Mapping floods in the middle Zambezi Basin using earth observation and hydrological modeling techniques

摘要

The Lower Middle Zambezi catchment, on the Zimbabwean side, is vulnerable to floods almost every year. In this work, the causes and impacts of floods in the Mbire District of the Middle Zambezi Basin are investigated. An algorithm based on the binary logistic regression is used together with MODIS NDVI images to determine the spatial and temporal variation of flood inundation. The HEC-HMS model is used to simulate rainfall time series at daily time step. The quantified peak flow is given as an input to a mono-dimensional hydraulic model, HEC-RAS. Results from the mapped inundated areas for the period 2005 to 2015 showed that 16 January 2006 had the highest flooded area of 1934 km(2). Factors explaining causes of flooding were distance from surface water bodies. The simulated flooded areas obtained are used to deepen our understanding of the contribution of geomorphic features towards flooding as well as the extent of flooding. Results obtained contribute towards defining new strategies for prompt flood risk management in the District.