COMPARISON OF ACRU AND HEC-HMS MODELS IN RUNOFF PREDICTION IN A WATERSHED, SOUTHWEST NIGERIA

Abstract

The frequency in the occurrence of hydrological extremes has necessitated the use of models to forecast
and mitigate such disasters. Agricultural Catchments Research Unit (ACRU) model and Environmental
(HEC-HMS) were used to simulate runoff from Agbogbo catchment in Ile-Ife (Southwestern Nigeria).
The objective of the study was to compare both models performance in simulating streamflow in the
Agbogbo catchment. Model input data for both models were obtained and used for model simulation.
Three years streamflow records were obtained for Agbogbo catchment and used for calibrating and
validating the models. Data for the first hydrologic year (April 1987 March 1988) was used to calibrate
the two models while that of the two remaining years was used for validating the models. When the Nash-
Sutcliffe Model Efficiency Coefficient was used to evaluate the performance of the models, a value of
0.83695 and 0.78232 was obtained for the ACRU model simulation for the 2nd and 3rd hydrologic years
while values of 0.87748 and 0.54706 were obtained by the HEC-HMS model for the two periods. ACRU
model performed better with an overall (April 1988 March 1990) model efficiency coefficient of 0.81218
when compared with that of HEC-HMS which was obtained to be 0.71498. When the hydrographs of the
observed and simulated streamflow were compared, ACRU model showed more sensitivity to changes
within the catchment as demonstrated by the similarity in the timing of the peaks than HEC-HMS, which
implies that ACRU model can be used for flood forecasting in Agbogbo catchment.