Articles | Volume 20, issue 1
https://doi.org/10.5194/hess-20-299-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
https://doi.org/10.5194/hess-20-299-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
Research article
| Highlight paper
| 
19 Jan 2016
Research article | Highlight paper |
| 19 Jan 2016
Aggregation in environmental systems – Part 2: Catchment mean transit times and young water fractions under hydrologic nonstationarity
ETH Zürich, Zurich, Switzerland
Swiss Federal Research Institute WSL, Birmensdorf, Switzerland
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Hydrol. Earth Syst. Sci., 24, 1101–1107, https://doi.org/10.5194/hess-24-1101-2020, https://doi.org/10.5194/hess-24-1101-2020, 2020
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James W. Kirchner and Scott T. Allen
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Julia L. A. Knapp, Colin Neal, Alessandro Schlumpf, Margaret Neal, and James W. Kirchner
Hydrol. Earth Syst. Sci., 23, 4367–4388, https://doi.org/10.5194/hess-23-4367-2019, https://doi.org/10.5194/hess-23-4367-2019, 2019
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Scott T. Allen, Scott Jasechko, Wouter R. Berghuijs, Jeffrey M. Welker, Gregory R. Goldsmith, and James W. Kirchner
Hydrol. Earth Syst. Sci., 23, 3423–3436, https://doi.org/10.5194/hess-23-3423-2019, https://doi.org/10.5194/hess-23-3423-2019, 2019
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Andrea Rücker, Stefan Boss, James W. Kirchner, and Jana von Freyberg
Hydrol. Earth Syst. Sci., 23, 2983–3005, https://doi.org/10.5194/hess-23-2983-2019, https://doi.org/10.5194/hess-23-2983-2019, 2019
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Scott T. Allen, James W. Kirchner, Sabine Braun, Rolf T. W. Siegwolf, and Gregory R. Goldsmith
Hydrol. Earth Syst. Sci., 23, 1199–1210, https://doi.org/10.5194/hess-23-1199-2019, https://doi.org/10.5194/hess-23-1199-2019, 2019
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James W. Kirchner
Hydrol. Earth Syst. Sci., 23, 303–349, https://doi.org/10.5194/hess-23-303-2019, https://doi.org/10.5194/hess-23-303-2019, 2019
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Jana von Freyberg, Bjørn Studer, Michael Rinderer, and James W. Kirchner
Hydrol. Earth Syst. Sci., 22, 5847–5865, https://doi.org/10.5194/hess-22-5847-2018, https://doi.org/10.5194/hess-22-5847-2018, 2018
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We show event- and pre-event-water volumes as fractions of precipitation, rather than discharge, to provide an alternative and more insightful approach to study catchment hydrological processes. For this, we analyze 24 storm events using high-frequency measurements of stable water isotopes in stream water and precipitation at a pre-Alpine catchment. Antecedent wetness and storm characteristics are dominant controls on event-water discharge and pre-event-water mobilization from storage.
Daniele Penna, Luisa Hopp, Francesca Scandellari, Scott T. Allen, Paolo Benettin, Matthias Beyer, Josie Geris, Julian Klaus, John D. Marshall, Luitgard Schwendenmann, Till H. M. Volkmann, Jana von Freyberg, Anam Amin, Natalie Ceperley, Michael Engel, Jay Frentress, Yamuna Giambastiani, Jeff J. McDonnell, Giulia Zuecco, Pilar Llorens, Rolf T. W. Siegwolf, Todd E. Dawson, and James W. Kirchner
Biogeosciences, 15, 6399–6415, https://doi.org/10.5194/bg-15-6399-2018, https://doi.org/10.5194/bg-15-6399-2018, 2018
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Nikos Theodoratos, Hansjörg Seybold, and James W. Kirchner
Earth Surf. Dynam., 6, 779–808, https://doi.org/10.5194/esurf-6-779-2018, https://doi.org/10.5194/esurf-6-779-2018, 2018
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Jana von Freyberg, Scott T. Allen, Stefan Seeger, Markus Weiler, and James W. Kirchner
Hydrol. Earth Syst. Sci., 22, 3841–3861, https://doi.org/10.5194/hess-22-3841-2018, https://doi.org/10.5194/hess-22-3841-2018, 2018
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We explored how the fraction of streamflow younger than ca. 3 months (Fyw) varies with landscape characteristics and climatic forcing, using an extensive isotope data set from 22 Swiss catchments. Overall, Fyw tends to be larger when catchments are wet and discharge is correspondingly higher, indicating an increase in the proportional contribution of faster flow paths at higher flows. We quantify this
discharge sensitivityof Fyw and relate it to the dominant streamflow-generating mechanisms.
Paolo Benettin, Till H. M. Volkmann, Jana von Freyberg, Jay Frentress, Daniele Penna, Todd E. Dawson, and James W. Kirchner
Hydrol. Earth Syst. Sci., 22, 2881–2890, https://doi.org/10.5194/hess-22-2881-2018, https://doi.org/10.5194/hess-22-2881-2018, 2018
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Evaporation causes the isotopic composition of soil water to become different from that of the original precipitation source. If multiple samples originating from the same source are available, they can be used to reconstruct the original source composition. However, soil water is influenced by seasonal variability in both precipitation sources and evaporation patterns. We show that this variability, if not accounted for, can lead to biased estimates of the precipitation source water.
Albrecht von Boetticher, Jens M. Turowski, Brian W. McArdell, Dieter Rickenmann, Marcel Hürlimann, Christian Scheidl, and James W. Kirchner
Geosci. Model Dev., 10, 3963–3978, https://doi.org/10.5194/gmd-10-3963-2017, https://doi.org/10.5194/gmd-10-3963-2017, 2017
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Jana von Freyberg, Bjørn Studer, and James W. Kirchner
Hydrol. Earth Syst. Sci., 21, 1721–1739, https://doi.org/10.5194/hess-21-1721-2017, https://doi.org/10.5194/hess-21-1721-2017, 2017
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We present a newly developed instrument package that enables the online analysis of stable water isotopes and major ion chemistry at 30 min intervals in the field. The resulting data streams provide an unprecedented view of hydrochemical dynamics on the catchment scale. Based on a detailed analysis of the variable behavior of isotopic and chemical tracers in stream water and precipitation over a 4-week period, we developed a conceptual hypothesis for runoff generation in the studied catchment.
Elham Rouholahnejad Freund and James W. Kirchner
Hydrol. Earth Syst. Sci., 21, 217–233, https://doi.org/10.5194/hess-21-217-2017, https://doi.org/10.5194/hess-21-217-2017, 2017
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Our analysis shows that averaging over sub-grid heterogeneity in precipitation and potential evapotranspiration (ET), as typical earth system models do, overestimates the average of the spatially variable ET. We also show when aridity index increases with altitude, lateral redistribution would transfer water from more humid uplands to more arid lowlands, resulting in a net increase in ET. Therefore, the Earth system models that neglect lateral transfer underestimate ET in those regions.
Alexander R. Beer, James W. Kirchner, and Jens M. Turowski
Earth Surf. Dynam., 4, 885–894, https://doi.org/10.5194/esurf-4-885-2016, https://doi.org/10.5194/esurf-4-885-2016, 2016
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Spatial bedrock erosion data from stream channels are important for engineering issues and landscape evolution model assessment. However, acquiring such data is challenging and only few data sets exist. Detecting changes in repeated photographs of painted bedrock surfaces easily allows for semi-quantitative conclusions on the spatial distribution of sediment transport and its effects: abrasion on surfaces facing the streamflow and shielding of surfaces by abundant sediment.
Albrecht von Boetticher, Jens M. Turowski, Brian W. McArdell, Dieter Rickenmann, and James W. Kirchner
Geosci. Model Dev., 9, 2909–2923, https://doi.org/10.5194/gmd-9-2909-2016, https://doi.org/10.5194/gmd-9-2909-2016, 2016
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Debris flows are characterized by unsteady flows of water with different content of clay, silt, sand, gravel, and large particles, resulting in a dense moving mixture mass. Here we present a three-dimensional fluid dynamic solver that simulates the flow as a mixture of a pressure-dependent rheology model of the gravel mixed with a Herschel–Bulkley rheology of the fine material suspension. We link rheological parameters to the material composition. The user must specify two free model parameters.
J. W. Kirchner
Hydrol. Earth Syst. Sci., 20, 279–297, https://doi.org/10.5194/hess-20-279-2016, https://doi.org/10.5194/hess-20-279-2016, 2016
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Catchment mean transit times have been widely inferred from seasonal cycles of environmental tracers in precipitation and streamflow. Here I show that these cycles yield strongly biased estimates of mean transit times in spatially heterogeneous catchments (and, by implication, in real-world catchments). However, I also show that these cycles can be used to reliably estimate the fraction of "young" water in streamflow, meaning water that fell as precipitation less than roughly 2–3 months ago.
F. Kobierska, T. Jonas, J. W. Kirchner, and S. M. Bernasconi
Hydrol. Earth Syst. Sci., 19, 3681–3693, https://doi.org/10.5194/hess-19-3681-2015, https://doi.org/10.5194/hess-19-3681-2015, 2015
A. von Boetticher, J. M. Turowski, B. W. McArdell, D. Rickenmann, M. Hürlimann, C. Scheidl, and J. W. Kirchner
Geosci. Model Dev. Discuss., https://doi.org/10.5194/gmdd-8-6379-2015, https://doi.org/10.5194/gmdd-8-6379-2015, 2015
Preprint withdrawn
F. U. M. Heimann, D. Rickenmann, J. M. Turowski, and J. W. Kirchner
Earth Surf. Dynam., 3, 15–34, https://doi.org/10.5194/esurf-3-15-2015, https://doi.org/10.5194/esurf-3-15-2015, 2015
F. U. M. Heimann, D. Rickenmann, M. Böckli, A. Badoux, J. M. Turowski, and J. W. Kirchner
Earth Surf. Dynam., 3, 35–54, https://doi.org/10.5194/esurf-3-35-2015, https://doi.org/10.5194/esurf-3-35-2015, 2015
James W. Kirchner
Hydrol. Earth Syst. Sci., 28, 4427–4454, https://doi.org/10.5194/hess-28-4427-2024, https://doi.org/10.5194/hess-28-4427-2024, 2024
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Here, I present a new way to quantify how streamflow responds to rainfall across a range of timescales. This approach can estimate how different rainfall intensities affect streamflow. It can also quantify how runoff response to rainfall varies, depending on how wet the landscape already is before the rain falls. This may help us to understand processes and landscape properties that regulate streamflow and to assess the susceptibility of different landscapes to flooding.
