Quantifying the Impacts of Land Use and Land Cover Change on Watershed Hydrology Using Spatial Cloud Computing

Climate change and Land Use Land Cover Change (LULCC) impact on rainfall and runoff is globally evident. However, flash flood impacts on drylands are rarely investigated. A comparable watershed in the dryland of Sudan experienced devastating flash flood impacts for the last four decades (1980s-2020s). The unexpected severity of the 2013 flash flood prompted an investigation into hydrologic and LULCC to determine its cause. We combined spatial cloud computing with hydrological analysis to investigate the relationship between LULCC and peri-hydrological processes for four decades. The Landsat time series analysis shows significant LULC changes: agricultural and rangelands decreased by over 80%, while urban and barren areas increased by 81% and 31%, respectively. The daily rainfall analysis shows that rainstorms exceeding 40 mm were classified as destructive only under wet antecedent soil moisture conditions (1988, 2009, and 2019). Unexpectedly, the 41 mm rainstorm in 2013 occurred under dry conditions. The respective flood magnitude was 4.6 Mm3 according to the US-Natural Resources Conservation Service (US-NRCS). This represents only 14% of the potential runoff under wet conditions (32.3 Mm3) for the same rainstorm. Therefore, the devastating impact of the rainstorm emphasizes the impact of LULCC on flood dynamics in peri-urban areas of drylands.