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The mobility of sediments and associated particulate pollutants is a complicating factor in assessing ecological risks. A technique that could help provide such information is the sediment trend analysis, an empirical method that examines relative changes in grain size distributions to determine the net transport path, along with the dynamic behavior (e.g., Sunamura & Horikawa, 1971; Mc Laren & Bowles, 1985; Gao & Collins, 1992, 1994; LeRoux, 2002; Poizot & Mear, 2008). Because many pollutants are adsorbed on sediment particles, this information can help assess the relationship between the load of pollutants and their sources and provide an understanding of the fate and behavior of contaminants in sediments (e.g., Carriquiry & Sanchez, 1999; Sanchez et al., 2008; Sanchez et al., 2009). Theory to predict the relative change that occurs in the distribution of particle size through erosion, transport and deposition was given by Sunamura & Horikawa (1971). Later, McLaren & Bowles (1985) conducted a one dimensional approach, whereby changes in grain size distribution along a sequence of individual samples and a Z test of statistical validity to determine the direction of preferential transport. Gao & Collins (1991, 1992) and Gao (1996) propose a two-dimensional model to determine the trend on the basis of vector analysis. A different approach based on analytic geometry and vector analysis to determine the sediment transport was produced by LeRoux (1994) and LeRoux et al. (2002). A summary of all these techniques is provided by Poizot et al. (2008). In all sediment transport models, based on trend analysis of clastic material, there are considerations that limit the inferences of the net transport of sediment. However, the most important limitation is the validation of transport trends observed through hydrodynamic reports of the area under study. In the present study used the model proposed by LeRoux et al. (2002) in order to identify the individual environments of sediment transport based on sediment characteristics and dynamic performance. The sediment transport model was compared with sediment transport reported by Sanchez et al. (2009). Subsequently, the model will be validated by reports of the hydrodynamic conditions of the bay. The average grain size decreases from coastal regions into the canyon, with two very large areas of sediment: (1) muddy at the top and bottom of the canyon and (2) very fine to fine sand on the inner shelf of the Bay. The sediments are best sorting in the shallow areas and the value of this coefficient increases toward the Todos Santos canyon. In the outer region of the bay, opposite Punta Banda and Todos Santos Islands are seen bad sorting. Negative skewness values are found in shallow areas, increasing in the central part of the bay and back to negative values into the canyon.The residual transport observed indicates the existence of two patterns of net sediment transport, which converge in the central region of the bay with a general direction in the direction NE to SW. In the Todos Santos canyon there is a sediment transport in the direction W to E (into bay) adjacent to the Punta Banda, and in the direction NE to SW (out of the canyon) adjacent to the island of Todos Santos. This pattern residual transport are consistent with measurements.

Palabras clave: Sediment transport; Bahia Todos Santos; grain-size

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