Christian Roumelis, Fabian Willert, Maria Scaccia, Susan Welch, Rachel Gabor, Jesús Carrera, Albert Folch, Miquel Salgot, Audrey H. Sawyer
Coastal aquifers experience water table fluctuations that push and pull water and air through organic-rich soils. This exchange affects the supply of oxygen, dissolved organic carbon (DOC), and nitrogen (N) to shallow aquifers and influences groundwater quality. To investigate the fate of N species, we used a meter-long column containing a sequence of natural organic topsoil and aquifer sediments. A fluctuating head was imposed at the column bottom with local, nitrate-rich groundwater (16.5 mg/L NO3-N). We monitored in-situ redox potential and collected pore water samples for analysis of inorganic N species and DOC over 16 days. Reactive processes were more complex than anticipated. The organic-rich topsoil remained anaerobic, while mineral sediments beneath alternated between aerobic, when the water table dropped and sucked air across preferential flow paths, and anaerobic conditions, when the water table was high. A fluid flow and reactive transport model shows that when the water table rises into organic-rich soils, it limits the flow of oxygen, while the soils release DOC, which stimulates the removal of nitrate from groundwater by denitrification. At the end of the experiment, we introduced seawater to the column to mimic a storm surge. Seawater mobilized N and DOC from shallow soil horizons, which could reach the aquifer if the surge is long enough. These processes are relevant for groundwater quality in developed coastal areas with anthropogenic N sources, as climate change and rising seas will drive changes in water table and flood dynamics.
{"title":"Water Table Fluctuations Control Nitrate and Ammonium Fate in Coastal Aquifers","authors":"Christian Roumelis, Fabian Willert, Maria Scaccia, Susan Welch, Rachel Gabor, Jesús Carrera, Albert Folch, Miquel Salgot, Audrey H. Sawyer","doi":"10.1029/2024wr038087","DOIUrl":"https://doi.org/10.1029/2024wr038087","url":null,"abstract":"Coastal aquifers experience water table fluctuations that push and pull water and air through organic-rich soils. This exchange affects the supply of oxygen, dissolved organic carbon (DOC), and nitrogen (N) to shallow aquifers and influences groundwater quality. To investigate the fate of N species, we used a meter-long column containing a sequence of natural organic topsoil and aquifer sediments. A fluctuating head was imposed at the column bottom with local, nitrate-rich groundwater (16.5 mg/L NO<sub>3</sub>-N). We monitored in-situ redox potential and collected pore water samples for analysis of inorganic N species and DOC over 16 days. Reactive processes were more complex than anticipated. The organic-rich topsoil remained anaerobic, while mineral sediments beneath alternated between aerobic, when the water table dropped and sucked air across preferential flow paths, and anaerobic conditions, when the water table was high. A fluid flow and reactive transport model shows that when the water table rises into organic-rich soils, it limits the flow of oxygen, while the soils release DOC, which stimulates the removal of nitrate from groundwater by denitrification. At the end of the experiment, we introduced seawater to the column to mimic a storm surge. Seawater mobilized N and DOC from shallow soil horizons, which could reach the aquifer if the surge is long enough. These processes are relevant for groundwater quality in developed coastal areas with anthropogenic N sources, as climate change and rising seas will drive changes in water table and flood dynamics.","PeriodicalId":23799,"journal":{"name":"Water Resources Research","volume":"72 1","pages":""},"PeriodicalIF":5.4,"publicationDate":"2025-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142967886","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Shufeng Qiao, Rui Ma, Yunquan Wang, Ziyong Sun, Helen Kristine French, Yanxin Wang
Understanding the change in soil hydraulic conductivity with temperature is key to predicting groundwater flow and solute transport in cold regions. The most commonly used models for hydraulic conductivity during freeze‒thaw cycles only consider the flow of capillary water in the soil and neglect water flowing along thin films around the particle surface. This paper proposed a new hydraulic conductivity model of frozen soil via the Clausius–Clapeyron equation based on an unsaturated soil hydraulic conductivity model over the entire moisture range using an analogy between freeze‒thaw and dry‒wet processes in soils. The new model used a single equation to describe the conductivity behaviors resulting from both capillary and adsorption forces, thus accounting for the effect of both capillary water and thin liquid film around soil. By comparison with other existing models, the results demonstrated that the new model is applicable to various types of soils and that the predicted hydraulic conductivity is in the highest agreement with the observed data, while reducing the root mean square error by 38.9% compared to the van Genuchten–Mualem model. Finally, our new model was validated with thermal–hydrological benchmark problem and laboratory experiment result. The benchmark results indicated that the advective heat transfer was more significant, and the phase change was completed earlier when considering both capillary and adsorption forces than when only considering capillary forces. Furthermore, the coupled flow–heat model with the new hydraulic conductivity expression replicated well the results from a laboratory column experiment.
