L’Algérie, caractérisée par un climat semi-aride, est menacée par l’érosion des terres agricoles qui provoque l’augmentation du transport solide et l’envasement croissant des barrages. Cet article décrit une nouvelle méthode d’estimation des flux de matières en suspension (MES) au niveau d’un barrage algérien (barrage de Beni Amrane) basée sur la logique floue. Cette dernière utilise des termes flous tels que « faible », « moyen » et « élevé », pour décomposer le processus débit-MES en plusieurs sous-ensembles flous et d’en déduire les quantités de matières solides en fonction du débit observé de la rivière. Les performances de cette méthode ont été évaluées en période de calage, mais aussi en période de validation, pour mieux juger de la capacité prédictive du modèle à ces deux échelles. En comparant la logique floue avec un modèle empirique régressif utilisant une relation de puissance, nous avons démontré la robustesse du modèle flou en tant qu’outil de quantification du transport solide.Sediment transport and erosion is a complex natural process that is strongly influenced by human activities such as deforestation, agriculture and urbanization. In particular, suspended sediments play a key role in controlling water quality and they can cause a major reduction in the capacity of a stream for handling floods. In Algeria, increasing erosion and suspended loads are responsible for serious problems in agricultural land and hydraulic reservoirs, since the suspended load and its sedimentation lead to flooding and dam silting. Water and soil conservation practices, such as contour ridges and areas of reforestation, were introduced in many regions of Algeria in order to decrease erosion and to collect runoff in hill-slope catchments.Relationships for water discharge and suspended sediment load can be divided into three types: empirical models that allow quantification of erosion on annual time scales, such as the Wischmeier and Smith soil loss equation; conceptual models, which include several reservoirs estimating sediment load on different time scales; and finally, physically-based models, which introduce physical laws such as the Saint-Venant equation. These models represent another category, and allow the estimation of sediment load in different areas of the watershed and supply spatial results. These models also take into account numerous variables that are difficult to obtain on a regional scale.The objective of this research was to develop runoff-suspended sediment models for the Beni Amrane reservoir. This reservoir is located in the Isser watershed, situated in northern Algeria. This basin covers an area of 4,000 km2 and is characterized by a semi-arid climate and a very high soil erosion rate, exceeding 2,000 tons/km2/year. The Beni Amrane reservoir represents an important dam as it supplies the Keddara dam, which in turn supplies the town of Algiers with drinking water.In the present study, two approaches to suspended sediment simulation were applied on hourly time scales for suspended sediment concentratio...