Kooperativer Bibliotheksverbund

Berlin Brandenburg

and
and

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Ground Water
Type of Medium
Language
Year
  • 1
    Language: English
    In: Journal of Hydrology, 2005, Vol.310(1), pp.294-315
    Description: Simulating infiltration in soils containing macropores still provides unsatisfactory results, as existing models seem not to capture all relevant processes. Recent studies of macropore flow initiation in natural soils containing earthworm channels revealed a distinct flow rate variability in the macropores depending on the initiation process. When macropore flow was initiated at the soil surface, most of the macropores received very little water while a few macropores received a large proportion of the total inflow. In contrast, when macropore flow was initiated from a saturated or nearly saturated soil layer, macropore flow rate variation was much lower. The objective of this study was to develop, evaluate, and test a model, which combines macropore flow variability with several established approaches to model dual permeability soils. We then evaluate the INfiltration–INitiation–INteraction Model (IN M) to explore the influence of macropore flow variability on infiltration behavior by performing a sensitivity analysis and applying IN M to sprinkling and dye tracer experiments at three field sites with different macropore and soil matrix properties. The sensitivity analysis showed that the flow variability in macropores reduces interaction between the macropores and the surrounding soil matrix and thus increases bypass flow, especially for surface initiation of macropore flow and at higher rainfall intensities. The model application shows reasonable agreement between IN M simulations and field data in terms of water balance, water content change, and dye patterns. The influence of macropore flow variability on the hydrological response of the soil was considerable and especially pronounced for soils where initiation occurs at the soil surface. In future, the model could be applied to explore other types of preferential flow and hence to get a generally better understanding of macropore flow.
    Keywords: Macropore Flow ; Infiltration ; Soil Moisture ; Unsaturated Zone ; Dual-Permeability Model ; Earthworm Burrow ; Geography
    ISSN: 0022-1694
    E-ISSN: 1879-2707
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    In: Geophysical Research Letters, February 2011, Vol.38(3), pp.n/a-n/a
    Description: Due to temperature differences of groundwater and streamwater, localized groundwater inflows into small streams can directly be detected with ground‐based thermographic systems in summer or winter. Infrared radiation temperatures of surface water were used to determine mixing length and to calculate the relative fraction of groundwater inflow to downstream discharge. These fractions were comparable to groundwater inflow fractions derived from electrical conductivity, kinetic water temperatures and discharge measurements. This approach advances the immediate detection and quantification of localized groundwater inflow for hydrology, geology and ecology.
    Keywords: Groundwater‐Surface Water Interaction ; Water Temperature ; Infrared Thermography
    ISSN: 0094-8276
    E-ISSN: 1944-8007
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    Language: English
    In: Journal of Hydrology, 2006, Vol.319(1), pp.339-356
    Description: The delivery mechanisms of labile nutrients (e.g. NO , DON and DOC) to streams are poorly understood. Recent work has quantified the relationship between storm DOC dynamics and the connectedness of catchment units and between pre-storm wetness and transient groundwater NO flushing potential. While several studies have shown N and C flushing during storm events as the important mechanism in the export of DOC and DON in small catchments, the actual mechanisms at the hillslope scale have remained equivocal. The difficulty in isolating cause and effect in field studies is made difficult due to the spatial variability of soil properties, the limited ability to detect flow pathways within the soil, and other unknowns. Some hillslopes show preferential flow behavior that may allow transmission of hillslope runoff and labile nutrients with little matrix interaction; others do not. Thus, field studies are only partially useful in equating C and N sources with water flow and transport. This paper presents a new approach to the study of hydrological controls on labile nutrient flushing at the hillslope scale. We present virtual experiments that focus on quantifying the first-order controls on flow pathways and nutrient transport in hillslopes. We define virtual experiments as numerical experiments with a model driven by collective field intelligence. We present a new distributed model that describes the lateral saturated and vertical unsaturated water flow from hypothetical finite nutrient sources in the upper soil horizons. We describe how depth distributions of transmissivity and drainable porosity, soil depth variability, as well as mass exchange between the saturated and unsaturated zone influence the mobilization, flushing and release of labile nutrients at the hillslope scale. We argue that this virtual experiment approach may provide a well-founded basis for defining the first-order controls and linkages between hydrology and biogeochemistry at the hillslope scale and perhaps form a basis for predicting flushing and transport of labile nutrients from upland to riparian zones.
