Revisiting hydraulic hysteresis based on long‐term monitoring of hydraulic states in lysimeters

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• 作者：M. Hannes ; U. Wollschläger ; T. Wöhling ; H.‐J. Vogel
• 刊名：Water Resources Research
• 出版年：2016
• 出版时间：May 2016
• 年：2016
• 卷：52
• 期：5
• 页码：3847-3865
• 全文大小：7.7MB
• ISSN：1944-7973

文摘

Hysteretic processes have been recognized for decades as an important characteristic of soil hydraulic behavior. Several studies confirmed that wetting and drying periods cannot be described by a simple functional relationship, and that some nonequilibrium of the water retention characteristics has to be taken into account. A large number of models describing the hysteresis of the soil water retention characteristic were successfully tested on soil cores under controlled laboratory conditions. However, its relevance under field conditions under natural forcings has rarely been investigated. In practice, the modeling of field soils usually neglects the hysteretic nature of soil hydraulic properties. In this study, long-term observations of water content and matric potential in lysimeters of the lysimeter network TERENO-SoilCan are presented, clearly demonstrating the hysteretic behavior of field soils. We propose a classification into three categories related to different time scales. Based on synthetic and long-term monitoring data, three different models of hysteresis were applied to data sets showing different degrees of hysteresis. We found no single model to be superior to the others. The model ranking depended on the degree of hysteresis. All models were able to reflect the general structure of hysteresis in most cases but failed to reproduce the detailed trajectories of state variables especially under highly transient conditions. As an important result we found that the temporal dynamics of wetting and drying significantly affects these trajectories which should be accounted for in future model concepts.