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  • 1
    Language: English
    In: Journal of Hydrology, July 2016, Vol.538, pp.399-415
    Description: Mountainous headwaters include a variety of spatial landscape units; however, the flow contribution from different hydrologic components is complex and often unclear. In addition to complex landscape controls, temporal meteorological drivers play an important role in the distribution between surface runoff and subsurface storage changes. This spatiotemporal variability in partitioning can influence catchment-wide flow accumulation and nutrient and sediment loading. We use a multi-year, multi-method analysis of stable isotopes, geochemical indicators, and discharge distributed throughout the Haean catchment in South Korea to identify temporal variability in hydrologic flow partitioning from surface runoff, springs, shallow interflow, and groundwater under monsoonal conditions. By combining a weighted, multi-method discharge approach, high frequency, synoptic, catchment-wide isotopic and geochemical sampling, and baseflow analysis, we characterize watershed-scale spatiotemporal hydrologic flow partitioning. Meteorological drivers are spatially variable throughout the catchment and temporally between individual events. Baseflow contributions in the high elevation, forested areas are up to 50%, while the majority of the catchment is approximately 20%. Our study builds on previously reported seasonality of isotopic signatures by quantifying trends in distributed event-based partitioning of isotopic tracers. We demonstrate that high frequency flow partitioning can accurately be determined in mountainous topography with high precipitation and that there is a need for multiple method characterizations. Our results further show the benefit of spatially distributed synoptic sampling for process understanding of hydrologic partitioning throughout the watersheds.
    Keywords: Discharge ; Baseflow ; Flow Partitioning ; Stable Isotopes ; Terreco ; Korea ; Geography
    ISSN: 0022-1694
    E-ISSN: 1879-2707
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  • 2
    Language: English
    In: Science of the Total Environment, 01 December 2015, Vol.536, pp.391-405
    Description: Effective management of surface waters requires a robust understanding of spatiotemporal constituent loadings from upstream sources and the uncertainty associated with these estimates. We compared the total dissolved solids loading into the Great Salt Lake (GSL) for water year 2013 with estimates of previously sampled periods in the early 1960s. We also provide updated results on GSL loading, quantitatively bounded by sampling uncertainties, which are useful for current and future management efforts. Our statistical loading results were more accurate than those from simple regression models. Our results indicate that TDS loading to the GSL in water year 2013 was 14.6 million metric tons with uncertainty ranging from 2.8 to 46.3 million metric tons, which varies greatly from previous regression estimates for water year 1964 of 2.7 million metric tons. Results also indicate that locations with increased sampling frequency are correlated with decreasing confidence intervals. Because time is incorporated into the LOADEST models, discrepancies are largely expected to be a function of temporally lagged salt storage delivery to the GSL associated with terrestrial and in-stream processes. By incorporating temporally variable estimates and statistically derived uncertainty of these estimates, we have provided quantifiable variability in the annual estimates of dissolved solids loading into the GSL. Further, our results support the need for increased monitoring of dissolved solids loading into saline lakes like the GSL by demonstrating the uncertainty associated with different levels of sampling frequency.
    Keywords: Great Salt Lake ; Utah ; Salt Balance ; Dissolved Solids ; Surface Discharge ; Loadest ; Inland Sea/Lake ; Salinity ; Water Quality ; Environmental Sciences ; Biology ; Public Health
    ISSN: 0048-9697
    E-ISSN: 1879-1026
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  • 3
    Language: English
    In: Journal of Hydrology, Feb 13, 2014, Vol.509, p.601(14)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.jhydrol.2013.12.005 Byline: Svenja Bartsch, Sven Frei, Marianne Ruidisch, Christopher L. Shope, Stefan Peiffer, Bomchul Kim, Jan H. Fleckenstein Abstract: acents Temporal variability of river-aquifer exchange fluxes is controlled by the monsoon. acents Monsoonal extreme precipitation events are dominant drivers for flow reversals. acents Frequent flow reversals affect the local water quality. Article History: Received 26 August 2013; Revised 3 December 2013; Accepted 5 December 2013 Article Note: (miscellaneous) This manuscript was handled by Peter K. Kitanidis, Editor-in-Chief, with the assistance of Philippe Negrel, Associate Editor
    Keywords: Aquifers ; Rain ; Climate
    ISSN: 0022-1694
    Source: Cengage Learning, Inc.