Marius G. Floriancic, Scott T. Allen, and James W. Kirchner
Hydrol. Earth Syst. Sci., 28, 4295–4308, https://doi.org/10.5194/hess-28-4295-2024, https://doi.org/10.5194/hess-28-4295-2024, 2024
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We use a 3-year time series of tracer data of streamflow and soils to show how water moves through the subsurface to become streamflow. Less than 50% of soil water consists of rainfall from the last 3 weeks. Most annual streamflow is older than 3 months, and waters in deep subsurface layers are even older; thus deep layers are not the only source of streamflow. After wet periods more rainfall was found in the subsurface and the stream, suggesting that water moves quicker through wet landscapes.
Marius G. Floriancic, Michael P. Stockinger, James W. Kirchner, and Christine Stumpp
Hydrol. Earth Syst. Sci., 28, 3675–3694, https://doi.org/10.5194/hess-28-3675-2024, https://doi.org/10.5194/hess-28-3675-2024, 2024
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The Alps are a key water resource for central Europe, providing water for drinking, agriculture, and hydropower production. To assess water availability in streams, we need to understand how much streamflow is derived from old water stored in the subsurface versus more recent precipitation. We use tracer data from 32 Alpine streams and statistical tools to assess how much recent precipitation can be found in Alpine rivers and how this amount is related to catchment properties and climate.
Shaozhen Liu, Ilja van Meerveld, Yali Zhao, Yunqiang Wang, and James W. Kirchner
Hydrol. Earth Syst. Sci., 28, 205–216, https://doi.org/10.5194/hess-28-205-2024, https://doi.org/10.5194/hess-28-205-2024, 2024
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We study the seasonal and spatial patterns of soil moisture in 0–500 cm soil using 89 monitoring sites in a loess catchment with monsoonal climate. Soil moisture is highest during the months of least precipitation and vice versa. Soil moisture patterns at the hillslope scale are dominated by the aspect-controlled evapotranspiration variations (a local control), not by the hillslope convergence-controlled downslope flow (a nonlocal control), under both dry and wet conditions.
Tobias Nicollier, Gilles Antoniazza, Lorenz Ammann, Dieter Rickenmann, and James W. Kirchner
Earth Surf. Dynam., 10, 929–951, https://doi.org/10.5194/esurf-10-929-2022, https://doi.org/10.5194/esurf-10-929-2022, 2022
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Monitoring sediment transport is relevant for flood safety and river restoration. However, the spatial and temporal variability of sediment transport processes makes their prediction challenging. We investigate the feasibility of a general calibration relationship between sediment transport rates and the impact signals recorded by metal plates installed in the channel bed. We present a new calibration method based on flume experiments and apply it to an extensive dataset of field measurements.
Sebastian A. Krogh, Lucia Scaff, James W. Kirchner, Beatrice Gordon, Gary Sterle, and Adrian Harpold
Hydrol. Earth Syst. Sci., 26, 3393–3417, https://doi.org/10.5194/hess-26-3393-2022, https://doi.org/10.5194/hess-26-3393-2022, 2022
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We present a new way to detect snowmelt using daily cycles in streamflow driven by solar radiation. Results show that warmer sites have earlier and more intermittent snowmelt than colder sites, and the timing of early snowmelt events is strongly correlated with the timing of streamflow volume. A space-for-time substitution shows greater sensitivity of streamflow timing to climate change in colder rather than in warmer places, which is then contrasted with land surface simulations.
Nikos Theodoratos and James W. Kirchner
Earth Surf. Dynam., 9, 1545–1561, https://doi.org/10.5194/esurf-9-1545-2021, https://doi.org/10.5194/esurf-9-1545-2021, 2021
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We examine stream-power incision and linear diffusion landscape evolution models with and without incision thresholds. We present a steady-state relationship between curvature and the steepness index, which plots as a straight line. We view this line as a counterpart to the slope–area relationship for the case of landscapes with hillslope diffusion. We show that simple shifts and rotations of this line graphically express the topographic response of landscapes to changes in model parameters.
Scott T. Allen and James W. Kirchner
Hydrol. Earth Syst. Sci. Discuss., https://doi.org/10.5194/hess-2020-683, https://doi.org/10.5194/hess-2020-683, 2021
Revised manuscript not accepted
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Extracting water from plant stems can introduce analytical errors in isotope analyses. We demonstrate that sensitivities to suspected errors can be evaluated and that conclusions drawn from extracted plant water isotope ratios are neither generally valid nor generally invalid. Ultimately, imperfect measurements of plant and soil water isotope ratios can continue to support useful inferences if study designs are appropriately matched to their likely biases and uncertainties.
Jana von Freyberg, Julia L. A. Knapp, Andrea Rücker, Bjørn Studer, and James W. Kirchner
Hydrol. Earth Syst. Sci., 24, 5821–5834, https://doi.org/10.5194/hess-24-5821-2020, https://doi.org/10.5194/hess-24-5821-2020, 2020
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Automated water samplers are often used to collect precipitation and streamwater samples for subsequent isotope analysis, but the isotopic signal of these samples may be altered due to evaporative fractionation occurring during the storage inside the autosamplers in the field. In this article we present and evaluate a cost-efficient modification to the Teledyne ISCO automated water sampler that prevents isotopic enrichment through evaporative fractionation of the water samples.
Joost Buitink, Lieke A. Melsen, James W. Kirchner, and Adriaan J. Teuling
Geosci. Model Dev., 13, 6093–6110, https://doi.org/10.5194/gmd-13-6093-2020, https://doi.org/10.5194/gmd-13-6093-2020, 2020
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This paper presents a new distributed hydrological model: the distributed simple dynamical systems (dS2) model. The model is built with a focus on computational efficiency and is therefore able to simulate basins at high spatial and temporal resolution at a low computational cost. Despite the simplicity of the model concept, it is able to correctly simulate discharge in both small and mesoscale basins.
James W. Kirchner and Julia L. A. Knapp
Hydrol. Earth Syst. Sci., 24, 5539–5558, https://doi.org/10.5194/hess-24-5539-2020, https://doi.org/10.5194/hess-24-5539-2020, 2020
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Ensemble hydrograph separation is a powerful new tool for measuring the age distribution of streamwater. However, the calculations are complex and may be difficult for researchers to implement on their own. Here we present scripts that perform these calculations in either MATLAB or R so that researchers do not need to write their own codes. We explain how these scripts work and how to use them. We demonstrate several potential applications using a synthetic catchment data set.
Marius G. Floriancic, Wouter R. Berghuijs, Tobias Jonas, James W. Kirchner, and Peter Molnar
Hydrol. Earth Syst. Sci., 24, 5423–5438, https://doi.org/10.5194/hess-24-5423-2020, https://doi.org/10.5194/hess-24-5423-2020, 2020
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Low river flows affect societies and ecosystems. Here we study how precipitation and potential evapotranspiration shape low flows across a network of 380 Swiss catchments. Low flows in these rivers typically result from below-average precipitation and above-average potential evapotranspiration. Extreme low flows result from long periods of the combined effects of both drivers.
James W. Kirchner, Sarah E. Godsey, Madeline Solomon, Randall Osterhuber, Joseph R. McConnell, and Daniele Penna
Hydrol. Earth Syst. Sci., 24, 5095–5123, https://doi.org/10.5194/hess-24-5095-2020, https://doi.org/10.5194/hess-24-5095-2020, 2020
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Streams and groundwaters often show daily cycles in response to snowmelt and evapotranspiration. These typically have a roughly 6 h time lag, which is often interpreted as a travel-time lag. Here we show that it is instead primarily a phase lag that arises because aquifers integrate their inputs over time. We further show how these cycles shift seasonally, mirroring the springtime retreat of snow cover to higher elevations and the seasonal advance and retreat of photosynthetic activity.
Elham Rouholahnejad Freund, Massimiliano Zappa, and James W. Kirchner
Hydrol. Earth Syst. Sci., 24, 5015–5025, https://doi.org/10.5194/hess-24-5015-2020, https://doi.org/10.5194/hess-24-5015-2020, 2020
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Evapotranspiration (ET) is the largest flux from the land to the atmosphere and thus contributes to Earth's energy and water balance. Due to its impact on atmospheric dynamics, ET is a key driver of droughts and heatwaves. In this paper, we demonstrate how averaging over land surface heterogeneity contributes to substantial overestimates of ET fluxes. We also demonstrate how one can correct for the effects of small-scale heterogeneity without explicitly representing it in land surface models.
Nikos Theodoratos and James W. Kirchner
Earth Surf. Dynam., 8, 505–526, https://doi.org/10.5194/esurf-8-505-2020, https://doi.org/10.5194/esurf-8-505-2020, 2020
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We non-dimensionalized a commonly used model of landscape evolution that includes an incision threshold. Whereas the original model included four parameters, we obtained a dimensionless form with a single parameter, which quantifies the relative importance of the incision threshold. Working with this form saves computational time and simplifies theoretical analyses.
Julia L. A. Knapp, Jana von Freyberg, Bjørn Studer, Leonie Kiewiet, and James W. Kirchner
Hydrol. Earth Syst. Sci., 24, 2561–2576, https://doi.org/10.5194/hess-24-2561-2020, https://doi.org/10.5194/hess-24-2561-2020, 2020
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Changes of stream water chemistry in response to discharge changes provide important insights into the storage and release of water from the catchment. Here we investigate the variability in concentration–discharge relationships among different solutes and hydrologic events and relate it to catchment conditions and dominant water sources.
Elham Rouholahnejad Freund, Ying Fan, and James W. Kirchner
Hydrol. Earth Syst. Sci., 24, 1927–1938, https://doi.org/10.5194/hess-24-1927-2020, https://doi.org/10.5194/hess-24-1927-2020, 2020
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Evapotranspiration (ET) rates and properties that regulate them are spatially heterogeneous. Averaging over spatial heterogeneity in precipitation (P) and potential evapotranspiration (PET) as the main drivers of ET may lead to biased estimates of energy and water fluxes from the land to the atmosphere. We show that this bias is largest in mountainous terrains, in regions with temperate climates and dry summers, and in landscapes where spatial variations in P and PET are inversely correlated.
