The diurnal course of soil moisture as measured by various dielectric sensors: Effects of soil temperature and the implications for evaporation estimates

Verhoef, Anne; Fernández‐Gálvez, J.; Díaz-Espejo, Antonio; Main, B. E.; El-Bishti, M.

doi:10.1016/j.jhydrol.2005.07.039

Cited by 59 publications

(45 citation statements)

References 11 publications

(18 reference statements)

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“…Figures 13 and 14 corroborate the results found by K01. However, we cannot rule out that a temperature effect on the TDR sensors, employed by K01 to calculate adsorption, exaggerated the values of adsorption (see Verhoef et al 2006), despite the fact that K01 attempted to filter out this spurious oscillation. With the help of these figures we can also explain why K01 report that vapor adsorption decreases with increasing minimum values of h a (and hence increasing values of e a ).…”

Section: ϫ3mentioning

confidence: 96%

“…The soil state variable T 0 can be monitored relatively easily by currently available methods (e.g., infrared thermometry). However, it is less straightforward to obtain reliable values of 0 : apart from the fact that the sensors are too large to sample a very thin layer of soil, there is the added problem that at low water contents many capacitance-based sensors are strongly influenced by temperature (see Verhoef et al 2006). Alternatively, a detailed soil water and heat transfer model (e.g., Milly 1984), coupled to Eq.…”

Section: ͑5͒mentioning

confidence: 99%

“…Surface temperature, T 0 , (i.e., T s at depth, z, ϭ 0 m), for each lysimeter, was derived from a harmonic analysis (12 harmonics) performed on values of T s measured at 0.02-m depth. Then T 0 was calculated using these harmonic constants, knowledge of the distance between the installation depth of the thermistor and the surface (i.e., 0.02 m), and an estimate of the thermal diffusivity obtained with the Arctangent equation (see Verhoef 2004) which employed measurements of T s at 0.02-and 0.05-m depth.…”

Section: A Experimental Setupmentioning

confidence: 99%

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Adsorption of Water Vapor by Bare Soil in an Olive Grove in Southern Spain

Verhoef

Díaz-Espejo

Knight

et al. 2006

Journal of Hydrometeorology

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Data for water vapor adsorption and evaporation are presented for a bare soil (sandy loam, clay content 15%) in a southern Spanish olive grove. Water losses and gains were measured using eight high-precision minilysimeters, placed around an olive tree, which had been irrigated until the soil reached field capacity (ϳ0.22 m 3 m Ϫ3). They were subsequently left to dry for 10 days. A pair of lysimeters was situated at each of the main points of the compass (N, E, S, W), at a distance of 1 m (the inner set of lysimeters; ILS) and 2 m (the outer set of lysimeters; OLS), respectively, from the tree trunk.Distinct periods of moisture loss (evaporation) and moisture gain (vapor adsorption) could be distinguished for each day. Vapor adsorption often started just after noon and generally lasted until the (early) evening. Values of up to 0.7 mm of adsorbed water per day were measured. Adsorption was generally largest for the OLS (up to 100% more on a daily basis), and increased during the dry down. This was mainly the result of lower OLS surface soil moisture contents (period-average absolute difference ϳ0.005 m 3 m Ϫ3), as illustrated using various analyses employing a set of micrometeorological equations describing the exchange of water vapor between bare soil and the atmosphere. These analyses also showed that the amount of water vapor adsorbed by soils is very sensitive to changes in atmospheric forcing and surface variables. The use of empirical equations to estimate vapor adsorption is therefore not recommended.

