Measurement and analysis of the yearly characteristics of deep-buried phreatic evaporation in a hyper-arid area

Li, Hongshou; Wang, Wanfu; Zhan, Hongbin; Qiu, Fei; Wu, Fasi; Zhang, Guobing

doi:10.1016/j.chnaes.2016.10.001

Cited by 7 publications

(34 citation statements)

References 16 publications

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“…The soil temperature changes are thought to be the basic cause of the air pressure pulsation (Li, ; Li et al, ). The temperature, RH, and absolute humidity (AH) were recorded every 10 min at soil depths of 10, 20, 30, and 40 cm by micromonitors HOBO‐U23‐001 (made in USA and accurate to ±0.18 °C between 0 and 50 °C and ±2.5% RH in the range 10% to 90%).…”

Section: Methodsmentioning

confidence: 99%

“…The results were used to analyze the variation of daily soil air pressure and the mechanism of pulse formation. Monitoring results at soil depths of 1.0, 2.0, 3.0, 4.0, and 5.0 m have also been used to analyze the mechanism of yearly soil air pressure pulsation (Li et al, ).…”

Section: Methodsmentioning

confidence: 99%

“…Soil moisture mainly consists of water of crystallization with very low hydraulic potential. The water content lies in the range 2.0–9.0% and fluctuates with daily temperature changes (Li et al, , , , ). The burial depth of the phreatic water is over 200 m. The water content of the deep soil is 1.0–1.5%.…”

Section: Research Areamentioning

confidence: 99%

“…Conversely, as temperature drops, the soil absorbs moisture and the humidity of the soil air drops (Li et al, ). Similarly, on a yearly timescale, there is conversion between combined water and water vapor in the yearly HTZ of 20–30 m (Li et al, ). It can be inferred that this transformation in the water phase will result in fluctuation of the water vapor concentration in the soil pores and further cause the soil vapor and air pressure to pulsate.…”

Section: Introductionmentioning

confidence: 99%

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The Characteristics and Mechanism of the Formation of Earth‐Air Pulsation in Extremely Arid Areas

Zhan

2018

JGR Atmospheres

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The term earth-air refers to the air inside the vadose zone. The observation of earth-air was called hou-qi, which was used to enact meter calendar in ancient China. Currently, however, as a detailed knowledge of hou-qi has been lost for a long time, it has been denounced as a pseudoscience, as earth-air is not scientifically and systematically monitored, and its characteristics and formation mechanism are unclear. We have attempted to scientifically monitor and measure earth-air pressure and reveal its formation mechanism. Results from a specially devised set of air pressure measurements show that the pressure exhibits daily and yearly pulses at different depths. The main cause of the pulsation is soil temperature variation, which results in the soil-combined water decomposing and air pressurization in warming, and water vapor recombining and air depressurization when cooling, leading to pulsation of the air pressure in the soil. Therefore, rather than a myth, hou-qi has great significance in the geosciences and studies of the ancient Chinese civilization. Plain Language SummaryThe air inside the soil is called earth-air. The observation of earth-air was called hou-qi in ancient China, which was used to enact meter calendar. However, as detailed knowledge of hou-qi has been lost, it was thought to be one of the most astonishing frauds in the history of Chinese science in 2,000 years. A specially devised set of air pressure measurements show that there really exists the earth-air pulsation. This study presented monitoring real-time data interactions of soil physical parameters that explained the mechanism of pulsations of the air pressure in the soil. Heat transfer in the hetero-thermo-zone during the conduction process makes the soil temperature change cyclically on a daily/yearly basis. This results in the soil-combined water decomposing and recombining, leading to the earth-air pulsation. The earth-air pulsation is a basic natural law. Therefore, hou-qi is not a pseudoscience. Earth-air, rather than a myth, has solid scientific foundation.In arid and semiarid regions, the soil does not usually contain liquid water, especially those that are in extremely arid areas. The moisture in soil is composed of waters in different forms, for example, adsorbed water, film water, and water of crystallization . It has been shown that the daily/yearly temperature in the zone of variable temperature or "hetero-thermo-zone (HTZ)" changes on a daily/yearly basis with the intensity of the solar radiation. As temperature increases, combined water decomposes and the humidity of the soil air increases. Conversely, as temperature drops, the soil absorbs moisture and the humidity of the soil air drops (Li et al., 2011). Similarly, on a yearly timescale, there is conversion between combined water and water vapor in the yearly HTZ of 20-30 m (Li et al., 2017). It can be inferred

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Research Areamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The Characteristics and Mechanism of the Formation of Earth‐Air Pulsation in Extremely Arid Areas