{"title":"A New Capillary and Adsorption‒Force Model Predicting Hydraulic Conductivity of Soil During Freeze‒thaw Processes","authors":"Shufeng Qiao, Rui Ma, Yunquan Wang, Ziyong Sun, Helen Kristine French, Yanxin Wang","doi":"10.1029/2023wr036857","DOIUrl":"https://doi.org/10.1029/2023wr036857","url":null,"abstract":"Understanding the change in soil hydraulic conductivity with temperature is key to predicting groundwater flow and solute transport in cold regions. The most commonly used models for hydraulic conductivity during freeze‒thaw cycles only consider the flow of capillary water in the soil and neglect water flowing along thin films around the particle surface. This paper proposed a new hydraulic conductivity model of frozen soil via the Clausius–Clapeyron equation based on an unsaturated soil hydraulic conductivity model over the entire moisture range using an analogy between freeze‒thaw and dry‒wet processes in soils. The new model used a single equation to describe the conductivity behaviors resulting from both capillary and adsorption forces, thus accounting for the effect of both capillary water and thin liquid film around soil. By comparison with other existing models, the results demonstrated that the new model is applicable to various types of soils and that the predicted hydraulic conductivity is in the highest agreement with the observed data, while reducing the root mean square error by 38.9% compared to the van Genuchten–Mualem model. Finally, our new model was validated with thermal–hydrological benchmark problem and laboratory experiment result. The benchmark results indicated that the advective heat transfer was more significant, and the phase change was completed earlier when considering both capillary and adsorption forces than when only considering capillary forces. Furthermore, the coupled flow–heat model with the new hydraulic conductivity expression replicated well the results from a laboratory column experiment.","PeriodicalId":23799,"journal":{"name":"Water Resources Research","volume":"1 1","pages":""},"PeriodicalIF":5.4,"publicationDate":"2025-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142940196","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
R. Blaine McCleskey, Robert L. Runkel, Sheila F. Murphy, David A. Roth
Stream discharge is often determined by wading the stream and measuring the point velocity at fixed widths and depths. However, there are conditions when wading measurements are not safe or the measurements are poor because of high turbulence, rocky streambeds, non-standard velocity distributions, shallow or sheet flow, aquatic plants, or inaccessibility due to ice. Under these conditions, it is often preferable to determine discharge using salt slug addition and downstream measurement of salt concentration with time. A new method for determining stream discharge using specific conductance as a surrogate for salt concentrations is presented. The method adapts an approach that accurately calculates the specific conductance by utilizing ionic molal conductivities to determine the concentration of salt. The method was applied at four mountainous stream sites where a total of twenty-nine slug-additions were performed. The discharge determined from the new method was compared to four alternative methods including discharge from continuous injection, slug addition with discrete sample calibration, wading measurements with velocity measurement, and a stream gage. The discharge ranged from 21.5 to 778 L/s and the median difference between the new method and the traditional methods was −0.01%. Additionally, the p-value (0.75) determined from a paired t-test indicates that there is no significant difference between the discharge determined from the new and alternative discharge methods. The primary advantage of the new method is that it obviates the need to collect and analyze discrete samples to accurately quantify the specific conductance-salt surrogate relationship, allowing for rapid, low-cost determination of discharge.
