Streams as Mirrors: Reading Subsurface Water Chemistry From Stream Chemistry

Water Resources Research, Journal Year: 2021, Volume and Issue: 58(1)

Published: Oct. 22, 2021

Abstract The shallow and deep hypothesis suggests that stream concentration‐discharge (CQ) relationships are shaped by distinct source waters from different depths. Under this hypothesis, baseflows typically dominated groundwater mostly reflect chemistry, whereas high flows soil water chemistry. Aspects of draw on applications like end member mixing analyses hydrograph separation, yet direct data support for the remains scarce. This work tests using co‐located measurements water, groundwater, streamwater chemistry at two intensively monitored sites, W‐9 catchment Sleepers River (Vermont, United States) Hafren Plynlimon (Wales). At both depth profiles subsurface CQ 10 solutes analyzed broadly consistent with hypothesis. Solutes more abundant (e.g., calcium) exhibit dilution patterns (concentration decreases increasing discharge). Conversely, enriched in soils nitrate) generally flushing increases may hold true catchments share such biogeochemical stratifications subsurface. Soil chemistries were estimated high‐ low‐flow average relative errors ranging 24% to 82%. indicates streams mirror waters: can be used infer scarcely measured especially where there members.

Language: Английский

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Spatial and Temporal Variability in Concentration‐Discharge Relationships at the Event Scale

Water Resources Research, Journal Year: 2021, Volume and Issue: 57(10)

Published: Sept. 29, 2021

Abstract The analysis of concentration‐discharge (C‐Q) relationships from low‐frequency observations is commonly used to assess solute sources, mobilization, and reactive transport processes at the catchment scale. High‐frequency concentration measurements are increasingly available offer additional insights into event‐scale export dynamics. However, only few studies have integrated inter‐annual C‐Q relationships. Here, we analyze high‐frequency specific conductance (EC), nitrate (NO 3 ‐N) concentrations spectral absorbance 254 nm (SAC , as a proxy for dissolved organic carbon) over two year period four neighboring catchments in Germany ranging more pristine forested agriculturally managed settings. We apply an method that adds hysteresis term established power law model so intercept, slope can be characterized simultaneously. found inter‐event variability were most pronounced SAC all NO ‐N catchments. event responses smallest closely coupled explainable by antecedent conditions hint common near‐stream source. In contrast, patterns EC agricultural without buffer zones around streams less variable similar relationship indicating homogeneity mobilization time. Event‐scale thus added key functioning whenever contrasted with responses. Analyzing long‐term behavior one coherent framework helps disentangle these scattered patterns.

Language: Английский

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Climate Controls on River Chemistry

Earth s Future, Journal Year: 2022, Volume and Issue: 10(6)

Published: May 16, 2022

Abstract How does climate control river chemistry? Existing literature has examined extensively the response of chemistry to short‐term weather conditions from event seasonal scales. Patterns and drivers long‐term, baseline have remained poorly understood. Here we compile analyze data 506 minimally impacted rivers (412,801 points) in contiguous United States (CAMELS‐Chem) identify patterns chemistry. Despite distinct sources diverse reaction characteristics, a universal pattern emerges for 16 major solutes at continental scale. Their long‐term mean concentrations ( C m ) decrease with discharge Q ), elevated arid climates lower humid climates, indicating overwhelming regulation by compared local Critical Zone characteristics such as lithology topography. To understand pattern, parsimonious watershed reactor model was solved bringing together hydrology (storage–discharge relationship) biogeochemical theories traditionally separate disciplines. The derivation steady state solutions lead power law form relationships. illuminates two competing processes that determine solute concentrations: production subsurface chemical weathering reactions, export (or removal) discharge, water flushing capacity dictated vegetation. In other words, watersheds function primarily reactors produce accumulate transporters climates. With space‐for‐time substitution, these results indicate places where dwindles warming climate, will elevate even without human perturbation, threatening quality aquatic ecosystems. Water deterioration therefore should be considered global calculation future risks.

Language: Английский

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Hydrologic connectivity and source heterogeneity control concentration–discharge relationships

Hydrological Processes, Journal Year: 2022, Volume and Issue: 36(9)

Published: Aug. 25, 2022

Abstract Changes in streamwater chemistry have frequently been used to understand the storage and release of water solutes at catchment scale. Streamwater typically varies space time, depending on sources, mobilization mechanisms, pathways solutes. However, less is known about role lateral hydrologic connectivity how it may influence solute export patterns under different wetness conditions. This study analyses long‐term low‐frequency data from four UK catchments using antecedent as proxy for connectivity. We demonstrate that mechanisms can vary wetness, areas become hydrologically connected or disconnected streams. show flow are mostly decoupled dry conditions, leading stronger impacts heterogeneity sources during conditions compared wet Our results vertical distributions need be integrated considered together with temporally variable these stream when assessing chemistry. combined analysis thus enables inferences regarding distribution throughout catchment; also indicates a better understanding relationship between concentrations help identify particularly vulnerable points their potential polluting effects

Language: Английский

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A coupled model to improve river water quality prediction towards addressing non-stationarity and data limitation

Water Research, Journal Year: 2023, Volume and Issue: 248, P. 120895 - 120895

Published: Nov. 20, 2023

Language: Английский

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Catchment characterization: Current descriptors, knowledge gaps and future opportunities

Earth-Science Reviews, Journal Year: 2024, Volume and Issue: 252, P. 104739 - 104739

