Seasonal variation of water quality parameters of river Dikhow in Nagaland and Assam

Abstract

Dikhow River is one of the largest tributaries of the Brahmaputra river basin originating from Yezami village near Zunheboto town of Nagaland. It debouches into the mighty river Brahmaputra river at Dikhowmukh, Sivasagar district, Asam covering a length of 255.8 km contributing 0.7% runoff. The geographical area of the Dikhow catchment is approximately 3100 km 2 , covering 85% of Nagaland, 10% of Assam and 5% of Arunachal Pradesh. The study area of the entire river stretch was divided into 6 stations whose elevation ranged from 90.83 msl to 669.9 msl (3 in Nagaland and 3 in Assam). These stations were selected to study the hydro-biological profile of the river stretch, its pollution status and fish diversity from January 2019 to February 2020. The important physico-chemical water quality parameters of the river in these stations like Dissolved Oxygen (5.2-10.1 mg/L), pH (7.0-8.2), Turbidity (3.8-143.8 NTU), Total Hardness (24.02-121.01 mg/L), Total alkalinity (33-89 mg/L), etc. were found to be ambient for the survival of aquatic fauna in some parts in some period of the year.

Optic flow in the natural habitats of zebrafish supports spatial biases in visual self-motion estimation

“…It is important to consider that changes in water turbidity occur throughout the year in Assam. Turbidity levels increase dramatically during the monsoon season that spans the summer months, 83 which can influence underwater visual statistics. We did not experience precipitation during the period when recordings were obtained, although there was substantial rainfall in the preceding weeks.…”