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  • 4
    Language: English
    In: Journal of Hydrology, 13 February 2014, Vol.509, pp.601-614
    Description: An important prerequisite to better understand the transport of nutrients and contaminants across the river-aquifer interface and possible implications for biogeochemical transformations is to accurately characterize and asses the exchange fluxes. In this study we investigate how monsoonal precipitation events and the resulting variability in river discharge affect the dynamics of river-aquifer exchange and the corresponding flux rates. We evaluate potential impacts of the investigated exchange fluxes on local water quality. Hydraulic gradients along a piezometer transect were monitored at a river reach in a small catchment in South Korea, where the hydrologic dynamics are driven by the East-Asian Monsoon. We used heat as a tracer to constrain river-aquifer exchange fluxes in a two-dimensional flow and heat transport model implemented in the numerical code HydroGeoSphere, which was calibrated to the measured temperature and total head data. To elucidate potential effects of river-aquifer exchange dynamics on biogeochemical transformations at the river-aquifer interface, river water and groundwater samples were collected and analyzed for dissolved organic carbon (DOC), nitrate (NO ) and dissolved oxygen saturation (DO ). Our results illustrate highly variable hydrologic conditions during the monsoon season characterized by temporal and spatial variability in river-aquifer exchange fluxes with frequent flow reversals (changes between gaining and losing conditions). Intense monsoonal precipitation events and the associated rapid changes in river stage are the dominant driver for the observed riverbed flow reversals. The chemical data suggest that the flow reversals, when river water high in DOC is pushed into the nitrate-rich groundwater below the stream and subsequently returns to the stream may facilitate and enhance the natural attenuation of nitrate in the shallow groundwater.
    Keywords: River-Aquifer Exchange Fluxes ; Heat As a Natural Tracer ; Monsoonal-Type Climate ; Hydraulic Gradient Reversals ; Hydrogeosphere ; Natural Attenuation of Nitrate ; Geography
    ISSN: 0022-1694
    E-ISSN: 1879-2707
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  • 5
    Language: English
    In: 2015
    Keywords: Discharge ; Forests ; Base Flow ; Altitude ; Subsurface Flow ; Watersheds ; Terreco ; Baseflow ; Korea ; Isotope Labeling ; Stable Isotopes ; Flow Partitioning ; Temporal Variation ; Spatial Variation ; Groundwater ; Mountains ; Pollution Load ; Sediment Yield ; Runoff ; Landscapes ; Stable Isotopes
    Source: AGRIS (Food and Agriculture Organization of the United Nations)
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  • 6
    Language: English
    In: Journal of Hydrology, 12 December 2013, Vol.507, pp.149-162
    Description: The linkage between hydrologic dynamics and the delivery of nitrate and DOC (dissolved organic carbon) to streams was studied in the Haean catchment, a mixed land-use mountainous catchment in South Korea. Three monsoonal precipitation events were analyzed, which varied in total rainfall amount (39–70 mm) and intensities (mean: 1.6–5.6 mm h ), by high-resolution (2–4 h interval) stream water-quality sampling along the topographic elevation gradient of the catchment, from an upland deciduous forest stream, over areas intensively used for agriculture (dryland farming and rice paddies) down to the catchment outlet. The dynamics of river-aquifer exchange were investigated at two piezometer transects at mid and lower elevations. DOC and nitrate sources and their transport pathways to the receiving surface waters differed between the forested and the agricultural stream site. In the forest stream, elevated DOC concentrations (max: 3.5 mgC l ) during precipitation events were due to hydrologic flushing of soluble organic matter in upper soil horizons, with a strong dependency on pre-storm wetness conditions. Nitrate contributions to the forested stream occurred along shallow subsurface transport pathways. At the agricultural sites stream DOC concentrations were considerably higher (max: 23.5 mgC l ) supplied from adjacent rice paddies. The highest in-stream nitrate concentrations (max: 4.1 mgN l ) occurred at river reaches located in the lower agricultural part of the catchment, affected by groundwater inputs. Groundwater nitrate concentrations were high (max: 7.4 mgN l ) owing to chemical fertilizer leaching from dryland fields forced by monsoonal rainfalls. Overall, this study demonstrates that the hydrologic dynamics resulting from the monsoonal climate drive the in-stream DOC dynamics in the forested 1st-order catchment whereas sources and mobilization of DOC in downstream agricultural areas are mainly controlled by the prevailing land-use type and irrigation management. Nitrate dynamics in higher order agricultural streams and their connected aquifers reflect combined effects of land-use type and monsoonal hydrology.
