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Erich T. Hester - One of the best experts on this subject based on the ideXlab platform.
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Electrical resistivity imaging of Hydrologic Flow through surface coal mine valley fills with comparison to other landforms
Hydrological Processes, 2017Co-Authors: Breeyn M. Greer, Thomas J. Burbey, Carl E. Zipper, Erich T. HesterAbstract:Surface coal mining has altered land cover, near-surface geologic structure, and Hydrologic processes of large areas in central Appalachia, USA. These alterations are associated with changes in water quality such as elevated total-dissolved solids, which is usually measured via its surrogate, specific conductance (SC). The SC of valley fill effluent streams is a function of fill construction methods, materials, and age; yet Hydrologic studies that relate these variables to water quality are sparse due to the difficulty of conducting traditional Hydrologic studies in mined landscapes. We used electrical resistivity imaging (ERI) to visualize the subsurface geologic structure and Hydrologic Flow paths within a valley fill. ERI is a noninvasive geophysical technique that maps spatiotemporal changes in resistivity of the subsurface. We paired ERI with artificial rainfall experiments to track infiltrated water as it moved through the valley fill. Results indicate that ERI can be used to identify subsurface geologic structure and track advancing wetting fronts or preferential Flow paths. Our results suggest that the upper portion of the fill contains significant fines, whereas the deeper profile is primarily large rocks and void spaces. Water tended to pond on the surface of compacted areas until it reached preferential Flow paths, where it appeared to infiltrate quickly down to >15 m depth in 75 min. ERI applications can improve understanding of how fill construction techniques influence subsurface water movement, and in turn may aid in the development of valley fill construction methods to reduce water quality effects.
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Hydrologic Effects of Surface Coal Mining in Appalachia (U.S.)
JAWRA Journal of the American Water Resources Association, 2015Co-Authors: Daniel M. Evans, Carl E. Zipper, Erich T. Hester, Stephen H. SchoenholtzAbstract:Surface coal mining operations alter landscapes of the Appalachian Mountains, United States, by replacing bedrock with mine spoil, altering topography, removing native vegetation, and constructing mine soils with Hydrologic properties that differ from those of native soils. Research has demonstrated Hydrologic effects of mining and reclamation on Appalachian landscapes include increased peakFlows at newly mined and reclaimed watersheds in response to strong storm events, increased subsurface void space, and increased base Flows. We review these investigations with a focus on identifying changes to Hydrologic Flow paths caused by surface mining for coal in the Appalachian Mountains. We introduce two conceptual control points that govern Hydrologic Flow paths on mined lands, including the soil surface that partitions infiltration vs. surface runoff and a potential subsurface zone that partitions subsurface storm Flow vs. deeper percolation. Investigations to improve knowledge of Hydrologic pathways on reclaimed Appalachian mine sites are needed to identify effects of mining on Hydrologic processes, aid development of reclamation methods to reduce Hydrologic impacts, and direct environmental mitigation and public policy.
Henry Lin - One of the best experts on this subject based on the ideXlab platform.
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garnierite mineralization from a serpentinite derived lateritic regolith sulawesi island indonesia mineralogy geochemistry and link to Hydrologic Flow regime
Journal of Geochemical Exploration, 2018Co-Authors: Yinmeng Zhang, Ya Shao, Chongjin Pang, Xiangwei Zeng, Xiaorong Huang, Mengli Yang, Henry LinAbstract:Abstract Garnierite represents a significant nickel ore in many lateritic Ni deposits worldwide. To gain a better understanding of its nature and origin, a well-developed garnierite-hosting transect from the Kolonodale area of East Sulawesi, Indonesia, has been investigated using field geology, mineralogy and geochemical data. Garnierite occurs mainly in veins in the lower saprolite of a serpentinite-derived regolith. Mineralogically, it can be determined as an intimate mixture of Ni-rich serpentine-like (lizardite-Nepouite) and talc-like (kerolite-pimelite) phases. Results of EMP analyses indicate that Ni is preferentially enriched in the talc-like phases rather than the serpentine-like phases. A sequential precipitation of mineral phases progressively enriched in Ni and Si to form garnierite during weathering is suggested. The Ni-lizardite (2.63–8.49 wt% Ni) with elevated Fe (4.02–6.44 wt%) may have been inherited from saprolite in a first instance and enriched in Ni by cation exchange processes. Newly precipitated minerals are kerolite-pimelite (7.84–23.54 wt% Ni) and then followed by Ni-free quartz. Minor amount of Nepouite (23.47–28.51 wt% Ni) occur in laths along shrinkage cracks of previously formed minerals, indicating a late stage paragenetic sequence. With emphasis on a Hydrologic consideration, indicators of a preferential Flow regime are identified in the garnierite-hosting regolith, including: (i) non-uniform pattern of the garnierite field occurrence, (ii) syn-weathering active nature of the garnierite-hosting structures, (iii) close relationship between the garnierite occurrence and vertical Fe Mn oxides pipes as well as Fe Mn oxides patched areas, and (iv) specific physico-chemical property of the garnierite location with higher organic matter concentrations but lower pH values compared to surroundings. It is proposed that the origin of garnierite is closely linked to a preferential Flow of oversaturated solutions through accessible conduits in the regolith. Garnierite features as colloidal nature, high organic matter and low pH are key-parameters in metal transport and deposition.
