Population and Landslide Risk Evolution in Long Time Series: Case Study of the Valencian Community (1920–2021)

Assessing the size and situation of the population exposed to natural hazards is a fundamental step in addressing natural hazard management and emergency planning. Although much progress has been made in recent years in population geolocation by competent public bodies, gathering historical data beyond the present century to learn about the sequential evolution the affected population has experienced remains a difficult task. The recent publication of a historical population grid with adequate resolution allows progress to be made in resolving this problem. This paper is based on these data together with a map of landslide susceptibility in the study area and on the abundant resources provided by the Spanish Cadastre on dates of construction, surface area, and location of built plots. The size of the residential area built in the risk zone and its affected population was calculated since the early 1900s and with a decennial sequence. The risk to the population has been found to be stable or decreasing slightly over the entire historical series in the study area. However, the intensive tourism in some coastal municipalities in the north of Alicante has led to the construction of holiday homes in unsuitable locations in mountainous areas and with it an appreciable increase in risk.