Rainfall-Runoff Relationships and flow forecasting, Ogun river Nigeria
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An excess or a lack of rainfall are the major causes of most hydrological hazards, and the need
for a systematic approach to river flow forecasting based on rainfall is imperative, especially
in Nigeria. A study was carried out on three major gauging stations of the Ogun river basin
to determine the rainfall-discharge relationship and model equations for use in the basin and
similar basins. Stream flow and rainfall data for at least seven consecutive years for each
station were collected and analyzed. The rainfall-runoff data were subjected to linear,
exponential and higher order analysis. Stream flow data were also fitted to normal, log-normal
and log-Pearson Type III distributions. The selection of the appropriate probability distribution
model for each gauging station was based on graphical comparisons between observed
and predicted flows and goodness-of-fit tests using chi-square and probability correlation
coefficients. Results show that model equations with logarithmic and exponential relationships
between rainfall and discharge gave better and more realistic prediction estimates and can be
used for the basin. It was determined that the peak discharges occurred when the rainfall
values were at their maximum, and a distinct relationship between the discharge and rainfall
exists at each of the gauging stations.
Keywords
TA Engineering (General). Civil engineering (General)