David Mulla, Jake Galzki, Aaron Hanson, Jirka Simunek
Ground-mounted photovoltaic sites are often treated as impervious surfaces in stormwater permits. This ignores the pervious soils beneath and between solar arrays and leads to an overestimation of runoff. Our objective was to improve solar farm stormwater hydrology models by explicitly considering the disconnected impervious nature of solar design and site characteristics. Experimental sites established on utility scale solar farms in Colorado, Georgia, Minnesota, New York, and Oregon had perennial vegetative plantings with mean precipitation ranging from 40.6 to 124.5 cm, and soil texture ranging from loamy sand to clay. Soil moisture measurements were collected beneath arrays, under drip edges, and in the vegetated area between arrays at each site. Hydrus-3D models for soil moisture and stormwater hydrology were developed that accounted for precipitation falling on solar panels, drip edge redistribution of rainfall, infiltration, and runoff in the pervious areas between solar arrays and beneath panels. Drip edge runoff averaged 3- to 10-times incident precipitation at the New York and Minnesota sites, respectively. Root mean square error values between measured sub-hourly soil moisture and predicted moisture for large measured single storm events averaged 0.029 across all five sites. Predicted runoff depths were strongly affected by precipitation depth, soil texture, soil profile depth, and soil bulk density. Runoff depths across the five experimental sites averaged 13%, 25%, and 45% of the 2-, 10-, and 100-year design storm depths, clearly showing that these solar farms do not behave like impervious surfaces, but rather as disconnected impervious surfaces with substantial infiltration of runoff in the vegetated areas between and beneath solar arrays.
{"title":"Measuring and modeling soil moisture and runoff at solar farms using a disconnected impervious surface approach","authors":"David Mulla, Jake Galzki, Aaron Hanson, Jirka Simunek","doi":"10.1002/vzj2.20335","DOIUrl":"https://doi.org/10.1002/vzj2.20335","url":null,"abstract":"Ground-mounted photovoltaic sites are often treated as impervious surfaces in stormwater permits. This ignores the pervious soils beneath and between solar arrays and leads to an overestimation of runoff. Our objective was to improve solar farm stormwater hydrology models by explicitly considering the disconnected impervious nature of solar design and site characteristics. Experimental sites established on utility scale solar farms in Colorado, Georgia, Minnesota, New York, and Oregon had perennial vegetative plantings with mean precipitation ranging from 40.6 to 124.5 cm, and soil texture ranging from loamy sand to clay. Soil moisture measurements were collected beneath arrays, under drip edges, and in the vegetated area between arrays at each site. Hydrus-3D models for soil moisture and stormwater hydrology were developed that accounted for precipitation falling on solar panels, drip edge redistribution of rainfall, infiltration, and runoff in the pervious areas between solar arrays and beneath panels. Drip edge runoff averaged 3- to 10-times incident precipitation at the New York and Minnesota sites, respectively. Root mean square error values between measured sub-hourly soil moisture and predicted moisture for large measured single storm events averaged 0.029 across all five sites. Predicted runoff depths were strongly affected by precipitation depth, soil texture, soil profile depth, and soil bulk density. Runoff depths across the five experimental sites averaged 13%, 25%, and 45% of the 2-, 10-, and 100-year design storm depths, clearly showing that these solar farms do not behave like impervious surfaces, but rather as disconnected impervious surfaces with substantial infiltration of runoff in the vegetated areas between and beneath solar arrays.","PeriodicalId":23594,"journal":{"name":"Vadose Zone Journal","volume":"16 1","pages":""},"PeriodicalIF":2.8,"publicationDate":"2024-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140578529","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mariel F. Davies, Ottfried Dietrich, Horst H. Gerke, Christoph Merz
Degraded peatlands release large amounts of greenhouse gases. The development of effective mitigation and management measures requires an understanding of relevant site‐specific biogeochemical and hydraulic processes. However, the simulation of water fluxes and vadose zone state variables of degrading peatlands relies on proper process description, parameterization of hydraulic functions, and representation of the boundary conditions. The objective of this study was to analyze the effects of unimodal versus bimodal soil hydraulic functions and pressure head versus flux‐type lower boundary conditions (LBCs) on the calculated hydraulic characteristics of a degraded peat profile. HYDRUS‐1D was used to study the hydraulic flow dynamics parameterized with data from a weighable groundwater lysimeter for the period from May 1 to December 31, 2019. Simulations comparing uni‐ and bimodal hydraulic functions showed only minor differences. Simulations of soil water pressure at a depth of 30 cm using a flux‐type LBC (RMSE: 27 cm, where RMSE is root mean square error) performed better than simulations using a pressure head LBC (RMSE: 48 cm). The pressure head LBC performed better at simulating volumetric water contents in 30‐cm depth than the flux LBC variant (RMSE: 0.05 vs. 0.09 cm3 cm−3). For specific site conditions with a shallow, fluctuating groundwater table and temporary air entrapment, the choice of LBC was important for a more accurate simulation of soil water fluxes and volumetric water content.
