Estimation of Total and Unit Stream Power along Bhagirathi River, Uttarakhand, India

Stream power is mostly used as an indicator for investigating engineering structures along the river banks. It has a considerable influence on forms and processes of the river system. It also provides information regarding the potential of a river to move sediments. The objective of this study is to estimate the total and unit stream power of Bhagirathi River and thereby to find the relationship of average unit stream power with landslides along the river. In this study, the longitudinal profile of the Bhagirathi River has been drawn using filled ASTER DEM in GIS environment. The smoothed longitudinal profile has been further used for the computation of slope at 1 km interval. The power function relationship has been established between peak discharge and drainage area to estimate peak discharge for ungauged points along the Bhagirathi River at 1 km interval. Channel slope, the specific weight of water and discharge are vital parameters for stream power computation. Total and unit stream power have been estimated at 1 km interval along the Bhagirathi River. The slope is found to be 0.04 and 0.0014 mm(-1) along the extreme upper and lower reaches of the Bhagirathi River, respectively. Due to the steep slope, the total and unit stream power profiles show high peaks in the mid-stream of the Bhagirathi. The fluctuations in the total stream power along the Bhagirathi River signify the variation in sub-regional slope as well as in discharge contributing areas. The unit stream power is high in the upper reaches of the river, and it shows decreasing trend in downstream. Unit stream power mainly governs the bar deposition in the active channel of the Bhagirathi River. The association between average unit stream power and number of exposures/landslides has been found to be statistically significant at the 0.01 level of significance.