| 1. |
- van der Velde, Ype, et al.
(författare)
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Quantifying catchment-scale mixing and its effect on time-varying travel time distributions
- 2012
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Ingår i: Water resources research. - 0043-1397 .- 1944-7973. ; 48, s. W06536-
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Tidskriftsartikel (refereegranskat)abstract
- Travel time distributions are often used to characterize catchment discharge behavior, catchment vulnerability to pollution and pollutant loads from catchments to downstream waters. However, these distributions vary with time because they are a function of rainfall and evapotranspiration. It is important to account for these variations when the time scale of interest is smaller than the typical time-scale over which average travel time distributions can be derived. Recent studies have suggested that subsurface mixing controls how rainfall and evapotranspiration affect the variability in travel time distributions of discharge. To quantify this relation between subsurface mixing and dynamics of travel time distributions, we propose a new transformation of travel time that yields transformed travel time distributions, which we call Storage Outflow Probability (STOP) functions. STOP functions quantify the probability for water parcels in storage to leave a catchment via discharge or evapotranspiration. We show that this is equal to quantifying mixing within a catchment. Compared to the similar Age function introduced by Botter et al. (2011), we show that STOP functions are more constant in time, have a clearer physical meaning and are easier to parameterize. Catchment-scale STOP functions can be approximated by a two-parameter beta distribution. One parameter quantifies the catchment preference for discharging young water; the other parameter quantifies the preference for discharging old water from storage. Because of this simple parameterization, the STOP function is an innovative tool to explore the effects of catchment mixing behavior, seasonality and climate change on travel time distributions and the related catchment vulnerability to pollution spreading.
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| 2. |
- Rozemeijer, Joachim, et al.
(författare)
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Application and Evaluation of a New Passive Sampler for Measuring Average Solute Concentrations in a Catchment Scale Water Quality Monitoring Study
- 2010
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 44:4, s. 1353-1359
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Tidskriftsartikel (refereegranskat)abstract
- We present a field based testing, optimization, and evaluation study of the SorbiCell sampler (SC-sampler); a new passive sampling technique that measures average concentrations over longer periods of time (days to months) for various substances. We tested the SC-sampler within a catchment-scale monitoring study of NO(3) and P concentrations in surface water and the drain effluent. Based on our field experiences, we optimized the flow velocity control and the sample volume capacity of the SC-samplers. The SC-samplers were capable of reproducing the NO(3) concentration levels and the seasonal patterns that were observed with weekly conventional grab sampling and continuous water quality measurements. Furthermore, we demonstrated that average measurements produce more consistent load estimates than “snapshot” concentrations from grab sampling. Therefore, when the purpose of a monitoring program is to estimate reliable (trends in) average concentrations or loads, the SC-samplers are a cost-effective alternative for grab sampling.
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| 3. |
- Rozemeijer, Joachim C., et al.
(författare)
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Improving Load Estimates for NO(3) and P in Surface Waters by Characterizing the Concentration Response to Rainfall Events
- 2010
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 44, s. 6305-6312
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Tidskriftsartikel (refereegranskat)abstract
- For the evaluation of action programs to reduce surface water pollution, water authorities invest heavily in water quality monitoring. However, sampling frequencies are generally insufficient to capture the dynamical behavior of solute concentrations For this study, we used on-site equipment that performed semicontinuous (15 min interval) NO(3) and P concentration measurements from June 2007 to July 2008 We recorded the concentration responses to rainfall events with a wide range in antecedent conditions and rainfall durations and intensities. Through sequential linear multiple regression analysis, we successfully related the NO(3) and P event responses to high-frequency records of precipitation, discharge, and groundwater levels We applied the regression models to reconstruct concentration patterns between low-frequency water quality measurements. This new approach significantly improved load estimates from a 20% to a 1% bias for NO(3) and from a 63% to a 5% bias for P. These results demonstrate the value of commonly available precipitation, discharge, and groundwater level data for the interpretation of water quality measurements. Improving load estimates from low-frequency concentration data Just requires a period of high-frequency concentration measurements and a conceptual, statistical, or physical model for relating the rainfall event response of solute concentrations to quantitative hydrological changes.
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| 4. |
- van der Velde, Ype, et al.