{"title":"Modeling water flow and volumetric water content in a degraded peat comparing unimodal with bimodal porosity and flux with pressure head boundary condition","authors":"Mariel F. Davies, Ottfried Dietrich, Horst H. Gerke, Christoph Merz","doi":"10.1002/vzj2.20328","DOIUrl":"https://doi.org/10.1002/vzj2.20328","url":null,"abstract":"Degraded peatlands release large amounts of greenhouse gases. The development of effective mitigation and management measures requires an understanding of relevant site‐specific biogeochemical and hydraulic processes. However, the simulation of water fluxes and vadose zone state variables of degrading peatlands relies on proper process description, parameterization of hydraulic functions, and representation of the boundary conditions. The objective of this study was to analyze the effects of unimodal versus bimodal soil hydraulic functions and pressure head versus flux‐type lower boundary conditions (LBCs) on the calculated hydraulic characteristics of a degraded peat profile. HYDRUS‐1D was used to study the hydraulic flow dynamics parameterized with data from a weighable groundwater lysimeter for the period from May 1 to December 31, 2019. Simulations comparing uni‐ and bimodal hydraulic functions showed only minor differences. Simulations of soil water pressure at a depth of 30 cm using a flux‐type LBC (RMSE: 27 cm, where RMSE is root mean square error) performed better than simulations using a pressure head LBC (RMSE: 48 cm). The pressure head LBC performed better at simulating volumetric water contents in 30‐cm depth than the flux LBC variant (RMSE: 0.05 vs. 0.09 cm<jats:sup>3</jats:sup> cm<jats:sup>−3</jats:sup>). For specific site conditions with a shallow, fluctuating groundwater table and temporary air entrapment, the choice of LBC was important for a more accurate simulation of soil water fluxes and volumetric water content.","PeriodicalId":23594,"journal":{"name":"Vadose Zone Journal","volume":"44 1","pages":""},"PeriodicalIF":2.8,"publicationDate":"2024-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140578527","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Luwen Zhuang, Hao Chen, Ping Yan, Xingmei Liang, Wenceslau G. Teixera, Martinus Th. van Genuchten, Kairong Lin
Many anthropogenic soils, often referred to as red bed or purple soils, are distributed in various areas of southern China. Purple soils typically are highly weathered and often lead to natural and engineering hazards because of their relatively poor water retention properties. Knowledge of the unsaturated soil hydraulic properties of purple soils is crucial for their optimal management and various assessment studies. In this work, the hydraulic properties of purple soils from southern China were measured in the laboratory over the full moisture range using a combination of evaporation (HYPROP) and psychrometer (WP4C) approaches. Measured data were analyzed in terms of four different unimodal and bimodal soil hydraulic models. The measurements and analyses showed that bimodality was not overly significant for most samples. The good fit of the Peters–Durner–Iden models furthermore suggested that corner and film flows were important under relative dry conditions. Existing soil pedotransfer functions were found to provide a fairly close match for the slope of water retention curves with the exception of near saturated water contents and the saturated conductivity. To the best of our knowledge, this is the first time that unsaturated hydraulic data of purple soils are provided over the full moisture range.