{"title":"Stream Discharge Determinations Using Slug Additions and Specific Conductance","authors":"R. Blaine McCleskey, Robert L. Runkel, Sheila F. Murphy, David A. Roth","doi":"10.1029/2024wr037771","DOIUrl":"https://doi.org/10.1029/2024wr037771","url":null,"abstract":"Stream discharge is often determined by wading the stream and measuring the point velocity at fixed widths and depths. However, there are conditions when wading measurements are not safe or the measurements are poor because of high turbulence, rocky streambeds, non-standard velocity distributions, shallow or sheet flow, aquatic plants, or inaccessibility due to ice. Under these conditions, it is often preferable to determine discharge using salt slug addition and downstream measurement of salt concentration with time. A new method for determining stream discharge using specific conductance as a surrogate for salt concentrations is presented. The method adapts an approach that accurately calculates the specific conductance by utilizing ionic molal conductivities to determine the concentration of salt. The method was applied at four mountainous stream sites where a total of twenty-nine slug-additions were performed. The discharge determined from the new method was compared to four alternative methods including discharge from continuous injection, slug addition with discrete sample calibration, wading measurements with velocity measurement, and a stream gage. The discharge ranged from 21.5 to 778 L/s and the median difference between the new method and the traditional methods was −0.01%. Additionally, the p-value (0.75) determined from a paired <i>t</i>-test indicates that there is no significant difference between the discharge determined from the new and alternative discharge methods. The primary advantage of the new method is that it obviates the need to collect and analyze discrete samples to accurately quantify the specific conductance-salt surrogate relationship, allowing for rapid, low-cost determination of discharge.","PeriodicalId":23799,"journal":{"name":"Water Resources Research","volume":"48 1","pages":""},"PeriodicalIF":5.4,"publicationDate":"2025-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142940197","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Manhua Luo, Hailong Li, Gang Li, Wei Wang, Shengchao Yu, Qian Ma, Yan Zheng
Coastal groundwater dynamics and solute transport were influenced by multiple factors including aquitards, tides, evaporation, and slope breaks in coastal aquifers. However, quantification of the impacts of these factors on groundwater flow and salinity distribution remains a challenge. In this study, both field observations and numerical modeling were applied to investigate hydraulic heads and groundwater salinity in a tidal flat with large-scale seepage faces at Laizhou Bay, China. Results showed that seepage-face evaporation increased groundwater salinity landward and promoted groundwater and salt exchange within the intertidal zone significantly in comparison to the case without evaporation. Seawater infiltrated the aquifer on the left of the slope break and discharged on the right, forming a groundwater circulation cell, which notably influenced leakage flow between unconfined and confined aquifers through the aquitard. The aquitard prevented approximately 85% of inland freshwater discharge near the slope break, resulting in the formation of two atypical freshwater discharge tubes in the upper and middle intertidal zones. Two additional groundwater circulation cells developed in the lower intertidal zone due to the spring-neap tidal cycle. The outflow and inflow fluxes over a spring-neap tidal cycle were numerically estimated to be 1.46 and 1.27 m2/d, respectively, with evaporation accounting for 45% of the outflow flux. These findings provide significant insights for further investigations on groundwater dynamics and solute transport in multi-layered coastal aquifers, and have strong implications for biogeochemical processes within the intertidal zone.
{"title":"The Influences of Evaporation and Aquitard on Groundwater Dynamics and Solute Transport in a Tidal Flat With a Slope Break","authors":"Manhua Luo, Hailong Li, Gang Li, Wei Wang, Shengchao Yu, Qian Ma, Yan Zheng","doi":"10.1029/2024wr038231","DOIUrl":"https://doi.org/10.1029/2024wr038231","url":null,"abstract":"Coastal groundwater dynamics and solute transport were influenced by multiple factors including aquitards, tides, evaporation, and slope breaks in coastal aquifers. However, quantification of the impacts of these factors on groundwater flow and salinity distribution remains a challenge. In this study, both field observations and numerical modeling were applied to investigate hydraulic heads and groundwater salinity in a tidal flat with large-scale seepage faces at Laizhou Bay, China. Results showed that seepage-face evaporation increased groundwater salinity landward and promoted groundwater and salt exchange within the intertidal zone significantly in comparison to the case without evaporation. Seawater infiltrated the aquifer on the left of the slope break and discharged on the right, forming a groundwater circulation cell, which notably influenced leakage flow between unconfined and confined aquifers through the aquitard. The aquitard prevented approximately 85% of inland freshwater discharge near the slope break, resulting in the formation of two atypical freshwater discharge tubes in the upper and middle intertidal zones. Two additional groundwater circulation cells developed in the lower intertidal zone due to the spring-neap tidal cycle. The outflow and inflow fluxes over a spring-neap tidal cycle were numerically estimated to be 1.46 and 1.27 m<sup>2</sup>/d, respectively, with evaporation accounting for 45% of the outflow flux. These findings provide significant insights for further investigations on groundwater dynamics and solute transport in multi-layered coastal aquifers, and have strong implications for biogeochemical processes within the intertidal zone.","PeriodicalId":23799,"journal":{"name":"Water Resources Research","volume":"27 1","pages":""},"PeriodicalIF":5.4,"publicationDate":"2025-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142940195","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ze Yang, Zhi Dou, Alberto Guadagnini, Xiaoteng Li, Chaoqi Wang, Jinguo Wang
