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The effects of large-scale human intervention on inlet dynamics are studied. In particular, the response of the largest of the Wadden Sea inlets (Texel Inlet) to the closure of a major part of its inner basin is re-analyzed. The re-analysis is based on datasets of bathymetry, discharges and water levels that have been obtained by intensive monitoring of both the inner basin and the ebb-tidal delta. Based on this re-analyisis and modern theoretical knowledge a conceptual model is postulated that describes the morphologic adjustment of tidal inlets due to large-scale human intervention. The kernel of this model is that the morphological adjustment towards a new overall equilibrium is split into two stages related to the existence of more than one temporal response scale.

Numerical and physical modeling studies were performed by the Coastal Inlets Research Program (CIRP) of the U.S. Army Corps of Engineers to investigate the spatial and temporal behavior of waves and wave-induced currents near jetties of an idealized coastal inlet. Hydrodynamics were examined in the vicinity of two extreme types of jetty structure: a highly absorbing jetty (resembling fairly porous rock rubble structure) and a fully reflective jetty (resembling a vertical sheet pile or caisson type breakwater). Laboratory experiments in a Froude scale of 1:50 were conducted with regular and irregular shore-normal (0°) and obliquely incident (20°) unidirectional waves. Current and wave measurements were made on the up-wave side and inside the inlet as well as in the bay, along a number of cross-shore and along-shore transects. Wave directions were measured by a remote-sensing video-camera system and Acoustic Doppler Velocimeters (ADV). Numerical modeling was performed with the Coastal Modeling System (CMS) consisting of a two-dimensional circulation model coupled to a spectral wave model. Calculated current and wave fields from CMS in the area around and between absorbing or reflected jetties were compared to measurements. The highly reflecting jetty created a circulation cell on the up-wave side of the inlet, whereas the absorbing jetty did not.

Chilaw inlet, with the affiliated lagoon, is located on the west coast of Sri Lanka about 120 km north of the capital Colombo. Each year during the summer monsoon, which lasts from May to September, the inlet closes due to a sand spit forming across the inlet. The morphological evolution at Chilaw inlet was studied during the summer monsoon in order to understand the physical mechanisms governing the process of closure and how to mathematically model it. A measurement campaign was performed from May to July, 2006, resulting in high-resolution topographic maps, from which the morphological changes at the inlet during the monsoon could be deduced. A mathematical model was developed based on the identified sediment pathways at the inlet using a reservoir-type model description to simulate the morphological elements including the spit and its growth across the inlet.