Occurrence of landslides and correlated mass removal processes in the Naranjo river microwatershed, Cachí, Paraíso, Costa Rica

Abstract

The research addresses the occurrence of landslides and correlated mass removal processes, whose territorial expression of risk occurs in the Naranjo River micro-basin. For this, field work was carried out to recognize and document the situations associated with the genesis of mass removal processes, population distribution, distribution of agricultural activities in relation to the presence of forest and hydrogeomorphology. Soil samples were collected, processed and characterized in the laboratory. Cartography was prepared that reliably represents the topography and the landslides present. Flights were carried out with unmanned aerial vehicles, from whose images orthophotos were made for a better understanding of the distribution of the population in the middle and upper micro-basin. As part of the results, it is confirmed that the micro-basin, due to its hydrological morphometry, constitutes a fluvial system with torrential behavior, favored by dissected irregular relief slopes and by numerous ravines born in them, which flow abruptly following tectonic fracture lines, causing torrential overflows and chaotic deposits of materials that put the infrastructure and the people who inhabit it at risk. It is expected that this hydrogeomorphological study contributes to the understanding of the hydrogeomorphological behavior of the micro-basin in pursuit of prospective disaster risk management, as well as carrying out similar studies in the rest of the micro-basins that make up the Orosi-Ujarrás valley, since they are of similar size, shape and relief with a common rainfall regime.