We document results of a set of laboratory experiments aimed at exploring impacts of injection rate and bacterial density on biomineralization across water-saturated porous media. The study relies on a Low-Field Nuclear Magnetic Resonance technology and the ensuing transverse spin-spin relaxation time distributions. The latter is documented to provide a robust quantification of temporal histories of pore size distributions during biomineralization. As such, our work explores and quantifies pore-size dependent biomineralization across the three-dimensional pore space. The study also provides a quantitative analysis of alterations in porosity and permeability induced by biomineralization, together with a quantification of (time-averaged) rates of pore volume change. A plugging ratio efficiency index is introduced to quantify the strength of pore-size-related biomineralization. Our results reveal that biomineralization induces significant alterations in the pore size distribution within a porous medium, these changes being modulated by bacterial density and injection rate. We find that CaCO3 mainly precipitates in macropores, consistent with the presence of favorable local hydrodynamic conditions and large surface areas therein. Precipitated CaCO3 volume is found to increase with bacterial density. High bacterial densities amplify rate of pore volume change within macropores and adequate plugging ratio of biomineralization and contribute to a significant permeability reduction. Otherwise, a diminished strength of biomineralization in mesopores and micropores is documented for the highest injection rates considered.
{"title":"Experimental Analyses of Pore-Size Dependent Biomineralization in Porous Media Under Various Flow Rate and Bacterial Density Scenarios","authors":"Ze Yang, Zhi Dou, Alberto Guadagnini, Xiaoteng Li, Chaoqi Wang, Jinguo Wang","doi":"10.1029/2024wr037674","DOIUrl":"https://doi.org/10.1029/2024wr037674","url":null,"abstract":"We document results of a set of laboratory experiments aimed at exploring impacts of injection rate and bacterial density on biomineralization across water-saturated porous media. The study relies on a Low-Field Nuclear Magnetic Resonance technology and the ensuing transverse spin-spin relaxation time distributions. The latter is documented to provide a robust quantification of temporal histories of pore size distributions during biomineralization. As such, our work explores and quantifies pore-size dependent biomineralization across the three-dimensional pore space. The study also provides a quantitative analysis of alterations in porosity and permeability induced by biomineralization, together with a quantification of (time-averaged) rates of pore volume change. A plugging ratio efficiency index is introduced to quantify the strength of pore-size-related biomineralization. Our results reveal that biomineralization induces significant alterations in the pore size distribution within a porous medium, these changes being modulated by bacterial density and injection rate. We find that CaCO<sub>3</sub> mainly precipitates in macropores, consistent with the presence of favorable local hydrodynamic conditions and large surface areas therein. Precipitated CaCO<sub>3</sub> volume is found to increase with bacterial density. High bacterial densities amplify rate of pore volume change within macropores and adequate plugging ratio of biomineralization and contribute to a significant permeability reduction. Otherwise, a diminished strength of biomineralization in mesopores and micropores is documented for the highest injection rates considered.","PeriodicalId":23799,"journal":{"name":"Water Resources Research","volume":"83 1","pages":""},"PeriodicalIF":5.4,"publicationDate":"2025-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142937720","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Huibin Gao, Qin Ju, Dawei Zhang, Zhenlong Wang, Zhenchun Hao, James W. Kirchner
Understanding streamflow generation at the catchment scale requires quantifying how different components of the system are linked, and how they respond to meteorological forcing. Here we present a proof-of-concept study characterizing and quantifying dynamic linkages between precipitation, groundwater recharge, and streamflow using a data-driven nonlinear deconvolution and demixing approach, Ensemble Rainfall-Runoff Analysis (ERRA). Streamflow in our mesoscale, intensively farmed test catchment is flashy, but occurs at time lags that are too long to be plausibly attributed to overland flow. Instead, ERRA's estimates of the impulse responses of groundwater recharge to precipitation, and of streamflow to groundwater recharge, imply that this intermittent streamflow is primarily driven by precipitation infiltrating to recharge groundwater, followed by discharge of groundwater to streamflow. ERRA reveals that streamflow increases nonlinearly with increasing precipitation intensity or groundwater recharge, and exhibits almost no response to precipitation or recharge rates of less than 10 mm d−1. Groundwater recharge is both nonlinear, increasing more-than-proportionally with precipitation intensity, and nonstationary, increasing with antecedent wetness. Simulations with the infiltration model Hydrus-1D can reproduce the observed water table time series reasonably well (NSE = 0.70). However, ERRA shows that the model's impulse response is inconsistent with the real-world impulse response estimated from measured precipitation and groundwater recharge, illustrating that conventional goodness-of-fit statistics can be weak tests of model realism. Thus, our proof-of-concept study demonstrates how impulse responses estimated by ERRA can help clarify linkages between precipitation and streamflow at the catchment scale, quantify nonlinearity and nonstationarity in hydrologic processes, and critically evaluate simulation models.
