Physical Interpretation of Time‐Varying StorAge Selection Functions in a Bench‐Scale Hillslope Experiment via Geophysical Imaging of Ages of Water

Water Resources Research, Journal Year: 2022, Volume and Issue: 58(4)

Published: Feb. 28, 2022

Abstract Understanding transit times (TT) and residence (RT) distributions of water in catchments has recently received a great deal attention hydrologic research since it can inform about important processes relevant to the quality delivered by streams landscape resilience anthropogenic inputs. The theory time (TTD) is practical framework for understanding TT natural landscapes but, due its lumped nature, only hint at possible internal taking place subsurface. While allowing direct observation movement, Electrical Resistivity Imaging (ERI) be leveraged better understand variability ages within subsurface, thus enabling investigation physical controlling time‐variability TTD. In this study, we estimated time‐variable TTD bench‐scale bare‐soil sloping soil lysimeter through StorAge Selection (SAS) framework, traditional lumped‐systems method, based on sampling output tracer concentrations, as well an ERI SAS one, spatially distributed images ages. We compared ERI‐based results with output‐based estimates discuss viability laboratory experiments ERI‐derived evolution were able elucidate mechanisms driving being discharged system, which was characterized delayed discharge younger starting highest storage level continuing throughout table recession.

Language: Английский

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The Role of Topography in Controlling Evapotranspiration Age

Journal of Geophysical Research Atmospheres, Journal Year: 2023, Volume and Issue: 128(18)

Published: Sept. 7, 2023

Abstract Evapotranspiration (ET) age is a key metric of water sustainability but major unknown partly due to the extreme difficulty in modeling it. Groundwater found be important ET variations small‐scale studies, yet our understanding insufficient because groundwater systems are nested across scales. Here, we conducted GPU‐accelerated particle tracking with integrated hydrologic quantify at regional scale ∼0.4 M km 2 . Simulation results reveal topography‐driven flow paths shaping spatial and temporal patterns variations. On ridges, where root zone decoupling deep subsurface storage, generally young, seasonal dominated by meteorological conditions. In valley bottom, old, significant subseasonal caused convergence paths. hillslopes table depths ranging from 1 10 m, shows strong connections lateral regulated demand. Our approach provides insights into basic linkages between topography large scale. work highlights perspective multiscale studies age, suggesting new field experiments test these process determine if such warrant inclusion Earth System Models.

Language: Английский

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Stepping beyond perfectly mixed conditions in soil hydrological modelling using a Lagrangian approach

Hydrology and earth system sciences, Journal Year: 2022, Volume and Issue: 26(6), P. 1615 - 1629

Published: March 25, 2022

Abstract. A recent experiment of Bowers et al. (2020) revealed that diffusive mixing water isotopes (δ2H and δ18O) over a fully saturated soil sample few centimetres in length required several days to equilibrate completely. In this study, we present an approach simulate such time-delayed processes, on the pore scale, beyond instantaneously perfectly mixed conditions. The (DIPMI) is based Lagrangian perspective particles moving by diffusion space volume carrying concentrations solutes or isotopes. idea DIPMI account for self-diffusion across characteristic scale using pore-size-dependent coefficients. model parameters can be derived from soil-specific retention curve, no further calibration needed. We test our simulating experimental data (2020). Simulation results show feasibility reproducing measured times at different tensions space. This result corroborates finding soils depends size distribution specific properties. Additionally, perform virtual with leaching processes solute vertical, column compare against simulations common perfect assumption. reveal frequently observed steep rise long tailing breakthrough curves, which are typically associated non-uniform transport heterogeneous soils, may also occur homogeneous media as imperfect subscale macroscopically matrix.

Language: Английский

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Stable water isotopes and tritium tracers tell the same tale: No evidence for underestimation of catchment transit times inferred by stable isotopes in SAS function models

Published: Dec. 13, 2022

Abstract. Stable isotopes (δ18O) and tritium (3H) are frequently used as tracers in environmental sciences to estimate the age distributions of water. However, it has previously been argued that seasonally variable tracers, such δ18O, generally systematically fail detect tails water therefore substantially underestimate ages compared radioactive 3H. In this study for Neckar river basin central Europe based on a >20-year record hydrological, 3H data, we scrutinized above postulate together with potential role spatial aggregation effects exacerbate underestimation ages. This was done by comparing inferred from δ18O total 12 different model implementations, including lumped parameter sine-wave (SW) convolution integral models (CO) well integrated hydrological combination SAS-functions (IM-SAS). We found that, indeed, commonly SW CO mean transit times (MTT) ~ 1–2 years lower than those obtained same models, reaching MTTs 10 years. contrast, several implementations IM-SAS did not only allow simultaneous representations stream flow signals, but these were 16 much higher similar 3H, which suggested 15 Characterized posterior distributions, particular parameters control age, individually constrained or observations, exhibited limited differences magnitudes parts temporal variability TTDs response changing wetness conditions. suggests both lead comparable descriptions how is routed through system. These findings provide evidence allowed us reject hypothesis tracer “cannot see older about 4 years” truncates corresponding leading underestimations Instead, our results broad equivalence systems characterized at least 15–20 The question degree heterogeneity can further adversely affect estimates remains unresolved distributed provided inconclusive results. Overall, demonstrates reported most likely result use other per se. Rather, be largely attributed choices approaches complexity considering next aspects. Given additional vulnerability due potentially other, still unknown effects, we, therefore, advocate avoid type if possible, instead adopt SAS-based formulations.

Language: Английский

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Comment on hess-2022-400

Published: Jan. 8, 2023

Stable isotopes (δ18O) and tritium (3H) are frequently used as tracers in environmental sciences to estimate the age distributions of water. However, it has previously been argued that seasonally variable tracers, such δ18O, generally systematically fail detect tails water therefore substantially underestimate ages compared radioactive 3H. In this study for Neckar river basin central Europe based on a >20-year record hydrological, 3H data, we scrutinized above postulate together with potential role spatial aggregation effects exacerbate underestimation ages. This was done by comparing inferred from δ18O total 12 different model implementations, including lumped parameter sine-wave (SW) convolution integral models (CO) well integrated hydrological combination SAS-functions (IM-SAS). We found that, indeed, commonly SW CO mean transit times (MTT) ~ 1–2 years lower than those obtained same models, reaching MTTs 10 years. contrast, several implementations IM-SAS did not only allow simultaneous representations stream flow signals, but these were 16 much higher similar 3H, which suggested 15 Characterized posterior distributions, particular parameters control age, individually constrained or observations, exhibited limited differences magnitudes parts temporal variability TTDs response changing wetness conditions. suggests both lead comparable descriptions how is routed through system. These findings provide evidence allowed us reject hypothesis tracer “cannot see older about 4 years” truncates corresponding leading underestimations Instead, our results broad equivalence systems characterized at least 15–20 The question degree heterogeneity can further adversely affect estimates remains unresolved distributed provided inconclusive results. Overall, demonstrates reported most likely result use other per se. Rather, be largely attributed choices approaches complexity considering next aspects. Given additional vulnerability due potentially other, still unknown effects, we, therefore, advocate avoid type if possible, instead adopt SAS-based formulations.

Language: Английский

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