Linkages between flow regime, biota, and ecosystem processes: Implications for river restoration

Science, Journal Year: 2019, Volume and Issue: 365(6459)

Published: Sept. 19, 2019

River ecosystems are highly biodiverse, influence global biogeochemical cycles, and provide valued services. However, humans increasingly degrading fluvial by altering their streamflows. Effective river restoration requires advancing our mechanistic understanding of how flow regimes affect biota ecosystem processes. Here, we review emerging advances in hydroecology relevant to this goal. Spatiotemporal variation exerts direct indirect control on the composition, structure, dynamics communities at local regional scales. Streamflows also processes, such as nutrient uptake transformation, organic matter processing, metabolism. We deepening biological not just static patterns, affected stream research nexus flow-biota-ecosystem processes is an early stage. illustrate frontier with evidence from altered regulated rivers urban streams. identify challenges that should be prioritized advance process-based restoration.

Language: Английский

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A review of CO₂ and associated carbon dynamics in headwater streams: A global perspective

Reviews of Geophysics, Journal Year: 2017, Volume and Issue: 55(2), P. 560 - 585

Published: May 31, 2017

Abstract Terrestrial carbon export via inland aquatic systems is a key process in the global cycle. It includes loss of to atmosphere outgassing from rivers, lakes, or reservoirs and fixation water column as well sediments. This review focuses on headwater streams that are important because their stream biogeochemistry directly reflects input soils groundwaters. Major drivers dioxide partial pressures ( p CO 2 ) mechanisms terrestrial dissolved inorganic, organic particulate (DIC, DOC, POC) influxes summarized this work. Our analysis indicates river average 3100 ppmV more often exceeded by contributions small when compared rivers with larger catchments (> 500 km ). Because large proportion networks 96% total number streams), headwaters contribute large—but still poorly quantified—amounts atmosphere. Conservative estimates imply globally 36% (i.e., 0.93 Pg C yr −1 originate headwaters. We also discuss challenges determination sources, concentrations, fluxes. To overcome uncertainties sources its scale, new investigations needed should include groundwater data. Such studies would benefit applications integral isotope approaches multiscale geophysical imaging techniques.

Language: Английский

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Generality of Hydrologic Transport Limitation of Watershed Organic Carbon Flux Across Ecoregions of the United States

Geophysical Research Letters, Journal Year: 2018, Volume and Issue: 45(21)

Published: Oct. 25, 2018

Abstract Although the flux of dissolved organic carbon (DOC) through freshwaters is nearly equivalent to net uptake all terrestrial ecosystems, uncertainty remains about how source processes (carbon production and location) transport (hydrologic connectivity routing) interact determine DOC across flow conditions ecoregions. This limits our ability predict fluvial responses changes in climate land use. We used concentration discharge patterns with ensemble modeling techniques quantify behavior for 1,006 U.S. watersheds spanning diverse cover conditions. found that was transport‐limited (concentration increased discharge) 80% this spanned ecoregions watershed sizes. The generality limitation demonstrates coupling models widely available properties could allow be efficiently integrated into landscape Earth system models.

Language: Английский

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Using SAS functions and high‐resolution isotope data to unravel travel time distributions in headwater catchments

Water Resources Research, Journal Year: 2017, Volume and Issue: 53(3), P. 1864 - 1878

Published: Feb. 11, 2017

Abstract We use high‐resolution tracer data from an experimental site to test theoretical approaches that integrate catchment‐scale flow and transport processes in a unified framework centered on selective age sampling by streamflow evapotranspiration fluxes. Transport operating at the catchment scale are reflected evolving residence time distribution of water storage selection operated out‐fluxes. Such described here through StorAge Selection (SAS) functions parameterized as power laws normalized rank storage. computed appropriate solution master equation defining formally evolution travel times. By representing way which generates outflows composed different ages, main mechanism regulating composition runoff is clearly identified detailed comparison with empirical sets possible. Properly calibrated numerical tools provide simulations convincingly reproduce complex measured signals daily deuterium content stream waters during wet dry periods. Results for under consideration consistent other recent studies indicating tendency natural catchments preferentially release younger available water. The study shows law SAS prove powerful tool explain also has potential less intensively monitored sites.

Language: Английский

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In situ fluorescence measurements of dissolved organic matter: A review

The Science of The Total Environment, Journal Year: 2019, Volume and Issue: 699, P. 134361 - 134361

Published: Sept. 10, 2019

Language: Английский

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Distinct Source Water Chemistry Shapes Contrasting Concentration‐Discharge Patterns

Water Resources Research, Journal Year: 2019, Volume and Issue: 55(5), P. 4233 - 4251

