Flood Routing of River Kaduna and its Catchment Using Muskingum Model

Abstract

This paper aims to use Muskingum Models to simulate the storage volume of flooding in the Kaduna River channel and generate the outflow hydrograph by routing the inflow. The simulation was based on thirty (30) years of monthly inflow stream data for the Kaduna River, with the peak value for each year being used. The hydrograph clearly depicts the flow pattern between the inflow and outflow, with the outflow lagging the inflow by around 2.3 hours, which was the value of K utilized in the computations and represents the transit time in the reach. The peak inflow is 801.18 m³/s, with an outflow of 736.74 m³/s; the storage level at this time is 64.44 cumesc (flood advancement). On the other hand, the highest outflow is 756.99 m³/s at an input of 706.30 m³/s, with a recessive storage of 50.69 m³/s, which is the volume of inundation at that moment (volumetric rate lost by the river). The average storage is a negative differential (-1.061 m3/s), while an approximate storage balance was maintained at an inflow and outflow of 694.16 m3/s and 694.46 m³/s respectively. The average negative storage differential implies that the outflow exceeds the inflow at this point, thereby shrinking the capacity of the river and possibly causing surface inundation downstream, as more outflows exceed the inflows. The model validation shows a good correlation (r²= 0.8989) between the inflow and outflow. The Muskingum technique has shown to be an efficient model for flood routing, based on the result, hence the study recommends it for river routing in areas with flood history.