Erosion Risk Assessment of Active Coastal Cliffs in Temperate

The potentially negative consequences resulting from cliff recession are a matter of serious concern in many coastal areas worldwide. The assessment of these kind of processes has traditionally been performed by calculating average cliff recession rates and projecting them into the future, without taking into consideration the diverse factors affecting cliff dynamics and stability. In this work a new, practical method is presented to evaluate cliff erosion risk on temperate environments, by analysing the main factors responsible for both the physical and the socioeconomic aspects of erosion, representing cliff loss potential and damage potential respectively. For this purpose an integration of 11 physical variables (such as cliff lithology, beach characteristics or rainfall regime) and 6 socioeconomic variables (such as land use type or population density) is proposed. These variables are weighted and combined into a Hazard Index and an Impact Index, which in turn are merged into a composite Risk Index, where the resulting values are normalized and expressed as a percentage of the maximum theoretical risk. The method is tested and validated by using data about cliff retreat rates and mass movement processes in the coast of Cádiz province (SW Spain). The proposed approach allows the zoning of coastal cliffs according to the risk, hazard and/or impact levels, including the recognition of critical areas where specific intervention strategies should be adopted. It is believed that the method presented in this work is practical and at the same time scientifically valid, without requiring extensive and detailed surveys of the area where it is to be applied. This way, it constitutes an easy to use, valuable tool for decision-making regarding land use planning and management strategies in active coastal cliffs. EROSION RISK ASSESSMENT OF ACTIVE COASTAL CLIFFS IN TEMPERATE 1 ENVIRONMENTS 2 3 Del Río, Laura (*) and Gracia, F. Javier 4 5 Earth Sciences Department, CASEM, University of Cádiz. Av. República Saharaui s/n 6 11510 Puerto Real, Cádiz, Spain. Tel. +34956016276. Fax +34956016195. E-mail 7 [email protected] 8 9 (*) Corresponding author 10 11 12 Abstract 13 14 The potentially negative consequences resulting from cliff recession are a matter of serious 15 concern in many coastal areas worldwide. The assessment of such processes has 16 traditionally been performed by calculating average cliff recession rates and projecting 17 them into the future, without taking into consideration the diverse factors affecting cliff 18 dynamics and stability. In this work a new, practical method is presented to evaluate cliff 19 erosion risk in temperate environments, by analysing the main factors responsible for both 20 the physical and the socioeconomic aspects of erosion, representing cliff loss potential and 21 damage potential, respectively. For this purpose an integration of 11 physical variables 22 (such as cliff lithology, beach characteristics or rainfall regime) and 6 socioeconomic 23 variables (such as land use type or population density) is proposed. These variables are 24 weighted and combined into a Hazard Index and an Impact Index, which in turn are merged 25 Manuscript Click here to view linked References