Comparing Developed Runoff Coefficients for Some Selected Soils of Gidan Kwano with Exiting Values

An analysis of the rainfall-runoff relationship and subsequently an assessment of relevant runoff coefficients should best be based on actual, simultaneous measurements of both rainfall and runoff in the project area. Models that describe watershed hydrology are classified according to several criteria. A non-pressure rainfall simulator with a dimension of 22.9m by 2m and adjustable feet with minimum height of 1.5m was used for the research. The five runoff plots were set up to measure surface runoff for the five types of soil under controlled conditions. The plot was established directly in the project area with a slope size of 9%. The various types of soil were determined and excavated where necessary at 20cm depth and replaced with the current type of soil existing within the runoff plots. Based on the available parameters, three runoff equations were considered. The calculated values using the rational formula ranged between 0.01 and 0.026; FAA values ranged between -0.162 and -1.321 while for that of Izzard method, the values ranged between 0.212 and 0.458. It was concluded that if the slope of 6% is maintained the values of runoff coefficient will be the same as those that are in existence.