Characteristics of bed sediments during the dry season in the Modaomen estuary of the Pearl River

Based on the grain size analysis of bed materials sampled from the Modaomen estuary of the Pearl River in December 2003, the gradation, distribution and transport properties of bed materials and their indication of dynamic environment have been studied. It has been showed that in the Modaomen estuary, the bed sediments are mainly composed of silt, and clay and sand in the next place; the mean median grain size is 6.356(0.012 2 mm); the gradation of bed sediments and that of suspended sediments are similar; the mean median grain size and sorting coefficient of the bed sediment have no big changes in Modaomen estuary area; the suspension is the main transport form of the sediments; and the bed load and saltation transport seldom take place. Owing to the intense human activities, the grain size of bed sediments is becoming finer than that in the past. The characteristics of the bed materials during the dry season in the Modaomen estuary indicate that the weak dynamic environment and tidal current are the main dynamic process.