{"title":"Unsaturated hydraulic property measurements of subtropical anthropogenic (purple) soils in China","authors":"Luwen Zhuang, Hao Chen, Ping Yan, Xingmei Liang, Wenceslau G. Teixera, Martinus Th. van Genuchten, Kairong Lin","doi":"10.1002/vzj2.20334","DOIUrl":"https://doi.org/10.1002/vzj2.20334","url":null,"abstract":"Many anthropogenic soils, often referred to as red bed or purple soils, are distributed in various areas of southern China. Purple soils typically are highly weathered and often lead to natural and engineering hazards because of their relatively poor water retention properties. Knowledge of the unsaturated soil hydraulic properties of purple soils is crucial for their optimal management and various assessment studies. In this work, the hydraulic properties of purple soils from southern China were measured in the laboratory over the full moisture range using a combination of evaporation (HYPROP) and psychrometer (WP4C) approaches. Measured data were analyzed in terms of four different unimodal and bimodal soil hydraulic models. The measurements and analyses showed that bimodality was not overly significant for most samples. The good fit of the Peters–Durner–Iden models furthermore suggested that corner and film flows were important under relative dry conditions. Existing soil pedotransfer functions were found to provide a fairly close match for the slope of water retention curves with the exception of near saturated water contents and the saturated conductivity. To the best of our knowledge, this is the first time that unsaturated hydraulic data of purple soils are provided over the full moisture range.","PeriodicalId":23594,"journal":{"name":"Vadose Zone Journal","volume":"91 1","pages":""},"PeriodicalIF":2.8,"publicationDate":"2024-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140578313","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jan Vanderborght, Valentin Couvreur, Mathieu Javaux, Daniel Leitner, Andrea Schnepf, Harry Vereecken
Water uptake by plant roots is an important component of the soil water balance. Predicting to what extent potential transpiration from the canopy, that is, transpiration demand, can be met by supply of water from the soil through the root system is crucial to simulate the actual transpiration and assess vegetation water stress. In models that simulate the dynamics of vertical soil water content profiles as a function of water fluxes and soil water potential gradients, the root water uptake (RWU) distribution is represented by macroscopic sink terms. We present RWU functions that calculate sink terms based on a mechanistic model of water flow in the soil–root system. Based on soil–root hydraulics, we define α‐supply functions representing the maximal uptake by the root system from a certain soil depth when the root collar water potential equals the wilting point, ω‐supply factors representing the maximal supply from the entire root system, and a critical ωc factor representing the potential transpiration demand. These functions and factors are subsequently used to calculate RWU distributions directly from potential transpiration or demand and the soil water potentials. Unlike currently used approaches, which define α‐stress functions and ω factors representing ratios of actual uptake to uptake demand, the supply‐based formulations can be derived directly from soil and root hydraulic properties and can represent processes like root hydraulic redistribution and hydraulic lift.
{"title":"Mechanistically derived macroscopic root water uptake functions: The α and ω of root water uptake functions","authors":"Jan Vanderborght, Valentin Couvreur, Mathieu Javaux, Daniel Leitner, Andrea Schnepf, Harry Vereecken","doi":"10.1002/vzj2.20333","DOIUrl":"https://doi.org/10.1002/vzj2.20333","url":null,"abstract":"Water uptake by plant roots is an important component of the soil water balance. Predicting to what extent potential transpiration from the canopy, that is, transpiration demand, can be met by supply of water from the soil through the root system is crucial to simulate the actual transpiration and assess vegetation water stress. In models that simulate the dynamics of vertical soil water content profiles as a function of water fluxes and soil water potential gradients, the root water uptake (RWU) distribution is represented by macroscopic sink terms. We present RWU functions that calculate sink terms based on a mechanistic model of water flow in the soil–root system. Based on soil–root hydraulics, we define <jats:italic>α</jats:italic>‐supply functions representing the maximal uptake by the root system from a certain soil depth when the root collar water potential equals the wilting point, <jats:italic>ω</jats:italic>‐supply factors representing the maximal supply from the entire root system, and a critical <jats:italic>ω<jats:sub>c</jats:sub></jats:italic> factor representing the potential transpiration demand. These functions and factors are subsequently used to calculate RWU distributions directly from potential transpiration or demand and the soil water potentials. Unlike currently used approaches, which define <jats:italic>α</jats:italic>‐stress functions and <jats:italic>ω</jats:italic> factors representing ratios of actual uptake to uptake demand, the supply‐based formulations can be derived directly from soil and root hydraulic properties and can represent processes like root hydraulic redistribution and hydraulic lift.","PeriodicalId":23594,"journal":{"name":"Vadose Zone Journal","volume":"22 1","pages":""},"PeriodicalIF":2.8,"publicationDate":"2024-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140578455","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Julie N. Weitzman, J. Renée Brooks, Jana E. Compton, Barton R. Faulkner, R. Edward Peachey, William D. Rugh, Robert A. Coulombe, Blake Hatteberg, Stephen R. Hutchins
A substantial fraction of nitrogen (N) fertilizer applied in agricultural systems is not incorporated into crops and moves below the rooting zone as nitrate (NO3−). Understanding mechanisms for soil N retention below the rooting zone and leaching to groundwater is essential for our ability to track the fate of added N. We used dual stable isotopes of nitrate (δ15N–NO3− and δ18O–NO3−) and water (δ18O–H2O and δ2H–H2O) to understand the mechanisms driving nitrate leaching at three depths (0.8, 1.5, and 3.0 m) of an irrigated corn field sampled every 2 weeks from 2016 to 2020 in the southern Willamette Valley, Oregon, USA. Distinct periods of high nitrate concentrations with lower δ15N–NO3− values indicated that a portion of that nitrate was from recent fertilizer applications. We used a mixing model to quantify nitrate fluxes associated with recently added fertilizer N versus older, legacy soil N during these “fertilizer signal periods.” Nitrate leached below 3.0 m in these periods made up a larger proportion of the total N leached at that depth (∼52%) versus the two shallower depths (∼13%–16%), indicating preferential movement of recently applied fertilizer N through the deep soil into groundwater. Further, N associated with recent fertilizer additions leached more easily when compared to remobilized legacy N. A high volume of fall and winter precipitation may push residual fertilizer N to depth, potentially posing a larger threat to groundwater than legacy N. Optimizing fertilizer N additions could minimize fertilizer losses and reduce nitrate leaching to groundwater.