(författare)
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Field-Scale Measurements for Separation of Catchment Discharge into Flow Route Contributions
- 2010
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Ingår i: Vadose Zone Journal. - : Wiley. - 1539-1663. ; 9:1, s. 25-35
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Tidskriftsartikel (refereegranskat)abstract
- Agricultural pollutants in catchments are transported toward the discharging stream through various flow routes such as tube drain flow, groundwater flow, interflow, and overland flow. Direct measurements of flow route contributions are difficult and often impossible. We developed a field-scale setup that can measure the contribution of the tube drain flow route to the total discharge toward the surface water system. We then embedded these field-scale measurements in a nested measurement setup to asses the value of field-scale measurements for interpretation of catchment-scale discharge and nitrate concentrations using a linear flow route mixing model. In a lowland catchment, we physically separated the tube drain effluent from the discharge of all other flow routes. Upscaling the field-scale flow route discharge contributions to the subcatchment and the catchment scale with a linear flow route mixing model gave a good prediction of the catchment discharge. Catchment-scale nitrate concentrations were simulated well for a heavy rainfall event but poorly for a small rainfall event. The nested measurement setup revealed that the fluxes at a single field site cannot be representative for the entire catchment at all times. However, the distinctly different hydrograph reaction of the individual flow routes on rainfall events at the field site made it possible to interpret the catchment-scale hydrograph and nitrate concentrations. This study showed that physical separation of flow route contributions at the field scale is feasible and essential for understanding catchment-scale discharge generation and solute transport processes.
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| 5. |
- Berghuijs, Wouter R., et al.
(författare)
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Groundwater recharge is sensitive to changing long-term aridity
- 2024
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Ingår i: Nature Climate Change. - 1758-678X .- 1758-6798. ; 14, s. 357-363
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Tidskriftsartikel (refereegranskat)abstract
- Sustainable groundwater use relies on adequate rates of groundwater recharge, which are expected to change with climate change. However, climate impacts on recharge remain uncertain due to a paucity of measurements of recharge trends globally. Here we leverage the relationship between climatic aridity and long-term recharge measurements at 5,237 locations globally to identify regions where recharge is most sensitive to changes in climatic aridity. Recharge is most sensitive to climate changes in regions where potential evapotranspiration slightly exceeds precipitation, meaning even modest aridification can substantially decrease groundwater recharge. Future climate-induced recharge changes are expected to be dominated by precipitation changes, whereby changes in groundwater recharge will be amplified relative to precipitation changes. Recharge is more sensitive to changes in aridity than global hydrological models suggest. Consequently, the effects of climatic changes on groundwater replenishment and their impacts on the sustainability of groundwater use by humans and ecosystems probably exceed previous predictions.
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| 6. |
- Bogaart, Patrick W., et al.
(författare)
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Streamflow recession patterns can help unravel the role of climate and humans in landscape co-evolution
- 2016
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Ingår i: Hydrology and Earth System Sciences. - : Copernicus GmbH. - 1027-5606 .- 1607-7938. ; 20:4, s. 1413-1432
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Tidskriftsartikel (refereegranskat)abstract
- Traditionally, long-term predictions of river discharges and their extremes include constant relationships between landscape properties and model parameters. However, due to the co-evolution of many landscape properties more sophisticated methods are necessary to quantify future landscape-hydrological model relationships. As a first step towards such an approach we use the Brutsaert and Nieber (1977) analysis method to characterize streamflow recession behaviour of approximate to 200 Swedish catchments within the context of global change and landscape co-evolution. Results suggest that the Brutsaert-Nieber parameters are strongly linked to the climate, soil, land use, and their interdependencies. Many catchments show a trend towards more non-linear behaviour, meaning not only faster initial recession but also slower recession towards base flow. This trend has been found to be independent from climate change. Instead, we suggest that land cover change, both natural (restoration of natural soil profiles in forested areas) and anthropogenic (reforestation and optimized water management), is probably responsible. Both change types are characterised by system adaptation and change, towards more optimal ecohydrological conditions, suggesting landscape co-evolution is at play. Given the observed magnitudes of recession changes during the past 50 years, predictions of future river discharge critically need to include the effects of landscape co-evolution. The interconnections between the controls of land cover and climate on river recession behaviour, as we have quantified in this paper, provide first-order handles to do so.
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| 7. |
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| 8. |
- Destouni, Georgia, et al.