Lixin Jin - One of the best experts on this subject based on the ideXlab platform.
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Impacts of glacial/interglacial cycles on continental rock weathering inferred using Sr/Ca and 87Sr/86Sr ratios in Michigan watersheds
Chemical Geology, 2012Co-Authors: Lixin Jin, Samuel B. Mukasa, Stephen K. Hamilton, Lynn M. WalterAbstract:Abstract Michigan soils have developed on thick glacial-drift deposits that include different proportions of ground granite and gneiss from the Canadian Shield region (with radiogenic Sr) and carbonate sedimentary rocks from within the Michigan Basin (with non-radiogenic Sr). This study of the Cheboygan, Huron and Kalamazoo watersheds shows how Sr-isotope and Sr/Ca ratios in soil waters, ground waters, and soils reflect relative weathering intensities of the dominant minerals in Michigan soils, including carbonates from the Michigan Basin, and amphibole, plagioclase and K-feldspar derived from the Canadian Shield. Soil water 87 Sr/ 86 Sr ratios evolve quickly to the carbonate weathering end-member (0.709–0.711) once a calcite and dolomite layer is reached at depth (~ 100–200 cm) in the Huron and the Kalamazoo watersheds. Dissolution of plagioclase and amphibole controls shallow soil water 87 Sr/ 86 Sr ratios (0.711–0.713), with minor contributions from K-feldspar weathering. In contrast, soils in the previously studied Cheboygan watershed are completely depleted in carbonate minerals and contain little plagioclase and amphibole in the top 300 cm of the profile. As a result, soil waters in this watershed are ionically dilute with high 87 Sr/ 86 Sr ratios (0.72 and 0.74), dominantly contributed by K-feldspar dissolution. Subsequent dissolution of plagioclase and amphibole at greater depths sharply increases soil water and ground water Mg 2 + , Ca 2 + , and Sr 2 + concentrations, and lowers the Sr-isotopic ratios to ~ 0.709 for the Cheboygan watershed. Similarly, along Hydrologic Flow paths, soil water Sr/Ca ratios move from the silicate end-member (defined by amphibole and plagioclase) towards the carbonate end-member. The Sr-isotopic compositions and Sr/Ca ratios of soil waters thus reveal the types, directions and extent of chemical weathering processes in Michigan soils, augmenting information from previous soil water chemistry and soil mineralogy studies. This work also highlights the two-fold impacts of glacial/interglacial cycles on the riverine and oceanic Sr isotopes: due to the great extent of continental glaciation, Paleozoic carbonate minerals from the Michigan Basin were redistributed widely within the interior of the North American continent, leading to elevated Sr fluxes with lower Sr-isotopic ratios in natural waters after glacial retreat. The glacial ice also ground up the ancient Precambrian Canadian Shield, accelerating mineral weathering rates and releasing highly radiogenic Sr from K-feldspar.
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soil chemistry and shale weathering on a hillslope influenced by convergent Hydrologic Flow regime at the susquehanna shale hills critical zone observatory
Applied Geochemistry, 2011Co-Authors: Lixin Jin, Susan L. BrantleyAbstract:Soil chemistry data (major and REEs) are presented from a swale transect for comparison to similar measurements on a planar transect published previously for the Susquehanna/Shale Hills Critical Zone Observatory. Similar reaction fronts are observed: plagioclase dissolution is indicated by Na and Ca depletion and a negative Eu anomaly; clay dissolution followed by particle loss is accompanied by depletion of Mg, K, Fe, Al and Si. However, in contrast to the planar transect, soils along the swale transect, especially in the topographically depressed site, do not show smooth elemental profiles. This documents both residuum soils and accumulation of colluvium sediments. The soils in the swale transect are thicker and on average wetter than those along the planar transect; however, the Ce anomaly observed in the swale soils is consistent with a generally oxic environment. Thus, preferential Flowpaths are an important mechanism for water transport, preventing swale soils from water saturation.
