Observations of suspended sediment dynamics in a highly turbid macrotidal estuary, derived from continuous monitoring

The Gironde estuary is the largest estuary of the European Atlantic coast, with a well developed turbidity maximum zone (TMZ) characterized by high suspended sediment concentrations (SSC), over 1 g.l−1. In a context of climate change, understanding and predicting trends of turbidity are crucial issues for better predicting the future evolution of this estuary and its associated ecosystem. The objective of this study is to present the MAGEST network, implemented in the Gironde estuary and in function since 2005. The MAGEST network consists of four automatic monitoring stations located along the Gironde fluvio-estuarine system. Each station records continuously salinity, temperature, dissolved oxygen and suspended sediment concentration. This network is one of the first operational continuous monitoring systems in European estuaries. We present its interest to record patterns of turbidity at different timescales. We also present a complementary dataset of sediment altimetry to highlight the link between turbidity and the functioning of an intertidal mudflat in the upper estuary. By these examples, we show how the MAGEST network can help to make progress in the understanding of dynamics of the turbidity maximum on a seasonal basis.