Influence of Hydrological Variation Pointers and Incorporated Muskingum Flow Scrutiny on Flooding Frequency in the Upper and Lower Ikpoba Stream, Southern Nigeria

Abstract

Flood frequency curve using River Ikpoba as Case study was estimated for a return period of 100 years, the flood magnitude is 461 m3/s as against the 380m3/s which was observed to be the highest discharge value throughout the simulation period. This value was found to have occurred in September 2012. The flood frequency curve therefore can aid in flood hazard preparedness since it can be employed to forecast the flood magnitude at different recurrent intervals. There is an increase in the number of wetted with corresponding increase in recurrence interval. For example, for 50yrs and 100 years return period, the number of wetted cells was observed to be 26171with a runoff volume of value of 0.14 x 108m3/s. Using the computed volume of runoff and the corresponding number of wetted cells, the spatial extent of flooding for each return period was generated. Similarly, red spots which are seen in areas such as Lucky Igbinedion Way, Temboga, Second Lagos Road, Mission Road, Ewah Road, Federal Road, Ikpoba, Oregbeni and MM Way shows that these areas are flood prone areas and requires adequate attention and effective early warnings systems in order to alleviate the magnitude of destruction that is caused by flood. Likewise, there is an indicate that as the day’s progress the flow rate was increasing for consecutive 30 days but at low flow rate, but at 90 days it declines. For maximum value as day progress the values decreases.