Francesc Gallart, Jana von Freyberg, María Valiente, James W. Kirchner, Pilar Llorens, and Jérôme Latron
Hydrol. Earth Syst. Sci., 24, 1101–1107, https://doi.org/10.5194/hess-24-1101-2020, https://doi.org/10.5194/hess-24-1101-2020, 2020
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How catchments store and release rain or melting water is still not well known. Now, it is broadly accepted that most of the water in streams is older than several months, and a relevant part may be many years old. But the age of water depends on the stream regime, being usually younger during high flows. This paper tries to provide tools for better analysing how the age of waters varies with flow in a catchment and for comparing the behaviour of catchments diverging in climate, size and regime.
James W. Kirchner and Scott T. Allen
Hydrol. Earth Syst. Sci., 24, 17–39, https://doi.org/10.5194/hess-24-17-2020, https://doi.org/10.5194/hess-24-17-2020, 2020
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Perhaps the oldest question in hydrology is
Where does water go when it rains?. Here we present a new way to measure how the terrestrial water cycle partitions precipitation into its two ultimate fates:
green waterthat is evaporated or transpired back to the atmosphere and
blue waterthat is discharged to stream channels. Our analysis may help in gauging the vulnerability of both water resources and terrestrial ecosystems to changes in rainfall patterns.
H. J. Ilja van Meerveld, James W. Kirchner, Marc J. P. Vis, Rick S. Assendelft, and Jan Seibert
Hydrol. Earth Syst. Sci., 23, 4825–4834, https://doi.org/10.5194/hess-23-4825-2019, https://doi.org/10.5194/hess-23-4825-2019, 2019
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Flowing stream networks extend and retract seasonally and in response to precipitation. This affects the distances and thus the time that it takes a water molecule to reach the flowing stream and the stream outlet. When the network is fully extended, the travel times are short, but when the network retracts, the travel times become longer and more uniform. These dynamics should be included when modeling solute or pollutant transport.
Julia L. A. Knapp, Colin Neal, Alessandro Schlumpf, Margaret Neal, and James W. Kirchner
Hydrol. Earth Syst. Sci., 23, 4367–4388, https://doi.org/10.5194/hess-23-4367-2019, https://doi.org/10.5194/hess-23-4367-2019, 2019
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We describe, present, and make publicly available two extensive data sets of stable water isotopes in streamwater and precipitation at Plynlimon, Wales, consisting of measurements at 7-hourly intervals for 17 months and at weekly intervals for 4.25 years. We use these data to calculate new water fractions and transit time distributions for different discharge rates and seasons, thus quantifying the contribution of recent precipitation to streamflow under different conditions.
Scott T. Allen, Scott Jasechko, Wouter R. Berghuijs, Jeffrey M. Welker, Gregory R. Goldsmith, and James W. Kirchner
Hydrol. Earth Syst. Sci., 23, 3423–3436, https://doi.org/10.5194/hess-23-3423-2019, https://doi.org/10.5194/hess-23-3423-2019, 2019
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We developed global maps that concisely quantify the seasonality of stable isotope ratios in precipitation, using data from 653 meteorological stations across all seven continents. We make these gridded global maps publicly available to support diverse stable isotope applications.
Andrea Rücker, Stefan Boss, James W. Kirchner, and Jana von Freyberg
Hydrol. Earth Syst. Sci., 23, 2983–3005, https://doi.org/10.5194/hess-23-2983-2019, https://doi.org/10.5194/hess-23-2983-2019, 2019
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To better understand how rain-on-snow (ROS) events affect snowpack outflow volumes and streamflow generation, we measured snowpack outflow volumes and isotopic composition during 10 ROS events with automated snowmelt lysimeters at three locations in a pre-Alpine catchment. We quantified the spatio-temporal variability of snowpack outflow and its relative contribution to streamflow, and identified rainfall characteristics and initial snow depth as major controls on snow hydrological processes.
Scott T. Allen, James W. Kirchner, Sabine Braun, Rolf T. W. Siegwolf, and Gregory R. Goldsmith
Hydrol. Earth Syst. Sci., 23, 1199–1210, https://doi.org/10.5194/hess-23-1199-2019, https://doi.org/10.5194/hess-23-1199-2019, 2019
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We used stable isotopes of xylem water to study differences in the seasonal origin of water in more than 900 individual trees from three dominant species in 182 Swiss forested sites. We discovered that midsummer transpiration was mostly supplied by winter precipitation across diverse humid climates. Our findings provide new insights into tree vulnerability to droughts, transport of water (and thus solutes) in soils, and the climatic information conveyed by plant-tissue isotopes.
James W. Kirchner
Hydrol. Earth Syst. Sci., 23, 303–349, https://doi.org/10.5194/hess-23-303-2019, https://doi.org/10.5194/hess-23-303-2019, 2019
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How long does it take for raindrops to become streamflow? Here I propose a new approach to this old problem. I show how we can use time series of isotope data to measure the average fraction of same-day rainfall appearing in streamflow, even if this fraction varies greatly from rainstorm to rainstorm. I show that we can quantify how this fraction changes from small rainstorms to big ones, and from high flows to low flows, and how it changes with the lag time between rainfall and streamflow.
Jana von Freyberg, Bjørn Studer, Michael Rinderer, and James W. Kirchner
Hydrol. Earth Syst. Sci., 22, 5847–5865, https://doi.org/10.5194/hess-22-5847-2018, https://doi.org/10.5194/hess-22-5847-2018, 2018
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We show event- and pre-event-water volumes as fractions of precipitation, rather than discharge, to provide an alternative and more insightful approach to study catchment hydrological processes. For this, we analyze 24 storm events using high-frequency measurements of stable water isotopes in stream water and precipitation at a pre-Alpine catchment. Antecedent wetness and storm characteristics are dominant controls on event-water discharge and pre-event-water mobilization from storage.
Daniele Penna, Luisa Hopp, Francesca Scandellari, Scott T. Allen, Paolo Benettin, Matthias Beyer, Josie Geris, Julian Klaus, John D. Marshall, Luitgard Schwendenmann, Till H. M. Volkmann, Jana von Freyberg, Anam Amin, Natalie Ceperley, Michael Engel, Jay Frentress, Yamuna Giambastiani, Jeff J. McDonnell, Giulia Zuecco, Pilar Llorens, Rolf T. W. Siegwolf, Todd E. Dawson, and James W. Kirchner
Biogeosciences, 15, 6399–6415, https://doi.org/10.5194/bg-15-6399-2018, https://doi.org/10.5194/bg-15-6399-2018, 2018
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Understanding how water flows through ecosystems is needed to provide society and policymakers with the scientific background to manage water resources sustainably. Stable isotopes of hydrogen and oxygen in water are a powerful tool for tracking water fluxes, although the heterogeneity of natural systems and practical methodological issues still limit their full application. Here, we examine the challenges in this research field and highlight new perspectives based on interdisciplinary research.
Nikos Theodoratos, Hansjörg Seybold, and James W. Kirchner
Earth Surf. Dynam., 6, 779–808, https://doi.org/10.5194/esurf-6-779-2018, https://doi.org/10.5194/esurf-6-779-2018, 2018
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We perform dimensional analysis on a frequently used landscape evolution model (LEM). Defining characteristic scales in a novel way, we significantly simplify the LEM and develop an efficient numerical modeling approach. Our characteristic scales are physically meaningful; they quantify competitions between landscape-forming processes and are related to salient properties of landscape topography. Dimensional analyses of other LEMs may benefit from our approach in defining characteristic scales.
Jana von Freyberg, Scott T. Allen, Stefan Seeger, Markus Weiler, and James W. Kirchner
Hydrol. Earth Syst. Sci., 22, 3841–3861, https://doi.org/10.5194/hess-22-3841-2018, https://doi.org/10.5194/hess-22-3841-2018, 2018
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We explored how the fraction of streamflow younger than ca. 3 months (Fyw) varies with landscape characteristics and climatic forcing, using an extensive isotope data set from 22 Swiss catchments. Overall, Fyw tends to be larger when catchments are wet and discharge is correspondingly higher, indicating an increase in the proportional contribution of faster flow paths at higher flows. We quantify this
discharge sensitivityof Fyw and relate it to the dominant streamflow-generating mechanisms.
Paolo Benettin, Till H. M. Volkmann, Jana von Freyberg, Jay Frentress, Daniele Penna, Todd E. Dawson, and James W. Kirchner
Hydrol. Earth Syst. Sci., 22, 2881–2890, https://doi.org/10.5194/hess-22-2881-2018, https://doi.org/10.5194/hess-22-2881-2018, 2018
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Evaporation causes the isotopic composition of soil water to become different from that of the original precipitation source. If multiple samples originating from the same source are available, they can be used to reconstruct the original source composition. However, soil water is influenced by seasonal variability in both precipitation sources and evaporation patterns. We show that this variability, if not accounted for, can lead to biased estimates of the precipitation source water.
Albrecht von Boetticher, Jens M. Turowski, Brian W. McArdell, Dieter Rickenmann, Marcel Hürlimann, Christian Scheidl, and James W. Kirchner
Geosci. Model Dev., 10, 3963–3978, https://doi.org/10.5194/gmd-10-3963-2017, https://doi.org/10.5194/gmd-10-3963-2017, 2017
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The open-source fluid dynamic solver presented in v. Boetticher et al. (2016) combines a Coulomb viscosplastic rheological model with a Herschel–Bulkley model based on material properties for 3-D debris flow simulations. Here, we validate the solver and illustrate the model sensitivity to water content, channel curvature, content of fine material and channel bed roughness. We simulate both laboratory-scale and large-scale debris-flow experiments, using only one of the two calibration parameters.
Jana von Freyberg, Bjørn Studer, and James W. Kirchner
Hydrol. Earth Syst. Sci., 21, 1721–1739, https://doi.org/10.5194/hess-21-1721-2017, https://doi.org/10.5194/hess-21-1721-2017, 2017
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We present a newly developed instrument package that enables the online analysis of stable water isotopes and major ion chemistry at 30 min intervals in the field. The resulting data streams provide an unprecedented view of hydrochemical dynamics on the catchment scale. Based on a detailed analysis of the variable behavior of isotopic and chemical tracers in stream water and precipitation over a 4-week period, we developed a conceptual hypothesis for runoff generation in the studied catchment.
