JEDDAH: Geology and hydrology experts, who warned that valleys in Jeddah pose major flood threats, stressed that only constructing dams of any kind – earth, concrete, arch or gravity – is not the correct scientific and logical solution to protect Jeddah from flooding. They told Okaz/Saudi Gazette that the only suitable scientific solution to overcome the flood problems in Jeddah is the construction of major drainage canals and that any other efforts would be a waste of money. The solution lies in a comprehensive approach that includes constructing canals from the edges of residential districts in eastern Jeddah to the Red Sea, they said. Jeddah is located in the flood plains of a number of valleys and in recent years, the city has encountered sweeping floods from 10 valleys located east of the city, said Dr. Nasser Bin Sulaiman Al-Amri, head of department of Hydrology and Water Resources Management, Faculty of Meteorology and the Environment at King Abdulaziz University. These valleys have sources high in the mountains in the east, he said. Water from these areas flows toward the sea and threatens whatever stands in its way because huge volumes of water and sandy and muddy sediment can cause major problems, he added. Development in the area has caused a number of changes to the eastern valleys, which has exacerbated flooding problems, Dr. Al-Amri believes. Urban expansion toward the north, south and east; changes in the ground levels of some areas; encroachments and building in valley routes; and construction of streets running north and south and east have all led to changing the features of the eastern valleys and altering the valley routes from their natural courses, he said. This has resulted in increasing the impermeable area, the area where water can soak into the ground, which has added to the force of the floods, their speed and the destructive hazards, he explained. All this is happening amid the almost total absence of stormwater-drainage networks while the sanitary-drainage network covers a meager 15 percent of Jeddah's total area, he noted. Dr. Al-Amri suggested a several solutions focusing on the construction of a number of dams on some of the eastern valleys and drainage canals. Some of these have been constructed and others are under construction. Dr. Al-Amri said the proposed solutions, in his opinion, lack a clear philosophy of integrated, comprehensive planning. One has to know if a proposed solution is for temporary treatment of the issue or if it is a radical, complete method of preventing flood hazards, he said. He stressed that a lot of effort and money are being directed toward eliminating flood hazards while very little effort is directed toward future prevention and raising the city's efficiency in resisting floods and their impacts. Dr. Al-Amri said the current approach to treat the problem is not clear, which is the real reason for the great losses; the money and efforts will not solve the problem unless they are directed correctly toward treatment and prevention. Temporary, limited solutions must be accompanied by long-term, strategic solutions, he said. He said construction-based solutions alone cannot solve the long-term problems. Those efforts must be joined by integrated efforts that encompass engineering, planning, legal, legislative and administrative dimensions. The challenges are greater because of climate change, said Dr. Abdul Aziz Abdul Malik Radain, professor of Geochemistry in the Faculty of Earth Sciences at King Abdulaziz University. “I recall that 10 years ago I said the Kingdom's climate would change due to the deflection of the earth's magnetic field,” he said. “These are scientific facts published in the specialist scientific journals. I warned that this change would be accompanied by a change in the quantity of rainfall. This necessitates speedy action in constructing drainage canals in the cities where valleys pass through urban areas. These old valleys dried up due to the lack of rainfall for many years.” Dr. Radain agreed that a drainage system is needed, a point scientists made many years ago. Engineer Dr. Hamoud Bin Matar Al-Thubaiti, a consultant hydrologist, is against the idea of constructing dams upstream of valleys to protect Jeddah from floods. Addressing Umm Al-Khair Dam, he noted that it was an earth dam and that they are not built to protect cities or other human settlements, but they can be built to divert flood routes from one valley to another. Dr. Al-Thubaiti also expressed some doubts as to whether Umm Al-Khair Dam had a spillway to drain excess water. He agreed with the suggestion to construct major drainage canals from the edges of residential districts in eastern Jeddah for all valleys flowing into Jeddah and that they should stretch across the city to the Red Sea.
