Modeling River hydro-morphological responses to Land Use Land Cover Change in Tropical Regions, case of Sebeya catchment, Rwanda.

Tropical regions have experienced rapid Land Use Land Cover Change (LULCC) in the last decades. Furthermore, climate change will likely intensify these changes due to global warming and increased frequency of extreme events. These changes have diverse effects on watershed and river hydro-morphological processes through alterations of the rainfall and runoff patterns, which translate into changes in the water balance components. The magnitude of these effects depends on the watershed characteristics, including the size, extent of change, topography, soil characteristics, and climate. Understanding the watershed hydro-morphological responses to changes in both climate and LULC –especially in tropical regions where rainy seasons are followed by dry seasons— is vital for effective land and water resources management in the face of future changes.

Sebeya catchment in the western part of Rwanda is prone to flooding, associated with erosive processes, and mass movements. Hence, destroying infrastructures and houses, damaging crops, and taking people’s lives yearly during long rainy season (February to May). This is partly attributed to the combination of steep topography and the loss of forest cover on fragile soils, coupled with the increased prevalence of extreme rainfall events. The hypothesis is that the hydro-morphological characteristics of Sebeya river have changed in the last few decades as a result of LULCC, including forest clearing from agriculture and built-up development. In light of it, this study intends to quantify changes in LULC of the Sebeya catchment over the last three decades, and predict future changes in the next three decades, using remote sensing data and LULC model. Furthermore, a hydrologic model will be used to simulate and forecast the associated changes in hydro-morphological and flood frequency.