Elham Rouholahnejad Freund and James W. Kirchner
Hydrol. Earth Syst. Sci., 21, 217–233, https://doi.org/10.5194/hess-21-217-2017, https://doi.org/10.5194/hess-21-217-2017, 2017
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Our analysis shows that averaging over sub-grid heterogeneity in precipitation and potential evapotranspiration (ET), as typical earth system models do, overestimates the average of the spatially variable ET. We also show when aridity index increases with altitude, lateral redistribution would transfer water from more humid uplands to more arid lowlands, resulting in a net increase in ET. Therefore, the Earth system models that neglect lateral transfer underestimate ET in those regions.
Alexander R. Beer, James W. Kirchner, and Jens M. Turowski
Earth Surf. Dynam., 4, 885–894, https://doi.org/10.5194/esurf-4-885-2016, https://doi.org/10.5194/esurf-4-885-2016, 2016
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Spatial bedrock erosion data from stream channels are important for engineering issues and landscape evolution model assessment. However, acquiring such data is challenging and only few data sets exist. Detecting changes in repeated photographs of painted bedrock surfaces easily allows for semi-quantitative conclusions on the spatial distribution of sediment transport and its effects: abrasion on surfaces facing the streamflow and shielding of surfaces by abundant sediment.
Albrecht von Boetticher, Jens M. Turowski, Brian W. McArdell, Dieter Rickenmann, and James W. Kirchner
Geosci. Model Dev., 9, 2909–2923, https://doi.org/10.5194/gmd-9-2909-2016, https://doi.org/10.5194/gmd-9-2909-2016, 2016
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Debris flows are characterized by unsteady flows of water with different content of clay, silt, sand, gravel, and large particles, resulting in a dense moving mixture mass. Here we present a three-dimensional fluid dynamic solver that simulates the flow as a mixture of a pressure-dependent rheology model of the gravel mixed with a Herschel–Bulkley rheology of the fine material suspension. We link rheological parameters to the material composition. The user must specify two free model parameters.
J. W. Kirchner
Hydrol. Earth Syst. Sci., 20, 279–297, https://doi.org/10.5194/hess-20-279-2016, https://doi.org/10.5194/hess-20-279-2016, 2016
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Catchment mean transit times have been widely inferred from seasonal cycles of environmental tracers in precipitation and streamflow. Here I show that these cycles yield strongly biased estimates of mean transit times in spatially heterogeneous catchments (and, by implication, in real-world catchments). However, I also show that these cycles can be used to reliably estimate the fraction of "young" water in streamflow, meaning water that fell as precipitation less than roughly 2–3 months ago.
F. Kobierska, T. Jonas, J. W. Kirchner, and S. M. Bernasconi
Hydrol. Earth Syst. Sci., 19, 3681–3693, https://doi.org/10.5194/hess-19-3681-2015, https://doi.org/10.5194/hess-19-3681-2015, 2015
A. von Boetticher, J. M. Turowski, B. W. McArdell, D. Rickenmann, M. Hürlimann, C. Scheidl, and J. W. Kirchner
Geosci. Model Dev. Discuss., https://doi.org/10.5194/gmdd-8-6379-2015, https://doi.org/10.5194/gmdd-8-6379-2015, 2015
Preprint withdrawn
F. U. M. Heimann, D. Rickenmann, J. M. Turowski, and J. W. Kirchner
Earth Surf. Dynam., 3, 15–34, https://doi.org/10.5194/esurf-3-15-2015, https://doi.org/10.5194/esurf-3-15-2015, 2015
F. U. M. Heimann, D. Rickenmann, M. Böckli, A. Badoux, J. M. Turowski, and J. W. Kirchner
Earth Surf. Dynam., 3, 35–54, https://doi.org/10.5194/esurf-3-35-2015, https://doi.org/10.5194/esurf-3-35-2015, 2015
Related subject area
Subject: Catchment hydrology | Techniques and Approaches: Theory development
Characterizing nonlinear, nonstationary, and heterogeneous hydrologic behavior using ensemble rainfall–runoff analysis (ERRA): proof of concept
Ratio limits of water storage and outflow in a rainfall–runoff process
Technical Note: The divide and measure nonconformity – how metrics can mislead when we evaluate on different data partitions
Bimodal hydrographs in a semi-humid forested watershed: characteristics and occurrence conditions
Flood drivers and trends: a case study of the Geul River catchment (the Netherlands) over the past half century
Power law between the apparent drainage density and the pruning area
Stream water sourcing from high-elevation snowpack inferred from stable isotopes of water: a novel application of d-excess values
Elasticity curves describe streamflow sensitivity to precipitation across the entire flow distribution
Seasonal and interannual dissolved organic carbon transport process dynamics in a subarctic headwater catchment revealed by high-resolution measurements
Links between seasonal suprapermafrost groundwater, the hydrothermal change of the active layer, and river runoff in alpine permafrost watersheds
Technical note: Isotopic fractionation of evaporating waters: effect of sub-daily atmospheric variations and eventual depletion of heavy isotopes
Increased nonstationarity of stormflow threshold behaviors in a forested watershed due to abrupt earthquake disturbance
HESS Opinions: Are soils overrated in hydrology?
Hydrologic implications of projected changes in rain-on-snow melt for Great Lakes Basin watersheds
A hydrological framework for persistent pools along non-perennial rivers
Evidence-based requirements for perceptualising intercatchment groundwater flow in hydrological models
Droughts can reduce the nitrogen retention capacity of catchments
Explaining changes in rainfall–runoff relationships during and after Australia's Millennium Drought: a community perspective
Three hypotheses on changing river flood hazards
A multivariate-driven approach for disentangling the reduction in near-natural Iberian water resources post-1980
Hydrology and riparian forests drive carbon and nitrogen supply and DOC : NO3− stoichiometry along a headwater Mediterranean stream
Event controls on intermittent streamflow in a temperate climate
Inclusion of flood diversion canal operation in the H08 hydrological model with a case study from the Chao Phraya River basin: model development and validation
Flood generation: process patterns from the raindrop to the ocean
Use of streamflow indices to identify the catchment drivers of hydrographs
Theoretical and empirical evidence against the Budyko catchment trajectory conjecture
Spatial distribution of groundwater recharge, based on regionalised soil moisture models in Wadi Natuf karst aquifers, Palestine
Barriers to mainstream adoption of catchment-wide natural flood management: a transdisciplinary problem-framing study of delivery practice
Low hydrological connectivity after summer drought inhibits DOC export in a forested headwater catchment
Rainbow color map distorts and misleads research in hydrology – guidance for better visualizations and science communication
Attribution of growing season evapotranspiration variability considering snowmelt and vegetation changes in the arid alpine basins
Event and seasonal hydrologic connectivity patterns in an agricultural headwater catchment
Exploring the role of hydrological pathways in modulating multi-annual climate teleconnection periodicities from UK rainfall to streamflow
Technical note: “Bit by bit”: a practical and general approach for evaluating model computational complexity vs. model performance
Hillslope and groundwater contributions to streamflow in a Rocky Mountain watershed underlain by glacial till and fractured sedimentary bedrock
A framework for seasonal variations of hydrological model parameters: impact on model results and response to dynamic catchment characteristics
Hydrology and beyond: the scientific work of August Colding revisited
The influence of a prolonged meteorological drought on catchment water storage capacity: a hydrological-model perspective
Hydrological and runoff formation processes based on isotope tracing during ablation period in the source regions of Yangtze River
Importance of snowmelt contribution to seasonal runoff and summer low flows in Czechia
Concentration–discharge relationships vary among hydrological events, reflecting differences in event characteristics
Recession analysis revisited: impacts of climate on parameter estimation
Understanding the effects of climate warming on streamflow and active groundwater storage in an alpine catchment: the upper Lhasa River
Technical note: An improved discharge sensitivity metric for young water fractions
Hydrological signatures describing the translation of climate seasonality into streamflow seasonality
Spatial and temporal variation in river corridor exchange across a 5th-order mountain stream network
Historic hydrological droughts 1891–2015: systematic characterisation for a diverse set of catchments across the UK
A topographic index explaining hydrological similarity by accounting for the joint controls of runoff formation
Trajectories of nitrate input and output in three nested catchments along a land use gradient
Contrasting rainfall-runoff characteristics of floods in desert and Mediterranean basins
James W. Kirchner
Hydrol. Earth Syst. Sci., 28, 4427–4454, https://doi.org/10.5194/hess-28-4427-2024, https://doi.org/10.5194/hess-28-4427-2024, 2024
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Here, I present a new way to quantify how streamflow responds to rainfall across a range of timescales. This approach can estimate how different rainfall intensities affect streamflow. It can also quantify how runoff response to rainfall varies, depending on how wet the landscape already is before the rain falls. This may help us to understand processes and landscape properties that regulate streamflow and to assess the susceptibility of different landscapes to flooding.
Yulong Zhu, Yang Zhou, Xiaorong Xu, Changqing Meng, and Yuankun Wang
Hydrol. Earth Syst. Sci., 28, 4251–4261, https://doi.org/10.5194/hess-28-4251-2024, https://doi.org/10.5194/hess-28-4251-2024, 2024
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A timely local flood forecast is an effective way to reduce casualties and economic losses. The current theoretical or numerical models play an important role in local flood forecasting. However, they still cannot bridge the contradiction between high calculation accuracy, high calculation efficiency, and simple operability. Therefore, this paper expects to propose a new flood forecasting model with higher computational efficiency and simpler operation.
Daniel Klotz, Martin Gauch, Frederik Kratzert, Grey Nearing, and Jakob Zscheischler
Hydrol. Earth Syst. Sci., 28, 3665–3673, https://doi.org/10.5194/hess-28-3665-2024, https://doi.org/10.5194/hess-28-3665-2024, 2024
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The evaluation of model performance is essential for hydrological modeling. Using performance criteria requires a deep understanding of their properties. We focus on a counterintuitive aspect of the Nash–Sutcliffe efficiency (NSE) and show that if we divide the data into multiple parts, the overall performance can be higher than all the evaluations of the subsets. Although this follows from the definition of the NSE, the resulting behavior can have unintended consequences in practice.
