Estuarine Wetland Assessment
A large estuarine wetland, resultant of post-earthquake subsidence in 1960, underwent dramatic sedimentary, floral and faunal changes. A large multi-phased investigation of the dynamics of the wetland is being conducted to assess the disappearance of submerged aquatic vegetation and sedimentation in the 40km long estuary.
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The causes and environmental consequences of these changes are being evaluated using fieldwork and 3D hydrodynamic and sediment transport modeling. The investigations will determine the cause of the disappearance of the aquatic plant Egeria Densa from the region.
- Assessment of estuary hydrodynamics
- Comprehensive study of sedimentation and contamination history
- Sediment core analyses examined heavy metals, microscopic fossils and radionuclide dating
- Hydrodynamic model calibration was problematic given lack of available historic data.
- Establish accurate modeling parameters for a large wetland covered with trees and dense vegetation.
- Very complex environmental history due to significant changes to the estuary in a short number of years.
- Comprehensive field studies including topographic and hydrographic surveys, and extensive marine instrumentation were completed.
- Site specific non-linear spatial roughness parameters that varied with depth were developed.
- An extensive data analysis plan was developed including geotechnical tests, organics, Pb210 and Cs137 dating, stable isotopes analysis, metals, diatoms, water quality, thecamebans, mass spectrometry and erodibility.