Riparian zone hydrology and soil water total organic carbon (TOC): implications for spatial variability and upscaling of lateral riparian TOC exports

Grabs, Thomas; Bishop, Kevin; Laudon, Hjalmar; Lyon, Steve W.; Seibert, Jan

doi:10.5194/bg-9-3901-2012

Cited by 131 publications

(238 citation statements)

References 67 publications

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“…The timing and change in groundwater levels can be an important driver of fluxes through the riparian zone, which have a strong influence on in-stream [DOC] (Bishop et al, 1995;Lyon et al, 2011;Grabs et al, 2012). Typically, soil solution [DOC] exceeds stream [DOC] and decreases with depth down the soil profile ).…”

Section: Riparian Controls On Stream Doc Concentrationmentioning

confidence: 99%

Long-term patterns in dissolved organic carbon, major elements and trace metals in boreal headwater catchments: trends, mechanisms and heterogeneity

Oni

Bishop

et al. 2013

Biogeosciences

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The boreal landscape is a complex, spatio-temporally varying mosaic of forest and mire landscape elements that control surface water hydrology and chemistry. Here, we assess long-term water quality time series from three nested headwater streams draining upland forest (C2), peat/mire (C4) and mixed (C7) (forest and mire) catchments. Acid deposition in this region is low and is further declining. Temporal trends in weather and runoff (1981–2008), dissolved organic carbon concentration [DOC] (1993–2010) and other water quality parameters (1987–2011) were assessed. There was no significant annual trend in precipitation or runoff. However, runoff increased in March and declined in May. This suggested an earlier snowmelt regime in recent years. Significant monotonic increasing trends in air temperature and length of growing season suggested a decrease in snowfall and less spring runoff. Stream [DOC] was positively correlated with some trace metals (copper, iron and zinc) and negatively with several other chemical parameters (e.g. sulfate, conductivity, calcium). Both sulfate and conductivity showed declining trends, while a significant increase was observed in pH during winter and spring. Calcium and magnesium showed monotonic decreasing trends. The declining trajectories of stream base cation and sulfate concentrations during other times of the year were not accompanied by changes in pH and alkalinity. These results indicate subtle effects of recovery from acidification. Water temperature increased significantly both annually and in most months. A simultaneous monotonic increase in iron (Fe) and [DOC] in autumn suggests co-transport of Fe-DOC in the form of organometallic complexes. A monotonic increase in UV absorbance in most months without co-occurring changes in DOC trend suggests a shift in DOC quality to a more humic-rich type. The observed increase in soil solution [DOC] and subtle trends in stream [DOC] suggest that climate rather than recovery from acidification is the dominant driver of DOC trends in the Svartberget catchment

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Section: Riparian Controls On Stream Doc Concentrationmentioning

confidence: 99%

Long-term patterns in dissolved organic carbon, major elements and trace metals in boreal headwater catchments: trends, mechanisms and heterogeneity

Oni

Bishop

et al. 2013

Biogeosciences

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“…Given the global relevance of increasing river nutrient concentrations, there is a critical need to develop a thorough mechanistic understanding of the variability and controls on nutrient mobilization and export from river catchments. In particular, identification of the dominant landscape source zones that contribute to nutrient export is often challenging [Bishop et al, 1994;Pacific et al, 2010;Grabs et al, 2012], despite the importance of this for their effective management.…”

