Estructura de la precipitación y su variabilidad espacio-temporal a lo largo de una gradiente altitudinal

Abstract

Rainfall is a phenomenon characterized by its high spatial-temporal variability. In mountain ranges, particularly in the Ecuadorian Andes, the variability in its distribution is extreme. In order to develop water resources, it is important to determine the real extension of the precipitation sub-regions in mountain basins with relation to the impact of the topography in its variability. The aim of this research was to improve the knowledge of the precipitation structure and its variability in an altitudinal gradient, to provide new insights about its continuity and dynamics at different altitudes and temporal scales.Data from six rain gauges were used during the period March 2014 - February 2015, being a particularly valuable network with no precedents, as it monitors the altitudinal range 2600 – 4000 m.a.s.l. along a 27 km transect, covering different ecosystems in a basin in the south of Ecuador.Also, specific methodology was applied according to the temporal scales of accumulation: annual, monthly, daily, events and hourly. A linear relationship between annual rainfall amount and elevation was not found, with the highest annual volume in the middle of the gradient. The altitudinal range 3060 – 3300 m.a.s.l. determines a break up in the continuity of the studied aspects of precipitation, with the temporal scale of analysis influencing this determination of the continuity.Aspects such as: regimes, seasonality, daily intensities and extreme values, are common for the rain gauges above 3300 m.a.s.l. with sharp differences from lower altitude locations.With a smaller accumulation scale, characteristics of dry spells, properties of events and intra-daily dynamics of rainfall, instead, are common below 2700 m.a.s.l., and above this altitude the characteristics are also similar among them.Both structure and variability of rainfall depend of the elevation, with significant differences between the inter-Andean valley and the páramo, with a less variable behavior in the latter.