Determination of the thresholds of the climatic classification according to the discharges in the Upper Senegal River Basin

Abstract

Floods are the most common type of natural disaster in the world and one of the most damaging. Changes in weather conditions such as precipitation and temperature result in changes in discharge. To better understand the floods and eventually develop a system to predict them, we must analyze in more detail the flow of rivers. The purpose of this article is to analyze the discharges in the upper Senegal River Basin by focusing on determining the limits of the climatic classification according to past discharges. The daily discharges from May 1, 1950 to April 30, 2018 were chosen as the study period. These flow data have been grouped into annual discharges and classified as very wet, moist, medium, dry and very dry each year. Then, the flow data were divided into two seasons or periods each year: high water and low water. The statistical variables used in this study are the average, the standard deviation, the coefficient of variation and the skewness. The results of the climate classification that corresponds to a log-normal distribution indicate a total of 17 years classified as averages (25% of the series), 14 classified as wet (20.6%), 29 classified as dry (42.6 %) and 8 classified as very wet (11.8%), very dry classifications being nil. Seasonal analysis showed that the months of the high water period, such as September, had the highest flow, and the period of low water, such as May, had the lowest flow. The results of the flow analysis were then compared with changes in rainfall. The results obtained show similar climatic classifications between rainfall and flow in the basin.