Section: Introductionmentioning

confidence: 99%

High‐frequency monitoring of catchment nutrient exports reveals highly variable storm event responses and dynamic source zone activation

et al. 2017

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Storm events can drive highly variable behavior in catchment nutrient and water fluxes, yet short‐term event dynamics are frequently missed by low‐resolution sampling regimes. In addition, nutrient source zone contributions can vary significantly within and between storm events. Our inability to identify and characterize time‐dynamic source zone contributions severely hampers the adequate design of land use management practices in order to control nutrient exports from agricultural landscapes. Here we utilize an 8 month high‐frequency (hourly) time series of streamflow, nitrate (NO3‐N), dissolved organic carbon (DOC), and hydroclimatic variables for a headwater agricultural catchment. We identified 29 distinct storm events across the monitoring period. These events represented 31% of the time series and contributed disproportionately to nutrient loads (42% of NO3‐N and 43% of DOC) relative to their duration. Regression analysis identified a small subset of hydroclimatological variables (notably precipitation intensity and antecedent conditions) as key drivers of nutrient dynamics during storm events. Hysteresis analysis of nutrient concentration‐discharge relationships highlighted the dynamic activation of discrete NO3‐N and DOC source zones, which varied on an event‐specific basis. Our results highlight the benefits of high‐frequency in situ monitoring for characterizing short‐term nutrient fluxes and unraveling connections between hydroclimatological variability and river nutrient export and source zone activation under extreme flow conditions. These new process‐based insights, which we summarize in a conceptual model, are fundamental to underpinning targeted management measures to reduce nutrient loading of surface waters.

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“…These effects might not have been covered by our experimental slope. Moreover, there is still a great need for research since the impact of the width of riparian areas on the hydrological subsurface connectivity between hillslope and stream is still not yet investigated sufficiently (Grabs et al, 2012;Jencso et al, 2010;Uchida et al, 2005). Especially for the shift from small-scale to mesoscale catchments the widths between hillslope and stream are increasing considerably.…”

Section: Controlling Factors For Discharge At the Meso-scale Catchmenmentioning

confidence: 99%

The significance of soil moisture in forecasting characteristics of flood events. A statistical analysis in two nested catchments

Chifflard

Kranl

Strassen

et al. 2017

Journal of Hydrology and Hydromechanics

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Abstract:We examine the feasibility and added value of upscaling point data of soil moisture from a small-to a mesoscale catchment for the purpose of single-event flood prediction. We test the hypothesis that in a given catchment, the present soil moisture status is a key factor governing peak discharge, flow volume and flood duration. Multiple regression analyses of rainfall, pre-event discharge, single point soil moisture profiles from representative locations and peak discharge, discharge duration, discharge volume are discussed. The soil moisture profiles are selected along a convergent slope connected to the groundwater in flood plain within the small-scale catchment Husten (2.6 km²), which is a headwater catchment of the larger Hüppcherhammer catchment (47.2 km², Germany). Results show that the number of explanatory variables in the regression models is higher in summer (up to 8 variables) than in winter (up to 3 variables) and higher in the meso-scale catchment than in the small-scale catchment (up to 2 variables). Soil moisture data from selected key locations in the small catchment improves the quality of regression models established for the meso-scale catchment. For the different target variables peak discharge, discharge duration and discharge volume the adding of the soil moisture from the flood plain and the lower slope as explanatory variable improves the quality of the regression model by 15%, 20% and 10%, respectively, especially during the summer season. In the winter season the improvement is smaller (up to 6%) and the regression models mainly include rainfall characteristics as explanatory variables. The appearance of the soil moisture variables in the stepwise regression indicates their varying importance, depending on which characteristics of the discharge are focused on. Thus, we conclude that point data for soil moisture in functional landscape elements describe the catchments' initial conditions very well and may yield valuable information for flood prediction and warning systems.

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Riparian zone hydrology and soil water total organic carbon (TOC): implications for spatial variability and upscaling of lateral riparian TOC exports

Cited by 131 publications

References 67 publications

Long-term patterns in dissolved organic carbon, major elements and trace metals in boreal headwater catchments: trends, mechanisms and heterogeneity

Long-term patterns in dissolved organic carbon, major elements and trace metals in boreal headwater catchments: trends, mechanisms and heterogeneity

High‐frequency monitoring of catchment nutrient exports reveals highly variable storm event responses and dynamic source zone activation

The significance of soil moisture in forecasting characteristics of flood events. A statistical analysis in two nested catchments

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