    Keywords: Virtual Experiments ; Hillslope Hydrology ; Nutrients ; Mobilization ; Flushing ; Runoff Generation ; Geography
    ISSN: 0022-1694
    E-ISSN: 1879-2707
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    In: Geophysical Research Letters, 16 September 2014, Vol.41(17), pp.6174-6183
    Description: Streamflow drought response depends to a large degree on groundwater recharge. To better predict and preempt streamflow droughts, the relationship between recharge deficit and streamflow response needs to be studied more systematically. We present a combined soil‐vegetation‐atmosphere transfer and conceptual groundwater model experiment that applies a novel set of recharge scenarios preceding drought events in humid‐temperate catchments with different dominant aquifer types. The recharge scenarios are based on the permutation of historical time series and on modified time series matching extreme (50 year) drought events. Karstic and fractured aquifers show short‐term sensitivity to drought with an event‐specific relationship between recharge and streamflow response. Porous and complex aquifers show long‐term sensitivity and a more catchment‐controlled propagation of drought. The sensitivity of drought deficit and recovery time correlates with the water age distribution in baseflow, which is trackable in the groundwater model and a characteristic that should be exploited to improve streamflow drought prediction. Recharge scenarios drive groundwater models to exacerbate streamflow droughtsShort‐ and long‐term sensitivity to drought can be explained by aquifer typesWater age correlates with drought deficit and recovery time
    Keywords: Drought ; Groundwater/Surface Water Interaction ; Modeling ; Water Budgets ; Extreme Events ; Streamflow
    ISSN: 0094-8276
    E-ISSN: 1944-8007
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    Language: English
    In: Agriculture, Ecosystems and Environment, 15 April 2016, Vol.222, pp.185-192
    Description: The European Water Framework Directive (EWFD) aims to achieve a good chemical status for the groundwater bodies in Europe by the year 2015. Despite the effort to reduce the nitrate pollution from agriculture within the last two decades, there are still many groundwater aquifers that exceed nitrate concentrations above the EWFD threshold of 50 mg L . Viticulture is seen as a major contributor of nitrate leaching and sowing of a green cover was shown to have a positive effect on lowering the nitrate loads in the upper 90 cm of the soil. However, the consequences for nitrate leaching into the subsoil were not yet tested. We analyzed the nitrate concentrations and pore water stable isotope composition ( H) to a depth of 380 cm in soil profiles under an old vineyard and a young vineyard with either soil tillage or permanent green cover in between the grapevines. The pore water H data was used to calibrate a soil physical model, which was then used to infer the age of the soil water at different depths. This way, we could relate elevated nitrate concentrations below an old vineyard to tillage processes that took place during the winter two years before the sampling. We further showed that the elevated nitrate concentration in the subsoil of a young vineyard can be related to the soil tillage prior to the planting of the new vineyard. If the soil was kept bare due to tillage, a nitrate concentration of 200 kg NO -N ha was found in 290⿿380 cm depth 2.5 years after the set-up of the vineyard. The amount of nitrate leaching was considerably reduced due to a seeded green cover between the grapevines that took up a high share of the mineralized nitrate reducing a potential contamination of the groundwater.
    Keywords: Soil Hydrology ; Isotope Hydrology ; Nitrate Leaching ; Groundwater Protection ; Viniculture ; Agriculture ; Environmental Sciences
    ISSN: 0167-8809
    E-ISSN: 1873-2305
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    Language: English
    In: Journal of Hydrology, 27 November 2014, Vol.519, pp.340-352
    Description: Assessing temporal variations in soil water flow is important, especially at the hillslope scale, to identify mechanisms of runoff and flood generation and pathways for nutrients and pollutants in soils. While surface processes are well considered and parameterized, the assessment of subsurface processes at the hillslope scale is still challenging since measurement of hydrological pathways is connected to high efforts in time, money and personnel work. The latter might not even be possible in alpine environments with harsh winter processes. Soil water stable isotope profiles may offer a time-integrating fingerprint of subsurface water pathways. In this study, we investigated the suitability of soil water stable isotope (δ O) depth profiles to identify water flow paths along two transects of steep subalpine hillslopes in the Swiss Alps. We applied a one-dimensional advection–dispersion model using δ O values of precipitation (ranging from −24.7 to −2.9‰) as input data to simulate the δ O profiles of soil water. The variability of δ O values with depth within each soil profile and a comparison of the simulated and measured δ O profiles were used to infer information about subsurface hydrological pathways. The temporal pattern of δ O in precipitation was found in several profiles, ranging from −14.5 to −4.0‰. This suggests that vertical percolation plays an important role even at slope angles of up to 46°. Lateral subsurface flow and/or mixing of soil water at lower slope angles might occur in deeper soil layers and at sites near a small stream. The difference between several observed and simulated δ O profiles revealed spatially highly variable infiltration patterns during the snowmelt periods: The δ O value of snow (−17.7 ± 1.9‰) was absent in several measured δ O profiles but present in the respective simulated δ O profiles. This indicated overland flow and/or preferential flow through the soil profile during the melt period. The applied methods proved to be a fast and promising tool to obtain time-integrated information on soil water flow paths at the hillslope scale in steep subalpine slopes.