Zhen Cui, Fuqiang Tian, Zilong Zhao, Zitong Xu, Yongjie Duan, Jie Wen, and Mohd Yawar Ali Khan
Hydrol. Earth Syst. Sci., 28, 3613–3632, https://doi.org/10.5194/hess-28-3613-2024, https://doi.org/10.5194/hess-28-3613-2024, 2024
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We investigated the response characteristics and occurrence conditions of bimodal hydrographs using 10 years of hydrometric and isotope data in a semi-humid forested watershed in north China. Our findings indicate that bimodal hydrographs occur when the combined total of the event rainfall and antecedent soil moisture index exceeds 200 mm. Additionally, we determined that delayed stormflow is primarily contributed to by shallow groundwater.
Athanasios Tsiokanos, Martine Rutten, Ruud J. van der Ent, and Remko Uijlenhoet
Hydrol. Earth Syst. Sci., 28, 3327–3345, https://doi.org/10.5194/hess-28-3327-2024, https://doi.org/10.5194/hess-28-3327-2024, 2024
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We focus on past high-flow events to find flood drivers in the Geul. We also explore flood drivers’ trends across various timescales and develop a new method to detect the main direction of a trend. Our results show that extreme 24 h precipitation alone is typically insufficient to cause floods. The combination of extreme rainfall and wet initial conditions determines the chance of flooding. Precipitation that leads to floods increases in winter, whereas no consistent trends are found in summer.
Soohyun Yang, Kwanghun Choi, and Kyungrock Paik
Hydrol. Earth Syst. Sci., 28, 3119–3132, https://doi.org/10.5194/hess-28-3119-2024, https://doi.org/10.5194/hess-28-3119-2024, 2024
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In extracting a river network from a digital elevation model, an arbitrary pruning area should be specified. As this value grows, the apparent drainage density is reduced following a power function. This reflects the fractal topographic nature. We prove this relationship related to the known power law in the exceedance probability distribution of drainage area. The power-law exponent is expressed with fractal dimensions. Our findings are supported by analysis of 14 real river networks.
Matthias Sprenger, Rosemary W. H. Carroll, David Marchetti, Carleton Bern, Harsh Beria, Wendy Brown, Alexander Newman, Curtis Beutler, and Kenneth H. Williams
Hydrol. Earth Syst. Sci., 28, 1711–1723, https://doi.org/10.5194/hess-28-1711-2024, https://doi.org/10.5194/hess-28-1711-2024, 2024
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Stable isotopes of water (described as d-excess) in mountain snowpack can be used to infer proportions of high-elevation snowmelt in stream water. In a Colorado River headwater catchment, nearly half of the water during peak streamflow is derived from melted snow at elevations greater than 3200 m. High-elevation snowpack contributions were higher for years with lower snowpack and warmer spring temperatures. Thus, we suggest that d-excess could serve to assess high-elevation snowpack changes.
Bailey J. Anderson, Manuela I. Brunner, Louise J. Slater, and Simon J. Dadson
Hydrol. Earth Syst. Sci., 28, 1567–1583, https://doi.org/10.5194/hess-28-1567-2024, https://doi.org/10.5194/hess-28-1567-2024, 2024
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Elasticityrefers to how much the amount of water in a river changes with precipitation. We usually calculate this using average streamflow values; however, the amount of water within rivers is also dependent on stored water sources. Here, we look at how elasticity varies across the streamflow distribution and show that not only do low and high streamflows respond differently to precipitation change, but also these differences vary with water storage availability.
Danny Croghan, Pertti Ala-Aho, Jeffrey Welker, Kaisa-Riikka Mustonen, Kieran Khamis, David M. Hannah, Jussi Vuorenmaa, Bjørn Kløve, and Hannu Marttila
Hydrol. Earth Syst. Sci., 28, 1055–1070, https://doi.org/10.5194/hess-28-1055-2024, https://doi.org/10.5194/hess-28-1055-2024, 2024
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The transport of dissolved organic carbon (DOC) from land into streams is changing due to climate change. We used a multi-year dataset of DOC and predictors of DOC in a subarctic stream to find out how transport of DOC varied between seasons and between years. We found that the way DOC is transported varied strongly seasonally, but year-to-year differences were less apparent. We conclude that the mechanisms of transport show a higher degree of interannual consistency than previously thought.
Jia Qin, Yongjian Ding, Faxiang Shi, Junhao Cui, Yaping Chang, Tianding Han, and Qiudong Zhao
Hydrol. Earth Syst. Sci., 28, 973–987, https://doi.org/10.5194/hess-28-973-2024, https://doi.org/10.5194/hess-28-973-2024, 2024
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The linkage between the seasonal hydrothermal change of active layer, suprapermafrost groundwater, and surface runoff, which has been regarded as a “black box” in hydrological analyses and simulations, is a bottleneck problem in permafrost hydrological studies. Based on field observations, this study identifies seasonal variations and causes of suprapermafrost groundwater. The linkages and framework of watershed hydrology responding to the freeze–thaw of the active layer also are explored.
Francesc Gallart, Sebastián González-Fuentes, and Pilar Llorens
Hydrol. Earth Syst. Sci., 28, 229–239, https://doi.org/10.5194/hess-28-229-2024, https://doi.org/10.5194/hess-28-229-2024, 2024
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Normally, lighter oxygen and hydrogen isotopes are preferably evaporated from a water body, which becomes enriched in heavy isotopes. However, we observed that, in a water body subject to prolonged evaporation, some periods of heavy isotope depletion instead of enrichment happened. Furthermore, the usual models that describe the isotopy of evaporating waters may be in error if the atmospheric conditions of temperature and relative humidity are time-averaged instead of evaporation flux-weighted.
Guotao Zhang, Peng Cui, Carlo Gualtieri, Nazir Ahmed Bazai, Xueqin Zhang, and Zhengtao Zhang
Hydrol. Earth Syst. Sci., 27, 3005–3020, https://doi.org/10.5194/hess-27-3005-2023, https://doi.org/10.5194/hess-27-3005-2023, 2023
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This study used identified stormflow thresholds as a diagnostic tool to characterize abrupt variations in catchment emergent patterns pre- and post-earthquake. Earthquake-induced landslides with spatial heterogeneity and temporally undulating recovery increase the hydrologic nonstationary; thus, large post-earthquake floods are more likely to occur. This study contributes to mitigation and adaptive strategies for unpredictable hydrologic regimes triggered by abrupt natural disturbances.
Hongkai Gao, Fabrizio Fenicia, and Hubert H. G. Savenije
Hydrol. Earth Syst. Sci., 27, 2607–2620, https://doi.org/10.5194/hess-27-2607-2023, https://doi.org/10.5194/hess-27-2607-2023, 2023
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It is a deeply rooted perception that soil is key in hydrology. In this paper, we argue that it is the ecosystem, not the soil, that is in control of hydrology. Firstly, in nature, the dominant flow mechanism is preferential, which is not particularly related to soil properties. Secondly, the ecosystem, not the soil, determines the land–surface water balance and hydrological processes. Moving from a soil- to ecosystem-centred perspective allows more realistic and simpler hydrological models.
Daniel T. Myers, Darren L. Ficklin, and Scott M. Robeson
Hydrol. Earth Syst. Sci., 27, 1755–1770, https://doi.org/10.5194/hess-27-1755-2023, https://doi.org/10.5194/hess-27-1755-2023, 2023
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We projected climate change impacts to rain-on-snow (ROS) melt events in the Great Lakes Basin. Decreases in snowpack limit future ROS melt. Areas with mean winter/spring air temperatures near freezing are most sensitive to ROS changes. The projected proportion of total monthly snowmelt from ROS decreases. The timing for ROS melt is projected to be 2 weeks earlier by the mid-21st century and affects spring streamflow. This could affect freshwater resources management.
Sarah A. Bourke, Margaret Shanafield, Paul Hedley, Sarah Chapman, and Shawan Dogramaci
Hydrol. Earth Syst. Sci., 27, 809–836, https://doi.org/10.5194/hess-27-809-2023, https://doi.org/10.5194/hess-27-809-2023, 2023
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Here we present a hydrological framework for understanding the mechanisms supporting the persistence of water in pools along non-perennial rivers. Pools may collect water after rainfall events, be supported by water stored within the river channel sediments, or receive inflows from regional groundwater. These hydraulic mechanisms can be identified using a range of diagnostic tools (critiqued herein). We then apply this framework in north-west Australia to demonstrate its value.
Louisa D. Oldham, Jim Freer, Gemma Coxon, Nicholas Howden, John P. Bloomfield, and Christopher Jackson
Hydrol. Earth Syst. Sci., 27, 761–781, https://doi.org/10.5194/hess-27-761-2023, https://doi.org/10.5194/hess-27-761-2023, 2023
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Water can move between river catchments via the subsurface, termed intercatchment groundwater flow (IGF). We show how a perceptual model of IGF can be developed with relatively simple geological interpretation and data requirements. We find that IGF dynamics vary in space, correlated to the dominant underlying geology. We recommend that IGF
loss functionsmay be used in conceptual rainfall–runoff models but should be supported by perceptualisation of IGF processes and connectivities.
Carolin Winter, Tam V. Nguyen, Andreas Musolff, Stefanie R. Lutz, Michael Rode, Rohini Kumar, and Jan H. Fleckenstein
Hydrol. Earth Syst. Sci., 27, 303–318, https://doi.org/10.5194/hess-27-303-2023, https://doi.org/10.5194/hess-27-303-2023, 2023
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The increasing frequency of severe and prolonged droughts threatens our freshwater resources. While we understand drought impacts on water quantity, its effects on water quality remain largely unknown. Here, we studied the impact of the unprecedented 2018–2019 drought in Central Europe on nitrate export in a heterogeneous mesoscale catchment in Germany. We show that severe drought can reduce a catchment's capacity to retain nitrogen, intensifying the internal pollution and export of nitrate.
Keirnan Fowler, Murray Peel, Margarita Saft, Tim J. Peterson, Andrew Western, Lawrence Band, Cuan Petheram, Sandra Dharmadi, Kim Seong Tan, Lu Zhang, Patrick Lane, Anthony Kiem, Lucy Marshall, Anne Griebel, Belinda E. Medlyn, Dongryeol Ryu, Giancarlo Bonotto, Conrad Wasko, Anna Ukkola, Clare Stephens, Andrew Frost, Hansini Gardiya Weligamage, Patricia Saco, Hongxing Zheng, Francis Chiew, Edoardo Daly, Glen Walker, R. Willem Vervoort, Justin Hughes, Luca Trotter, Brad Neal, Ian Cartwright, and Rory Nathan
Hydrol. Earth Syst. Sci., 26, 6073–6120, https://doi.org/10.5194/hess-26-6073-2022, https://doi.org/10.5194/hess-26-6073-2022, 2022
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Recently, we have seen multi-year droughts tending to cause shifts in the relationship between rainfall and streamflow. In shifted catchments that have not recovered, an average rainfall year produces less streamflow today than it did pre-drought. We take a multi-disciplinary approach to understand why these shifts occur, focusing on Australia's over-10-year Millennium Drought. We evaluate multiple hypotheses against evidence, with particular focus on the key role of groundwater processes.
