Presentation at Nigerian Society of Engineers, Asaba Chapter Technical Section of Study & Design of Stormwater Management. & Control by Engr. John Cee Onwualu, Jefcon & Associates Ltd – Engineering Consultants.
Climate change which is a direct effect of global warming has brought extreme weather changes to our environment, such as sea-level rise, more frequent rainfall with its associated flooding. The effects of these extreme changes have brought more flooding in our Cities, especially Asaba, Warri, Effurun, and Environs since they lie within the Niger Delta region of Southern Nigeria. Despite these extreme weather changes from global warming, less attention is being given to the management, and control of stormwater by government. The excess stormwater leads to loss of agricultural farmlands, contamination of groundwater and rivers and loss of lives and property of immeasurable values. Today, due to the global climate change, Asaba, Warri, Effurun, and its environs are experiencing more months and frequent rainfall rather than the old known pattern of six months dry and six months rainy seasons. The effect on these cities and environs has defied the efficacy of existing drainage systems put in place by government and corporate bodies over the years. Hence, there was an urgent need by the government of Delta State to study and construct sustainable drainage systems for the management and control of Stormwater in Asaba, Warri, Effurun, and Environs. This desire led to the Engineering Study and Design conducted in Asaba, Warri, Effurun, and Environs. Using interviews of locals, participatory meetings, and engineering survey, more in-depth knowledge of the flooding and causes was gathered. The study looked at how overland drainages can be incorporated into the nature-based gifts, such as Valleys, Waterways and Rivers for the safe evacuation of the excess runoff generated from the environment. Results obtained showed that improving the efficiency of these Natural Watercourses and Rivers would bring a better management and control of the outfalls of both existing and new drainages into these Natural Watercourses. For this to be successful, the inhabitants must be aware of the environmental hazards associated with blocking of Valleys and Waterways with structures and dumping of waste materials into Storm Sewers and Drains, which would create blockages for the efficient evacuation of the Stormwater generated from the Environment.