Carlo Giupponi - One of the best experts on this subject based on the ideXlab platform.
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Impact of the Farakka Dam on Thresholds of the Hydrologic Flow Regime in the Lower Ganges River Basin (Bangladesh)
Water, 2014Co-Authors: Animesh K. Gain, Carlo GiupponiAbstract:The variation of river Flow within a natural range plays an important role in promoting the social-ecological sustainability of a river basin. In order to determine the extent of the natural range of variation, this study assesses Hydrologic Flow thresholds for the Lower Ganges River Basin. The Flow threshold was calculated using twenty-two “Range of Variability (RVA)” parameters. The impact of Farakka Dam on the Lower Ganges River Flow was calculated by comparing threshold parameters for the pre-Farakka period (from 1934 to 1974) and the post-Farakka period (1975–2005). The results demonstrate that due to water diversion by the Farakka Dam, various threshold parameters, including the monthly mean of the dry season (December–May) and yearly minimum Flows, have been altered significantly. The ecological consequences of such Hydrologic alterations include the destruction of the breeding and raising grounds for a number of Gangetic species, the increase of salinity in the southwest coastal region of Bangladesh and a reduction of fish and agricultural diversity. The major findings in this paper have a number of policy-level implications to aid water sharing mechanisms and agreements between the government of Bangladesh and India. The methodological approach presented in this study is applicable to other river basins.
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thresholds of Hydrologic Flow regime of a river and investigation of climate change impact the case of the lower brahmaputra river basin
Climatic Change, 2013Co-Authors: Animesh K. Gain, Heiko Apel, Fabrice G Renaud, Carlo GiupponiAbstract:The sustainability of social-ecological systems depends on river Flows being maintained within a range to which those systems are adapted. In order to determine the extent of this natural range of variation, we assess ecological Flow thresholds and the occurrence of potentially damaging flood events to society in the context of the Lower Brahmaputra river basin. The ecological Flow threshold was calculated using twenty-two ‘Range of Variability (RVA)’ parameters, considering the range between ± 1 standard deviation from the mean of the natural Flow. Damaging flood events were calculated using flood frequency analysis of Annual Maxima series and using the flood classification of Bangladesh. The climate change impacts on future river Flow were calculated by using a weighted ensemble analysis of twelve global circulation models (GCMs) outputs driving a large-scale Hydrologic model. The simulated climate change induced altered Flow regime of the Lower Brahmaputra River Basin was then investigated and compared with the calculated threshold Flows. The results demonstrate that various parameters including the monthly mean of low Flow (January, February and March) and high Flow (June, July and August) periods, the 7-day average minimum Flow, and the yearly maximum Flow will exceed the threshold conditions by 1956–1995 under the business-as-usual A1B and A2 future scenarios. The results have a number of policy level implications for government agencies of the Lower Brahmaputra River Basin, specifically for Bangladesh. The calculated thresholds may be used as a good basis for negotiations with other riparian countries of the basin. The methodological approach presented in this study can be applied to other river basins and provide a useful basis for transboundary water resources management. Copyright Springer Science+Business Media Dordrecht 2013
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thresholds of Hydrologic Flow regime of a river and investigation of climate change impact the case of the lower brahmaputra river basin
Climatic Change, 2013Co-Authors: Animesh K. Gain, Heiko Apel, Fabrice G Renaud, Carlo GiupponiAbstract:The sustainability of social-ecological systems depends on river Flows being maintained within a range to which those systems are adapted. In order to determine the extent of this natural range of variation, we assess ecological Flow thresholds and the occurrence of potentially damaging flood events to society in the context of the Lower Brahmaputra river basin. The ecological Flow threshold was calculated using twenty-two ‘Range of Variability (RVA)’ parameters, considering the range between ± 1 standard deviation from the mean of the natural Flow. Damaging flood events were calculated using flood frequency analysis of Annual Maxima series and using the flood classification of Bangladesh. The climate change impacts on future river Flow were calculated by using a weighted ensemble analysis of twelve global circulation models (GCMs) outputs driving a large-scale Hydrologic model. The simulated climate change induced altered Flow regime of the Lower Brahmaputra River Basin was then investigated and compared with the calculated threshold Flows. The results demonstrate that various parameters including the monthly mean of low Flow (January, February and March) and high Flow (June, July and August) periods, the 7-day average minimum Flow, and the yearly maximum Flow will exceed the threshold conditions by 1956–1995 under the business-as-usual A1B and A2 future scenarios. The results have a number of policy level implications for government agencies of the Lower Brahmaputra River Basin, specifically for Bangladesh. The calculated thresholds may be used as a good basis for negotiations with other riparian countries of the basin. The methodological approach presented in this study can be applied to other river basins and provide a useful basis for transboundary water resources management.
