Rainfall-Intensity Duration Frequency Analysis and Peak-flow Estimations for Flood Risk Management Options within Gountiyena basin in Niamey, Niger.

Abstract

Information on peak discharge and related probabilities is essential for engineering structure designs. Many basins are ungauged and therefore, data for statistical analyses are missing and input for sophisticated hydrological modeling is insufficient. Design storm estimations based on intensity duration frequency analysis and peak discharge estimations is an essential component for planning water management interventions. The study aims to contribute to flood risk reduction within the Gountiyena basin in Niamey/Niger through intensity duration frequency analysis and peak discharge estimations based on a 5-minutes interval rainfall from 1990 to 2017 for two stations. The Gumbel distribution was applied for the intensity duration frequency analysis while the Rational and the Soil Conservation Service-Curve Number methods were used for peak discharge estimations. Short rainfall durations produced high rainfall intensities with increasing return period. The intensities varied from 100mm/hr to 226mm/hr for both stations for 1-year and 50-years return period respectively. Estimated average peak discharges vary from 84m3/s (1-year return period) to 290m3/s (50-years return period). The results can serve as basis for decision making for planning water management interventions. Alternatives on appropriate flood management options were summarized and described