Soil moisture (SM) plays an important role in determining the antecedent condition of a watershed, while topographic attributes define how and where soil moisture and rainfall interact to create floods. Based on this principle, we present a method to identify flood risk at a location in a watershed by using remotely sensed soil moisture and open access information on rainfall, soil properties and topography. The method consists of three hydrologic modules that represent the generation, transfer and accumulation of direct runoff. To simplify the modelling and provide timely warnings, the flood risk is ascertained based on frequency of exceedance, with warnings issued if above a specified threshold. The simplicity of the method is highlighted by the use of only three parameters for each watershed of interest, with effective regionalization allowing use in ungauged watersheds. For this proof-of-concept study, the proposed model was calibrated and tested for 65 hydrologic reference stations in the Murray-Darling Basin in Australia over a 35-year study period by using satellite-derived surface soil moisture. The three model parameters were first estimated using the first 10-year data and then the model performance was evaluated through flood threshold exceedance analyses over the remaining 25-year study period. The results for estimated parameters and skill scores showed promise. The three model parameters can be regionalized as a function of watershed characteristics, and/or representative values estimated from neighboring watersheds, allowing use in ungauged basins everywhere.
Refrences
Kim, S.; Paik, K.; Johnson, F. M.; Sharma, A. Building a flood warning framework for ungauged locations using low resolution, open access remotely sensed surface soil moisture, precipitation, soil and topographic information IEEE JOURNAL OF SELECTED TOPICS IN APPLIED EARTH OBSERVATIONS AND REMOTE SENSING. 2018