    Keywords: Nitrate ; Dissolved Organic Carbon ; Monsoonal-Type Climate ; Land-Use Type ; River-Aquifer Exchange Dynamics ; Topography ; Geography
    ISSN: 0022-1694
    E-ISSN: 1879-2707
    Source: ScienceDirect Journals (Elsevier)
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  • 7
    Language: English
    In: Journal of Hydrology, 28 June 2013, Vol.494, pp.72-82
    Description: River discharge is a commonly measured hydrologic variable; however, estimate uncertainty is often higher than acceptable limits. To quantify method limitations and spatiotemporal variability, a multi-year hydrologic flow partitioning investigation was completed under monsoonal conditions in the ungauged complex terrain of the Haean Catchment, South Korea. Our results indicate that sediment transport from a single annual monsoonal event can significantly modify the channel cross-sectional area resulting in inaccurate stage-discharge rating curves. We compare six discharge measurement methods at 13 locations that vary in slope from 1% to 80%, with discharge ranging up to four orders in magnitude, which enabled us to weight the accuracy of each method over a specific range in discharge. The most accurate discharge estimation methods are the weir, the acoustic Doppler current profiler, and the in-stream velocity area method; however, under certain conditions each of these methods is less desirable than other methods. The uncertainty in the three methods is on average 0.4%, 4.7%, and 6.1% of the total discharge, respectively. The accuracy of the discharge estimates has a direct influence on the characterization of basin-wide hydrologic partitioning, which can lead to significant variability in sediment erosion rates and nutrient fate and transport.
    Keywords: Terreco ; Korea ; Discharge ; Baseflow ; Topography ; River ; Geography
    ISSN: 0022-1694
    E-ISSN: 1879-2707
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  • 8
    In: Advances in Meteorology, 2015, Vol.2015, 16 pages
    Description: Characterization of precipitation is critical in quantifying distributed catchment-wide discharge. The gauge network is a key driver in hydrologic modeling to characterize discharge. The accuracy of precipitation is dependent on the location of stations, the density of the network, and the interpolation scheme. Our study examines 16 weather stations in a 64 km catchment. We develop a weighted, distributed approach for gap-filling the observed meteorological dataset. We analyze five interpolation methods (Thiessen, IDW, nearest neighbor, spline, and ordinary Kriging) at five gauge densities. We utilize precipitation in a SWAT model to estimate discharge in lumped parameter simulations and in a distributed approach at the multiple densities (1, 16, 50, 142, and 300 stations). Gauge density has a substantial impact on distributed discharge and the optimal gauge density is between 50 and 142 stations. Our results also indicate that the IDW interpolation scheme was optimum, although the Kriging and Thiessen polygon methods produced similar results. To further examine variability in discharge, we characterized the land use and soil distribution throughout each of the subbasins. The optimal rain gauge position and distribution of the gauges drastically influence catchment-wide runoff. We found that it is best to locate the gauges near less permeable locations.
