SENSITIVITY ANALYSIS AND COMPARISON OF INFILTRATION MODELS IN SOUTHERN GUINEA SAVANNAH ZONE OF NIGERIA

Abstract

This study aimed to compare the performance of three models for infiltration rate prediction for soils of Nigeria’s southern guinea savannah zone. The study area focused on 6 locations in Minna. Five infiltration rate tests were conducted for each site to investigate the soil infiltration characteristics of urban soil and its influencing factors. The results showed that the steady infiltration rates of urban soil were highly variable. High variations in the final infiltration rates were seen for different vegetation patterns (22.02, 17.06, 13.45 cm hr-1 ). Land with shrubs and grasses had the highest infiltration rate, while the bare land had the lowest rate of 7.14 cm hr-1 . Three infiltration models were applied (Horton, Kostiakov and Philip), and their performances were evaluated based on Root Mean Square Error (RMSE) and coefficient of determination (R2 ). The Philip model with the least RMSE values of 0.79 cm hr-1 and R2 of 0.97 most closely predicted the measured infiltration. On the other hand, Kostiakov’s and Horton's model provided less exact estimates of the measured infiltration with least RMSE values of 4.63 and 5.13cm hr-1and R2 of 0.92 and 0.91, respectively. Improper techniques to minimise and mitigate soil compaction should increase urban soil infiltration rate and water storage volume. In conclusion, these findings can supply helpful information for urban planners about maximising the water volume of urban soil and decreasing instantaneous urban flooding.

Keywords

• infiltration rates
• sensitivity analysis
• horton model
• kostiakov model