Groundwater rise problem and risk evaluation in major cities of arid lands – Jeddah case in Kingdom of Saudi Arabia

Arid lands are in the need of additional water supply but water transportation from outside of the natural hydrological cycle causes the groundwater to rise within the urban areas. Additonal water supply from surrounding areas or through the desalination plants provides comfort in domestic activities but after the usage, its disposition is necessary in an efficient manner. Unfortunately, arid region cities have neither sufficient nor efficient sewage system. Consequently, the water returned to surface cesspools and leakages from insufficient sewage system makes internal groundwater recharge within the urban area. Additionally, water supply system leakages further raise the groundwater level. Deterioration in water quality becomes a potential danger for the infrastructure and foundations. Surface depressions in the city may be flooded due to grundwater level rise and at times bed smells occur at various parts of the city. In this paper, a quantitative method is followed to assess groundwater level rise risks in addition to the few chemical risks associated with sulfate and chloride solids. It is observed that each one of these variables has different probability distribution function and exposure risk maps with different features.