{"title":"Vadose zone flushing of fertilizer tracked by isotopes of water and nitrate","authors":"Julie N. Weitzman, J. Renée Brooks, Jana E. Compton, Barton R. Faulkner, R. Edward Peachey, William D. Rugh, Robert A. Coulombe, Blake Hatteberg, Stephen R. Hutchins","doi":"10.1002/vzj2.20324","DOIUrl":"https://doi.org/10.1002/vzj2.20324","url":null,"abstract":"A substantial fraction of nitrogen (N) fertilizer applied in agricultural systems is not incorporated into crops and moves below the rooting zone as nitrate (NO<jats:sub>3</jats:sub><jats:sup>−</jats:sup>). Understanding mechanisms for soil N retention below the rooting zone and leaching to groundwater is essential for our ability to track the fate of added N. We used dual stable isotopes of nitrate (δ<jats:sup>15</jats:sup>N–NO<jats:sub>3</jats:sub><jats:sup>−</jats:sup> and δ<jats:sup>18</jats:sup>O–NO<jats:sub>3</jats:sub><jats:sup>−</jats:sup>) and water (δ<jats:sup>18</jats:sup>O–H<jats:sub>2</jats:sub>O and δ<jats:sup>2</jats:sup>H–H<jats:sub>2</jats:sub>O) to understand the mechanisms driving nitrate leaching at three depths (0.8, 1.5, and 3.0 m) of an irrigated corn field sampled every 2 weeks from 2016 to 2020 in the southern Willamette Valley, Oregon, USA. Distinct periods of high nitrate concentrations with lower δ<jats:sup>15</jats:sup>N–NO<jats:sub>3</jats:sub><jats:sup>−</jats:sup> values indicated that a portion of that nitrate was from recent fertilizer applications. We used a mixing model to quantify nitrate fluxes associated with recently added fertilizer N versus older, legacy soil N during these “fertilizer signal periods.” Nitrate leached below 3.0 m in these periods made up a larger proportion of the total N leached at that depth (∼52%) versus the two shallower depths (∼13%–16%), indicating preferential movement of recently applied fertilizer N through the deep soil into groundwater. Further, N associated with recent fertilizer additions leached more easily when compared to remobilized legacy N. A high volume of fall and winter precipitation may push residual fertilizer N to depth, potentially posing a larger threat to groundwater than legacy N. Optimizing fertilizer N additions could minimize fertilizer losses and reduce nitrate leaching to groundwater.","PeriodicalId":23594,"journal":{"name":"Vadose Zone Journal","volume":"80 1","pages":""},"PeriodicalIF":2.8,"publicationDate":"2024-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140578356","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Earthworms and plant roots are vital for macropore formation and stabilization. The organo‐mineral coating of biopore surfaces also regulates macropore‐matrix mass exchange during preferential flow. The influence of finer‐textured burrow coatings on macroscopic soil properties during shrinkage could potentially be assessed by upscaling pore‐scale hydraulic and mechanical simulations. The aim was to investigate the influence of micro parameters (particle size, stiffness, and bond strength) on macro parameters (i.e., shrinkage curve and soil hydraulic properties). Drainage experiments and simulations were carried out using biopore‐coated clod‐size samples compared to those without coating. Simulations were performed using a two‐phase pore‐scale finite volume coupled with discrete element model (DEM‐2PFV). The structural dynamics was characterized by analyzing the pore volume and soil shrinkage curve obtained from numerically determined data. The soil hydraulic parameters were described using uni‐ and bimodal van Genuchten (vG) functions. The drainage simulations revealed hydro‐mechanical dynamics characterized by Braudeau‐shrinkage curve subdomains: The matrix‐only samples, with lower particle bond strength, exhibited relatively higher shrinkage. The coated samples, with higher particle stiffness and bond strength, displayed greater hydro‐mechanical stability. The numerically determined initial value of the saturated hydraulic conductivity (Ks) was about 70 times larger for matrix‐only samples than for coated samples. As expected, for the nonrigid soil structures, constant Ks, α, and n values for bimodal vG model resulted in prediction errors. Upscaling DEM‐2PFV pore‐scale model outcomes quantifies micro‐coating effects on macro hydro‐mechanics. This yields void ratio‐based soil water retention and hydraulic conductivity functions, advancing macroscopic soil hydraulic models and enhancing structured soil flow and transport descriptions.
