Extreme environmental events, such as flood, have severe environmental and socio-economic effects. Reliable estimates of peak flow and flood forecasting are of great concerns in water resources management and development. Flooding is a common problem in Ethiopia. Frequency and magnitude have increased rapidly in the last few decades. The increase in flooding is a result of climate change as well as land-use change (particularly deforestation). The main impacts of flooding are loss of human lives and properties, destruction of roads and electric systems that result in great economical loss for the country. In flood frequency analysis, the objective is to estimate flood magnitude (Q) corresponding to any specified recurrent interval of (T) years. In this study the conventional way of flood frequency analysis is applied in determining flood magnitudes of 10, 25, 50, 100, and 200 years return period by selecting theoretically the best fit probability distributions. The result shows General Logistic (GLOG) and General Pareto (GPAR), distributions are the best fit probability distribution for Gumera and Megech rivers respectively.

Keywords: Peak flow, flood frequency analysis, flood, and return period