Zhan

2018

JGR Atmospheres

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“…However, these upward water fluxes are extremely low, thereby posing great challenges for accurate quantification. Reported rates from few studies that attempted to measure evaporation in such deserts are erratic, varying by up to 5 orders of magnitude, between 10 −2 and 10 2 mm per year (Li et al, , , ; Li & Wang, ). On the other hand, modeling these rates poses complexity challenges and is computationally demanding, as it involves processes of water flow in liquid and vapor phases over large temporal and spatial scales, in heterogeneous media.…”

Section: Introductionmentioning

confidence: 99%

Evaporation From Deep Aquifers in Arid Regions: Analytical Model for Combined Liquid and Vapor Water Fluxes

Kamai

Assouline

2018

Water Resources Research

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Evaporation is a significant part of the water cycle in hyper‐arid environments. The subsurface of these deserts is characterized by deep groundwater with negligible recharge, whereby water flows from the water table to the surface and evaporates. We propose an analytical model to predict the evaporation rate and the position of the evaporative front. The model accounts for water table depth, atmospheric conditions, and soil hydraulic properties. We consider steady state flow, with two distinct regions separated by an evaporative front, liquid‐phase flow from the water table to the front and vapor‐phase flow from the front toward the surface. The driving forces are pressure head gradients for Darcian liquid flow, and thermal and relative humidity gradients for Fickian diffusive vapor flow. Evaporation rates are predicted for different soil types. The impact of constitutive models applied for characterizing these soils, groundwater depth, and atmospheric conditions are evaluated. Evaporation increases as groundwater levels are shallower, and as atmospheric temperatures increase and/or relative humidity values decrease. Evaporation decreases exponentially with groundwater depth, approaching a constant value of about 0.02 mm per year under typical atmospheric conditions and water table depths below 500 m. The impact of soil type and other related uncertainties are important when groundwater is shallower than 300 m. The relative portion of the liquid phase region increases compared to that of the vapor one as evaporation rates increase. The actual size of the liquid phase flow region, however, reaches its maximum when the water flux approaches zero at hydrostatic conditions.

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Effect of earth–air breathing on evaporation of deeply buried phreatic water in extremely arid regions

Zhan

Wang

et al. 2021

Hydrological Processes

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In extremely arid regions, deeply buried phreatic water evaporates during the daytime from March to November in the northern hemisphere. It has been found that the earth-air undergoes 'autonomous breathing' and 'passive breathing', respectively caused by the changes of temperature and atmospheric pressure. In this paper, the effects of these breathing modes on phreatic evaporation (PhE) were investigated as well as the responsible mechanisms. Quantitative estimates suggest that the direct contribution from autonomous breathing is only 0.55 gÁm −2 Áyr −1 . Passive breathing pumps water vapour upwards from the deeply buried phreatic water table. Film water on the soil continuously migrates in pulsation from deep layers to the upper layer. Na 2 SO 4 in the shallow soil absorbs moisture from the earth-air at night and decomposes during the day, forming water vapour, which is critical to the occurrence of PhE. The diurnal PhE process can be elucidated in detail by the bimodal variation in the atmospheric pressure. PhE occurs mainly from 10:00 to 17:00 during daytime from March to November, which correlates with passive breathing of the earth-air.The amplitude of atmospheric fluctuation determines the amount of earth-air that outflows, while temperature determines the water vapour concentration. In calculation, PhE is equal to the net absolute humidity (AH) times the amount of earth-air.There is 1.55 mmÁyear −1 of PhE caused by daily peak!valley differences, and about 2.97 mmÁyear −1 in estimation caused by numerous atmospheric fluctuations smaller than 2.84 hPa. The results coincide with the actual amount of PhE monitored of 4.52 mmÁyear −1 . Therefore, the amount of PhE is proportional to the range and frequency of fluctuation in external atmospheric pressure, and is also positively related to soil temperature, salt content, water content, porosity, and vadose zone thickness.

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Measurement and analysis of the yearly characteristics of deep-buried phreatic evaporation in a hyper-arid area

Cited by 7 publications

References 16 publications

The Characteristics and Mechanism of the Formation of Earth‐Air Pulsation in Extremely Arid Areas

The Characteristics and Mechanism of the Formation of Earth‐Air Pulsation in Extremely Arid Areas

Evaporation From Deep Aquifers in Arid Regions: Analytical Model for Combined Liquid and Vapor Water Fluxes

Effect of earth–air breathing on evaporation of deeply buried phreatic water in extremely arid regions

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