The Experts below are selected from a list of 133626 Experts worldwide ranked by ideXlab platform
Jing Tan - One of the best experts on this subject based on the ideXlab platform.
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Watershed scale temporal stability of Soil Water Content
Geoderma, 2010Co-Authors: Mingan Shao, Fengpeng Han, Klaus Reichardt, Jing TanAbstract:article i nfo The recognition of temporally stable locations with respect to Soil Water Content is of importance for Soil Water management decisions, especially in sloping land of Watersheds. Neutron probe Soil Water Content (0 to 0.8 m), evaluated at 20 dates during a year in the Loess Plateau of China, in a 20 ha Watershed dominated by Ust-Sandiic Entisols and Aeolian sandy Soils, were used to define their temporal stability through two indices: the standard deviation of relative difference (SDRD) and the mean absolute bias error (MABE). Specific concerns were (a) the relationship of temporal stability with Soil depth, (b) the effects of Soil texture and land use on temporal stability, and (c) the spatial pattern of the temporal stability. Results showed that temporal stability of Soil Water Content at 0.2 m was significantly weaker than those at the Soil depths of 0.6 and 0.8 m. Soil texture can significantly (Pb0.05) affect the stability of Soil Water Content except for the existence of an insignificant difference between sandy loam and silt loam textures, while temporal stability of areas covered by bunge needlegrass land was not significantly different from those covered by korshinsk peashrub. Geostatistical analysis showed that the temporal stability was spatially variable in an organized way as inferred by the degree of spatial dependence index. With increasing Soil depth, the range of both temporal stability indices showed an increasing trend, being 65.8-120.5 m for SDRD and 148.8-214.1 m for MABE, respectively. This study provides a valuable support for Soil Water Content measurements for Soil Water management and hydrological applications on sloping land areas.
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Watershed scale temporal stability of Soil Water Content
Geoderma, 2010Co-Authors: Mingan Shao, Fengpeng Han, Klaus Reichardt, Jing TanAbstract:The recognition of temporally stable locations with respect to Soil Water Content is of importance for Soil Water management decisions, especially in sloping land of Watersheds. Neutron probe Soil Water Content (0 to 0.8 m), evaluated at 20 dates during a year in the Loess Plateau of China, in a 20 ha Watershed dominated by Ust-Sandiic Entisols and Aeolian sandy Soils, were used to define their temporal stability through two indices: the standard deviation of relative difference (SDRD) and the mean absolute bias error (MABE). Specific concerns were (a) the relationship of temporal stability with Soil depth, (b) the effects of Soil texture and land use on temporal stability, and (c) the spatial pattern of the temporal stability. Results showed that temporal stability of Soil Water Content at 0.2 m was significantly weaker than those at the Soil depths of 0.6 and 0.8 m. Soil texture can significantly (P
Mingan Shao - One of the best experts on this subject based on the ideXlab platform.
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Watershed scale temporal stability of Soil Water Content
Geoderma, 2010Co-Authors: Mingan Shao, Fengpeng Han, Klaus Reichardt, Jing TanAbstract:article i nfo The recognition of temporally stable locations with respect to Soil Water Content is of importance for Soil Water management decisions, especially in sloping land of Watersheds. Neutron probe Soil Water Content (0 to 0.8 m), evaluated at 20 dates during a year in the Loess Plateau of China, in a 20 ha Watershed dominated by Ust-Sandiic Entisols and Aeolian sandy Soils, were used to define their temporal stability through two indices: the standard deviation of relative difference (SDRD) and the mean absolute bias error (MABE). Specific concerns were (a) the relationship of temporal stability with Soil depth, (b) the effects of Soil texture and land use on temporal stability, and (c) the spatial pattern of the temporal stability. Results showed that temporal stability of Soil Water Content at 0.2 m was significantly weaker than those at the Soil depths of 0.6 and 0.8 m. Soil texture can significantly (Pb0.05) affect the stability of Soil Water Content except for the existence of an insignificant difference between sandy loam and silt loam textures, while temporal stability of areas covered by bunge needlegrass land was not significantly different from those covered by korshinsk peashrub. Geostatistical analysis showed that the temporal stability was spatially variable in an organized way as inferred by the degree of spatial dependence index. With increasing Soil depth, the range of both temporal stability indices showed an increasing trend, being 65.8-120.5 m for SDRD and 148.8-214.1 m for MABE, respectively. This study provides a valuable support for Soil Water Content measurements for Soil Water management and hydrological applications on sloping land areas.
