Abstract
This study deals with coastal process characteristics in Denmark, and targets at a morphodynamic parameterization with specific focus on the low-wave energetic, micro-tidal inner Danish seas. Historical shoreline change rates were quantified in a countrywide GIS-based study based on topographic maps embracing the past century. The computed shoreline-change rates were connected with a simple onshore and offshore coastal slope classification, and the observed coastal processes were parameterized by means of the directional distribution of incident wave-energy fluxes in local 5-years hindcast wave climates.
The countrywide overview of historical shoreline changes showed that ongoing shoreline straightening with a high alongshore variability of accretion and erosion was a dominant process especially in the sheltered parts of the inner Danish seas. Directional wave-climate parameters were thus introduced in a case study of two micro-tidal coastal embayments with depositional coastal landforms attached to glacial bluffs, whose low-energetic wave climates mainly differed in the number of dominant wave directions. In a next step, the directional wave parameters and coastal slope classification were applied at seven locations representing the variety of Danish coastal environments. In alongshore-flux dominated incident wave climates, two cases were distinguished: (1) incident bi-directional wave climates with converging alongshore fluxes, where accreting coasts prevailed, and (2) alongshore directed fluxes with a pronounced net-directionality, where erosive shores prevailed. The latter situation was connected with uni-directional deep-water wave climates as well as with refracted bi-directional deep-water wave climates. Varying shoreline-change trends occurred in cross-shore flux dominated incident wave climates, where mainly the offshore slopes discriminated erosive sites (steep slopes) from accretional sites (gentle slopes).
The coupling of historical shoreline-change trends with morphological coastal types identified through coastal slopes helped locate sediment sources and sinks, and the directional distribution of wave energy fluxes can verify sediment transport paths. However, the antecedent geomorphology had to be considered in establishing source-to-sink relationships in (para-)glacial coastal landscapes.
The countrywide overview of historical shoreline changes showed that ongoing shoreline straightening with a high alongshore variability of accretion and erosion was a dominant process especially in the sheltered parts of the inner Danish seas. Directional wave-climate parameters were thus introduced in a case study of two micro-tidal coastal embayments with depositional coastal landforms attached to glacial bluffs, whose low-energetic wave climates mainly differed in the number of dominant wave directions. In a next step, the directional wave parameters and coastal slope classification were applied at seven locations representing the variety of Danish coastal environments. In alongshore-flux dominated incident wave climates, two cases were distinguished: (1) incident bi-directional wave climates with converging alongshore fluxes, where accreting coasts prevailed, and (2) alongshore directed fluxes with a pronounced net-directionality, where erosive shores prevailed. The latter situation was connected with uni-directional deep-water wave climates as well as with refracted bi-directional deep-water wave climates. Varying shoreline-change trends occurred in cross-shore flux dominated incident wave climates, where mainly the offshore slopes discriminated erosive sites (steep slopes) from accretional sites (gentle slopes).
The coupling of historical shoreline-change trends with morphological coastal types identified through coastal slopes helped locate sediment sources and sinks, and the directional distribution of wave energy fluxes can verify sediment transport paths. However, the antecedent geomorphology had to be considered in establishing source-to-sink relationships in (para-)glacial coastal landscapes.
| Original language | English |
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| Publisher | Department of Geosciences and Natural Resource Management, Faculty of Science, University of Copenhagen |
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| Number of pages | 131 |
| Publication status | Published - 2013 |