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Section: ϫ3mentioning

confidence: 96%

Section: ͑5͒mentioning

confidence: 99%

Section: A Experimental Setupmentioning

confidence: 99%

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Adsorption of Water Vapor by Bare Soil in an Olive Grove in Southern Spain

Verhoef

Díaz-Espejo

Knight

et al. 2006

Journal of Hydrometeorology

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“…That confirms the validity of the sensor on one hand and that of the experimental procedure applied on the other hand. Actually, the performance of the ThetaProbe sensors in field conditions was confirmed in various works (Lukangu et al, 1999;Robinson et al, 1999;Verhoef et al, 2006;Smethurst et al, 2006;Zhan et al, 2007). The results obtained in this study show that the compaction procedure used allowed the sensors to be installed with negligible effect on soil density.…”

Section: Discussionmentioning

confidence: 81%

Development of a Large-Scale Infiltration Tank for Determination of the Hydraulic Properties of Expansive Clays

Tang

Cui

et al. 2009

Geotechnical Testing Journal

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A large-scale infiltration tank was developed to study the water transfer in compacted expansive clay. Volumetric water content sensors were buried in a soil column for water content monitoring during infiltration. In addition to water content, soil suction and temperature at various locations and the heave at the soil surface were also monitored. Emphasis was put in minimizing the effect of sensors installation on water transfer and soil deformation. The results obtained for 338 days of infiltration were presented in terms of changes in suction, volumetric water content, temperature, and the soil heave. Based on the recorded data, the performance and limitation of different suction and volumetric water content sensors and the adopted test procedure were analyzed. The recorded data on soil suction and volumetric water content were finally analyzed for determining the unsaturated hydraulic properties of soil, such as the water retention curve and the unsaturated hydraulic conductivity. Note also that the results constitute useful data for further physical analysis or numerical models’ calibration.

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“…Potential hydrological causes are the presence of dew and adsorption of water vapour by the soil, which cause an increase in soil moisture content during the night and morning (Agam and Berliner, 2006;Kosmas et al, 1998 Kizito et al, 2008;Rosenbaum et al, 2011;Verhoef et al, 2006). Figure 12 shows the largest soil-moisture-totemperature sensitivities measured at 5 cm depth, between 08:00 CET at day 1 and 08:00 CET at day 2, under the conditions of no precipitation on the day itself and the preceding 2 days, a maximum temperature difference between start and end time of 1.0 • C, and a maximum soil moisture difference between start and end time of 0.005 m 3 m −3 .…”

Section: Effect Of Temperaturementioning

confidence: 99%

The Raam regional soil moisture monitoring network in the Netherlands

Benninga

Carranza

Pezij

et al. 2018

Earth Syst. Sci. Data

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Abstract.We have established a soil moisture profile monitoring network in the Raam region in the Netherlands. This region faces water shortages during summers and excess of water during winters and after extreme precipitation events. Water management can benefit from reliable information on the soil water availability and water storing capacity in the unsaturated zone. In situ measurements provide a direct source of information on which water managers can base their decisions. Moreover, these measurements are commonly used as a reference for the calibration and validation of soil moisture content products derived from earth observations or obtained by model simulations. Distributed over the Raam region, we have equipped 14 agricultural fields and 1 natural grass field with soil moisture and soil temperature monitoring instrumentation, consisting of Decagon 5TM sensors installed at depths of 5, 10, 20, 40 and 80 cm. In total, 12 stations are located within the Raam catchment (catchment area of 223 km 2 ), and 5 of these stations are located within the closed sub-catchment Hooge Raam (catchment area of 41 km 2 ). Soil-specific calibration functions that have been developed for the 5TM sensors under laboratory conditions lead to an accuracy of 0.02 m 3 m −3 . The first set of measurements has been retrieved for the period 5 April 2016-4 April 2017. In this paper, we describe the Raam monitoring network and instrumentation, the soil-specific calibration of the sensors, the first year of measurements, and additional measurements (soil temperature, phreatic groundwater levels and meteorological data) and information (elevation, soil physical characteristics, land cover and a geohydrological model) available for performing scientific research. The data are available at https://doi.org/10.4121/uuid:dc364e97-d44a-403f-82a7-121902deeb56.

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The diurnal course of soil moisture as measured by various dielectric sensors: Effects of soil temperature and the implications for evaporation estimates

Cited by 59 publications

References 11 publications

Adsorption of Water Vapor by Bare Soil in an Olive Grove in Southern Spain

Adsorption of Water Vapor by Bare Soil in an Olive Grove in Southern Spain

Development of a Large-Scale Infiltration Tank for Determination of the Hydraulic Properties of Expansive Clays

The Raam regional soil moisture monitoring network in the Netherlands

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