Günter Blöschl
Hydrol. Earth Syst. Sci., 26, 5015–5033, https://doi.org/10.5194/hess-26-5015-2022, https://doi.org/10.5194/hess-26-5015-2022, 2022
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There is serious concern that river floods are increasing. Starting from explanations discussed in public, the article addresses three hypotheses: land-use change, hydraulic structures, and climate change increase floods. This review finds that all three changes have the potential to not only increase floods, but also to reduce them. It is crucial to consider all three factors of change in flood risk management and communicate them to the general public in a nuanced way.
Amar Halifa-Marín, Miguel A. Torres-Vázquez, Enrique Pravia-Sarabia, Marc Lemus-Canovas, Pedro Jiménez-Guerrero, and Juan Pedro Montávez
Hydrol. Earth Syst. Sci., 26, 4251–4263, https://doi.org/10.5194/hess-26-4251-2022, https://doi.org/10.5194/hess-26-4251-2022, 2022
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Near-natural Iberian water resources have suddenly decreased since the 1980s. These declines have been promoted by the weakening (enhancement) of wintertime precipitation (the NAOi) in the most humid areas, whereas afforestation and drought intensification have played a crucial role in semi-arid areas. Future water management would benefit from greater knowledge of North Atlantic climate variability and reforestation/afforestation processes in semi-arid catchments.
José L. J. Ledesma, Anna Lupon, Eugènia Martí, and Susana Bernal
Hydrol. Earth Syst. Sci., 26, 4209–4232, https://doi.org/10.5194/hess-26-4209-2022, https://doi.org/10.5194/hess-26-4209-2022, 2022
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We studied a small stream located in a Mediterranean forest. Our goal was to understand how stream flow and the presence of riparian forests, which grow in flat banks near the stream, influence the availability of food for aquatic microorganisms. High flows were associated with higher amounts of food because rainfall episodes transfer it from the surrounding sources, particularly riparian forests, to the stream. Understanding how ecosystems work is essential to better manage natural resources.
Nils Hinrich Kaplan, Theresa Blume, and Markus Weiler
Hydrol. Earth Syst. Sci., 26, 2671–2696, https://doi.org/10.5194/hess-26-2671-2022, https://doi.org/10.5194/hess-26-2671-2022, 2022
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This study is analyses how characteristics of precipitation events and soil moisture and temperature dynamics during these events can be used to model the associated streamflow responses in intermittent streams. The models are used to identify differences between the dominant controls of streamflow intermittency in three distinct geologies of the Attert catchment, Luxembourg. Overall, soil moisture was found to be the most important control of intermittent streamflow in all geologies.
Saritha Padiyedath Gopalan, Adisorn Champathong, Thada Sukhapunnaphan, Shinichiro Nakamura, and Naota Hanasaki
Hydrol. Earth Syst. Sci., 26, 2541–2560, https://doi.org/10.5194/hess-26-2541-2022, https://doi.org/10.5194/hess-26-2541-2022, 2022
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The modelling of diversion canals using hydrological models is important because they play crucial roles in water management. Therefore, we developed a simplified canal diversion scheme and implemented it into the H08 global hydrological model. The developed diversion scheme was validated in the Chao Phraya River basin, Thailand. Region-specific validation results revealed that the H08 model with the diversion scheme could effectively simulate the observed flood diversion pattern in the basin.
Günter Blöschl
Hydrol. Earth Syst. Sci., 26, 2469–2480, https://doi.org/10.5194/hess-26-2469-2022, https://doi.org/10.5194/hess-26-2469-2022, 2022
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Sound understanding of how floods come about allows for the development of more reliable flood management tools that assist in mitigating their negative impacts. This article reviews river flood generation processes and flow paths across space scales, starting from water movement in the soil pores and moving up to hillslopes, catchments, regions and entire continents. To assist model development, there is a need to learn from observed patterns of flood generation processes at all spatial scales.
Jeenu Mathai and Pradeep P. Mujumdar
Hydrol. Earth Syst. Sci., 26, 2019–2033, https://doi.org/10.5194/hess-26-2019-2022, https://doi.org/10.5194/hess-26-2019-2022, 2022
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With availability of large samples of data in catchments, it is necessary to develop indices that describe the streamflow processes. This paper describes new indices applicable for the rising and falling limbs of streamflow hydrographs. The indices provide insights into the drivers of the hydrographs. The novelty of the work is on differentiating hydrographs by their time irreversibility property and offering an alternative way to recognize primary drivers of streamflow hydrographs.
Nathan G. F. Reaver, David A. Kaplan, Harald Klammler, and James W. Jawitz
Hydrol. Earth Syst. Sci., 26, 1507–1525, https://doi.org/10.5194/hess-26-1507-2022, https://doi.org/10.5194/hess-26-1507-2022, 2022
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The Budyko curve emerges globally from the behavior of multiple catchments. Single-parameter Budyko equations extrapolate the curve concept to individual catchments, interpreting curves and parameters as representing climatic and biophysical impacts on water availability, respectively. We tested these two key components theoretically and empirically, finding that catchments are not required to follow Budyko curves and usually do not, implying the parametric framework lacks predictive ability.
Clemens Messerschmid and Amjad Aliewi
Hydrol. Earth Syst. Sci., 26, 1043–1061, https://doi.org/10.5194/hess-26-1043-2022, https://doi.org/10.5194/hess-26-1043-2022, 2022
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Temporal distribution of groundwater recharge has been widely studied; yet, much less attention has been paid to its spatial distribution. Based on a previous study of field-measured and modelled formation-specific recharge in the Mediterranean, this paper differentiates annual recharge coefficients in a novel approach and basin classification framework for physical features such as lithology, soil and LU/LC characteristics, applicable also in other previously ungauged basins around the world.
Thea Wingfield, Neil Macdonald, Kimberley Peters, and Jack Spees
Hydrol. Earth Syst. Sci., 25, 6239–6259, https://doi.org/10.5194/hess-25-6239-2021, https://doi.org/10.5194/hess-25-6239-2021, 2021
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Human activities are causing greater and more frequent floods. Natural flood management (NFM) uses processes of the water cycle to slow the flow of rainwater, bringing together land and water management. Despite NFM's environmental and social benefits, it is yet to be widely adopted. Two environmental practitioner groups collaborated to produce a picture of the barriers to delivery, showing that there is a perceived lack of support from government and the public for NFM.
Katharina Blaurock, Burkhard Beudert, Benjamin S. Gilfedder, Jan H. Fleckenstein, Stefan Peiffer, and Luisa Hopp
Hydrol. Earth Syst. Sci., 25, 5133–5151, https://doi.org/10.5194/hess-25-5133-2021, https://doi.org/10.5194/hess-25-5133-2021, 2021
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Dissolved organic carbon (DOC) is an important part of the global carbon cycle with regards to carbon storage, greenhouse gas emissions and drinking water treatment. In this study, we compared DOC export of a small, forested catchment during precipitation events after dry and wet preconditions. We found that the DOC export from areas that are usually important for DOC export was inhibited after long drought periods.
Michael Stoelzle and Lina Stein
Hydrol. Earth Syst. Sci., 25, 4549–4565, https://doi.org/10.5194/hess-25-4549-2021, https://doi.org/10.5194/hess-25-4549-2021, 2021
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We found with a scientific paper survey (~ 1000 papers) that 45 % of the papers used rainbow color maps or red–green visualizations. Those rainbow visualizations, although attracting the media's attention, will not be accessible for up to 10 % of people due to color vision deficiency. The rainbow color map distorts and misleads scientific communication. The study gives guidance on how to avoid, improve and trust color and how the flaws of the rainbow color map should be communicated in science.
Tingting Ning, Zhi Li, Qi Feng, Zongxing Li, and Yanyan Qin
Hydrol. Earth Syst. Sci., 25, 3455–3469, https://doi.org/10.5194/hess-25-3455-2021, https://doi.org/10.5194/hess-25-3455-2021, 2021
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Previous studies decomposed ET variance in precipitation, potential ET, and total water storage changes based on Budyko equations. However, the effects of snowmelt and vegetation changes have not been incorporated in snow-dependent basins. We thus extended this method in arid alpine basins of northwest China and found that ET variance is primarily controlled by rainfall, followed by coupled rainfall and vegetation. The out-of-phase seasonality between rainfall and snowmelt weaken ET variance.
Lovrenc Pavlin, Borbála Széles, Peter Strauss, Alfred Paul Blaschke, and Günter Blöschl
Hydrol. Earth Syst. Sci., 25, 2327–2352, https://doi.org/10.5194/hess-25-2327-2021, https://doi.org/10.5194/hess-25-2327-2021, 2021
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We compared the dynamics of streamflow, groundwater and soil moisture to investigate how different parts of an agricultural catchment in Lower Austria are connected. Groundwater is best connected around the stream and worse uphill, where groundwater is deeper. Soil moisture connectivity increases with increasing catchment wetness but is not influenced by spatial position in the catchment. Groundwater is more connected to the stream on the seasonal scale compared to the event scale.
William Rust, Mark Cuthbert, John Bloomfield, Ron Corstanje, Nicholas Howden, and Ian Holman
Hydrol. Earth Syst. Sci., 25, 2223–2237, https://doi.org/10.5194/hess-25-2223-2021, https://doi.org/10.5194/hess-25-2223-2021, 2021
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In this paper, we find evidence for the cyclical behaviour (on a 7-year basis) in UK streamflow records that match the main cycle of the North Atlantic Oscillation. Furthermore, we find that the strength of these 7-year cycles in streamflow is dependent on proportional contributions from groundwater and the response times of the underlying groundwater systems. This may allow for improvements to water management practices through better understanding of long-term streamflow behaviour.
