Evaluation of satellite-altimetry-derived river stage variation for the braided Brahmaputra River

Abstract

In this study, river stage variation derived from satellite altimetry was used to assess the water level, monthly discharge, and annual water yield at six virtual gauging stations at the braided reaches of the Brahmaputra River. The braided reaches of the river dynamically change their planform, thalweg line, and aggradation or degradation period. Stage records derived from the Envisat satellite of the European Space Agency and Topex/Poseidon of NASA/CNES were used for the period 2002-2010. Spatial interpolation and datum correction were applied on altimetry-derived river stage records before analysis. A correlation and error analysis between the in situ and satellite-altimetry-derived stages was carried out for these stations for both monsoon and non-monsoon seasons. Yearly optical satellite images were used for qualitative assessment of temporal variations in aggradation/degradation phases at the gauging stations. Using the pseudo-rating curve, discharges at two virtual gauging stations were estimated. The results show that the altimetry-estimated discharges are of good agreement with observed discharge for the monsoon months (June-September) as compared with the non-monsoon months (October-May). In order to assess the annual water yield variability, yearly variation in annual water yield from the altimetry data was also estimated and compared to that observed. The estimated annual water yields were 90% accurate. Similarly, the long-term averaged monthly discharge series estimated from satellite altimetry closely follows the temporal trend of that of the observed series.

A Review of Earth Observation-Based Analyses for Major River Basins

“…Accordingly, estimation of river discharge is possible using indirect EO-based approaches [204]. Regarding river basins, studies are performed the Amazon [205,206], Brahmaputra [207,208], Congo [209], Mekong (e.g., [210,211]), and Yangtze river (e.g., [212]). Here, common methods to retrieve river discharge are rating curves (e.g., [213]) or the Manning's equation (e.g., [214]).…”

“…A comparison of the predicted discharge with in situ observations resulted in a Nash-Sutcliffe efficiency of 0.71. Moreover, Dubey et al [207] retrieved water level based on TOPEX-Poseidon and ENVISAT-RA2 data for 6 virtual stations along the Brahmaputra river between the years 2002 and 2010. The rating curves were developed based on estimated water level and in situ discharge observations.…”

An improved methodology to estimate river stage and discharge using Jason-2 satellite data

“…River stage variations over the floodplains can provide the vital information about the flood wave distribution and energy dissipation over a period of time to the downstream of the nodal locations. Water level retrieval using satellite altimetry has shown the great potential to capture the river stage fluctuations over the sites, where installation and monitoring of traditional river gauge stations are difficult such as Brahmaputra river (Birkett, 1995;Frappart et al, 2006;Calmant et al, 2008;Dubey et al, 2014Dubey et al, , 2015. Satellite altimetry applications for monitoring inland water bodies can play a vital role in enhancing our ability to monitor the water cycle from the regional scale to the global scale (Berry, 2006).…”

“…Braided rivers change their flow frequently with multiple channels splitting and rejoining, hence to setup the virtual station is a difficult task. The altimeter derived water levels have shown poor accuracy over the braided reaches of the Brahmaputra river (Dubey et al, 2014). Hence, proper investigation is needed to devise a suitable methodology to define the virtual stations before applying any retracking algorithms to the waveform data.…”

Application of satellite altimetry in understanding river–wetland flow interactions of Kosi river

“…However, the limitation with satellite altimetry data is the coarse temporal resolution, which may vary from 10 to 35 days based on the satellite track (Roux et al 2008). Irrespective of these limitations, there are many applications of satellite altimetry in the field of inland water body monitoring, river flow depth and river flow estimation (Chander et al 2014;Dubey et al 2014Dubey et al , 2015aVerron et al 2018). The utilisation of satellite altimetry and optical satellite images has made it possible to estimate the water storage variations over lakes (Crétaux et al 2011) and over inundated areas of the Negro river basin, the lower Mekong basin and the lower Ob river basins (Frappart et al 2005(Frappart et al , 2006(Frappart et al , 2010.…”