Published: April 15, 2019

Abstract Understanding concentration‐discharge (C‐Q) relationships are essential for predicting chemical weathering and biogeochemical cycling under changing climate anthropogenic conditions. Contrasting C‐Q have been observed widely, yet a mechanistic framework that can interpret diverse patterns remains elusive. This work hypothesizes seemingly disparate driven by switching dominance of end‐member source waters their contrasts arising from subsurface heterogeneity. We use data Coal Creek, high‐elevation mountainous catchment in Colorado, recently developed watershed reactive transport model (BioRT‐Flux‐PIHM). Sensitivity analysis Monte‐Carlo simulations (500 cases) show reaction kinetics thermodynamics distribution materials across depths govern the chemistry gradients shallow soil water deeper groundwater entering stream. The alternating organic‐poor geo‐solute‐rich dry conditions organic‐rich geo‐solute‐poor during spring melt leads to flushing pattern dissolved organic carbon dilution geogenic solutes (e.g., Na, Ca, Mg). In addition, extent concentration regulates power law slopes ( b ) via general equation . At low ratios versus concentrations (C ratio = C sw /C gw < 0.6), occurs; at high > 1.8), arises; chemostasis occurs between. quantitatively interprets values 11 (dissolved carbon, P, NO 3 − , K, Si, Mg, Al, Mn, Fe) three catchments (Coal Shale Hills, Plynlimon) differing climate, geologic, land cover indicates potentially broad regulation heterogeneity determining wide applications this quantifying values, which implications transformation scale.

Language: Английский

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Trends and seasonality of river nutrients in agricultural catchments: 18 years of weekly citizen science in France

The Science of The Total Environment, Journal Year: 2017, Volume and Issue: 624, P. 845 - 858

Published: Dec. 27, 2017

Language: Английский

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Temporal dynamics in dominant runoff sources and flow paths in the Andean Páramo

Water Resources Research, Journal Year: 2017, Volume and Issue: 53(7), P. 5998 - 6017

Published: July 1, 2017

Abstract The relative importance of catchment's water provenance and flow paths varies in space time, complicating the conceptualization rainfall‐runoff responses. We assessed temporal dynamics source areas, paths, age by End Member Mixing Analysis (EMMA), hydrograph separation, Inverse Transit Time Proxies (ITTPs) estimation within a headwater catchment Ecuadorian Andes. Twenty‐two solutes, stable isotopes, pH, electrical conductivity from stream 12 potential sources were analyzed. Four end‐members required to satisfactorily represent hydrological system, i.e., rainfall, spring water, bottom layers Histosols Andosols. Water near riparian zone was highest contributor runoff throughout year (39% for drier season, 45% wetter season), highlighting that is stored zone. Spring contributions streamflow tripled during as evidenced geochemical signatures are consistent with deeper rather than shallow interflow through Rainfall exhibited low seasonal variation this contribution. Hydrograph separation revealed 94% 84% preevent seasons, respectively. From low‐flow high‐flow conditions, all increased their contribution except water. decreased periods, when contributing area expands. multimethod multitracer approach enabled closely study interchanging processes an interannual perspective.

Language: Английский

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Estimating Discharge and Nonpoint Source Nitrate Loading to Streams From Three End‐Member Pathways Using High‐Frequency Water Quality Data

Water Resources Research, Journal Year: 2017, Volume and Issue: 53(12), P. 10201 - 10216

Published: Nov. 21, 2017

Abstract The myriad hydrologic and biogeochemical processes taking place in watersheds occurring across space time are integrated reflected the quantity quality of water streams rivers. Collection high‐frequency data with sensors surface waters provides new opportunities to disentangle these quantify sources transport solutes coupled groundwater‐surface system. A approach for separating streamflow hydrograph into three components was developed nitrate estimate time‐variable loads from chemically dilute quick flow, concentrated slowflow groundwater end‐member pathways periods up 2 years a groundwater‐dominated quick‐flow‐dominated stream central Wisconsin, using only in‐stream data. flow end‐members were distinguished specific conductance Results indicate that contributed less than 5% load at both sites, whereas 89 ± 8% groundwater, 84 25% flow. Concentrated concentrations varied seasonally peak winter 2–3 times greater minimum during growing season. Application this an opportunity assess vulnerability nonpoint source loading expected responses current or changing conditions practices watersheds.

Language: Английский

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An Evaluation of Nitrate, fDOM, and Turbidity Sensors in New Hampshire Streams

Water Resources Research, Journal Year: 2018, Volume and Issue: 54(3), P. 2466 - 2479

Published: March 1, 2018

Abstract A state‐of‐the‐art network of water quality sensors was established in 2012 to gather year‐round high temporal frequency hydrochemical data streams and rivers throughout the state New Hampshire. This spatially extensive includes eight headwater stream two main stem river monitoring sites, spanning a variety orders land uses. Here we evaluate performance nitrate, fluorescent dissolved organic matter (fDOM), turbidity included sensor network. Nitrate were first evaluated laboratory for interference by different forms carbon (DOC), then accuracy field across range conditions. Turbidity assessed their effectiveness as proxy concentrations total suspended solids (TSS) particulate C N, fDOM matter. Overall platform also examined estimating percentage loss due failures or related malfunctions. Although trials show that DOC can affect optical nitrate measurements, our validations with grab samples showed provide reliable measurement NO 3 wide Results is good concentration ( r 2 = 0.82) but less effective nitrogen 0.41). measurements from correlated well TSS 0.78), PC 0.53), PN 0.51).

Language: Английский

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