Deriving water level and discharge estimation using satellite altimetry for Krishna River, Karnataka

Abstract

Radar altimetry is the most commonly used approach for monitoring ocean's water level or inland water bodies over ungauged or poorly gauged regions. In this study, a network of three altimetry missions (i.e., Jason 3, Sentinel 3A, and Sentinel 3B) was traced in the Krishna river, Karnataka, India, for 2018 and 2019. The network consists of 13 virtual stations, of which two are of Jason 3, five are of Sentinel 3A, and six are of Sentinel 3B. This paper proposes a method to find river discharge solely using remote sensing derived data. The river depth is calculated using satellite altimetry, and other hydraulic parameters (river width and river bed slope) are used in modified Manning's equation for calculation of discharge. To estimate river width, Google Earth Engine is used to process Sentinel 1 and Sentinel 2 images. All three missions showed excellent results with an average RMSE of 1.43 m, and the best correlation is showed by Sentinel 3B (>0.97). The discharge calculated using this method also provides adequate results, with NS value for station 1 is 0.53, and for station 2 is 0.63. These results show the potential of the proposed approach for monitoring water level and estimation of discharge solely using satellite-derived products. © 2021 Elsevier B.V.