Elnaz Azmi, Uwe Ehret, Steven V. Weijs, Benjamin L. Ruddell, and Rui A. P. Perdigão
Hydrol. Earth Syst. Sci., 25, 1103–1115, https://doi.org/10.5194/hess-25-1103-2021, https://doi.org/10.5194/hess-25-1103-2021, 2021
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Computer models should be as simple as possible but not simpler. Simplicity refers to the length of the model and the effort it takes the model to generate its output. Here we present a practical technique for measuring the latter by the number of memory visits during model execution by
Strace, a troubleshooting and monitoring program. The advantage of this approach is that it can be applied to any computer-based model, which facilitates model intercomparison.
Sheena A. Spencer, Axel E. Anderson, Uldis Silins, and Adrian L. Collins
Hydrol. Earth Syst. Sci., 25, 237–255, https://doi.org/10.5194/hess-25-237-2021, https://doi.org/10.5194/hess-25-237-2021, 2021
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We used unique chemical signatures of precipitation, hillslope soil water, and groundwater sources of streamflow to explore seasonal variation in runoff generation in a snow-dominated mountain watershed underlain by glacial till and permeable bedrock. Reacted hillslope water reached the stream first at the onset of snowmelt, followed by a dilution effect by snowmelt from May to June. Groundwater and riparian water were important sources later in the summer. Till created complex subsurface flow.
Tian Lan, Kairong Lin, Chong-Yu Xu, Zhiyong Liu, and Huayang Cai
Hydrol. Earth Syst. Sci., 24, 5859–5874, https://doi.org/10.5194/hess-24-5859-2020, https://doi.org/10.5194/hess-24-5859-2020, 2020
Dan Rosbjerg
Hydrol. Earth Syst. Sci., 24, 4575–4585, https://doi.org/10.5194/hess-24-4575-2020, https://doi.org/10.5194/hess-24-4575-2020, 2020
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August Colding contributed the first law of thermodynamics, evaporation from water and grass, steady free surfaces in conduits, the cross-sectional velocity distribution in conduits, a complete theory for the Gulf Stream, air speed in cyclones, the piezometric surface in confined aquifers, the unconfined elliptic water table in soil between drain pipes, and the wind-induced set-up in the sea during storms.
Zhengke Pan, Pan Liu, Chong-Yu Xu, Lei Cheng, Jing Tian, Shujie Cheng, and Kang Xie
Hydrol. Earth Syst. Sci., 24, 4369–4387, https://doi.org/10.5194/hess-24-4369-2020, https://doi.org/10.5194/hess-24-4369-2020, 2020
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This study aims to identify the response of catchment water storage capacity (CWSC) to meteorological drought by examining the changes of hydrological-model parameters after drought events. This study improves our understanding of possible changes in the CWSC induced by a prolonged meteorological drought, which will help improve our ability to simulate the hydrological system under climate change.
Zong-Jie Li, Zong-Xing Li, Ling-Ling Song, Juan Gui, Jian Xue, Bai Juan Zhang, and Wen De Gao
Hydrol. Earth Syst. Sci., 24, 4169–4187, https://doi.org/10.5194/hess-24-4169-2020, https://doi.org/10.5194/hess-24-4169-2020, 2020
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This study mainly explores the hydraulic relations, recharge–drainage relations and their transformation paths, and the processes of each water body. It determines the composition of runoff, quantifies the contribution of each runoff component to different types of tributaries, and analyzes the hydrological effects of the temporal and spatial variation in runoff components. More importantly, we discuss the hydrological significance of permafrost and hydrological processes.
Michal Jenicek and Ondrej Ledvinka
Hydrol. Earth Syst. Sci., 24, 3475–3491, https://doi.org/10.5194/hess-24-3475-2020, https://doi.org/10.5194/hess-24-3475-2020, 2020
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Changes in snow affect the runoff seasonality, including summer low flows. Here we analyse this effect in 59 mountain catchments in Czechia. We show that snow is more effective in generating runoff compared to rain. Snow-poor years generated lower groundwater recharge than snow-rich years, which resulted in higher deficit volumes in summer. The lower recharge and runoff in the case of a snowfall-to-rain transition due to air temperature increase might be critical for water supply in the future.
Julia L. A. Knapp, Jana von Freyberg, Bjørn Studer, Leonie Kiewiet, and James W. Kirchner
Hydrol. Earth Syst. Sci., 24, 2561–2576, https://doi.org/10.5194/hess-24-2561-2020, https://doi.org/10.5194/hess-24-2561-2020, 2020
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Changes of stream water chemistry in response to discharge changes provide important insights into the storage and release of water from the catchment. Here we investigate the variability in concentration–discharge relationships among different solutes and hydrologic events and relate it to catchment conditions and dominant water sources.
Elizabeth R. Jachens, David E. Rupp, Clément Roques, and John S. Selker
Hydrol. Earth Syst. Sci., 24, 1159–1170, https://doi.org/10.5194/hess-24-1159-2020, https://doi.org/10.5194/hess-24-1159-2020, 2020
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Recession analysis uses the receding streamflow following precipitation events to estimate watershed-average properties. Two methods for recession analysis use recession events individually or all events collectively. Using synthetic case studies, this paper shows that analyzing recessions collectively produces flawed interpretations. Moving forward, recession analysis using individual recessions should be used to describe the average and variability of watershed behavior.
Lu Lin, Man Gao, Jintao Liu, Jiarong Wang, Shuhong Wang, Xi Chen, and Hu Liu
Hydrol. Earth Syst. Sci., 24, 1145–1157, https://doi.org/10.5194/hess-24-1145-2020, https://doi.org/10.5194/hess-24-1145-2020, 2020
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In this paper, recession flow analysis – assuming nonlinearized outflow from aquifers into streams – was used to quantify active groundwater storage in a headwater catchment with high glacierization and large-scale frozen ground on the Tibetan Plateau. Hence, this work provides a perspective to clarify the impact of glacial retreat and frozen ground degradation due to climate change on hydrological processes.
Francesc Gallart, Jana von Freyberg, María Valiente, James W. Kirchner, Pilar Llorens, and Jérôme Latron
Hydrol. Earth Syst. Sci., 24, 1101–1107, https://doi.org/10.5194/hess-24-1101-2020, https://doi.org/10.5194/hess-24-1101-2020, 2020
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How catchments store and release rain or melting water is still not well known. Now, it is broadly accepted that most of the water in streams is older than several months, and a relevant part may be many years old. But the age of water depends on the stream regime, being usually younger during high flows. This paper tries to provide tools for better analysing how the age of waters varies with flow in a catchment and for comparing the behaviour of catchments diverging in climate, size and regime.
Sebastian J. Gnann, Nicholas J. K. Howden, and Ross A. Woods
Hydrol. Earth Syst. Sci., 24, 561–580, https://doi.org/10.5194/hess-24-561-2020, https://doi.org/10.5194/hess-24-561-2020, 2020
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In many places, seasonal variability in precipitation and evapotranspiration (climate) leads to seasonal variability in river flow (streamflow). In this work, we explore how climate seasonality is transformed into streamflow seasonality and what controls this transformation (e.g. climate aridity and geology). The results might be used in grouping catchments, predicting the seasonal streamflow regime in ungauged catchments, and building hydrological simulation models.
Adam S. Ward, Steven M. Wondzell, Noah M. Schmadel, Skuyler Herzog, Jay P. Zarnetske, Viktor Baranov, Phillip J. Blaen, Nicolai Brekenfeld, Rosalie Chu, Romain Derelle, Jennifer Drummond, Jan H. Fleckenstein, Vanessa Garayburu-Caruso, Emily Graham, David Hannah, Ciaran J. Harman, Jase Hixson, Julia L. A. Knapp, Stefan Krause, Marie J. Kurz, Jörg Lewandowski, Angang Li, Eugènia Martí, Melinda Miller, Alexander M. Milner, Kerry Neil, Luisa Orsini, Aaron I. Packman, Stephen Plont, Lupita Renteria, Kevin Roche, Todd Royer, Catalina Segura, James Stegen, Jason Toyoda, Jacqueline Hager, and Nathan I. Wisnoski
Hydrol. Earth Syst. Sci., 23, 5199–5225, https://doi.org/10.5194/hess-23-5199-2019, https://doi.org/10.5194/hess-23-5199-2019, 2019
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The movement of water and solutes between streams and their shallow, connected subsurface is important to many ecosystem functions. These exchanges are widely expected to vary with stream flow across space and time, but these assumptions are seldom tested across basin scales. We completed more than 60 experiments across a 5th-order river basin to document these changes, finding patterns in space but not time. We conclude space-for-time and time-for-space substitutions are not good assumptions.
Lucy J. Barker, Jamie Hannaford, Simon Parry, Katie A. Smith, Maliko Tanguy, and Christel Prudhomme
Hydrol. Earth Syst. Sci., 23, 4583–4602, https://doi.org/10.5194/hess-23-4583-2019, https://doi.org/10.5194/hess-23-4583-2019, 2019
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It is important to understand historic droughts in order to plan and prepare for possible future events. In this study we use the standardised streamflow index for 1891–2015 to systematically identify, characterise and rank hydrological drought events for 108 near-natural UK catchments. Results show when and where the most severe events occurred and describe events of the early 20th century, providing catchment-scale detail important for both science and planning applications of the future.
Ralf Loritz, Axel Kleidon, Conrad Jackisch, Martijn Westhoff, Uwe Ehret, Hoshin Gupta, and Erwin Zehe
Hydrol. Earth Syst. Sci., 23, 3807–3821, https://doi.org/10.5194/hess-23-3807-2019, https://doi.org/10.5194/hess-23-3807-2019, 2019
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In this study, we develop a topographic index explaining hydrological similarity within a energy-centered framework, with the observation that the majority of potential energy is dissipated when rainfall becomes runoff.
Sophie Ehrhardt, Rohini Kumar, Jan H. Fleckenstein, Sabine Attinger, and Andreas Musolff
Hydrol. Earth Syst. Sci., 23, 3503–3524, https://doi.org/10.5194/hess-23-3503-2019, https://doi.org/10.5194/hess-23-3503-2019, 2019
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This study shows quantitative and temporal offsets between nitrogen input and riverine output, using time series of three nested catchments in central Germany. The riverine concentrations show lagged reactions to the input, but at the same time exhibit strong inter-annual changes in the relationship between riverine discharge and concentration. The study found a strong retention of nitrogen that is dominantly assigned to a hydrological N legacy, which will affect future stream concentrations.