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Watershed scale temporal stability of Soil Water Content
Geoderma, 2010Co-Authors: Mingan Shao, Fengpeng Han, Klaus Reichardt, Jing TanAbstract:The recognition of temporally stable locations with respect to Soil Water Content is of importance for Soil Water management decisions, especially in sloping land of Watersheds. Neutron probe Soil Water Content (0 to 0.8 m), evaluated at 20 dates during a year in the Loess Plateau of China, in a 20 ha Watershed dominated by Ust-Sandiic Entisols and Aeolian sandy Soils, were used to define their temporal stability through two indices: the standard deviation of relative difference (SDRD) and the mean absolute bias error (MABE). Specific concerns were (a) the relationship of temporal stability with Soil depth, (b) the effects of Soil texture and land use on temporal stability, and (c) the spatial pattern of the temporal stability. Results showed that temporal stability of Soil Water Content at 0.2 m was significantly weaker than those at the Soil depths of 0.6 and 0.8 m. Soil texture can significantly (P
J A Huisman - One of the best experts on this subject based on the ideXlab platform.
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Effective calibration of low-cost Soil Water Content sensors
Sensors (Switzerland), 2017Co-Authors: H. R. Bogena, A. Weuthen, J A Huisman, Bernd Schilling, Harry VereeckenAbstract:Soil Water Content is a key variable for understanding and modelling ecohydrological processes. Low-cost electromagnetic sensors are increasingly being used to characterize the spatio-temporal dynamics of Soil Water Content, despite the reduced accuracy of such sensors as compared to reference electromagnetic Soil Water Content sensing methods such as time domain reflectometry. Here, we present an effective calibration method to improve the measurement accuracy of low-cost Soil Water Content sensors taking the recently developed SMT100 sensor (Truebner GmbH, Neustadt, Germany) as an example. We calibrated the sensor output of more than 700 SMT100 sensors to permittivity using a standard procedure based on five reference media with a known apparent dielectric permittivity (1 < Ka < 34.8). Our results showed that a sensor-specific calibration improved the accuracy of the calibration compared to single “universal” calibration. The associated additional effort in calibrating each sensor individually is relaxed by a dedicated calibration setup that enables the calibration of large numbers of sensors in limited time while minimizing errors in the calibration process.
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Measuring Soil Water Content with Ground Penetrating Radar
Vadose Zone Journal, 2013Co-Authors: J A Huisman, S.s. Hubbard, John D. Redman, A. P. AnnanAbstract:We present a comprehensive review of methods to measure Soil Water Content with ground penetrating radar (GPR). We distinguish four methodologies: Soil Water Content determined from reflected wave velocity, Soil Water Content determined from ground wave velocity, Soil Water Content determined from transmitted wave velocity between boreholes, and Soil Water Content determined from the surface reflection coefficient. For each of these four methodologies, we discuss the basic principles, illustrate the quality of the data with field examples, discuss the possibilities and limitations, and identify areas where future research is required.We hope that this review will further stimulate the community to consider ground penetrating radar as one of the possible tools to measure Soil Water Content.
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measuring Soil Water Content with ground penetrating radar a review
Vadose Zone Journal, 2003Co-Authors: J A Huisman, S.s. Hubbard, John D. Redman, A. P. AnnanAbstract:We present a comprehensive review of methods to measure Soil Water Content with ground penetrating radar (GPR). We distinguish four methodologies: Soil Water Content determined from reflected wave velocity, Soil Water Content determined from ground wave velocity, Soil Water Content determined from transmitted wave velocity between boreholes, and Soil Water Content determined from the surface reflection coefficient. For each of these four methodologies, we discuss the basic principles, illustrate the quality of the data with field examples, discuss the possibilities and limitations, and identify areas where future research is required. We hope that this review will further stimulate the community to consider ground penetrating radar as one of the possible tools to measure Soil Water Content.
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Soil Water Content interpolation using spatio temporal kriging with external drift
Geoderma, 2003Co-Authors: J J J C Snepvangers, Gerard B M Heuvelink, J A HuismanAbstract:Abstract In this study, two techniques for spatio-temporal (ST) kriging of Soil Water Content are compared. The first technique, spatio-temporal ordinary kriging, is the simplest of the two, and uses only information about Soil Water Content. The second technique, spatio-temporal kriging with external drift, uses also the relationship between Soil Water Content and net-precipitation to aid the interpolation. It is shown that the behaviour of the Soil Water Content predictions is physically more realistic when using spatio-temporal kriging with external drift. Also, the prediction uncertainties are slightly smaller. The data used in this study consist of Time Domain Reflectometry (TDR) measurements from a 30-day irrigation experiment on a 60×60-m grassland in the Netherlands.
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Soil Water Content measurements at different scales accuracy of time domain reflectometry and ground penetrating radar
Journal of Hydrology, 2001Co-Authors: J A Huisman, C Sperl, Willem Bouten, J M VerstratenAbstract:Abstract Accurate measurements of Soil Water Content with an appropriate support are important in many research fields. Ground-penetrating radar (GPR) is an interesting measurement technique for mapping Soil Water Content at an intermediate scale in between point and remote sensing measurements. To measure Soil Water Content with GPR, we used the velocity of the ground wave, which is the signal traveling directly from source to receiving antenna through the upper centimeters of the Soil. To evaluate GPR performance, we aggregated time domain reflectometry (TDR) and gravimetric Soil Water Content measurements to the support of GPR measurements. The results showed that the calibration equations between GPR measurements and aggregated gravimetrical Soil Water Content were similar to those obtained for TDR measurements, suggesting that available TDR calibrations (e.g. Topp's equation) can be used for GPR. Furthermore, we found that the accuracy of GPR to measure Soil Water Content is comparable with the accuracy of TDR, although it depended on the type of data acquisition used for the determination of the ground wave velocity.
