Flood Inundation Mapping of the Sparsely Gauged Large-Scale Brahmaputra Basin Using Remote Sensing Products

Abstract

Sustainable water management is one of the important priorities set out in the Sustainable Development Goals (SDGs) of the United Nations, which calls for efficient use of natural resources. Efficient water management nowadays depends a lot upon simulation models. However, the availability of limited hydro-meteorological data together with limited data sharing practices prohibits simulation modelling and consequently efficient flood risk management of sparsely gauged basins. Advances in remote sensing has significantly contributed to carrying out hydrological studies in ungauged or sparsely gauged basins. In particular, the global datasets of remote sensing observations (e.g., rainfall, evaporation, temperature, land use, terrain, etc.) allow to develop hydrological and hydraulic models of sparsely gauged catchments. In this research, we have considered large scale hydrological and hydraulic modelling, using freely available global datasets, of the sparsely gauged trans-boundary Brahmaputra basin, which has an enormous potential in terms of agriculture, hydropower, water supplies and other utilities. A semi-distributed conceptual hydrological model was developed using HEC-HMS (Hydrologic Modelling System from Hydrologic Engineering Centre). Rainfall estimates from Tropical Rainfall Measuring Mission (TRMM) was compared with limited gauge data and used in the simulation. The Nash Sutcliffe coefficient of the model with the uncorrected rainfall data in calibration and validation were 0.75 and 0.61 respectively whereas the similar values with the corrected rainfall data were 0.81 and 0.74. The output of the hydrological model was used as a boundary condition and lateral inflow to the hydraulic model. Modelling results obtained using uncorrected and corrected remotely sensed products of rainfall were compared with the discharge values at the basin outlet (Bahadurabad) and with altimetry data from Jason-2 satellite. The simulated flood inundation maps of the lower part of the Brahmaputra basin showed reasonably good match in terms of the probability of detection, success ratio and critical success index. Overall, this study demonstrated that reliable and robust results can be obtained in both hydrological and hydraulic modelling using remote sensing data as the only input to large scale and sparsely gauged basins.

An integrated modelling approach to evaluate the impacts of nature-based solutions of flood mitigation across a small watershed in the southeast United States

“…The simulated flood inundation maps of both hurricanes were transferred from HEC-RAS to a GIS 230 environment as raster files to process and compare with the observed data. Flood mapping performance is evaluated by using categorical verification statistics, which are usually implemented for estimating the accuracy of flood forecasts (Bhatt et al, 2017;Bhattacharya et al, 2019). The categorical verification statistics measure the correspondence between estimated and observed inundation patterns.…”

Preface: Remote Sensing for Flood Mapping and Monitoring of Flood Dynamics

“…Furthermore, in a case study in Sri Lanka, Alahacoon et al [16] combined the trend analysis from gridded observed rainfall data with flood maps derived from satellite SAR and multispectral data to analyze the spatiotemporal patterns of floods. Using satellite TRMM rainfall data, Bhattacharya et al [17] looked at flood modelling of the sparsely gauged but very large-scale Brahmaputra basin using the HEC-HMS hydrological model. Complementing TRMM rainfall with data from the Gravity Recovery and Climate Experiment (GRACE) satellite mission, Sun et al [18] used an index for flood potential to generate monthly terrestrial water storage anomalies in order to better understand the parameters affecting the hydrological state of the Yangtze River basin.…”

Examining the Effects of a Flood Event in the Lower Ceyhan Basin in 1980 Using Historical Satellite Data

“…Many studies and articles on the use of RS and/or GIS methods in flood mapping have been published in the literature [15][16][17][18][19][20][21][22][23][24][25][26][27][28]. Knowing the geographical extent of submerged regions during flood occurrences is crucial for organizing relief studies as well as detecting faults with flood control facilities [29].…”