Thresholds in the response of soil moisture to meteorological conditions on a high Andean hillslope | [Umbrales en la respuesta de humedad del suelo a condiciones meteorológicas en una ladera Altoandina]

Abstract

Soil and vegetation cover play a critical role in the hydrology of the Andean Páramo generating runoff primarily by shallow subsurface flow. Understanding the dynamics of soil moisture response under pristine vegetation cover during rainfall events is essential for water resource planning considering the increasing anthropogenic pressure. Hence, this study focuses on the evaluation of the factors and thresholds controlling maximum changes in soil moisture (Δθmax) during rainfall events and their dynamics during different wetness conditions (from dry to wet). To determine the factors controlling Δθmax, a nonparametric Spearman correlation coefficient test was applied. We found that the factors controlling Δθmax were the precipitated volume, intensity, moisture conditions just before the event and the 5- and 15-days antecedent weather conditions. The threshold analysis shows a response of increase or decrease as function of moisture state, topographic position and soil layer depth. This study demonstrates that under pristine Andean Páramo vegetation precipitation, antecedent moisture and weather conditions determine to a significant degree the soil moisture status affecting subsequently hillslope connectivity and hydrologic functioning.

Keywords

• soil moisture response
• rainfall event scale
• factors controlling soil moisture response
• rainfall thresholds
• Andean páramo hillslope