Assessment of River Water Intrusion at the Periphery of Bagmati River in Kathmandu Valley

The present study was carried out to find out the possible impact of Bagmati river water on its nearby ground water resource within Kathmandu valley (KV). For this, five sampling stations were selected viz. Gokarna, Tilganga, Sankhamul, Teku and Sundarighat . From each station, one river water sample and six ground water samples from both sides of the river were taken on proportion basis by dividing the strata lying within 50 m, 50-100 m and 100-150 m distance from the river collected. River water analysis showed that it was less polluted during winter season as compared to other seasons and got severely degraded as it entered to the urban core. Regression analysis showed that the mean value of ground water parameters like pH, conductivity, chlorides, free carbon dioxide, alkalinity, hardness, nitrate, ammonia, iron, and ortho-phosphate were decreased from within 50 m to 50-100 m, and 100-150 m distance from the river bank. Microbial analysis of ground water showed that 88% of the samples were contaminated with fecal matter. So the ground water along Bagmati river should could not be used as consumptive purposes without treatment. The finding showed that the ground water was more contaminated along the river banks and towards the urban corridor than the upstream parts which might be due to intrusion of nearby polluted river water. Nepal Journal of Science and Technology Vol. 14, No. 1 (2013) 137-146 DOI: http://dx.doi.org/10.3126/njst.v14i1.8934