Coastal Embayment Long-Term Erosion/Siltation Associated with P-A Relationships: A Case Study from Jiaozhou Bay, China

Abstract

The sedimentary environment of a large coastal embayment, Jiaozhou Bay, eastern China, in terms of erosion/siltation, has been assessed on the basis of seabed bathymetry and coastline data sets from sea charts (1936-2002) and Landsat-5 TM images (1986-2011). Nine types of sedimentary environment are identified according to the sedimentation rate. The results indicate that slow siltation was generally present from 1936 to 1963, with exceptions of some patchy, slightly eroding areas within the embayment. Transformation to a slow erosion pattern occurred in the main channels over the central embayment in 1963, and such a situation continued until 1982. Subsequently, since 1986, most of the coastlines extended toward the sea at a rate of 10(1)-10(2) m y(-1); this was mainly attributable to human activities, including reclamation over the NW tidal-flat and harbour construction along the east and south coastlines. Using the same data set, patterns of changes in tidal prism and deposition rate within the entrance channel were established. An equivalent friction coefficient (K) is proposed to evaluate the P-A relationship of the large tidal inlets in Jiaozhou Bay. The K value increases gradually over time, indicating a trend toward stable equilibrium in Jiaozhou Bay. This coefficient can be used to examine the status of morphological stability and equilibrium of coastal embayments.