蚯蚓和植物根系对大孔隙的形成和稳定至关重要。生物孔表面的有机矿物涂层还能在优先流动过程中调节大孔与基质之间的质量交换。通过放大孔隙尺度的水力和力学模拟，可以评估收缩过程中质地更细的孔穴涂层对土壤宏观特性的影响。目的是研究微观参数（粒度、硬度和粘结强度）对宏观参数（即收缩曲线和土壤水力特性）的影响。使用有生物孔涂层和无涂层的泥块大小样本进行了排水实验和模拟。模拟使用了两相孔隙尺度有限体积与离散元素耦合模型（DEM-2PFV）。通过分析从数值测定数据中获得的孔隙体积和土壤收缩曲线，对结构动力学进行了表征。土壤水力参数使用单峰和双峰 van Genuchten（vG）函数进行描述。排水模拟揭示了以布劳德收缩曲线子域为特征的水力学动态：纯基质样品的颗粒结合强度较低，收缩率相对较高。而具有较高颗粒刚度和粘结强度的涂层样品则表现出更高的水力学稳定性。通过数值确定的饱和水导率初始值（Ks），纯基质样品比涂层样品大 70 倍左右。正如预期的那样，对于非刚性土壤结构，双峰 vG 模型的 Ks、α 和 n 值恒定会导致预测误差。将 DEM-2PFV 孔隙尺度模型结果放大，可量化微涂层对宏观水力学的影响。这就产生了基于空隙率的土壤水分保持率和水力传导函数，从而推进了宏观土壤水力模型的发展，并增强了结构化土壤流动和传输描述。
{"title":"Coupled hydro‐mechanical pore‐scale modeling of biopore‐coated clods for upscaling soil shrinkage and hydraulic properties","authors":"Luis Alfredo Pires Barbosa, Horst H. Gerke","doi":"10.1002/vzj2.20325","DOIUrl":"https://doi.org/10.1002/vzj2.20325","url":null,"abstract":"Earthworms and plant roots are vital for macropore formation and stabilization. The organo‐mineral coating of biopore surfaces also regulates macropore‐matrix mass exchange during preferential flow. The influence of finer‐textured burrow coatings on macroscopic soil properties during shrinkage could potentially be assessed by upscaling pore‐scale hydraulic and mechanical simulations. The aim was to investigate the influence of micro parameters (particle size, stiffness, and bond strength) on macro parameters (i.e., shrinkage curve and soil hydraulic properties). Drainage experiments and simulations were carried out using biopore‐coated clod‐size samples compared to those without coating. Simulations were performed using a two‐phase pore‐scale finite volume coupled with discrete element model (DEM‐2PFV). The structural dynamics was characterized by analyzing the pore volume and soil shrinkage curve obtained from numerically determined data. The soil hydraulic parameters were described using uni‐ and bimodal van Genuchten (vG) functions. The drainage simulations revealed hydro‐mechanical dynamics characterized by Braudeau‐shrinkage curve subdomains: The matrix‐only samples, with lower particle bond strength, exhibited relatively higher shrinkage. The coated samples, with higher particle stiffness and bond strength, displayed greater hydro‐mechanical stability. The numerically determined initial value of the saturated hydraulic conductivity (<jats:italic>K<jats:sub>s</jats:sub></jats:italic>) was about 70 times larger for matrix‐only samples than for coated samples. As expected, for the nonrigid soil structures, constant <jats:italic>K<jats:sub>s</jats:sub></jats:italic>, <jats:italic>α</jats:italic>, and <jats:italic>n</jats:italic> values for bimodal vG model resulted in prediction errors. Upscaling DEM‐2PFV pore‐scale model outcomes quantifies micro‐coating effects on macro hydro‐mechanics. This yields void ratio‐based soil water retention and hydraulic conductivity functions, advancing macroscopic soil hydraulic models and enhancing structured soil flow and transport descriptions.","PeriodicalId":23594,"journal":{"name":"Vadose Zone Journal","volume":"6 1","pages":""},"PeriodicalIF":2.8,"publicationDate":"2024-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140578354","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Efstathios Diamantopoulos, Jirka Simunek, Tobias K. D. Weber
The Brunswick modular framework for modeling unsaturated soil hydraulic properties (SHP) over the full moisture range was implemented in the Hydrus suite. Users can now additionally choose between four different variants of the Brunswick model: (i) van Genuchten–Mualem (VGM), (ii) Brooks–Corey, (iii) Kosugi, and (iv) modified van Genuchten. For demonstration purposes, simulation results for two different setups, (i) bare soil evaporation and (ii) root water uptake, are presented, along with a comparison of the original VGM model and its Brunswick variant. Results show that the original VGM model underestimates the simulated cumulative evaporation and cumulative transpiration due to the inconsistent representation of the SHP in the dry moisture range. We also implemented a two‐step hydro‐PTF (pedotransfer function) into the Hydrus suite that converts the parameters of the original VGM model (from Rosetta) to the corresponding Brunswick variant. In that way, physically comprehensive simulations are ensured if no data on SHP are directly available, but information on physical soil properties (e.g., texture and bulk density) exists.
