Author(s): Jaime Gaona

Linked Author(s): Jaime Gaona

Keywords: Semi-arid environment; Drought; Radiation; Soil moisture; Upper catchment

Abstract: Many upper reaches of important catchments around the world locate in sub-humid to semi-arid environments. The water balance of these areas experiences remarkable variability. Beyond precipitation anomalies, water and energy variables such as relative humidity and radiation can have notable impact on these fluctuations, with consequences at hydrological, agricultural, and environmental level. This study aims to characterize the role of several secondary atmospheric variables such as relative humidity and radiation in the generation of dry anomalies in sub-humid to semi-arid environments. Lag analysis of the interactions between anomalies allows the interpretation of the interplay between energy- and water-related factors. The study case focus on the area of the Critical zone Observatory BUREAUX-Sierra de Atapuerca, located in the basin of the River Vena, a tributary of Duero River in North Spain, a basin comprising from humid to arid conditions in the hydrological division between upper Duero and Ebro River. Results highlight the notable role of secondary factors such as radiation in driving dry anomalies. Radiation shows significant long-lasting influence over water-related variables, particularly over rainfall, given the low contribution of heavy rains to the water balance of the region, especially in winter, the productive season for soil water recharge. Interactions are overly reciprocal showing a notable role of precedent surface soil moisture on the latter conditions of atmospheric variables. Deeper levels of soil moisture are less responsive to the quicks changes of atmospheric anomalies which indicates an important resilience of deep soils to dry anomalies, at least when not affected by radiation. These results suggest distinct evolution of the surface and deep levels of the land-atmosphere system, with implications to the water available for agriculture and hydrology.

DOI: https://doi.org/10.3850/IAHR-39WC2521711920221735

Year: 2022