(författare)
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Hydro-Biogeochemical and Environmental-Management Functions of Wetland Networks in Landscapes
- 2012
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Ingår i: 9th INTECOL International Wetlands Conference, Wetlands in a Complex World. ; , s. 915-
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- A main application goal of ecohydrological science is to amplify opportunities of achieving water quality improvements, biodiversity enhancements and sustainable development, by improved understanding and use of ecosystem properties as a management tool. This paper draws on and synthesizes main result implications for the function and possible enhanced use of wetland networks in the landscape as such a tool, from a series of hydro-biogeochemical and environmental economics studies of nutrient/pollutant loading and abatement in different Swedish hydrological catchments. Results show large potential of wetland networks to reduce the cost of abating nutrient and metal loads within and from hydrological catchments, and emphasize some main research questions for further investigations of actual possibilities to realize this potential. The questions regard in particular the ability of wetland networks to extend the travel times and reduce the uncertainty of hydrological nutrient/pollutant transport through catchments.The paper further presents and discusses some main joint conclusions of the participants in a recently held International Workshop on Ecohydrology and Integrated Water Resource Management (1) at the Navarino Environmental Observatory in Messinia, Greece (2), regarding essential goals for collaborative international efforts in wetland network research. The goals include to investigate on different spatiotemporal scales and in different world regions: a) the dynamics of natural and managed wetland networks across a gradient of different climate, human disturbance, energy and organization conditions; b) the reciprocal interactions between wetland networks and associated hydrological catchments; c) how climate change and different human activities in the wetland network catchments influence these interactions (in b) and generally the ecohydrology of individual wetlands and the whole wetland networks; and d) the ecosystem services provided by networks of wetlands.
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| 9. |
- Elmhagen, Bodil, et al.
(författare)
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Interacting effects of change in climate, human population, land use, and water use on biodiversity and ecosystem services
- 2015
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Ingår i: Ecology and Society. - 1708-3087. ; 20:1
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Tidskriftsartikel (refereegranskat)abstract
- Human population growth and resource use, mediated by changes in climate, land use, and water use, increasingly impact biodiversity and ecosystem services provision. However, impacts of these drivers on biodiversity and ecosystem services are rarely analyzed simultaneously and remain largely unknown. An emerging question is how science can improve the understanding of change in biodiversity and ecosystem service delivery and of potential feedback mechanisms of adaptive governance. We analyzed past and future change in drivers in south-central Sweden. We used the analysis to identify main research challenges and outline important research tasks. Since the 19th century, our study area has experienced substantial and interlinked changes; a 1.6 degrees C temperature increase, rapid population growth, urbanization, and massive changes in land use and water use. Considerable future changes are also projected until the mid-21st century. However, little is known about the impacts on biodiversity and ecosystem services so far, and this in turn hampers future projections of such effects. Therefore, we urge scientists to explore interdisciplinary approaches designed to investigate change in multiple drivers, underlying mechanisms, and interactions over time, including assessment and analysis of matching-scale data from several disciplines. Such a perspective is needed for science to contribute to adaptive governance by constantly improving the understanding of linked change complexities and their impacts.
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| 10. |
- Jaramillo, Fernando, et al.
(författare)
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Dominant effect of increasing forest biomass on evapotranspiration: Interpretations of movement in Budyko space
- 2018
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Ingår i: Hydrology and Earth System Sciences. - : Copernicus GmbH. - 1027-5606 .- 1607-7938. ; 22, s. 567-580
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Tidskriftsartikel (refereegranskat)abstract
- During the last 6 decades, forest biomass has increased in Sweden mainly due to forest management, with a possible increasing effect on evapotranspiration. However, increasing global CO 2 concentrations may also trigger physiological water-saving responses in broadleaf tree species, and to a lesser degree in some needleleaf conifer species, inducing an opposite effect. Additionally, changes in other forest attributes may also affect evapotranspiration. In this study, we aimed to detect the dominating effect(s) of forest change on evapotranspiration by studying changes in the ratio of actual evapotranspiration to precipitation, known as the evaporative ratio, during the period 1961-2012. We first used the Budyko framework of water and energy availability at the basin scale to study the hydroclimatic movements in Budyko space of 65 temperate and boreal basins during this period. We found that movements in Budyko space could not be explained by climatic changes in precipitation and potential evapotranspiration in 60% of these basins, suggesting the existence of other dominant drivers of hydroclimatic change. In both the temperate and boreal basin groups studied, a negative climatic effect on the evaporative ratio was counteracted by a positive residual effect. The positive residual effect occurred along with increasing standing forest biomass in the temperate and boreal basin groups, increasing forest cover in the temperate basin group and no apparent changes in forest species composition in any group. From the three forest attributes, standing forest biomass was the one that could explain most of the variance of the residual effect in both basin groups. These results further suggest that the water-saving response to increasing CO 2 in these forests is either negligible or overridden by the opposite effect of the increasing forest biomass. Thus, we conclude that increasing standing forest biomass is the dominant driver of long-term and large-scale evapotranspiration changes in Swedish forests.
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