Transit Time Estimation in Catchments: Recent Developments and Future Directions

Water Resources Research, Journal Year: 2022, Volume and Issue: 58(11)

Published: Nov. 1, 2022

Abstract Water transit time is now a standard measure in catchment hydrological and ecohydrological research. The last comprehensive review of modeling approaches was published 15+ years ago. But since then the field has largely expanded with new data, theory applications. Here, we these developments focus on water‐age‐balance data‐based approaches. We discuss compare methods including StorAge‐Selection functions, well/partially mixed compartments, water age tracking through spatially distributed models, direct estimates from controlled experiments, young fractions, ensemble hydrograph separation. unify some heterogeneity literature that crept many approaches, an attempt to clarify key differences similarities among them. Finally, point open questions research, what still need theory, work, community practice.

Language: Английский

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Instructive Surprises in the Hydrological Functioning of Landscapes

Annual Review of Earth and Planetary Sciences, Journal Year: 2023, Volume and Issue: 51(1), P. 277 - 299

Published: Jan. 10, 2023

Landscapes receive water from precipitation and then transport, store, mix, release it, both downward to streams upward vegetation. How they do this shapes floods, droughts, biogeochemical cycles, contaminant the health of terrestrial aquatic ecosystems. Because many key processes occur invisibly in subsurface, our conceptualization them has often relied heavily on physical intuition. In recent decades, however, much intuition been overthrown by field observations emerging measurement methods, particularly involving isotopic tracers. Here we summarize surprises that have transformed understanding hydrological at scale hillslopes drainage basins. These forced a shift perspective process conceptualizations are relatively static, homogeneous, linear, stationary ones predominantly dynamic, heterogeneous, nonlinear, nonstationary. ▪Surprising novel measurements transforming functioning landscapes.▪Even during storm peaks, streamflow is composed mostly stored landscape for weeks, months, or years.▪Streamflow tree uptake originate different subsurface storages seasons’ precipitation.▪Stream networks dynamically extend retract as wets dries, stream reaches lose flow into underlying aquifers.

Language: Английский

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Phloem water isotopically different to xylem water: Potential causes and implications for ecohydrological tracing

Ecohydrology, Journal Year: 2022, Volume and Issue: 15(3)

Published: March 16, 2022

Abstract The stable isotopes of hydrogen and oxygen in xylem water are often used to investigate tree sources. But this traditional approach does not acknowledge the contribution stored phloem transpiration how may affect source interpretations. Additionally, there is a prevailing assumption that no isotope fractionation during transport. Here, we systematically sampled at daily subdaily resolutions large lysimeter planted with Salix viminalis . Stem diurnal change storage rates were also measured. Our results show significantly less enriched heavy than water. At resolution, observed larger isotopic difference between refilling under periods deficit. These findings contrast expectation heavy‐isotope due downward transport leaf signatures. Because previous evidence aquaporin mediated higher osmotic permeability lighter isotopologues across aquaporins, propose radial xylem–phloem boundary drive relative depletion their enrichment xylem.

Language: Английский

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Challenges in studying water fluxes within the soil-plant-atmosphere continuum: A tracer-based perspective on pathways to progress

The Science of The Total Environment, Journal Year: 2023, Volume and Issue: 881, P. 163510 - 163510

Published: April 12, 2023

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 StorAge Selection (SAS)-function models

Hydrology and earth system sciences, Journal Year: 2023, Volume and Issue: 27(16), P. 3083 - 3114

Published: Aug. 24, 2023

Abstract. Stable isotopes (δ18O) and tritium (3H) are frequently used as tracers in environmental sciences to estimate age distributions of water. However, it has previously been argued that seasonally variable tracers, such δ18O, generally systematically fail detect the 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, δ18O 3H data, we scrutinized above postulate together with potential role spatial aggregation effects exacerbating underestimation ages. This was done by comparing inferred from total 21 different model implementations, including time-invariant, lumped-parameter sine-wave (SW) convolution integral (CO) models well StorAge Selection (SAS)-function (P-SAS) integrated hydrological combination SAS functions (IM-SAS). We found that, indeed, commonly SW CO mean transit times (MTTs) ∼ 1–2 years lower than those obtained same models, reaching MTTs ∼10 years. contrast, several implementations P-SAS IM-SAS not only allowed simultaneous representations storage variations streamflow stream signals, but these were, 11–17 years, also much higher similar 3H, which suggested 11–13 Characterized parameter posterior distributions, particular parameters control age, individually constrained or observations exhibited limited differences magnitudes parts temporal variability time (TTDs) response changing wetness conditions. suggests both lead comparable descriptions how is routed through system. These findings provide evidence 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 lumped distributed provided inconclusive results. Overall, demonstrates reported most likely result use other per se. Rather, largely be attributed choices approaches complexity considering transient conditions next aspects. Given additional vulnerability due potentially still unknown effects, advocate avoiding type if possible instead adopting SAS-based time-variant formulations models.

