PROJECT TITLE :

Understanding the Geophysical Sources of Uncertainty for Satellite Interferometric (SRTM)-Based Discharge Estimation in River Deltas: The Case for Bangladesh

ABSTRACT:

Like most river deltas, Bangladesh represents a geographically little region with various crisscrossing rivers. The overall variety of rivers in Bangladesh exceeds three hundred, of that 57 rivers are transboundary. Given the widespread unavailability of flow knowledge across the whole river basins of Ganges, Brahmaputra, and Meghna, combined with a declining measurement network and political challenges of sharing the info, satellite remote sensing of discharge has recently become a viable different. This study was motivated by the necessity to understand the geophysical sources of uncertainty of satellite interferometric-based discharge estimation in Bangladesh. A consequential goal of this study was to contextualize the understanding as a function of river's geophysical characteristics (river width, reach averaging length, and bed/water slope) and conjointly to explore a pragmatic approach to uncertainty reduction using water level climatology. Discharge was estimated in step with the slope-space (Manning's) method using elevation knowledge from Shuttle Radar Topography Mission (SRTM). A high-resolution hydrodynamic (HD) model was accurately calibrated to simulate water level and flow dynamics along the river reaches of the river network and function reference for comparison with satellite-primarily based estimates. It had been found that satellite interferometric (SRTM)-based discharge estimates yielded estimation error variance an order smaller than the natural flow variability solely if the river width was a minimum of 3 times larger the width of the native resolution of satellite elevation knowledge. Rivers narrower than this width (for SRTM, this cutoff is 270 m) yielded a coefficient of variation larger than one due to contamination of land elevation data in hydraulic parameter calculations. It had been additionally found that water level climatology will be useful in significantly reducing the estimation uncertainty for these slender rivers. Whereas reach averaging length appeared insensitive to accuracy for wide rivers (wid- h $bf gt! 1nbsphboxkm$), a few rivers appeared to own an optimal reach averaging length at that the best accuracy is obtained. Finally, it absolutely was found that if reach-averaged hydraulic parameters (area, slope, and radius) are used for the calculation of reach-averaged discharge, the needed linear (bias) correction factors, though distinctive and arbitrary for each river reach, can improve accuracy of flow simulations.