Identifying the stability trajectory of a large braided Brahmaputra river using reach-scale process-based approach

Abstract

The dynamic evolution of a large braided river system is characterized by sporadic operation, impacted by a diverse range of natural and anthropogenic factors. The hydro-geomorphological interaction within the river corridor and its surrounding ecosystem presents a complex process, posing challenges in comprehending its dynamics. This study investigated the spatiotemporal heterogeneity in the vegetation-flow regime of a large braided reach of mighty Brahmaputra river. A detailed statistical analysis for the last three decades (1990 to 2019) was performed to demonstrate the in-stream vegetation characteristics for the selected middle reach (240 km) of the river. Google earth engine platform and advanced geospatial techniques have been used in this study. A novel indicator called stability trajectory indicator was developed that utilized vegetation information to identify the stability state of braided reaches. The findings of this study indicate a substantial increase in moderate and dense vegetation cover compared to light vegetation cover over the past decade. These results highlight the pronounced influence of increased moderate and dense vegetation type on the stability criteria of the reach, surpassing the contribution of light vegetation. The approach outlined in this study holds potential for river engineers to develop an effective management strategy for monitoring and maintaining river health.