A survey conducted by Sindh Irrigation Department and the Karachi Metropolitan Corporation (KMC) few years ago pointed out thousands of built houses on Gujjar Nullah, stretched over a distance of 13.5 kilometers.
The downpour in Karachi and other parts of the provinces claimed seven lives today including four killed by lightning strikes in Tharparker's Mithi and Chachro and one in Thatta.
Current wet spell could continue till Sunday, according to the weather department. The clouds could down pour around 100 millimetres of water on Friday and Saturday, the weather forecast said.
The armed forces were summoned in the city to assist the civil administration in dealing with the urban flooding situation, said the ISPR.
The parts of Karachi which received heavy rain include Clifton, I I Chundrigar Road, Saddar, Gulistan-e-Johar, Korangi, Akhtar Colony, Mahmoodabad, Manzoor Colony, Malir, M A Jinnah Road, Sharea Faisal.
Funds of Rs 1.76 billion will be utilized for cleaning of nullahs, earmarked under a World Bank project.
Heavy falls may also generate urban flooding in districts of Hyderabad, Thatta, Badin and Karachi on Saturday and Sunday, weather office said.
The heavy rainfall from Friday could generate urban flooding in Karachi and other cities of Sindh
The weather office also warned of possibility of urban flooding in Lahore, Gujranwala, Faisalabad, Rawalpindi divisions during the period.