An environment expert, Mr Babarinde Mukaila said last week that the dredging of River Niger alone would not address the problem of flooding in Nigeria. Mukaila, who is the Head of Climate Change Unit in the Federal Ministry of Water Resources, made the statement in Abuja. He said Nigeria required a holistic approach if it was to prevent persistent flooding and added that the dredging of the major rivers in the country would only help reduce the impact of flooding.
An environment expert, Mr Babarinde Mukaila said last week that the dredging of River Niger alone would not address the problem of flooding in Nigeria. Mukaila, who is the Head of Climate Change Unit in the Federal Ministry of Water Resources, made the statement in Abuja. He said Nigeria required a holistic approach if it was to prevent persistent flooding and added that the dredging of the major rivers in the country would only help reduce the impact of flooding.
According to him, “this is issue of sedimentation in the reservoirs; but remember, that when the sediments are removed through dredging, after about two, three or five years, the reservoir fills back to its capacity. So, if the water resources management – the inflow and outflow systems within the reservoirs are not properly managed, it could still lead to flooding over time. “Sedimentation is just one of the components. Sedimentation and river training are one of the components or the causes of flooding. “Other factors are there, just like if there is excessive rainfall due to climate change except you are going to predicate accurately when the rain is coming.’’
The official said that weather forecast too would not be enough to address flooding, considering that the predication could only be estimation. He said if the water in the reservoirs was dropped to forestall flooding, other aspects of the dams’ components would suffer. Cue in audio 2 “All your predictions could happen and may never happen. Now you need to manage between the competing demands; you need to generate electricity from hydro power and you need certain volume of water. “You need water for irrigation, you need water for water supply, if you are now drawing down your reservoir in anticipation of inflow into your reservoir, you should take the precautionary measures. The precautionary measures allow you to factor in the uncertainties.''
He said that the building of more dams and dredging of major rivers to store both surface and underground water could help reduce flooding. Mukaila said that recent developments had shown that the amount of sediments being transported from some of the streams in the country was so large that most of the streams, channels and reservoirs were losing their storage capacities.
“The carrying capacities of the reservoirs and the stream channels are reducing due to sedimentation and the primary cause of this is what is called the land use management within the catchments. “In this land use management, the strategy is that upper catchment areas that contribute majority of the flash flood need to be protected so that when the rain falls there, the holding capacity of these catchments will reduce the amount of run-off coming down stream. “But a situation when development plan did not take into accounts the development in the upper catchments, once the upper catchment is opened up, the amount of infiltration that is supposed to occur there starts reducing and once it reduces, more flash flood comes to the main channel.’’ Cue out audio He added that the trend could also result to dead rivers, which could cause street erosion and gully erosion rather than a well-defined channel stream flow.
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