Language: Английский

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Modelling temporal variability of in situ soil water and vegetation isotopes reveals ecohydrological couplings in a riparian willow plot

Biogeosciences, Journal Year: 2022, Volume and Issue: 19(9), P. 2465 - 2485

Published: May 12, 2022

Abstract. The partitioning of water fluxes in the critical zone is great interest due to implications for understanding cycling and quantifying availability various ecosystem services. We used tracer-aided ecohydrological model EcH2O-iso use stable isotopes help evaluate water, energy, biomass dynamics at an intensively monitored study plot under two willow trees, a riparian species, Berlin, Germany. Importantly, we assessed value situ soil plant isotope data helping quantify xylem sources transit times, with coupled estimates temporal ages root uptake water. willows showed high through evapotranspiration, limited percolation summer precipitation deeper layers dominance shallow (>80 % upper 10 cm, 70 %–78 transpiration/evapotranspiration). Lower evapotranspiration grass (52 %–55 transpiration/evapotranspiration) resulted higher moisture storage, greater evaporation, more Biomass allocation was predominantly foliage growth (57 78 willow). Shallow age estimated be similar (15–17 d). Considering potential times substantial improvement model's capability simulate isotopic composition demonstrates using aid modelling. Root predominately derived from events (56 %) had average 35 d, transport taking least 6.2–8.1 d. By evaluating mass balances along partitioning, energy budgets, allocation, proved useful tool assessing within resolution, particularly transport, which are all necessary short- long-term assessment growth.

Language: Английский

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Spatially Explicit Linkages Between Redox Potential Cycles and Soil Moisture Fluctuations

Water Resources Research, Journal Year: 2023, Volume and Issue: 59(3)

Published: Feb. 17, 2023

Abstract Reduction‐oxidation cycles measured through soil redox potential ( E h ) are associated with dynamic microbial activity. Understanding changes in the composition of, and resource use by, communities requires predictability under shifting hydrologic drivers. Here, 50‐cm column installations manipulated to vary geochemical conditions, extensively monitored by a dense instrumental deployment record depth‐time variation of physical biogeochemical conditions. We contrast measurements , saturation key compounds water samples (probing majority metabolisms) computations relevant state variables, investigate interplay between moisture dynamics. Our results highlight importance joint spatially resolved flow/transport processes, worth contrasting experiments for sufficient understanding dynamics, minimum amount biogeochemistry needed characterize dynamics electron donors/acceptors that responsible patterns not directly explained oxic/anoxic transitions. As an example, concentrations sulfate, ammonium iron II suggest coexistence both oxic anoxic find local velocity (a threshold value time derivative saturation) exerts significant hysteretic control on oxygen intrusion cycling potentials, approaches using single level as determinant findings improve our ability target how where hotspots activity develop within communities.

Language: Английский

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Upscaling Tracer‐Aided Ecohydrological Modeling to Larger Catchments: Implications for Process Representation and Heterogeneity in Landscape Organization

Water Resources Research, Journal Year: 2023, Volume and Issue: 59(3)

Published: Feb. 21, 2023

Abstract Stable isotopes of water are ideal tracers to integrate into process‐based models, advancing ecohydrological understanding. Current tracer‐aided modeling is mostly conducted in relatively small‐scale catchments, due limited tracer data availability and often highly damped stream isotope signals larger catchments (>100 km 2 ). Recent model developments have prioritized better spatial representation, offering new potential for upscaling modeling. Here, we adapted the fully distributed EcH O‐iso Selke catchment (456 , Germany), incorporating monthly sampled from seven sites between 2012 2017. Parameter sensitivity analysis indicated that information content was generally complementary discharge more sensitive runoff partitioning, soil energy dynamics. Multi‐criteria calibrations revealed inclusion could significantly improve performance during validations simulations, resulting reasonable estimates seasonality ages. However, capturing isotopic non‐linear near‐surface processes remained challenging upscaled model, but still allowed plausible simulation ages reflecting non‐stationarity transport mixing. The detailed also helped unravel spatio‐temporally varying patterns storage‐flux‐age interactions their interplay under severe drought conditions. Embracing challenges, this study demonstrated even coarsely can be value aiding consequent process representation catchments. derived innovative insights functioning at scales commensurate with management decision making, particular importance guiding science‐based measures tackling environmental changes.

Language: Английский

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Drought in a warmer, CO ₂ -rich climate restricts grassland water use and soil water mixing

Science, Journal Year: 2025, Volume and Issue: 387(6731), P. 290 - 296

Published: Jan. 16, 2025

Soil water sustains terrestrial life, yet its fate is uncertain under a changing climate. We conducted deuterium labeling experiment to determine whether elevated atmospheric carbon dioxide (CO 2 ), warming, and drought impact soil storage transport in temperate grassland. Elevated CO created wetter rootzone compared with ambient conditions, whereas warming decreased moisture. remained well mixed all global change treatments except for summer combined . These caused the grassland conserve restricted flow large, rapidly draining pores without mixing small, slowly pores. Our results suggest that warmer, more -rich climate can severely alter ecohydrology by constraining postdrought use.

Language: Английский

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A Continuous Root Water Uptake Isotope Mixing Model

Water Resources Research, Journal Year: 2024, Volume and Issue: 60(8)

Published: Aug. 1, 2024

Abstract The depth‐wise distribution of root water uptake is typically inferred through linear mixing models that utilize knowledge stable isotopes in soil and plants. However, these existing often represent the profile discrete segments, potentially introducing significant uncertainty bias into results. In this study, we introduced a novel model combines Bayesian framework with continuous pattern, named CrisPy. To evaluate performance CrisPy, conducted virtual field‐based tests under several types prior information. CrisPy showed accurate robust reconstruction true various information settings test. By contrast, model, MixSIAR was greatly influenced by deviated from profile. mean squared error proportions ranged 3.6% to 7.4%, while exhibited values 6.3%–15.2%. Furthermore, posterior predictive checking indicated effectively reconstructed standard deviations plant isotopic compositions both tests. MixSIAR, however, underestimated overestimated deviation compositions. These findings collectively support enhanced accuracy, greater robustness, reduced comparison MixSIAR. Therefore, provides powerful tool for partitioning sources.

Language: Английский

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