    Keywords: Catchment Area ; Atmospheric Precipitations ; Resource Management ; Quantitative Distribution ; Soils ; River Discharge ; Land Use ; Methodology ; Modelling ; Rain Gauges ; Catchment Basins ; Numerical Simulations ; Interpolation Methods ; Precipitation ; Land Use ; Interpolation ; Soil ; Weather ; Rainfall ; Catchments ; Simulation ; Meteorology ; Land Use ; Freshwater ; General (556) ; Issues in Sustainable Development ; Instruments/Methods ; Air-Sea Coupling;
    ISSN: 1687-9309
    E-ISSN: 1687-9317
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  • 9
    In: Water Resources Research, August 2014, Vol.50(8), pp.6986-6999
    Description: Effective science‐based management of water resources in large basins requires a qualitative understanding of hydrologic conditions and quantitative measures of the various components of the water budget, including difficult to measure components such as baseflow discharge to streams. Using widely available discharge and continuously collected specific conductance (SC) data, we adapted and applied a long established chemical hydrograph separation approach to quantify daily and representative annual baseflow discharge at 14 streams and rivers at large spatial (〉 1000 km watersheds) and temporal (up to 37 years) scales in the Upper Colorado River Basin. On average, annual baseflow was 21–58% of annual stream discharge, 13–45% of discharge during snowmelt, and 40–86% of discharge during low‐flow conditions. Results suggest that reservoirs may act to store baseflow discharged to the stream during snowmelt and release that baseflow during low‐flow conditions, and that irrigation return flows may contribute to increases in fall baseflow in heavily irrigated watersheds. The chemical hydrograph separation approach, and associated conceptual model defined here provide a basis for the identification of land use, management, and climate effects on baseflow. Baseflow can be estimated continuously from surface water data A conceptual model was developed to accurately interpret baseflow estimates The approach provides a tool for assessing environmental effects on streamflow
    Keywords: Baseflow
    ISSN: 0043-1397
    E-ISSN: 1944-7973
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  • 10
    Language: English
    In: CLEAN - Soil, Air, Water, Dec, 2013, Vol.41(12), p.1235(7)
    Description: Byline: Jung Eun Lim, Mahtab Ahmad, Sang Soo Lee, Christopher L. Shope, Yohey Hashimoto, Kwon-Rae Kim, Adel R. A. Usman, Jae E. Yang, Yong Sik Ok Keywords: Eggshell; Heavy metal contamination; Maize; Metal immobilization; Oyster shell Abstract Low cost lime-based waste materials have recently been used to immobilize metals in contaminated soils. This study was conducted to evaluate the effects of oyster shells and eggshells as lime-based waste materials on immobilization of cadmium (Cd) and lead (Pb) in contaminated soil, as well as their effects on metal availability to maize plants (Zea mays L.). Oyster shells and eggshells were applied to soils at 1 and 5% w/w, after which they were subject to 420 days of incubation. The toxicity characteristic leaching procedure (TCLP) test was employed to determine the mobility of Cd and Pb in soils. The results showed that the addition of waste materials effectively reduced the metal mobility as indicated by the decrease in the concentration of TCLP-extractable Cd and Pb, and this was mainly due to significant increases in soil pH (from 6.74 in untreated soil to 7.85-8.13 in treated soil). A sequential extraction indicated that the addition of such alkaline wastes induced a significant decline in the concentration of Cd in the exchangeable fraction (from 23.64% in untreated soil to 1.90-3.81% in treated soil), but it increased the concentration of Cd in the carbonate fraction (from 19.59% in untreated soil to 36.66-46.36% in treated soil). In the case of Pb, the exchangeable fraction was also reduced (from 0.67% in untreated soil to 0.00-0.01% in treated soil), and the fraction of Pb bound to carbonate was slightly increased (from 16.61% in untreated soil to 16.41-18.25% in treated soil). Phytoavailability tests indicated that the metal concentrations in the shoots of maize plant were reduced by 63.39-77.29% for Cd and by 47.34-75.95% for Pb in the amended soils, with no significant differences being observed for the amendment types and the application rates. Overall, these results indicate that oyster shells and eggshells can be used as low cost lime-based amendments for immobilizing Cd and Pb in contaminated soils. Author Affiliation: Department of Biological Environment, Kangwon National University, Chuncheon, Korea Department of Hydrology, University of Bayreuth, Bayreuth, Germany Department of Bioapplications and Systems Engineering, Tokyo University of Agriculture and Technology, Koganei, Tokyo, Japan Department of Agronomy and Medicinal Plant Resources, Gyeongnam National University of Science and Technology, Jinju, Korea Department of Soils and Water, University of Assiut, Assiut, Egypt
    Keywords: Soil Acidity -- Analysis ; Cadmium -- Analysis ; Carbonates -- Analysis ; Hydrology -- Analysis
    ISSN: 1863-0650
    E-ISSN: 18630669
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