations into four clusters and the pollution index level indicated that the all the sites are slightly polluted. Meanwhile, the quantitative pollution level exhibited in different clustering sites by using Pollution Index that indicated the outlet area was relatively more polluted than inlet sides. Keywords: Lentic environments, Physicochemical properties, Water quality, Pollution index, Multivariate statistical analysi