理解流域尺度上的水流产生需要量化系统的不同组成部分是如何联系在一起的，以及它们如何对气象强迫作出反应。在这里，我们提出了一项概念验证研究，利用数据驱动的非线性反褶积和分解方法，即集合降雨径流分析（ERRA），表征和量化降水、地下水补给和河流流量之间的动态联系。在我们的中尺度、集约化养殖的测试集水区，水流是浮华的，但发生的时间滞后太长，无法合理地归因于陆上水流。相反，对地下水补给对降水的脉冲响应和径流对地下水补给的脉冲响应的估计表明，这种间歇性的径流主要是由降水入渗补给地下水驱动的，然后是地下水向径流的排放。地磁重构显示，径流随降水强度或地下水补给量的增加呈非线性增加，对降水或补给量小于10 mm d−1几乎没有响应。地下水补给是非线性的，随着降水强度的增加而增加，而非平稳性的，随着前期湿度的增加而增加。采用Hydrus-1D入渗模式模拟可以较好地再现观测到的地下水位时间序列（NSE = 0.70）。然而，该模型的脉冲响应与实测降水和地下水补给估计的真实脉冲响应不一致，说明传统的拟合优度统计可能是模型真实性的弱检验。因此，我们的概念验证研究证明了ERRA估计的脉冲响应如何有助于澄清流域尺度上降水和河流流量之间的联系，量化水文过程中的非线性和非平稳性，并批判性地评估模拟模型。
{"title":"Quantifying Dynamic Linkages Between Precipitation, Groundwater Recharge, and Streamflow Using Ensemble Rainfall-Runoff Analysis","authors":"Huibin Gao, Qin Ju, Dawei Zhang, Zhenlong Wang, Zhenchun Hao, James W. Kirchner","doi":"10.1029/2024wr037821","DOIUrl":"https://doi.org/10.1029/2024wr037821","url":null,"abstract":"Understanding streamflow generation at the catchment scale requires quantifying how different components of the system are linked, and how they respond to meteorological forcing. Here we present a proof-of-concept study characterizing and quantifying dynamic linkages between precipitation, groundwater recharge, and streamflow using a data-driven nonlinear deconvolution and demixing approach, Ensemble Rainfall-Runoff Analysis (ERRA). Streamflow in our mesoscale, intensively farmed test catchment is flashy, but occurs at time lags that are too long to be plausibly attributed to overland flow. Instead, ERRA's estimates of the impulse responses of groundwater recharge to precipitation, and of streamflow to groundwater recharge, imply that this intermittent streamflow is primarily driven by precipitation infiltrating to recharge groundwater, followed by discharge of groundwater to streamflow. ERRA reveals that streamflow increases nonlinearly with increasing precipitation intensity or groundwater recharge, and exhibits almost no response to precipitation or recharge rates of less than 10 mm d<sup>−1</sup>. Groundwater recharge is both nonlinear, increasing more-than-proportionally with precipitation intensity, and nonstationary, increasing with antecedent wetness. Simulations with the infiltration model Hydrus-1D can reproduce the observed water table time series reasonably well (NSE = 0.70). However, ERRA shows that the model's impulse response is inconsistent with the real-world impulse response estimated from measured precipitation and groundwater recharge, illustrating that conventional goodness-of-fit statistics can be weak tests of model realism. Thus, our proof-of-concept study demonstrates how impulse responses estimated by ERRA can help clarify linkages between precipitation and streamflow at the catchment scale, quantify nonlinearity and nonstationarity in hydrologic processes, and critically evaluate simulation models.","PeriodicalId":23799,"journal":{"name":"Water Resources Research","volume":"27 1","pages":""},"PeriodicalIF":5.4,"publicationDate":"2025-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142937733","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Modeling water stable isotope transport in soil is crucial to sharpen our understanding of water cycles in terrestrial ecosystems. Although several models for soil water isotope transport have been developed, many rely on a semi-coupled numerical approach, solving isotope transport only after obtaining solutions from water and heat transport equations. However, this approach may increase instability and errors of model. Here, we developed an algorithm that solves one-dimensional water, heat, and isotope transport equations with a fully coupled method (MOIST). Our results showed that MOIST is more stable under various spatial and temporal discretization than semi-coupled method and has good agreement with semi-analytical solutions of isotope transport. We also validated MOIST with long-term measurements from a lysimeter study under three scenarios with soil hydraulic parameters calibrated by HYDRUS-1D in the first two scenarios and by MOIST in the last scenario. In