Published: March 8, 2024

The ability to characterize hydrologically relevant differences between places is at the core of our science. A common way quantitatively hydrological catchments through use descriptors that summarize physical aspects system, typically by aggregating heterogeneous geospatial information into a single number. Such capture various facets catchment functioning and structure, identify similarity or dissimilarity among catchments, transfer unobserved locations. However, so far there no agreement on how should be selected, aggregated, evaluated. Even worse, little known about existence potential biases in current practices catchments. In this systematic review, we analyze 742 research articles published 1967 2021 provide categorized overview historical characterization (i.e., data sources, aggregation evaluation methods) science related disciplines. We uncover substantial characterization: (1) only 16% analyzed studies are dry environments, even though such environments cover 42% global land surface, suggesting most tailored represent energy-limited potentially less effective water-limited environments; (2) 30% subsurface features for despite dominance flow; (3) 4% 9% aggregated spatially- vertically-differentiated way, respectively, while majority simple averages do not account hydrologically-relevant variabilities within catchments; (4) 25% all evaluate usefulness descriptors, none quantifies their uncertainty. demonstrate effects these effectively functional behavior with illustrative examples. Finally, suggest possible ways derive more robust, comprehensive meaningful descriptors.

Language: Английский

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Vertical Connectivity Regulates Water Transit Time and Chemical Weathering at the Hillslope Scale

Water Resources Research, Journal Year: 2021, Volume and Issue: 57(8)

Published: July 13, 2021

Abstract How does hillslope structure (e.g., shape and permeability variation) regulate its hydro‐geochemical functioning (flow paths, solute export, chemical weathering)? Numerical reactive transport experiments particle tracking were used to answer this question. Results underscore the first‐order control of variations (with depth) on vertical connectivity (VC), defined as fraction water flowing into streams from below soil zone. Where decreases sharply VC is low, >95% flows through top 6 m subsurface, barely interacting with rock at depth. High also elongates mean transit times (MTTs) weathering rates. however less an influence under arid climates where long drive equilibrium. The results lead three working hypotheses that can be further tested. H1 : depth MTTs stream more strongly than shapes; shapes instead younger . H2 arising high depths enhances by promoting deeper penetration water‐rock interactions; weakens larger hillslopes longer H3 regulates contrasts between shallow deep waters (C ratio ) export patterns encapsulated in power law slope b concentration‐discharge (CQ) relationships Higher leads similar versus chemistry ∼1) chemostatic CQ Although supporting data already exist, these tested carefully designed, co‐located modeling measurements soil, rock, waters. Broadly, importance subsurface indicate it essential regulating earth surface hydrogeochemical response changing climate human activities.

Language: Английский

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Nitrate concentrations predominantly driven by human, climate, and soil properties in US rivers

Water Research, Journal Year: 2022, Volume and Issue: 226, P. 119295 - 119295

Published: Oct. 24, 2022

Language: Английский

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From Soils to Streams: Connecting Terrestrial Carbon Transformation, Chemical Weathering, and Solute Export Across Hydrological Regimes

Water Resources Research, Journal Year: 2022, Volume and Issue: 58(7)

Published: June 13, 2022

Abstract Soil biota generates carbon that exports vertically to the atmosphere (CO 2 ) and transports laterally streams rivers (dissolved organic inorganic carbon, DOC DIC). These processes, together with chemical weathering, vary flow paths across hydrological regimes; yet an integrated understanding of these interactive processes is still lacking. Here we ask: How what extent do subsurface transformation, solute export differ structure regimes? We address this question using a hillslope reactive transport model calibrated soil CO water chemistry data from Fitch, temperate forest at ecotone boundary Eastern mid‐continent grasslands in Kansas, USA. Model results show droughts (discharge 0.08 mm/day) promoted deeper paths, longer transit time, carbonate precipitation, mineralization (OC) into (IC) (∼98% OC). Of IC produced, ∼86% was emitted upward as gas ∼14% exported DIC stream. Storms (8.0 led dissolution but reduced OC (∼88% OC) production (∼12% lateral fluxes (∼53% produced IC). Differences shallow‐versus‐deep permeability contrasts smaller difference (<10%) than discharge‐induced differences were most pronounced under wet conditions. High (low vertical connectivity) enhanced fluxes. generally delineate hillslopes active producers transporters dry conditions, transporter

Language: Английский

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Explaining the Variability in High‐Frequency Nitrate Export Patterns Using Long‐Term Hydrological Event Classification

Water Resources Research, Journal Year: 2022, Volume and Issue: 58(1)

Published: Jan. 1, 2022

Abstract Runoff events play an important role in nitrate export from catchments, but the variability of patterns between and catchments is high dominant drivers remain difficult to disentangle. Here, we rigorously asses if detailed knowledge on runoff event characteristics can help explain this variability. To end, conducted a long‐term (1955–2018) classification using hydro‐meteorological data, including rainfall characteristics, soil moisture snowmelt, six neighboring mesoscale with contrasting land use. We related these high‐frequency concentration monitoring (2013–2017) concentration‐discharge (CQ) relationships. Our results show that low‐magnitude rainfall‐induced dry antecedent conditions exported lowest concentrations loads exhibited highly variable CQ by low fraction active flow paths, revealing spatial heterogeneity sources within increased impact biogeochemical retention processes. In contrast, high‐magnitude or snowmelt‐induced highest converged similar chemostatic across all without exhibiting source limitation. homogeneous catchment wetness activated number paths higher availability during high‐flow seasons. Long‐term data indicated summer decreased snow‐influenced events. These trends will likely continue cause low‐flow seasons changes timing peaks

Language: Английский

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