Hydric erosion in touristic beaches influenced by extreme rainfall events: case contribution of the pluvial drainage of the Ancon Hotel, Cuba

In some areas of the world, due to climate change, some natural hazards have expected return periods shorter than those considered to build single infrastructures long decades ago. The delays in adopting corrective actions join this issue, increasing the number of disrupting events triggered by natural hazards. Specifically, the tourism and entertainment industry disruptions induced by natural events may cause severe environmental, economic, and service functionality losses. In Cuba, 89 % of the beaches show signs of erosion; therefore, this problem represents a national priority established in the Cuban State Plan to Confront Climate Change. This plan sets the identification of existing vulnerability and the undertaking of actions to reduce it, as well as the recovery of beaches, prioritizing those for tourist use. The goal was to evaluate the contribution of one hotel's storm drainage system to the hydric erosion in the hotel's beach sector and its mitigation. The Ancon Hotel, located in Trinidad, Cuba, was used as a study case. The hydrologic calculations of the design rainstorm used the isoyetic map of maximum daily rainfall for 1 % probability and the calculation nomogram for different probabilities and time duration in the Republic of Cuba. Two scenarios were performed: Scenario 1: A 20 % probability of rainfall with a duration time of 10 minutes, a rain intensity of 1.83 mm/min was taken. Scenario 2: A 5 % probability of rainfall with a duration time of 5 minutes, established according to the degree of protection to be provided to the installation, considering the category of the work and the ecological damage it may cause, a rain intensity of 3.1 mm/min was taken. It was shown that erosion is predominantly of hydric origin, with gully-type erosion manifestations evaluated as critical and intense, limiting the tourist use of the beach. The rainfall erosivity, enhanced by technical and organizational deficiencies in the hotel's storm drainage system, the erodability of soil, and the presence of built elements, lead to increased flows towards the beach berm and influence changes in flow velocities. A corrective measures plan was designed to mitigate erosion based on minimizing the stormwater runoff to the beach and good beach management practices. The radical solutions contemplated eliminating the built environment and evacuating rainwater from the roofs for reuse to irrigate green areas. Implementing the proposed measures by beach operators enabled the Ancon Hotel's requalification, reducing the risk caused by natural events, building resilience against natural events, and contributing to the sustainability of tourism in Cuba.