Assessing the impact of climate change to landslides using public data, a case study from Vejle, Denmark

Abstract. The possibility of increased landslide activity as a result of climate change has often been suggested, but few studies quantify this connection. Here, we present and utilize a workflow for using publicly available data to assess the impact of future changes in landslide dynamic conditioning factors on landslide movement. In our case of three slow-moving coastal landslides at Vejle, Denmark the examined dynamic conditioning factor is modelled water table depth (WTD). The DK-HIP-model simulates historic and future WTD and the data shows a clear correlation with landslide movement as recorded by InSAR time series, for the period 2015 to 2019. Movement occurs especially during wet winter seasons when normalized WTD exceeds +0.5 m. In dry winters no, or very little, seasonal landslide movement is observed. The DK-HIP-model predicts an increase of up to 0.7 m in WTD at the field site by 2100 AD under the RCP8.5 scenario (95 % confidence). With such an increase, the WTD will exceed levels above what this area has experienced in recent decades. This will result in increased landslide activity and acceleration of movement. In a previous episode of increased landslide activity in early 1980’ies (1981 was the then wettest year on record), one of the examined landslides accelerated, causing damage to infrastructure and buildings. Our study highlights the potential of utilizing high-quality, publicly available data to address complex scientific questions. The quality and quantity of such data is ever increasing and so is the potential of such approach.