NEW SEDIMENTATION, RESUSPENSION, AND BURIAL

A model is derived for the probability of burial of a sediment particle as a function of time after initial deposition, in an environment where bottom sediment resuspension exceeds the amount of new sediment deposited in the interval between resuspension episodes. Under steady state conditions, the probability of burial is predicted to exponentially approach 1.0 over time. The characteristic burial time scale T(b) is a simple function of the ratio of resuspension to sedimentation N and the time between resuspension episodes T(r). T(b) has a secondary dependence on the fraction of T(r) during which bottom sediments are in suspension. but this dependence becomes negligible for large N. Allowing for erosion of previously buried sediments under nonsteady state conditions causes the probability of burial to vary about the exponential curve. Moderate departures from steady state do not seriously affect the validity of the results. but large departures from steady state cause large fluctuations in probability of burial and some departure from the exponential trend. Nevertheless, T(b) and the exponential burial probability model that it represents should be useful indicators under most conditions. Example calculations of T(b) are carried out with resuspension and sedimentation data from northern Chesapeake Bay. These estimates of T(b) range between a minimum of 7 d in the midbay channel in summer to a maximum of 30 d in the turbidity maximum channel.