Physico-chemical properties of Lohit River in the Eastern Himalayan region, India

Abstract

In the past decade, research has been conducted on the river Brahmaputra with little or no importance accorded to the lesser-known rivers such as the Lohit, Dibang and Siang that forms the tributaries of the Brahmaputra River. The present study was conducted to assess the water quality of the Lohit River at Parshuram Kund area in Eastern Himalayan region. The water samples from four different stations were collected from up and down stream for four different seasons, namely, winter, pre-monsoon, monsoon and post-monsoon. The collected water samples were analysed for different physicochemical characteristics such as water temperature, pH, Dissolved Oxygen (DO), Conductivity, Turbidity, Total Dissolved Solids (TDS), Calcium and Chloride. The highest temperature was recorded during monsoon (31.8 degree C). The water was slightly acidic to slightly basic in nature (6.8-7.4) with highest DO during winter (8.6 mg/l). Maximum turbidity and conductivity (123.6 NTU and 97.5 μmho/cm respectively) with lowest TDS (50.1 ppm) were observed during monsoon. High chloride and calcium content (12.35 mg/l and 23.3 mg/l respectively) was recorded during winter. The results showed that the water quality is being altered during different seasons which may be attributed to various infrastructure development in and around the area.