    Keywords: Stable Isotopes ; Soil Water ; Steep Hillslopes ; Modeling ; Water Pathways ; Snowmelt ; Geography
    ISSN: 0022-1694
    E-ISSN: 1879-2707
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    Language: English
    In: Environmental Earth Sciences, 2012, Vol.65(8), pp.2377-2389
    Description: For water management purposes, information about an entire aquifer system is generally more important than information about a specific spring. Since a karstic aquifer system might drain to several outlets, conclusions derived from a single spring can be misleading for characterization and modeling. In this study we apply a conceptual model to an Alpine dolomite karst system in Austria. The particular challenge was that several small springs with strongly varying hydrological behavior and diffuse flow into surrounding streams drain this system. Instead of applying the model to a single spring, it was calibrated simultaneously to several observations within the system aiming to identify the karst system’s intrinsic hydrodynamic parameters. Parameter identification is supported by modeling the transport of water isotopes (δ 18 O). The parameters were transferred to the whole system with a simple upscaling procedure and a sensitivity analysis was performed to unfold influence of isotopic information on parameter sensitivity and simulation uncertainty. The results show that it is possible to identify system intrinsic parameters. But the sensitivity analysis revealed that some are hardly identifiable. Only by considering uncertainty reasonable predictions can be provided for the whole system. Including isotopic information increases the sensitivity of some intrinsic parameters, but it goes along with a sensitivity decrease for others. However, a possible reduction of prediction uncertainty by isotopic information is compensated by deficiencies in the transport modeling routines.
    Keywords: Karst aquifer ; Karst modeling ; Water isotopes ; Solute transport modeling ; Upscaling ; Rainfall-runoff modeling
    ISSN: 1866-6280
    E-ISSN: 1866-6299
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    In: Wiley Interdisciplinary Reviews: Water, November 2017, Vol.4(6), pp.n/a-n/a
    Description: We review the state‐of‐the‐art of cross‐disciplinary knowledge on phosphorus (P) cycling in temperate forest ecosystems, focused at studies from hydrology, biology, biogeochemistry, soil‐, and geosciences. Changes in soil P stocks during long‐term ecosystem development are addressed briefly; the general ranges of specific P pools and P fluxes within the ecosystem and the presumed underlying processes are covered more in depth. Wherever possible, we differentiate between coniferous and deciduous forests. As the most important P pools, mineral soil, forest floor, vegetation, and microbial biomass are described in terms of pool size, molecular composition, and turnover. Litterfall, soil water seepage, atmospheric deposition, and biotic uptake as the most studied P fluxes in the forest ecosystem are discussed in detail, spotlighting biogeochemical processes relevant for mobilization and retention of P in the rooting zone. Through a meta‐analysis of available literature, we build a dataset that allows the quantification of major P‐cycle components in temperate forests in terms of range and distribution, highlighting similarities and differences between coniferous and deciduous forests. The two forest types are notably distinct in their distribution of P within compartments of the plant biomass and forest floor. The possibility to construct closed local P balances is often hindered by missing information on fluxes of dissolved and particulate P across the ecosystem boundary, be it in the atmosphere, soil, or on the surface. These fluxes are irregular in space and time and feature large overall mass fluxes but comparatively small P fluxes, making the latter one difficult to quantify. 2017, 4:e1243. doi: 10.1002/wat2.1243 This article is categorized under: A schematic respresentation of the Phosphorus cycle in temperate forests. Pools and fluxes are scaled to their average size. See the full paper for more detailed information and data sources.