scenario 1, MOIST showed an overall NSE, KGE, and MAE of simulated δ18O of 0.47, 0.58, and 0.92‰, respectively, compared to the 0.31, 0.60, and 1.00‰ from HYDRUS-1D; In scenario 2, these indices of MOIST were 0.33, 0.52, and 1.04‰, respectively, compared to the 0.19, 0.58, and 1.15‰ from HYDRUS-1D; In scenario 3, calibrated MOIST exhibited the highest NSE (0.48) and KGE (0.76), the smallest MAE (0.90) among all scenarios. These findings indicate MOIST has better performance in simulating water flow and isotope transport in simplified ecosystems than HYDRUS-1D, suggesting the great potential of MOIST in furthering our understandings of ecohydrological processes in terrestrial ecosystems.
{"title":"A Fully Coupled Numerical Solution of Water, Vapor, Heat, and Water Stable Isotope Transport in Soil","authors":"Han Fu, Eric John Neil, Huijie Li, Bingcheng Si","doi":"10.1029/2024wr037068","DOIUrl":"https://doi.org/10.1029/2024wr037068","url":null,"abstract":"Modeling water stable isotope transport in soil is crucial to sharpen our understanding of water cycles in terrestrial ecosystems. Although several models for soil water isotope transport have been developed, many rely on a semi-coupled numerical approach, solving isotope transport only after obtaining solutions from water and heat transport equations. However, this approach may increase instability and errors of model. Here, we developed an algorithm that solves one-dimensional water, heat, and isotope transport equations with a fully coupled method (MOIST). Our results showed that MOIST is more stable under various spatial and temporal discretization than semi-coupled method and has good agreement with semi-analytical solutions of isotope transport. We also validated MOIST with long-term measurements from a lysimeter study under three scenarios with soil hydraulic parameters calibrated by HYDRUS-1D in the first two scenarios and by MOIST in the last scenario. In scenario 1, MOIST showed an overall <i>NSE</i>, <i>KGE</i>, and <i>MAE</i> of simulated δ<sup>18</sup>O of 0.47, 0.58, and 0.92‰, respectively, compared to the 0.31, 0.60, and 1.00‰ from HYDRUS-1D; In scenario 2, these indices of MOIST were 0.33, 0.52, and 1.04‰, respectively, compared to the 0.19, 0.58, and 1.15‰ from HYDRUS-1D; In scenario 3, calibrated MOIST exhibited the highest <i>NSE</i> (0.48) and <i>KGE</i> (0.76), the smallest <i>MAE</i> (0.90) among all scenarios. These findings indicate MOIST has better performance in simulating water flow and isotope transport in simplified ecosystems than HYDRUS-1D, suggesting the great potential of MOIST in furthering our understandings of ecohydrological processes in terrestrial ecosystems.","PeriodicalId":23799,"journal":{"name":"Water Resources Research","volume":"24 1","pages":""},"PeriodicalIF":5.4,"publicationDate":"2025-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142937763","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Heat storage change (HSC) is a crucial component of lake's thermal energy budget. Conventional temperature profile based models of HSC require location specific parameters such as lakebed topography. Based on the half-order time-derivative formula of heat fluxes, an analytical model was formulated for estimating HSC from water surface temperature and solar radiation without using geography dependent parameters. The proposed model was tested against field measurements at Poyang Lake, a shallow inland lake, which has pronounced seasonal variations in water level and lake area. Our analysis indicates that the model accurately simulates diurnal HSC with a coefficient of determination of 0.94 and a root mean squared error (RMSE) of 77.5 ± 21.6 Wm−2 for the study period. Larger nighttime RMSE (75.0 ± 26.8 Wm−2) than the daytime value (55.1 ± 19.7 W m−2) is attributable to larger measurement errors of nighttime turbulent fluxes. The estimation of HSC independent of temperature profile and lake-specific parameters by the proposed model facilitates remote sensing monitoring the HSC of global water bodies.
