Short-term observations of suspended particulate matter in a macro-tidal inverse estuary: The Upper Gulf of California

Studies on suspended matter in inverse estuaries are relatively scarce compared with similar studies in classic estuaries. The longitudinal circulation pattern in such estuaries is opposite to that observed in classic estuaries and may significantly affect the transport of suspended sediments. The Upper Gulf of California is a macrotidal inverse estuary having negligible river input but sustaining a high concentration of suspended matter, mainly derived from erosion of bed sediments. The amount of suspended particulate matter in the water column is controlled by tidal resuspension. On the western side of the Upper Gulf, horizontal fluxes of suspended particulate matter integrated between I m and 5 m above the bed were influenced by near-bed density-driven flow during neap tides. Maximum neap tide fluxes during ebb tide were - 21.5 g(.)m(-1.)s(-1) to -24.9 g(.)m(-1.)s(-1) while peak fluxes during flood tide were one order of magnitude smaller. The loss of suspended sediment to deeper water was controlled by gravity currents, which are typical of the near-bed circulation of inverse estuaries. Similar outflow from the Upper Gulf was not observed on the eastern side.