Approche quantitative de l'érosion hydrique à différentes échelles spatiales: bassin versant de l'Oued Mina

Abstract

Nous examinons ici le phénomène très complexe de l'érosion hydrique de bassins versants. L'approche adoptée consiste d'une part à quantifier l'érosion à plusieurs échelles spatiales, au sens de la méthode Wischmeier, de la simulation de pluies sur 1 et 87 m , de micro-bassins expérimentaux, de retenues collinaires et d'un barrage en exploitation, et d'autre part à rechercher un modèle régressif pouvant expliquer la relation débit solide-débit liquide pour les différentes formes d'érosion. Une zone de marnes du bassin de la Mina en Algérie, productive en sédiments pour un barrage en aval et représentant le cinquième de la surface, a constitué la zone expérimentale. Les résultats montrent que, vu la complexité des facteurs mis enjeu, il est quasiment impossible d'extrapoler à différentes échelles. Le modèle puissance caractérise la relation débit solide-débit liquide, quelle que soit l'échelle spatiale considérée.Abstract The complex phenomenon of water erosion in river basins is examined. The approach adopted aimed to (a) quantify erosion at several spatial scales, using the Wischmeier method, rainfall simulation over 1 and 87 m~ plots, experimental basins, small dams and a reservoir, and (b) to seek the regression model which best explains the relationship between sediment transport and flow rates for the different forms of erosion. The marl zone, which is the main source of sediment for the reservoir and represents a fifth of the total area of the Mina basin in Algeria, was the experimental area. The results show that, considering the complexity of the factors, it is impossible to extrapolate at different scales. The power model characterizes the relationship between sediment transport and flow rates, whatever the spatial scale considered.

Erosion, Suspended Sediment Transport and Sedimentation on the Wadi Mina at the Sidi M’Hamed Ben Aouda Dam, Algeria

“…Since the Independence of Algeria, the total number of dams in exploitation at national level increased from 14 in 1962 to 65 in 2014 and, if we add the inter-basin water transfer major works, The watershed of Wadi Mina (6048 km 2 , northwest Algeria) is the subject of numerous works in the field of water erosion and siltation of dams [52][53][54][55][56][57][58][59][60][61][62][63][64][65][66][67].…”

Sediment Transport and Rainfall Erosivity Evolution in Twelve Basins in Central and Western Algeria

“…The absence of this kind of data has led many researchers to develop relationships for the estimation of this factor through annual or monthly rainfall. Many relationships have been established to calculate the R factor according to annual and monthly rainfall (annual rainfall, Fournier index, modified Fournier index) around the world (Roose, 1977;Renard & Freimund, 1994;Touabia, 1999;De Luis et al, 2010;Diodato et al, 2007;Torri et al, 2006); Yang et al, 2003;Loureiro et al, 2001;Ufoegbune et al, 2011;USDA-ARS, 2008). Yu et al(1996) and Renard et al (1994) have shown that in Australia and the United States respectively, the annual rainfall is highly correlated with the R factor.…”

Spatial and temporal variability of the rainfall erosivity factor in Northern Algeria

“…For each rainfall event, EI 30 is calculated as the product of the kinetic energy of rainfall (E) and the maximum intensity over 30 min. To estimate R, many relationships based on annual or monthly rainfall, and on the Fournier index or modified Fournier index, have been developed (Cohen et al 2005;Coutinho and Tomas 1994;Da Silva 2004;De Luis et al 2010;Diodato 2004;Diodato 2005;Diodato and Bellocchi 2007;Kalman 1970;Loureiro and Coutinho 2001;Meddi 1992;Morgan 1996;Renard and Freimund 1994;Roose 1977;Torri et al 2006;Touabia 1999;Ufoegbune et al 2011;Usda 2008;Yang et al 2003). Yu and Rosewell (1996) and Renard and Freimund (1994) have shown that annual rainfall is strongly correlated with R in Australia and the USA.…”

“…For their part, Mati et al (2000) subdivided annual rainfall in order to develop two models according to the agroclimatological setting of the rainfall gauging station. In Mediterranean countries, this approach has been used to develop a representative formulation of rainfall erosivity to be used instead of R of the universal equation: in Southern Portugal (Coutinho and Tomas 1994), in Algeria (Touabia 1999), in Morocco (Kalman 1970), in Spain (De Luis et al 2010, and in Italy (Diodato 2004;Torri et al 2006;Diodato 2005).…”

“…The R values were derived for three stations and for a very short time period (2 years), and although these results cannot be considered representative for calculating a mean value, they do provide an indication of the magnitude of rainfall erosivity. Mazour (1991) worked on two stations in far Western Algeria; Touabia (1999) estimated R in the Relizane area for one station, over 2 years of measurements; and Arabi et al (2007) focused on the Medea area in the Tell Atlas of Central Algeria. In the present study, rain gauge data from 241 stations are used to study the spatial and temporal variability of R as an indicator of annual rainfall erosivity, to develop a simple formula applicable to all regions of Northern Algeria where monthly rainfall data are available and, finally, to produce a map of the spatial distribution of rainfall erosivity (R).…”