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.
Highlights
Efficient water resources management requires the availability of hydrological and hydraulic information at various spatial and temporal scales
This paper aims at exploring possibilities of using various remote sensing products as the primary input to a cascade of hydrological and hydraulic models of the poorly gauged Brahmaputra basin
While this paper presents the use of remote sensing information in hydrological and hydraulic models to generate flood maps, another possible solution exists in extracting flood information using geomorphic digital elevation model (DEM)-based approach that refers only to the topographic information
Summary
Efficient water resources management requires the availability of hydrological and hydraulic information at various spatial and temporal scales. This is usually accomplished with simulation models, which are calibrated with data measured at selected locations and at selected time intervals. Collection of hydro-meteorological data for a large basin is hampered by several reasons such as high operational costs, availability of limited road network, shortages of technical manpower and accessibility issues due to difficult terrains. In trans-boundary basins data sharing practices may cause an extra challenge to accessing collected data. Many catchments are totally unprepared for disasters such as floods and droughts or are unable to harness the benefits of available water resources in socio-economic development
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