Urbanization Growth Effect on Hydrological Parameters in Mega Cities

Rapid urbanization in the 5th settlement—Cairo, Egypt, led to a dramatic impact on the hydrological parameters within the area, due to a reduction in the soil infiltration, and consequently increased runoff volumes. Many researches were conducted for similar cases throughout the world to assess the urbanization hydrological impact. In the current study, remote sensing raster classification is utilized to assess the land use and associated Curve Number (CN) variation within the study area, and the SCS method was used to estimate the runoff volume. A Long-Term Hydrologic Impact Assessment (LTHIA) GIS tool has been developed to assess the temporal variation of hydrological parameters through different stages of development from 2006 to 2016 in the study area. It was concluded that during 10 years of development, the impervious areas increased and covered 30% of the study catchment area, the runoff volume increased by about 800% more than the 2006 base line runoff. This study clearly shows the excessive increase in runoff due to urban development and raises the flag for the urban planners at this area, particularly the New Administrative Capital in Egypt which lies along the extent of the 5th district to take necessary flood mitigation measures into account.