Mass Movement Hazard in a Changing Climate:Spatial and Temporal Analysis of Hydrological Triggering at the Rest and Be Thankful Pass, Scotland
MetadataShow full item record
The Rest and be Thankful pass is one of the most active sites of the UK considering mass movement. The pass has experienced frequent closure in the past years and large investments are made to secure accessibility. Alterations of the hydrological cycle through climate change will have strong consequences on the frequency, severity and nature of mass movement. Naturally, this has implications for adaptation and mitigation measures to cope with future trends and the corresponding costs. To understand future hazard, the main spatial and temporal implications for mass movement through climate change are addressed. A hydrological threshold, based on the daily precipitation and antecedent precipitation index, is derived from precipitation data of historical mass movement events. This threshold is applied to hydrological forecasts from the United Kingdom Climate Projections to determine future mass movement frequency. Additionally, it is addressed whether daily or antecedent precipitation is determent in various hydrological forecasts. Subsequently, a selection of precipitation realizations is simulated in the CLiDE environmental modelling platform, providing insight in the dominant source areas and the effects of antecedent precipitation regimes on source areas and runout paths of precipitation induced mass movement. In conclusion, 61.3 mm of daily precipitation will likely facilitate mass movement and every mm accounted for in the antecedent precipitation index reduces this threshold with 0.1527 mm when the antecedent precipitation index is based on 8 days. Although an increase of days accounted for in the antecedent precipitation index positively influenced the correlation between displaced mass and antecedent precipitation, the resulting thresholds do not agree with values applied in other studies (Ballantyne, 2004; Pennington et al., 2014). Furthermore, mass movement frequency declines under most hydrological. Nonetheless, severity likely increases as mass movement in dryer scenarios are largely driven by intense daily precipitation, whereas wetter scenarios experience extension of source areas and an increase in material entrainment due to persisting wetting. Additionally, the simulations show that the main source areas, situated between 300 and 500 metres altitude, extend upslope when antecedent precipitation regime has a late peak.