High geomorphic and climatic variability in Arctic coastlines makes evaluating future coastal erosion in a changing climate a challenge. Predictions must, among other things, incorporate modifications to sediment supply and accommodation space, changes in the permafrost regime, climate variability including rising air and sea temperatures, stronger winds, less sea ice, and increased precipitation. This thesis explores processes and climate variables associated with coastal development throughout the Holocene and within modern times. In so doing, it illustrates how research builds upon itself and can be extended into applied science sectors concerning coastal protection and mitigation strategies.
In response to the need for more detailed surface maps in coastal regions on Svalbard, a combination of geomorphological field observations, differential GPS measurements, and aerial image analysis were used to produce detailed Quaternary maps for two field sites in Central Spitsbergen, Skansbukta and Fredheim. These provide the basis for further study, as mapping in itself is not sufficient for future projections relevant to mitigation strategies and cultural heritage protection. One site of significant value to the cultural memories of Svalbard was chosen for further investigations. The development of Fredheim’s unconsolidated coast has been reviewed in relation to climatic changes during the Holocene, sediment supply and accommodation space, and geomorphic processes such as: beach aggradation, unconsolidated sediment coastal erosion, bedrock erosion, ice push and melt out, and longshore drift.
The relation between coastal processes and climatic variability are reviewed using relative and absolute chronology through spatial analysis and radiocarbon dating. Results from this study are compared to published data from other locations in Central Spitsbergen. Incorporation of rates and age restraints has produced a shoreline displacement curve providing relative time constraints on uplift and thereby understanding of climatic influences on coastal processes in the past. Present day coastal processes are used as a key to past shoreline development and when the past processes are seen from the context of the present, it is possible to outline possible future changes that may threaten the cultural heritage.
To further assess the modern processes and current state of the coastline at Fredheim, the new Digital Shoreline Analysis System tool (DSAS) was used to quantify coastal erosion rates. Three other sites with unconsolidated coastlines, showing variations in geomorphology, sedimentology, and exposure to environmental forces, are also reviewed to illustrate disparities in erosional response. Results reveal that even within a single site, such as the 290 m long coastal section at Fredheim, large variations in erosion rate occur. This implies that spatial differences are significant in coastal development and need to be assessed in combination with temporal variability for future assessments and cultural heritage mitigation. The spatial and temporal analysis of Holocene coastal development and modern erosion rates are applied to erosion protection within the field of engineering in the final chapter of this thesis. Having examined the mechanisms behind coastal erosion, in relation to sediment type and bedrock stability, it is suggested that a wooden barricade using posts drilled into the permafrost be built at Fredheim to protect the coast from further erosion. Such a barricade has previously been used on Svalbard and has shown to be extremely resistant to erosion and sea ice impacts and will also prevent sediments from washing away due to fluvial activity through relict channels.