{"title":"A Half-Order Derivative Based Model of Lake Heat Storage Change","authors":"Yuanbo Liu, Liangjun Tang, Wanqiu Xing, Jingfeng Wang, Ruonan Wang, Yifan Cui, Qi Li","doi":"10.1029/2024wr038269","DOIUrl":"https://doi.org/10.1029/2024wr038269","url":null,"abstract":"Heat storage change (HSC) is a crucial component of lake's thermal energy budget. Conventional temperature profile based models of HSC require location specific parameters such as lakebed topography. Based on the half-order time-derivative formula of heat fluxes, an analytical model was formulated for estimating HSC from water surface temperature and solar radiation without using geography dependent parameters. The proposed model was tested against field measurements at Poyang Lake, a shallow inland lake, which has pronounced seasonal variations in water level and lake area. Our analysis indicates that the model accurately simulates diurnal HSC with a coefficient of determination of 0.94 and a root mean squared error (RMSE) of 77.5 ± 21.6 Wm<sup>−2</sup> for the study period. Larger nighttime RMSE (75.0 ± 26.8 Wm<sup>−2</sup>) than the daytime value (55.1 ± 19.7 W m<sup>−2</sup>) is attributable to larger measurement errors of nighttime turbulent fluxes. The estimation of HSC independent of temperature profile and lake-specific parameters by the proposed model facilitates remote sensing monitoring the HSC of global water bodies.","PeriodicalId":23799,"journal":{"name":"Water Resources Research","volume":"7 1","pages":""},"PeriodicalIF":5.4,"publicationDate":"2025-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142937722","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Lena M. Scheiffele, Matthias Munz, Till Francke, Gabriele Baroni, Sascha E. Oswald
Vadose zone models, calibrated with state variables, may offer a robust approach for deriving groundwater recharge. Cosmic-ray neutron sensing (CRNS) provides soil moisture over a large support volume (horizontal extent of hectares) and offers the opportunity to estimate water fluxes at this scale. However, the horizontal and vertical sensitivity of the method results in an inherently weighted water content, which poses a challenge for its application in soil hydrologic modeling. We systematically assess calibrating a soil hydraulic model in HYDRUS 1D at a cropped field site. Calibration was performed using different field-scale soil moisture time series and the ability of the model to represent root zone soil moisture and derive groundwater recharge was assessed. As our benchmark, we used a distributed point sensor network from within the footprint of the CRNS. Models calibrated on CRNS data or combinations of CRNS with deeper point measurements resulted in cumulative groundwater recharge comparable to the benchmark. While models based exclusively on CRNS data do not represent the root zone soil moisture dynamics adequately, combining CRNS with profile soil moisture overcomes this limitation. Models calibrated on CRNS data also perform well in timing the downward flux compared to an independent estimate based on soil water tension measurements. However, the latter provides quantitative groundwater recharge estimates spanning a wide range of values, including unrealistic highs exceeding local annual precipitation. Conversely, modeled groundwater recharge based on the distributed sensor network or on CRNS resulted in estimates ranging between 30% and 40% of annual precipitation.
