Multi-Temporal Cliff Erosion Analysis Using Airborne Laser Scanning Surveys

Abstract

Rock cliffs are a significant component of world coastal zones. However, rocky coasts and factors contributing to their erosion have not received as much attention as soft cliffs. In this study, two rocky-cliff systems in the southern Baltic Sea were analyzed with Airborne Laser Scanners (ALS) to track changes in cliff morphology. The present contribution aimed to study the volumetric changes in cliff profiles, spatial distribution of erosion, and rate of cliff retreat corresponding to the cliff exposure and rock resistance of the Jasmund National Park chalk cliffs in Rugen, Germany. The study combined multi-temporal Light Detection and Ranging (LiDAR) data analyses, rock sampling, laboratory analyses of chemical and mechanical resistance, and along-shore wave power flux estimation. The spatial distribution of the active erosion areas appear to follow the cliff exposure variations; however, that trend is weaker for the sections of the coastline in which structural changes occurred. The rate of retreat for each cliff–beach profile, including the cliff crest, vertical cliff base, and cliff base with talus material, indicates that wave action is the dominant erosive force in areas in which the cliff was eroded quickly at equal rates along the cliff profile. However, the erosion proceeded with different rates in favor of cliff toe erosion. The effects of chemical and mechanical rock resistance are shown to be less prominent than the wave action owing to very small differences in the measured values, which proves the homogeneous structure of the cliff. The rock resistance did not follow the trends of cliff erosion revealed by volume changes during the period of analysis.

Bringing Bathymetry LiDAR to Coastal Zone Assessment: A Case Study in the Southern Baltic

“…The application of remote sensing techniques is useful to coastal research [36,[79][80][81], the development of satellite techniques enables their use in different types of coasts. Most studies have focussed on determining and measuring trends of change [3,5,[9][10][11][12][13][14][15][16]. This study aimed to evaluate the suitability of airborne bathymetry LiDAR in determining the factors causing coastal degradation, by combining topographic and bathymetric data.…”

“…The existing protection, in the form of a gabion structure and slope protection, have not proven to be successful in the long-term and they have not improved the stability of the cliff slopes. The studies conducted so far have not been sufficient in determining the factors threatening the shore [11][12][13]. The existing protection, in the form of a gabion structure and slope protection, have not proven to be successful in the long-term and they have not improved the stability of the cliff slopes.…”

“…The existing protection, in the form of a gabion structure and slope protection, have not proven to be successful in the long-term and they have not improved the stability of the cliff slopes. The studies conducted so far have not been sufficient in determining the factors threatening the shore [11][12][13].…”

“…Figure 9a,b show the results obtained from a bathymetric scanner recording at a depth of up to 1 Secchi disc, under conditions 3-4 and 4-5, respectively. All scanners can be used to determine the tendency of the shoreline to change, but this can also be determined by aerial, satellite or a laser scanner operating in the red band [11,13,65]. When analysing the results of Figure 9, a very important factor was noticed that should be taken into account when planning measurement fieldwork.…”

Cliff erosion monitoring dataset on selected sites of Polish coast

“…Coasts are extremely dynamic environments. To track cliff changes and identify the processes of its modifications, data must be collected frequently over consistent time intervals [ 1 , 2 ]. The data presented here cover a survey timeline from November 2016 to June 2018.…”