    Keywords: Phosphorus Cycle ; Phosphorus ; Phosphorus Cycle ; Compartments ; Phosphorus ; Uptake ; Biogeochemistry ; Biomass ; Plant Biomass ; Environmental Changes ; Soil Water ; Pools ; Soil Water ; Distribution ; Composition ; Forests ; Phosphorus Cycle ; Biogeochemistry ; Biogeochemistry ; Biomass ; Biology ; Phosphorus ; Forests ; Microorganisms ; Ecosystems ; Moisture Content ; Forest Floor ; Forest Ecosystems ; Forests ; Stocks ; Hydrology ; Forests ; Rooting ; Pools ; Seepage ; Components ; Hydrology ; Deciduous Forests ; Forest Floor ; Fluxes ; Atmospheric Pollutant Deposition ; Soils ; Hydrology ; Seepage ; Biomass ; Hydrology ; Forest Biomass;
    ISSN: 2049-1948
    E-ISSN: 2049-1948
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 9
    Language: English
    In: Journal of Hydrology, 2009, Vol.369(3), pp.241-252
    Description: To address the effects of land use and land cover (LULC) on soil structure formation and the significance on preferential flow during infiltration, dye tracer experiments were conducted on five sites differing in LULC, yet displaying similar soil textural characteristics and parent material. Two grassland sites, two farmland sites (tilled and untilled) and one site located in a deciduous forest were investigated. At each site, the same sprinkling experiment was carried out with a Brilliant Blue FCF solution of 4 g L to visualize flow paths. To explore the effects of different rainfall amounts (20, 40 and 60 mm), each 1.2 × 1.5 m experimental plot was subdivided into three smaller subplots, which were irrigated with an intensity of 15 mm h for 80, 160 and 240 min, respectively. During the tracer application, water content changes were continuously measured with 16 time domain reflectometry probes horizontally installed into the profile at different depths. After the experiments vertical and horizontal soil sections were excavated and photographed. The pictures were processed using digital image analysis and the resulting dye patterns analyzed for volume and surface density, maximum infiltration depth and macropore structure. Additionally, flow processes were classified into distinct flow type categories. The tracer experiments revealed that preferential flow processes significantly differed among sites of differing LULC yet similar soil texture. As primary controlling factors soil structure, surface micro-topography, surface cover and topsoil matrix characteristics were identified. The effects of different rainfall application amounts were complex and strongly varied among sites, stressing the strong control LULC exerts on water flow in soils. Overall this suggests that land use effects on soil properties need to be considered in hydrological models to obtain realistic predictions concerning water quality and quantity.
    Keywords: Dye Tracer Experiments ; Preferential Flow ; Soil Structure Formation ; Land Use and Land Cover (Lulc) ; Time Domain Reflectometry ; Geography
    ISSN: 0022-1694
    E-ISSN: 1879-2707
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 10
    Language: English
    In: Computers and Geosciences, December 2013, Vol.61, pp.116-125
    Description: An analytical Excel-based toolkit called Gas-Tracer-Interpretation (GTI) was developed for determining mean residence time (MRT) of groundwater samples and for validating conceptual model assumptions. This novel data interpretation toolkit improves data handling during analysis and resolves some problems in the interpretation of data from environmental tracers. The toolkit can assist error detection, uncertainty and ambiguity during data analysis, particularly ambiguity due to the decline in atmospheric data of CFC input functions (air-mixing ratios of tracers). The innovative interpretation methodologies are: (1) corrections of environmental tracer data are conducted in concentrations in water instead of air (atmosphere), allowing comparison of different tracer input functions under similar conditions and thereby replacing the use of unique global atmospheric data; (2) a multi-model, multi-tracer approach is adopted to improve the number of different combinations of environmental tracers and lumped-parameter models (piston flow (PM), exponential (EM), exponential-piston flow (EPM), advection-dispersion (DM) and gamma (GM)); and (3) generation of sufficient information for determination of erroneous, unclear and ambiguous outcomes. Results are linked to graphical analysis to improve data view. GTI supports the environmental tracers CFC-11, CFC-12, CFC-113, SF , H, and also SF CF , which is included as it represents a promising environmental tracer in hydrological research. The toolkit compares modeled input functions of tracers and data from samples. The apparent recharge age and MRT are estimated by combining explicit graphical and numerical data presentation. Due to the multi-model approach, it is possible to contrast selected models and estimate the best fit for a given sample, which is particularly useful for validating conceptual model assumptions. The toolkit has been developed in Microsoft ®Excel, and hence is user-friendly such that advanced programming skills or detailed understanding of the calculations and mathematical procedures are unnecessary.
    Keywords: Lumped-Parameter Modeling ; Environmental Tracer ; Groundwater Dating ; Water Age ; Environmental Tracers Concentrations in Water ; Geology
    ISSN: 0098-3004
    E-ISSN: 1873-7803
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. Further information can be found on the KOBV privacy pages