A SIMPLE RAINFALL-RUNOFF MODEL FOR WATER HARVESTING IN SEMI-ARID REGION OF NORTH EASTERN NIGERIA
Publication Date : 01/08/2010
A linear regression model for predicting runoff from daily rainfall was developed for rainwater harvesting in the northeast arid region of Nigeria. A deterministic model, EUROSEM, was used to partition rainfall into infiltration, surface detention and runoff. High resolution rainfall data collected over three years for seven areas within the northeast arid region was used by the EUROSEM model to predict runoffs from individual storms. The runoffs predicted by the model were plotted against their respective rainfall events and regression was performed to obtain a linear relationship. The linear model thus obtained was y = 0.44x + 16. The result indicated that runoff coefficient and threshold value obtained from the linear relationship were 0.44 and 16 mm respectively. The predictions by the model were compared with that estimated by the Soil Conservation Service (SCS) Curve number (CN) method. Compared to the CN model estimates, the developed linear model produced very similar estimates of runoff. This indicates that the model developed can be used to make estimates of runoff resulting from individual rainfall events for the purposes of designing simple structures such as bunds for water harvesting in the arid region of northeast Nigeria.
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