水文学套件中采用了用于模拟全湿度范围内非饱和土壤水力特性（SHP）的布朗斯维克模块框架。现在，用户还可以在 Brunswick 模型的四个不同变体之间进行选择：(i) van Genuchten-Mualem (VGM)，(ii) Brooks-Corey，(iii) Kosugi 和 (iv) 改进的 van Genuchten。为演示起见，本文介绍了两种不同设置的模拟结果：(i) 裸土蒸发和 (ii) 根系吸水，并对原始 VGM 模型及其不伦瑞克变体进行了比较。结果表明，原始 VGM 模型低估了模拟累积蒸发量和累积蒸腾量，原因是在干湿度范围内对 SHP 的表示不一致。我们还在 Hydrus 套件中实施了一个两步水文转换函数（hydro-PTF），将原始 VGM 模型（来自 Rosetta）的参数转换为相应的不伦瑞克变体。这样，如果无法直接获得有关 SHP 的数据，但存在有关土壤物理特性（如质地和容重）的信息，也能确保进行物理上全面的模拟。
{"title":"Implementation of the Brunswick model system into the Hydrus software suite","authors":"Efstathios Diamantopoulos, Jirka Simunek, Tobias K. D. Weber","doi":"10.1002/vzj2.20326","DOIUrl":"https://doi.org/10.1002/vzj2.20326","url":null,"abstract":"The Brunswick modular framework for modeling unsaturated soil hydraulic properties (SHP) over the full moisture range was implemented in the Hydrus suite. Users can now additionally choose between four different variants of the Brunswick model: (i) van Genuchten–Mualem (VGM), (ii) Brooks–Corey, (iii) Kosugi, and (iv) modified van Genuchten. For demonstration purposes, simulation results for two different setups, (i) bare soil evaporation and (ii) root water uptake, are presented, along with a comparison of the original VGM model and its Brunswick variant. Results show that the original VGM model underestimates the simulated cumulative evaporation and cumulative transpiration due to the inconsistent representation of the SHP in the dry moisture range. We also implemented a two‐step hydro‐PTF (pedotransfer function) into the Hydrus suite that converts the parameters of the original VGM model (from Rosetta) to the corresponding Brunswick variant. In that way, physically comprehensive simulations are ensured if no data on SHP are directly available, but information on physical soil properties (e.g., texture and bulk density) exists.","PeriodicalId":23594,"journal":{"name":"Vadose Zone Journal","volume":"48 1","pages":""},"PeriodicalIF":2.8,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140578256","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Recent models of the unsaturated hydraulic conductivity curve (UHCC) are the sum of separate UHCCs for domains of capillary water, film water, and water vapor. This requires parallel, noninteracting domains. A theoretical framework for aggregating domain conductivities to a bulk soil UHCC is presented to identify and possibly relax implicit assumptions about domain configuration. The paper develops arithmetic, harmonic, and geometric averages of the liquid-water conductivities that can be arithmetically averaged with the vapor conductivity. However, current models for capillary and film conductivities are intrinsic, that is, valid within their respective domain. The vapor conductivity is a bulk conductivity, that is, it gives the conductivity of the gaseous domain as it manifests itself in the soil. Conversion relationships use the domain volume fractions as approximations of the as-yet unknown weighting factors to convert between intrinsic and bulk conductivities. This facilitates consistent averaging of domain conductivities. Even with consistent averaging, a truly physically accurate model of the UHCC based on domain conductivities is fundamentally elusive. Nevertheless, models based on the three averages and the unweighted sum of the domain conductivities produce good fits to data for two soils but diverge in the dry range. The fitted curves for the capillary and film water depend on the averaging (or adding) method. Hence, they are not strictly characteristic of their respective domains. The true intrinsic domain conductivity functions may be impossible to determine.
