Suspended Sediment Responses in a Wind-Dominated Estuary of the Texas Gulf Coast

Abstract

ABSTRACT Time-sequence measurements were made of suspended sediment and hydrographic characteristics in Corpus Christi Bay, which is a shallow, restricted estuary typical of the Texas Gulf Coast. Quasi-synoptic measurements, obtained during eight surveys over a two-year period, indicate that wind is the dominant forcing agent regulating estuarine sedimentary processes. Surface-sediment dispersal patterns are primarily controlled by wind direction, with offshore-directed northerly winds producing substantially different patterns than the onshore-directed prevailing southeasterly winds. The wind direction determines the spatial intensity of bayfloor-sediment resuspension and the direction and efficiency of water-exchange processes that control sediment dispersal within the estuarine system. Suspended-sediment characteristics within the water column are primarily influenced by wind speed. Temporal trends of correlation coefficients indicate that the baywater turbidity is directly related to mean wind speed and is a short-term response parameter, being influenced mainly by cumulative wind effects within a 30-hour period prior to observation. Texturally, the suspensate consists of poorly sorted clay-size to very fine silt-size particles. Sediment grain size is inversely related to mean wind speed and is a relatively long-term response parameter, being influenced mainly by cumulative wind effects that occur 30 hours or longer prior to observation; wind speed at the time of observation has no significant influence on sediment grain size. The temporal trends of both turbidity nd sediment grain size indicate that they are response parameters that reflect the water-column-residence time of muddy bayfloor sediments episodically resuspended by wind-generated wave activity.