Affiliation:
1. Institute of Soil and Water Conservation Northwest A & F University Yangling China
2. Institute of Soil and Water Conservation Chinese Academy of Sciences and Ministry of Water Resources Yangling China
3. Faculty of Geo‐information and Earth Observation (ITC) University of Twente Enschede The Netherlands
4. The New Zealand Institute for Plant and Food Research Limited Christchurch New Zealand
5. Research Institute for Geo‐Hydrological Protection National Research Council Perugia Italy
Abstract
AbstractThe extent and mechanisms by which precipitation extremes affect hydrological processes in the critical zone (CZ) of loess possessing a thick unsaturated zone remains poorly understood. To this end, we here employed a coupled liquid‒vapor‒heat‒airflow STEMMUS (simultaneous transfer of energy, mass, and momentum in unsaturated soil) model to investigate the impact of extreme precipitation, at both event and annual scales, on CZ hydrological processes within a semiarid loess site vegetated by apple trees on China's Loess Plateau. At the event scale, the vapor flux was two orders of magnitude lower than the liquid water flux. However, the thermal vapor flux penetrated to depths of 200 cm, whereas the isothermal liquid water flux only infiltrated to 100 cm during the study period, implying that thermal‐gradient‐driven vapor transfer is an important mechanism for deep‐layer recharge (DLR). At the annual scale, the DLR below 200 cm during extremely wet years was 6.5 times larger than that during extremely dry years. In contrast, extreme changes in climate had only limited impacts on evapotranspiration; the difference between extremely wet and extremely dry years averaged only 35 mm, much less than the difference in precipitation, which averaged 310 mm. However, the extremely dry years showed a higher ratio (0.58) between transpiration and evapotranspiration than did the extremely wet years (0.51). The findings reported here improve our understanding of CZ hydrological processes related to precipitation extremes in semiarid loess regions.
Funder
National Natural Science Foundation of China
Publisher
American Geophysical Union (AGU)
Subject
Water Science and Technology
Cited by
12 articles.
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