{"title":"Enhancing Hectare-Scale Groundwater Recharge Estimation by Integrating Data From Cosmic-Ray Neutron Sensing Into Soil Hydrological Modeling","authors":"Lena M. Scheiffele, Matthias Munz, Till Francke, Gabriele Baroni, Sascha E. Oswald","doi":"10.1029/2024wr037641","DOIUrl":"https://doi.org/10.1029/2024wr037641","url":null,"abstract":"Vadose zone models, calibrated with state variables, may offer a robust approach for deriving groundwater recharge. Cosmic-ray neutron sensing (CRNS) provides soil moisture over a large support volume (horizontal extent of hectares) and offers the opportunity to estimate water fluxes at this scale. However, the horizontal and vertical sensitivity of the method results in an inherently weighted water content, which poses a challenge for its application in soil hydrologic modeling. We systematically assess calibrating a soil hydraulic model in HYDRUS 1D at a cropped field site. Calibration was performed using different field-scale soil moisture time series and the ability of the model to represent root zone soil moisture and derive groundwater recharge was assessed. As our benchmark, we used a distributed point sensor network from within the footprint of the CRNS. Models calibrated on CRNS data or combinations of CRNS with deeper point measurements resulted in cumulative groundwater recharge comparable to the benchmark. While models based exclusively on CRNS data do not represent the root zone soil moisture dynamics adequately, combining CRNS with profile soil moisture overcomes this limitation. Models calibrated on CRNS data also perform well in timing the downward flux compared to an independent estimate based on soil water tension measurements. However, the latter provides quantitative groundwater recharge estimates spanning a wide range of values, including unrealistic highs exceeding local annual precipitation. Conversely, modeled groundwater recharge based on the distributed sensor network or on CRNS resulted in estimates ranging between 30% and 40% of annual precipitation.","PeriodicalId":23799,"journal":{"name":"Water Resources Research","volume":"107 1","pages":""},"PeriodicalIF":5.4,"publicationDate":"2025-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142936553","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jiahao Zhang, Mengzhen Xu, Boris Huber, Markus Grünzner, Koen Blanckaert
Mussel biofouling increases energy losses in hydraulic structures. The first contribution of this paper is the quantification of the mussel-induced equivalent sand roughness ks as function of the mussel attachment density N and the shell length L. Laboratory experiments reveal that ks/L ≈ 1.5 for a continuous regular layer of mussels, which is found for N L2 > 1.2. For 0.5 < N L2 < 1.2, the mussels form a continuous irregular roughness layer with increased values of ks/L of up to 2.4. These geometrical irregularities are interpreted as macro-roughness elements, that is, roughness elements with a spatial scale larger than that of an individual mussel. For N L2 < 0.5, the density of the irregularities is too low to act as macro-roughness elements leading to ks/L < 1.5. The second contribution is the establishment of a threshold criterion for the importance of filtering activity on ks based on data from the here reported experiments and data reported in literature in other configurations and/or with other mussel species. It is found that laboratory conditions are often close to the threshold value but that mussel filtering is always negligible in large hydraulic structures. The third contribution is the development of a method based on 3-D numerical simulations for estimating a Darcy-Weisbach friction factor f for walls that are only partially covered with patches of mussels. An application example illustrates how the thus obtained f can be used in a 1-D model for quantifying the additional energy losses in large water transfer projects.
{"title":"Roughness and Energy Losses Induced by Mussel Growth on the Walls of Hydraulic Structures and Application to a Water Transfer Project","authors":"Jiahao Zhang, Mengzhen Xu, Boris Huber, Markus Grünzner, Koen Blanckaert","doi":"10.1029/2023wr036503","DOIUrl":"https://doi.org/10.1029/2023wr036503","url":null,"abstract":"Mussel biofouling increases energy losses in hydraulic structures. The first contribution of this paper is the quantification of the mussel-induced equivalent sand roughness <i>k</i><sub><i>s</i></sub> as function of the mussel attachment density <i>N</i> and the shell length <i>L</i>. Laboratory experiments reveal that <i>k</i><sub><i>s</i></sub><i>/L</i> ≈ 1.5 for a continuous regular layer of mussels, which is found for <i>N L</i><sup>2</sup> > 1.2. For 0.5 < <i>N L</i><sup>2</sup> < 1.2, the mussels form a continuous irregular roughness layer with increased values of <i>k</i><sub><i>s</i></sub><i>/L</i> of up to 2.4. These geometrical irregularities are interpreted as macro-roughness elements, that is, roughness elements with a spatial scale larger than that of an individual mussel. For <i>N L</i><sup>2</sup> < 0.5, the density of the irregularities is too low to act as macro-roughness elements leading to <i>k</i><sub><i>s</i></sub><i>/L</i> < 1.5. The second contribution is the establishment of a threshold criterion for the importance of filtering activity on <i>k</i><sub><i>s</i></sub> based on data from the here reported experiments and data reported in literature in other configurations and/or with other mussel species. It is found that laboratory conditions are often close to the threshold value but that mussel filtering is always negligible in large hydraulic structures. The third contribution is the development of a method based on 3-D numerical simulations for estimating a Darcy-Weisbach friction factor <i>f</i> for walls that are only partially covered with patches of mussels. An application example illustrates how the thus obtained <i>f</i> can be used in a 1-D model for quantifying the additional energy losses in large water transfer projects.","PeriodicalId":23799,"journal":{"name":"Water Resources Research","volume":"23 1","pages":""},"PeriodicalIF":5.4,"publicationDate":"2025-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142936552","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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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