River and coastal management

Recurrent flooding problems during the monsoon season, garbage-clogged drains serving as breeding ground for malaria mosquitoes, protected mangrove wetlands polluted with oil and sewage – these are some of the serious challenges facing the low-lying coastal city of Banjul, capital of The Gambia. In a recent Banjul newspaper interview, Mayor Faal affirmed his commitment to making Banjul a cleaner, ‘liveable city’, stating that it is also President’s Jammeh’s top priority to solve the flooding problems of Banjul yet this year. They have contracted Royal Haskoning to help address these issues, together with a local consultancy firm, CityScape Associates.

With the next rainy season due in just a few months, the scope of Royal Haskoning’s contract with the Gambian government, signed last December, is to start with mitigation: to rehabilitate Banjul’s old pumping station and to redesign the city’s derelict drainage system. Within this framework, RH and its local partner are currently working on a complete survey of the city and its drainage system, to provide input data for a modeling exercise in Sobek.

A more permanent solution to the flooding problems will require a thorough reconstruction of the drainage system. Most importantly, the new system should have fewer open gutters and be less prone to garbage accumulation. Any technical solutions (pumps, sluices) should be as low-maintenance as possible. To protect the water quality of the water storage area, – which in fact is part of a RAMSAR protected wetland site –, the first few millimeters of run-off after a rainstorm should somehow be captured and treated to remove lead, oil, and sewage. And the system should include enough water movement to prevent mosquito breeding in stagnant water. But whatever the design solutions, the system will only work if Banjul City improves its garbage collection and residents stop dumping garbage into the drains. This much has already been made clear to Banjul’s mayor.

In the meantime, RH hopes that this short-term mitigation project will open the door to larger projects. “The Gambian government has the ambition to improve the road infrastructure and sewage system of the greater Banjul area. Obviously, it would be most efficient to combine reconstruction of the drainage system with infrastructural and sewage system improvements,” says project manager Martijn Lips of the Coast & Rivers Division Rotterdam. “So we are preparing a comprehensive design that reflects our trademark ‘thinking in all dimensions’.”

This means that, in addition to drains, sewers and roads, the dimension ‘tourism’ is included into the picture. As the smallest country of mainland Africa, with a very small economy, The Gambia is keen to raise more income from tourism. The internationally renowned mangrove wetlands of the Senegambian coast already attract many visitors, but tourists generally avoid the dirty, malaria-infested city of Banjul. A clean-up of Banjul would definitely make the area more attractive. As a result of ‘Thinking in all dimensions’, the concept design proposes to combine the main drainage channel with a boulevard along the wetland area. For local residents, and international birdwatchers.