{"title":"Averaging or adding domain conductivities to calculate the unsaturated soil hydraulic conductivity","authors":"Gerrit H. de Rooij","doi":"10.1002/vzj2.20329","DOIUrl":"https://doi.org/10.1002/vzj2.20329","url":null,"abstract":"Recent models of the unsaturated hydraulic conductivity curve (UHCC) are the sum of separate UHCCs for domains of capillary water, film water, and water vapor. This requires parallel, noninteracting domains. A theoretical framework for aggregating domain conductivities to a bulk soil UHCC is presented to identify and possibly relax implicit assumptions about domain configuration. The paper develops arithmetic, harmonic, and geometric averages of the liquid-water conductivities that can be arithmetically averaged with the vapor conductivity. However, current models for capillary and film conductivities are intrinsic, that is, valid within their respective domain. The vapor conductivity is a bulk conductivity, that is, it gives the conductivity of the gaseous domain as it manifests itself in the soil. Conversion relationships use the domain volume fractions as approximations of the as-yet unknown weighting factors to convert between intrinsic and bulk conductivities. This facilitates consistent averaging of domain conductivities. Even with consistent averaging, a truly physically accurate model of the UHCC based on domain conductivities is fundamentally elusive. Nevertheless, models based on the three averages and the unweighted sum of the domain conductivities produce good fits to data for two soils but diverge in the dry range. The fitted curves for the capillary and film water depend on the averaging (or adding) method. Hence, they are not strictly characteristic of their respective domains. The true intrinsic domain conductivity functions may be impossible to determine.","PeriodicalId":23594,"journal":{"name":"Vadose Zone Journal","volume":"144 1","pages":""},"PeriodicalIF":2.8,"publicationDate":"2024-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140324490","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
I am extremely honored to receive the 2023 Wolf Prize in the field of agriculture for “groundbreaking work in understanding water flow and predicting contaminant transport in soils,” and for that reason, being invited to contribute an autobiography to this special section of Vadose Zone Journal. Receiving the Wolf Prize reflects the guidance, support, and input I received from so many over the years, starting from the very beginning from my parents who instilled in me the beauty of the natural environment through their careful management of a small family farm in the Netherlands. They encouraged me to pursue my MS studies in Holland, after which I went to the United States, subsequently to Brazil, and back to the Netherlands. Throughout my life, I enjoyed enormous freedom to pursue whatever I felt was important to better describe fluid flow and contaminant transport processes in the near-surface environment. I could interact with a large number of colleagues from all over the world. This collaboration made me see not only the important gaps in science but also the difficulties of applying what we know to the many environmental and socio-economic problems facing this planet. As such, my appreciation goes to the Wolf Foundation for recognizing, through this award, the importance of us taking care of this planet and its inhabitants.