A K Guber - One of the best experts on this subject based on the ideXlab platform.
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temporal stability in Soil Water Content patterns across agricultural fields
Catena, 2008Co-Authors: A K Guber, T J Gish, Yakov Pachepsky, M T Van Genuchten, C S T Daughtry, T J Nicholson, R E CadyAbstract:When a field or a small Watershed is repeatedly surveyed for Soil Water Content, locations can often be identified where Soil Water Contents are either consistently larger or consistently less than the study area average. This phenomenon has been called temporal stability, time stability, temporal persistence, or rank stability in spatial patterns of Soil Water Contents. Temporal stability is of considerable interest in terms of facilitating upscaling of observed Soil Water Contents to obtain average values across the observation area, improving Soil Water monitoring strategies, and correcting the monitoring results for missing data. The objective of this work was to contribute to the existing knowledge base on temporal stability in Soil Water patterns using frequent multi-depth measurements with Multisensor Capacitance Probes (MCPs) installed in a coarse-texture Soil under multi-year corn production. Water Contents at 10, 30, 50, and 80 cm depths were measured every 10 min for 20 months of continuous observation from May 2001 to December 2002. The MCPs revealed temporal stability in Soil Water Content patterns. Temporal stability was found to increase with depth. The statistical hypothesis could not be rejected (P < 0.0001) that data collected each 10 min, each 2 h, each day, and each week had the same temporal stability. The locations that were best for estimating the average Water Contents were different for different depths. The best three locations for the whole observation period were the same as the best locations for a month of observations in about 60% of the cases. Temporal stability for a specific location and depth could serve as a good predictor of the utility of this location for estimating the area-average Soil Water Content for that depth. Temporal stability could be efficiently used to correct area-average Water Contents for missing data. Soil Water Contents can be upscaled and efficiently monitored using the temporal stability of Soil Water Content patterns.
Fengpeng Han - One of the best experts on this subject based on the ideXlab platform.
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Watershed scale temporal stability of Soil Water Content
Geoderma, 2010Co-Authors: Mingan Shao, Fengpeng Han, Klaus Reichardt, Jing TanAbstract:article i nfo The recognition of temporally stable locations with respect to Soil Water Content is of importance for Soil Water management decisions, especially in sloping land of Watersheds. Neutron probe Soil Water Content (0 to 0.8 m), evaluated at 20 dates during a year in the Loess Plateau of China, in a 20 ha Watershed dominated by Ust-Sandiic Entisols and Aeolian sandy Soils, were used to define their temporal stability through two indices: the standard deviation of relative difference (SDRD) and the mean absolute bias error (MABE). Specific concerns were (a) the relationship of temporal stability with Soil depth, (b) the effects of Soil texture and land use on temporal stability, and (c) the spatial pattern of the temporal stability. Results showed that temporal stability of Soil Water Content at 0.2 m was significantly weaker than those at the Soil depths of 0.6 and 0.8 m. Soil texture can significantly (Pb0.05) affect the stability of Soil Water Content except for the existence of an insignificant difference between sandy loam and silt loam textures, while temporal stability of areas covered by bunge needlegrass land was not significantly different from those covered by korshinsk peashrub. Geostatistical analysis showed that the temporal stability was spatially variable in an organized way as inferred by the degree of spatial dependence index. With increasing Soil depth, the range of both temporal stability indices showed an increasing trend, being 65.8-120.5 m for SDRD and 148.8-214.1 m for MABE, respectively. This study provides a valuable support for Soil Water Content measurements for Soil Water management and hydrological applications on sloping land areas.
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Watershed scale temporal stability of Soil Water Content
Geoderma, 2010Co-Authors: Mingan Shao, Fengpeng Han, Klaus Reichardt, Jing TanAbstract:The recognition of temporally stable locations with respect to Soil Water Content is of importance for Soil Water management decisions, especially in sloping land of Watersheds. Neutron probe Soil Water Content (0 to 0.8 m), evaluated at 20 dates during a year in the Loess Plateau of China, in a 20 ha Watershed dominated by Ust-Sandiic Entisols and Aeolian sandy Soils, were used to define their temporal stability through two indices: the standard deviation of relative difference (SDRD) and the mean absolute bias error (MABE). Specific concerns were (a) the relationship of temporal stability with Soil depth, (b) the effects of Soil texture and land use on temporal stability, and (c) the spatial pattern of the temporal stability. Results showed that temporal stability of Soil Water Content at 0.2 m was significantly weaker than those at the Soil depths of 0.6 and 0.8 m. Soil texture can significantly (P
