Historical flood risk analysis in island tourist enclaves: The Canary Islands (Spain)

Abstract

The Canary islands welcomed more tourist visitors in 2018, 13.7 million in total, than all but two of spain’s seventeen autonomous Communities. The importance of this industry in the islands is such that it accounts for 35% of the region’s gdp and around 40% of employment. in this context, assessments of all the aspects that might have a negative impact on the tourist industry offer are of fundamental importance. This is especially true of threats of a natural origin which can entail severe economic losses and the deterioration of the image held of the tourist destination. one of the most important of these threats is that of flooding, especially because of the damage that can be caused.The aim and focus of this work is to analyse the risk of flooding from various perspectives. in addition, a calculation is made of flood precipitation thresholds which are then used to determine the likelihood of their occurrence. The study area chosen for this work, the tourist resorts of puerto rico and amadores in the southwest of gran Canaria island, serves as a model of the characteristics of the growth of urban tourist development in the Canary islands from the 1960s to the present day. The results of the study can therefore be extrapolated to other similar tourist enclaves in the islands.The method that is followed comprises the identification of flooded areas and the frequency of recurrence using different information sources: maps published by public bodies using hydrologic/hydraulic models, information obtained from local press reports, and the databases of the general management of safety and emergencies department of the Canary government which contain details of emergency calls (112) related to flood incidents. The flood precipitation thresholds, above which flooding problems tend to be generated, are determined by analysing the available meteorological data series for the study area.The results show, firstly, significant differences between areas that would be expected to suffer flooding according to the hydrologic/hydraulic models and those which have actually flooded since the existence of references in the historical sources. secondly, it is found that precipitations considerably lower than those expected in a 5-year return period cause flooding. This is due to multiple deficiencies in the rainwater drainage networks of the studied areas which, in most cases, are the same as the wastewater networks. an additional factor has been the tourism-influenced need to occupy the maximum amount of available space possible, resulting in incursions into hydraulic public domain areas through the construction of water drainage channels which are unable to drain the runoff waters and the materials (abiotic, biotic and anthropic) that are swept along by them. in conclusion, this is a problem caused by inadequate territorial planning.