Investigating flash floods potential areas using ASCAT and TRMM satellites in the Western Cape Province,South Africa |
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| Authors: | Tsitsi Bangira Ben HP Maathuis Timothy Dube Tawanda W Gara |
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| Institution: | 1. Department of Geography and Environmental Studies, Stellenbosch University, Western Cape, South Africa;2. Faculty ITC, Department of Water Resources, University of Twente, Enschede, The Netherlands;3. Faculty ITC, Department of Water Resources, University of Twente, Enschede, The Netherlands;4. Discipline of Geography, University of KwaZulu-Natal, Pietermaritzburg, South Africa;5. Department of Geography and Environmental Science, University of Zimbabwe, Harare, Zimbabwe |
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| Abstract: | The aim of the study was to evaluate flash flood potential areas in the Western Cape Province of South Africa, by integrating remote sensing products of high rainfall intensity, antecedent soil moisture and topographic wetness index (TWI). Rainfall has high spatial and temporal variability, thus needs to be quantified at an area in real time from remote sensing techniques unlike from sparsely distributed, point gauge network measurements. Western Cape Province has high spatial variation in topography which results in major differences in received rainfall within areas not far from each other. Although high rainfall was considered as the major cause of flash flood, also other contributing factors such as topography and antecedent soil moisture were considered. Areas of high flash flood potential were found to be associated with high rainfall, antecedent precipitation and TWI. Although TRMM 3B42 was found to have better rainfall intensity accuracy, the product is not available in near real time but rather at a rolling archive of three months; therefore, Multi- sensor precipitation estimate rainfall estimates available in near real time are opted for flash flood events. Advanced Scatterometer (ASCAT) soil moisture observations were found to have a reasonable r value of 0.58 and relatively low MAE of 3.8 when validated with in situ soil moisture measurements. The results of this study underscore the importance of ASCAT and TRMM satellite datasets in mapping areas at risk of flooding. |
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| Keywords: | topographic wetness index satellite rainfall estimates antecedent soil moisture flash flood |
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