Davide Zoccatelli, Francesco Marra, Moshe Armon, Yair Rinat, James A. Smith, and Efrat Morin
Hydrol. Earth Syst. Sci., 23, 2665–2678, https://doi.org/10.5194/hess-23-2665-2019, https://doi.org/10.5194/hess-23-2665-2019, 2019
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This study presents a comparison of flood properties over multiple Mediterranean and desert catchments. While in Mediterranean areas floods are related to rainfall amount, in deserts we observed a strong connection with the characteristics of the more intense part of storms. Because of the different mechanisms involved, despite having significantly shorter and more localized storms, deserts are able to produce floods with a magnitude comparable to Mediterranean areas.
Cited articles
Benettin, P., van der Velde, Y., van der Zee, S., Rinaldo, A., and Botter,
G.: Chloride circulation in a lowland catchment and the formulation of
transport by travel time distributions, Water Resour. Res., 49, 4619–4632,
https://doi.org/10.1002/wrcr.20309, 2013.
Benettin, P., Kirchner, J., Rinaldo, A., and Botter, G.: Modeling chloride
transport using travel-time distributions at Plynlimon, Wales, Water Resour.
Res., 51, 3259–3276, https://doi.org/10.1002/2014WR016600, 2015.
Bethke, C. M., and Johnson, T. M.: Groundwater age and groundwater age
dating, Annu. Rev. Earth Planet. Sci., 36, 121–152, https://doi.org/10.1146/annurev.earth.36.031207.124210, 2008.
Beven, K.: On subsurface stormflow: predictions with simple kinematic theory
for saturated and unsaturated flows, Water Resour. Res., 18, 1627–1633, 1982.
Beven, K.: A manifesto for the equifinality thesis, J. Hydrol., 320, 18–36,
https://doi.org/10.1016/j.jhydrol.2005.07.007, 2006.
Birkel, C., Soulsby, C., and Tetzlaff, D.: Modelling catchment-scale water
storage dynamics: reconciling dynamic storage with tracer-inferred passive
storage, Hydrol. Process., 25, 3924–3936, 2011.
Birkel, C., Soulsby, C., Tetzlaff, D., Dunn, S., and Spezia, L.:
High-frequency storm event isotope sampling reveals time-variant transit
time distributions and influence of diurnal cycles, Hydrol. Process.,
26, 308–316, https://doi.org/10.1002/hyp.8210, 2012.
Botter, G.: Catchment mixing processes and travel time distributions, Water
Resour. Res., 48, 15, W05545, https://doi.org/10.1029/2011wr011160, 2012.
Botter, G., Bertuzzo, E., and Rinaldo, A.: Transport in the hydrological
response: Travel time distributions, soil moisture dynamics, and the old
water paradox, Water Resour. Res., 46, W03514, https://doi.org/10.1029/2009WR008371, 2010.
Botter, G., Bertuzzo, E., and Rinaldo, A.: Catchment residence and travel
time distributions: The master equation, Geophys. Res. Lett., 38, L11403,
https://doi.org/10.1029/2011GL047666, 2011.
Clark, M. P. and Kavetski, D.: Ancient numerical daemons of conceptual
hydrological modeling: 1. Fidelity and efficiency of time stepping schemes,
Water Resour. Res., 46, W10510, https://doi.org/10.1029/2009wr008894, 2010.
Duan, Q., Schaake, J., Andreassian, V., Franks, S., Goteti, G., Gupta, H. V.,
Gusev, Y. M., Habets, F., Hall, A., Hay, L., Hogue, T., Huang, M., Leavesley, G.,
Liang, X., Nasonova, O. N., Noilhan, J., Oudin, L., Sorooshian, S., Wagener, T.,
and Wood, E. F.: Model Parameter Estimation Experiment (MOPEX): An overview of
science strategy and major results from the second and third workshops,
J. Hydrol., 320, 3–17, https://doi.org/10.1016/j.jhydrol.2005.07.031, 2006.
Feng, X. H., Faiia, A. M., and Posmentier, E. S.: Seasonality of isotopes in
precipitation: A global perspective, J. Geophys. Res.-Atmos., 114, D08116,
https://doi.org/10.1029/2008jd011279, 2009.
Harman, C. J.: Time-variable transit time distributions and transport:
Theory and application to storage-dependent transport of chloride in a
watershed, Water Resour. Res., 51, 1–30, https://doi.org/10.1002/2014WR015707, 2015.
Heidbüchel, I., Troch, P. A., Lyon, S. W., and Weiler, M.: The master
transit time distribution of variable flow systems, Water Resour. Res., 48,
W06520, https://doi.org/10.1029/2011WR011293, 2012.
Hrachowitz, M., Soulsby, C., Tetzlaff, D., Malcolm, I. A., and Schoups, G.:
Gamma distribution models for transit time estimation in catchments:
Physical interpretation of parameters and implications for time-variant
transit time assessment, Water Resour. Res., 46, W10536, https://doi.org/10.1029/2010wr009148, 2010.
Hrachowitz, M., Savenije, H., Bogaard, T. A., Tetzlaff, D., and Soulsby, C.:
What can flux tracking teach us about water age distribution patterns and
their temporal dynamics?, Hydrol. Earth Syst. Sci., 17, 533–564, https://doi.org/10.5194/hess-17-533-2013, 2013.
Ibbitt, R. P. and O'Donnell, T.: Designing conceptual catchment models for
automatic fitting methods, in: Mathematical Models in Hydrology,
International Association of Hydrological Sciences Publication, Wallingford, UK, 461–475, 1974.
Kavetski, D. and Clark, M. P.: Ancient numerical daemons of conceptual
hydrological modeling: 2. Impact of time stepping schemes on model analysis
and prediction, Water Resour. Res., 46, W10511, https://doi.org/10.1029/2009wr008896, 2010.
Kavetski, D. and Clark, M. P.: Numerical troubles in conceptual hydrology:
Approximations, absurdities and impact on hypothesis testing, Hydrol.
Process., 25, 661–670, https://doi.org/10.1002/hyp.7899, 2011.
Kirchner, J. W.: A double paradox in catchment hydrology and geochemistry,
Hydrol. Process., 17, 871–874, 2003.
Kirchner, J. W.: Catchments as simple dynamical systems: catchment
characterization, rainfall-runoff modeling, and doing hydrology backward,
Water Resour. Res., 45, W02429, https://doi.org/10.1029/2008WR006912, 2009.
Kirchner, J. W.: Aggregation in environmental systems – Part 1: Seasonal tracer
cycles quantify young water fractions, but not mean transit times, in
spatially heterogeneous catchments, Hydrol. Earth Syst. Sci., 20, 279–297,
https://doi.org/10.5194/hess-20-279-2016, 2016.
Kirchner, J. W., Feng, X., and Neal, C.: Fractal stream chemistry and its
implications for contaminant transport in catchments, Nature, 403, 524–527, 2000.
Kirchner, J. W., Feng, X., and Neal, C.: Catchment-scale advection and
dispersion as a mechanism for fractal scaling in stream tracer
concentrations, J. Hydrol., 254, 81–100, 2001.
Kreft, A. and Zuber, A.: On the physical meaning of the dispersion equation
and its solutions for different initial and boundary conditions, Chem. Eng.
Sci., 33, 1471–1480, 1978.
McDonnell, J. J. and Beven, K.: Debates-The future of hydrological
sciences: A (common) path forward? A call to action aimed at understanding
velocities, celerities and residence time distributions of the headwater
hydrograph, Water Resour. Res., 50, 5342–5350, https://doi.org/10.1002/2013wr015141, 2014.
McGuire, K. J. and McDonnell, J. J.: A review and evaluation of catchment
transit time modeling, J. Hydrol., 330, 543–563, 2006.
Neal, C., Wilkinson, J., Neal, M., Harrow, M., Wickham, H., Hill, L., and
Morfitt, C.: The hydrochemistry of the headwaters of the River Severn, Plynlimon,
Hydrol. Earth Syst. Sci., 1, 583–617, https://doi.org/10.5194/hess-1-583-1997, 1997.
Neal, C., Reynolds, B., Norris, D., Kirchner, J. W., Neal, M., Rowland, P.,
Wickham, H., Harman, S., Armstrong, L., Sleep, D., Lawlor, A., Woods, C.,
Williams, B., Fry, M., Newton, G., and Wright, D.: Three decades of water
quality measurements from the Upper Severn experimental catchments at
Plynlimon, Wales: an openly accessible data resource for research,
modelling, environmental management and education, Hydrol. Process.,
25, 3818–3830, https://doi.org/10.1002/hyp.8191, 2011.
Peters, N. E., Burns, D. A., and Aulenbach, B. T.: Evaluation of
high-frequency mean streamwater transit-time estimates using groundwater age
and dissolved silica concentrations in a small forested watershed, Aquat.
Geochem., 20, 183–202, 2014.
Seeger, S. and Weiler, M.: Reevaluation of transit time distributions, mean
transit times and their relation to catchment topography, Hydrol. Earth
Syst. Sci., 18, 4751–4771, https://doi.org/10.5194/hess-18-4751-2014, 2014.
Tetzlaff, D., Malcolm, I. A., and Soulsby, C.: Influence of forestry,
environmental change and climatic variability on the hydrology,
hydrochemistry and residence times of upland catchments, J. Hydrol., 346, 93–111, 2007.
Van der Velde, Y., De Rooij, G. H., Rozemeijer, J. C., van Geer, F. C., and
Broers, H. P.: The nitrate response of a lowland catchment: on the relation
between stream concentration and travel time distribution dynamics, Water
Resour. Res., 46, W11534, https://doi.org/10.1029/2010WR009105, 2010.
Van der Velde, Y., Torfs, P. J. J. F., van der Zee, S. E. A. T. M., and
Uijlenhoet, R.: Quantifying catchment-scale mixing and its effect on
time-varying travel time distributions, Water Resour. Res., 48, W06536,
https://doi.org/10.1029/2011WR011310, 2012.
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Short summary
Here I show that seasonal tracer cycles yield strongly biased estimates of mean transit times in nonstationary catchments (and, by implication, in real-world catchments). However, they can be used to reliably estimate the fraction of "young" water in streamflow, meaning water that fell as precipitation less than roughly 2–3 months ago. This young water fraction varies systematically between high and low flows and may help in characterizing controls on stream chemistry.
Here I show that seasonal tracer cycles yield strongly biased estimates of mean transit times in...