Ryan W. Webb - One of the best experts on this subject based on the ideXlab platform.
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Hydrologic connectivity at the hillslope scale through intra snowpack Flow paths during snowmelt
Hydrological Processes, 2020Co-Authors: Ryan W. Webb, Oliver Wigmore, Keith S Jennings, Mike Fend, Noah P MolotchAbstract:The seasonal snowmelt period is a critical component of the Hydrologic cycle for many mountainous areas. Changes in the timing and rate of snowmelt as a result of physical Hydrologic Flow paths, such as longitudinal intra‐snowpack Flow paths, can have strong implications on the partitioning of meltwater amongst streamFlow, groundwater recharge, and soil moisture storage. However, intra‐snowpack Flow paths are highly spatially and temporally variable and thus difficult to observe. This study utilizes new methods to non‐destructively observe spatio‐temporal changes in the liquid water content of snow in combination with plot experiments to address the research question: What is the scale of influence that intra‐snowpack Flow paths have on the downslope movement of liquid water during snowmelt across an elevational gradient? This research took place in northern Colorado with study plots spanning from the rain‐snow transition zone up to the high alpine. Results indicate an increasing scale of influence from intra‐snowpack Flow paths with elevation, showing higher hillslope connectivity producing larger intra‐snowpack contributing areas for meltwater accumulation, quantified as the upslope contributing area required to produce observed changes in liquid water content from melt rate estimates. The total effective intra‐snowpack contributing area of accumulating liquid water was found to be 17, 6, and 0 m² for the above tree line, near tree line, and below tree line plots, respectively. Dye tracer experiments show capillary and permeability barriers result in increased number and thickness of intra‐snowpack Flow paths at higher elevations. We additionally utilized aerial photogrammetry in combination with ground penetrating radar surveys to investigate the role of this Hydrologic process at the small watershed scale. Results here indicate that intra‐snowpack Flow paths have influence beyond the plot scale, impacting the storage and transmission of liquid water within the snowpack at the small watershed scale.
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Hydrologic Flow path development varies by aspect during spring snowmelt in complex subalpine terrain
The Cryosphere, 2018Co-Authors: Ryan W. Webb, Steven R. Fassnacht, Michael N. GooseffAbstract:Abstract. In many mountainous regions around the world, snow and soil moisture are key components of the Hydrologic cycle. Preferential Flow paths of snowmelt water through snow have been known to occur for years with few studies observing the effect on soil moisture. In this study, statistical analysis of the topographical and Hydrological controls on the spatiotemporal variability of snow water equivalent (SWE) and soil moisture during snowmelt was undertaken at a subalpine forested setting with north, south, and flat aspects as a seasonally persistent snowpack melts. We investigated if evidence of preferential Flow paths in snow can be observed and the effect on soil moisture through measurements of snow water equivalent and near-surface soil moisture, observing how SWE and near-surface soil moisture vary on hillslopes relative to the toes of hillslopes and flat areas. We then compared snowmelt infiltration beyond the near-surface soil between flat and sloping terrain during the entire snowmelt season using soil moisture sensor profiles. This study was conducted during varying snowmelt seasons representing above-normal, relatively normal, and below-normal snow seasons in northern Colorado. Evidence is presented of preferential meltwater Flow paths at the snow–soil interface on the north-facing slope causing increases in SWE downslope and less infiltration into the soil at 20 cm depth; less association is observed in the near-surface soil moisture (top 7 cm). We present a conceptualization of the meltwater Flow paths that develop based on slope aspect and soil properties. The resulting Flow paths are shown to divert at least 4 % of snowmelt laterally, accumulating along the length of the slope, to increase the snow water equivalent by as much as 170 % at the base of a north-facing hillslope. Results from this study show that snow acts as an extension of the vadose zone during spring snowmelt and future Hydrologic investigations will benefit from studying the snow and soil together.
