Flood Frequency Analysis in the White Volta River in Ghana

The study was done on the White Volta River that flows from Burkina Faso through Ghana into the Atlantic Ocean to analyze the frequency of flooding so as to provide a basis for flood prediction to protect life and property. Analysis of floods is important in management of peak discharges in rivers and through this analysis, the relationship between peak discharges and their frequency of occurrence is established through probability distributions. Furthermore, prediction of floods at various return periods is helpful in planning, designing and management of hydraulic structures such as dams and spillways, irrigation canals, dykes and barrages, roads and bridges including human settlement. Flood frequency analysis is done using various methods and this study used Gumbel's, California and Hazen's methods which are all probability distribution methods used to model stream flows. From regression analysis (R2 = 0.85) and a plot of discharge against recurrence intervals, Gumbel's method suited the best with a longer return period and the distribution was proved suitable for predicting the expected flow in the river. Using the same method, the peak flood values for different return periods of 5 to 100 years were also obtained, which can prove useful for the storm management in the area. Gumbel’s probability curve was plotted from which future floods with their probability of occurrence could be obtained