The sewerage system is an essential component of urban infrastructure. It is responsible for the occurrence of environmental pollution, when appears on the surface of the earth because of a flood resulting from a blockage or break in the pipe or the pipe not accommodating additional amounts of drainage. The future concerns the drainage system to avoid floods when the population increases suddenly during festivals or religious visits. This research presents a model based on geographical information systems to report the occurrence of a flood with a smartphone application that sends the number of the manhole causing the sewage overflow to the dashboard, so that the appropriate decision can then be taken by decision-makers to solve the problem. The city center of Karbala—Iraq—was taken as a case study because this city is visited by many visitors during the religious visit period. Various experimental operations of the model have shown that it allows real monitoring, helps in treating sewage overflows, and reduces the resulting environmental pollution.