Hydrological Investigation and Characterization of Sokouraba Watershed, Burkina Faso

Abstract

The purpose of this study is to determine the hydrological characteristics and the morphometric parameters of the Sokouraba watershed (BV) where the climatic hazards make the water resource increasingly insufficient. This watershed has never been the subject of morphometric and hydrological characterization in the past. The present study made it possible thus, to better understand the functioning of the hydrographic networks as well as the quantity of water likely to be used for the construction of a dam in this watershed. According to the hydrologic analysis results, from 1960 to 2019, the annual precipitation values range from 347,3 to 1596,6 mm with an average of 1099,28 mm. The maximum daily rainfall values for the same period vary between 42 and 287 mm with an average of 82.85 mm. The values of wet decennial and wet quinquennial rainfall are respectively 1380 and 1280 mm. The dry five-year and dry ten-year rainfall values are 917 mm and 821 mm respectively. According to the watershed characterization results, the calculated Sokouraba watershed surface is 77,34 Km² and its perimeter is 44,3 Km. The values of the length and the width of the equivalent rectangle of the basin are respectively 17,81 Km and 4,34 Km. The longitudinal slope and the overall slope index values are 3.24 m/km and 3.20 m/Km respectively. The value of the corrected overall slope index of the watershed is 7.05 m/Km while the Gravelius compactness index is 1.42. This value of KG higher than 1 indicates that the watershed of sokouraba is of elongated shape. The specific gradient value of the watershed is 61.99. This value is included between 50 and 100 m, thus according to the classification of the reliefs the latter, the relief of the catchment area of Sokouraba can be qualified as moderate. The values of the length of the main watercourse and the total length of the watercourses calculated are respectively 15,41Km and 63,25 Km. The calculated value of the drainage density of the catchment area is 0.21 Km-1. The value of the attenuation coefficient and the ten-year rainfall calculated in this study are 0,78 and 100,062 mm respectively. The value of the decennial runoff coefficient thus calculated is 27,83%.