Análisis de la relación entre la sequía hidrológica, los factores climáticos a gran escala y cobertura vegetal, en las cuencas de los ríos Machángara y Tomebamba

Abstract

Changes in global climatic patterns modify the regional climate; which leads to an increase in the frequency of extreme hydrological events, such as droughts. The Andean basins of the Machángara and Tomebamba rivers provide essential ecosystem services for the southern region of Ecuador, and are also prone to alterations in their hydrology due to the influence of macroclimatic factors. The aim of this study was to analyze the relationships among the hydrological and agricultural drought of the mentioned basins with climate indices of the Pacific and Atlantic oceans. The standardized flow index (SSI) and the vegetation condition index (VCI) were used to characterize hydrological drought events and the agricultural drought respectively. Two correlation methods were estimated. Cross-correlation between SSI & VCI, and wavelet coherence between climate indices and SSI-VCI. The results suggest that (1) there is no obvious association between the two types of drought. (2) The Pacific indices associated with the ENSO influence the VCI and SSI. (3) The Niño 4 and TNI indices are better linked to the SSI of the Machángara basin, and MEI, ONI and SOI, with the SSI of the Tomebamba basin. (4) The Atlantic TSA index has a remarkable effect on the hydrological and agricultural droughts of the Tomebamba river basin. The results obtained provide a basis for future studies of hydrological variability in the Andean basins, in order to minimize uncertainty and vulnerability to drought risk.