Interacciones de la humedad del suelo durante eventos de lluvia en una ladera de Páramo andino

Abstract

Soil and vegetation cover play a critical role in Andean Páramo water supply system, providing runoff primarily by shallow subsurface flow. Understanding the dynamics of soil moisture response to meteorological conditions is essential for water resource planning under future land use because of anthropogenic influences (e.g. grazing for cattle, agriculture). Hence, this study focuses on the evaluation of maximum soil moisture response (Δθmax) during rainfall events, to identify the main factors and thresholds controlling its dynamics during dry and wet conditions. For this purpose, a hillslope transect under tussock grass (pristine Páramo land cover) was monitored. To determine the factors controlling Δθmax, a nonparametric spearman correlation coefficient test was used. We found that the factors controlling Δθmax were the precipitated volume, intensity, antecedent moisture conditions, antecedent weather conditions of 5 and 15 days and the influence of the Δθmax of the soil layer located above the analyzed location. The last factor revealed a predominance of vertical flow during the dry moisture state. However, at the middle and bottom locations, Δθmax were mainly influenced by the upper and middle zones respectively, revealing influence of the lateral subsurface flow during the intermediate and wet moisture states. Moreover, the threshold analysis shows a response of increase or decrease as function of the moisture state, the topographic location and soil layer depth. The study demonstrates that under pristine vegetation cover, precipitation features, antecedent moisture and weather conditions have a strong influence on the soil moisture status and enable subsequent hillslope connectivity and functioning.