Contribution of Remote Sensing and GIS for Monitoring Land Use Change and Its Impact on Flood Risks in the Wadi Tessa Watershed

The study aims to assess changes in land use from multi-date satellite data and to estimate the impact of these changes on the risk of flooding in the Wadi Tessa watershed, a tributary of Wadi Medjerda, northern Tunisia. To monitor the effect of changing vegetation cover on flooding, multi-source and multi-date data were used. The methodological approach used is based on mapping using GIS and the processing of satellite images. The diachronic comparison of the supervised classifications of the Landsat satellite images used made it possible to determine the rate of land use change over 28 years, between 1990 and 2018. The results show that urban areas and scrubland experienced an increase in their surface areas with respective growth rates of (+ 0.08%) and (+ 10.64%). On the other hand, for other land uses, there has been a decrease in their surface area, with decline rates for forests (− 0.14%), agricultural areas (− 1.82%), rangeland (− 2.59%), and bare ground (− 5.83%). These results are very interesting since these land uses have given us an idea of worsening the flooding phenomenon, particularly in certain areas classified as sensitive. Furthermore, the comparison of the two flood risk maps shows an increase in the extension of the high-risk regions, which mainly cover urban areas, during this monitoring period (1990–2018).