In front of his audience (ANASAP, Town Planning, Housing, Sanitation, ANPC, ONIT etc.) who really wanted to understand why, at the slightest rain, Lome is found in water and the credible alternatives to submit to the government, Dr. Semanou Gbafa graduated from ENSI delivered relevant reflections.
"Looking at the topography of the city of Lome, after the sea, there is the shoreline that is a bit high (2 to 5 m) above the sea. Then there is the lagoon area which follows and has coasts lower than that of the sea. It is difficult to drain the rainwater because when you take them from a point, you meet a climb before going down", indicates Dr. Gbafa.
As a result, he points out, at "each rain, a group of water is observed in the topographic basins inherent to the city".
"The old master plan of the city has taken into account the retention of water for the setting up of the basins that we currently have, which we find really abnormal. If we use the height of rain, it is really not effective, that's why we suggest to take into account the intensities of rains. It is this bad calculation which makes that with each rain, the basins are filled", he analyzes.
He bases his conclusions on the surveys carried out on the rainwater drainage works of the 172 covered lanes of Lome and 50 years of rainfall records of the airport station of Lome.
Essentially, there is a notorious insufficiency of rainwater drainage works in the city, because of gutters nonexistent on some roads developed; gutters without outlets; open gutters and makeshift gutters built by the population.
He proposes a new master plan to respond to the constraints of climate change and integrated management of rainwater in the city of Lome for a total estimated cost of about 800 billion CFA.
In cities, the sustainable management of rainwater remains an important issue. The storage capacity of the retention ponds is insufficient because the threshold intensities that overflow them are less than the rains of 2 years return period.
Finally, Dr. Gbafa proposes a rehabilitation and construction of 40 retention ponds (100 km of secondary networks and 350 km of tertiary networks); the construction of 04 treatment or rainwater treatment plants; 08 lifting stations; an expropriation and rehousing of populations in risk areas (40 ha disused and relocation of populations) and the strengthening of ecological, hydraulic and hydrological research laboratories.
The government is invited to work with the research community, especially with the National Association of Engineers of Togo (ONIT) for pragmatic solutions to the aggravating floods affecting the city of Lome.
The order wants to be a force of proposal and urges the public authorities to take into account in its plans and programs its various proposals for the control of the floods in Togo.