Khartoum Geohazard: An Assessment and a Future Warning

Khartoum is the national capital of Sudan; it is located in the confluence of the White and Blue Niles (the main tributaries of the Nile River). The city is densely populated and continues to follow a pattern of accelerated urbanization owing to the consolidation of the population in urban centers and suburbs, as well as the displacement of the rural population brought on by deprivation. This rapid urbanization, which is often synonymous with urban sprawl, results in an exceptionally high population density, resulting in a steady reduction in urban infrastructure, including disaster risk management. Another challenge is the significant climate change which will include an increase in the intensity of the rainstorms or the Nile’s inter-annual discharge, which will contribute eventually to flooding hazards, such as the one on August 5, 1988, which menaced the city. Furthermore, destructive earthquakes such as of November 20, 1995, when an earthquake followed by many aftershocks took place. Such cases require comprehensive risk reduction and management policies. In this study, we firstly presented an assessment of the 1988 Khartoum flood, which was described to be unrivaled due to the severe rainstorm and the Blue Nile’s overflow. Based on the available data, we developed a land-use map for flood-prone regions; however, we argued that most of the problems were created by complacency, lack of planning, and mismanagement. Secondly, we assessed the potential for earthquake-induced soil liquefaction in the city’s central business district due to its functionality with many multi-story buildings, besides the loose and saturated alluvial deposits underlying this area based on Seed and Idriss’s 1997 simplified approach by combining seismic hazard with the liquefaction likelihood. The study revealed that the possibility of liquefaction is minimal in the considered region.