{"title":"Rien van Genuchten: A short autobiography","authors":"Martinus Th. van Genuchten","doi":"10.1002/vzj2.20322","DOIUrl":"https://doi.org/10.1002/vzj2.20322","url":null,"abstract":"<h2>1 INTRODUCTION</h2>\u0000<p>I am extremely honored to receive the 2023 Wolf Prize in the field of agriculture for “groundbreaking work in understanding water flow and predicting contaminant transport in soils,” and for that reason, being invited to contribute an autobiography to this special section of <i>Vadose Zone Journal</i>. Receiving the Wolf Prize reflects the guidance, support, and input I received from so many over the years, starting from the very beginning from my parents who instilled in me the beauty of the natural environment through their careful management of a small family farm in the Netherlands. They encouraged me to pursue my MS studies in Holland, after which I went to the United States, subsequently to Brazil, and back to the Netherlands. Throughout my life, I enjoyed enormous freedom to pursue whatever I felt was important to better describe fluid flow and contaminant transport processes in the near-surface environment. I could interact with a large number of colleagues from all over the world. This collaboration made me see not only the important gaps in science but also the difficulties of applying what we know to the many environmental and socio-economic problems facing this planet. As such, my appreciation goes to the Wolf Foundation for recognizing, through this award, the importance of us taking care of this planet and its inhabitants.</p>","PeriodicalId":23594,"journal":{"name":"Vadose Zone Journal","volume":"93 1","pages":""},"PeriodicalIF":2.8,"publicationDate":"2024-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140298857","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Soil moisture (SM) is a critical element of the hydrological cycle, land surface processes, and surface energy balance. However, the low spatial resolution of commonly used SM products limits the application of SM in agriculture and eco‐hydrology in cold and arid regions. In this study, the normalized difference soil index (NDSI) and bare soil index (BSI) were added to traditional downscaling factors including land surface temperature, normalized difference vegetation index, digital elevation mode, apparent thermal inertia, Albedo, and temperature vegetation dryness index, as they are more strongly correlated with surface SM in the bare soil‐vegetation alternation zone of such region. Using the random forest algorithm, a downscaling model of SM was constructed for such region. The accuracy of the downscaled SM estimates was validated by comparing them with the original SM data collected from May to September 2021, which is the non‐freezing period of the soil. The findings indicate that the newly added NDSI and BSI have good correlation with SM. Incorporating NDSI and BSI to construct the downscaled model enhances the accuracy by over 19% compared to excluding them, while also providing a more comprehensive representation of SM information. NDSI and BSI can be well applied to the downscaled research of SM in the bare soil‐vegetation alternation zone, which is of great value for the study of eco‐hydrology and agricultural drought monitoring in cold and arid regions.
土壤水分（SM）是水文循环、地表过程和地表能量平衡的关键要素。然而，常用土壤水分产品的空间分辨率较低，限制了土壤水分在寒冷干旱地区农业和生态水文学中的应用。本研究在传统降尺度因子（包括地表温度、归一化差异植被指数、数字高程模式、视热惯性、反照率和温度植被干燥指数）的基础上，增加了归一化差异土壤指数（NDSI）和裸土指数（BSI），因为它们与此类地区裸土-植被交替区的地表SM具有更强的相关性。利用随机森林算法，为该区域构建了 SM 的降尺度模型。通过与 2021 年 5 月至 9 月（土壤非冰冻期）收集的原始 SM 数据进行比较，验证了降尺度 SM 估计值的准确性。结果表明，新加入的 NDSI 和 BSI 与 SM 具有良好的相关性。在构建降尺度模型时加入 NDSI 和 BSI，其精度比不加入 NDSI 和 BSI 时提高了 19% 以上，同时还能更全面地反映土壤信息。NDSI和BSI可以很好地应用于裸露土壤-植被交替区SM的降尺度研究，对寒冷干旱地区的生态水文研究和农业干旱监测具有重要价值。
{"title":"Downscaling SMAP soil moisture product in cold and arid region: Incorporating NDSI and BSI into the random forest algorithm","authors":"Mingxing Gao, Kui Zhu, Yanjun Guo, Xuhang Han, Dongsheng Li, Shujian Zhang","doi":"10.1002/vzj2.20323","DOIUrl":"https://doi.org/10.1002/vzj2.20323","url":null,"abstract":"Soil moisture (SM) is a critical element of the hydrological cycle, land surface processes, and surface energy balance. However, the low spatial resolution of commonly used SM products limits the application of SM in agriculture and eco‐hydrology in cold and arid regions. In this study, the normalized difference soil index (NDSI) and bare soil index (BSI) were added to traditional downscaling factors including land surface temperature, normalized difference vegetation index, digital elevation mode, apparent thermal inertia, Albedo, and temperature vegetation dryness index, as they are more strongly correlated with surface SM in the bare soil‐vegetation alternation zone of such region. Using the random forest algorithm, a downscaling model of SM was constructed for such region. The accuracy of the downscaled SM estimates was validated by comparing them with the original SM data collected from May to September 2021, which is the non‐freezing period of the soil. The findings indicate that the newly added NDSI and BSI have good correlation with SM. Incorporating NDSI and BSI to construct the downscaled model enhances the accuracy by over 19% compared to excluding them, while also providing a more comprehensive representation of SM information. NDSI and BSI can be well applied to the downscaled research of SM in the bare soil‐vegetation alternation zone, which is of great value for the study of eco‐hydrology and agricultural drought monitoring in cold and arid regions.","PeriodicalId":23594,"journal":{"name":"Vadose Zone Journal","volume":"30 1","pages":""},"PeriodicalIF":2.8,"publicationDate":"2024-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140200877","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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