The Experts below are selected from a list of 315 Experts worldwide ranked by ideXlab platform
Gilles Pinay - One of the best experts on this subject based on the ideXlab platform.
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upscaling nitrogen removal capacity from local hotspots to low stream orders Drainage Basins
Ecosystems, 2015Co-Authors: Gilles Pinay, Stefan Peiffer, Jeanraynald De Dreuzy, Stefan Krause, David M Hannah, Jan H Fleckenstein, Mathieu Sebilo, Kevin Bishop, Laurence HubertmoyAbstract:Denitrification is the main process removing nitrate in river Drainage Basins and buffer input from agricultural land and limits aquatic ecosystem pollution. However, the identification of denitrification hotspots (for example, riparian zones), their role in a landscape context and the evolution of their overall removal capacity at the Drainage basin scale are still challenging. The main approaches used (that is, mass balance method, denitrification proxies, and potential wetted areas) suffer from methodological drawbacks. We review these approaches and the key frameworks that have been proposed to date to formalize the understanding of the mechanisms driving denitrification: (i) Diffusion versus advection pathways of nitrate transfer, (ii) the biogeochemical hotspot, and (iii) the Damkohler ratio. Based on these frameworks, we propose to use high-resolution mapping of catchment topography and landscape pattern to define both potential denitrification sites and the dynamic hydrologic modeling at a similar spatial scale (<10 km2). It would allow the quantification of cumulative denitrification activity at the small catchment scale, using spatially distributed Damkohler and Peclet numbers and biogeochemical proxies. Integration of existing frameworks with new tools and methods offers the potential for significant breakthroughs in the quantification and modeling of denitrification in small Drainage Basins. This can provide a basis for improved protection and restoration of surface water and groundwater quality.
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Upscaling nitrogen removal capacity from local hotspots to low stream orders’ Drainage Basins
Ecosystems, 2015Co-Authors: Gilles Pinay, Stefan Peiffer, Jeanraynald De Dreuzy, Stefan Krause, David M Hannah, Jan H Fleckenstein, Mathieu Sebilo, Kevin Bishop, Laurence Hubert-moyAbstract:Denitrification is the main process removing nitrate in river Drainage Basins and buffer input from agricultural land and limits aquatic ecosystem pollution. However, the identification of denitrification hotspots (for example, riparian zones), their role in a landscape context and the evolution of their overall removal capacity at the Drainage basin scale are still challenging. The main approaches used (that is, mass balance method, denitrification proxies, and potential wetted areas) suffer from methodological drawbacks. We review these approaches and the key frameworks that have been proposed to date to formalize the understanding of the mechanisms driving denitrification: (i) Diffusion versus advection pathways of nitrate transfer, (ii) the biogeochemical hotspot, and (iii) the Damköhler ratio. Based on these frameworks, we propose to use high-resolution mapping of catchment topography and landscape pattern to define both potential denitrification sites and the dynamic hydrologic modeling at a similar spatial scale (
Achim A Beylich - One of the best experts on this subject based on the ideXlab platform.
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contemporary suspended sediment dynamics within two partly glacierized mountain Drainage Basins in western norway erdalen and bodalen inner nordfjord
Geomorphology, 2017Co-Authors: Achim A Beylich, Katja Laute, Joep E A StormsAbstract:Abstract This paper focuses on environmental controls, spatiotemporal variability and rates of contemporary fluvial suspended sediment transport in the neighboring, partly glacierized and steep Erdalen (79.5 km 2 ) and Bodalen (60.1 km 2 ) Drainage Basins in the fjord landscape of the inner Nordfjord in western Norway. Field work, including extended samplings and measurements, was conducted since 2004 in Erdalen and since 2008 in Bodalen. The distinct intra- and inter-annual temporal variability of suspended sediment transport found is mostly controlled by meteorological events, with most suspended sediment transport occurring during pluvial events in autumn (September–November), followed by mostly thermally determined glacier melt in summer (July–August), and by mostly thermally determined snowmelt in spring (April–June). Extreme rainfall events (> 70 mm d − 1 ) in autumn can trigger significant debris-flow activity that can cause significant transfers of suspended sediments from ice-free surface areas with sedimentary covers into main stream channels and is particularly important for fluvial suspended sediment transport. In years with occurring relevant debris-flow activity the total annual Drainage-basin wide suspended sediment yields are strongly determined by these single extreme events. The proportion of glacier coverage, followed by steepness of slopes, and degree of vegetation cover in ice-free surface areas with sedimentary covers are the main controls for the detected spatial variability of suspended sediment yields. The contemporary sediment supply from glacierized surface areas and the Jostedalsbreen ice cap through different defined outlet glaciers shows a high spatial variability. The fact that the mean annual suspended sediment yield of Bodalen is with 31.3 t km − 2 yr − 1 almost twice as high as the mean annual suspended sediment yield of Erdalen (16.4 t km − 2 yr − 1 ) is to a large extent explained by the higher proportion of glacier coverage in Bodalen (38% of the Drainage basin surface area) as compared to Erdalen (18% of the Drainage basin surface area) and by a significantly higher sediment yield from the glacierized area of the Bodalen Drainage basin compared to the glacierized surface area in Erdalen. When looking at the total annual mass of suspended sediments being fluvially exported from both entire Drainage basin systems, the total amount of suspended sediments coming from the ice-free Drainage basin surface areas altogether dominates over the total amount of suspended sediments coming from the glacierized surface area of both Drainage Basins. Drainage-basin wide annual suspended sediment yields are rather low when compared with yields of other partly glacierized Drainage basin systems in Norway and in other cold climate environments worldwide, which is mainly due to the high resistance of the predominant gneisses towards glacial erosion and weathering, the altogether only small amounts of sediments being available within the entire Drainage basin systems, the stable and nearly closed vegetation cover in the ice-free surface areas with sedimentary covers, and the efficiency of proglacial lakes in trapping sediments supplied by defined outlet glaciers. Both contemporary and long-term suspended sediment yields are altogether supply-limited. Contemporary suspended sediment transport accounts for nearly two-thirds of the total fluvial transport and, accordingly, plays an important role within the sedimentary budgets of the entire Erdalen and Bodalen Drainage Basins.
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sediment sources spatiotemporal variability and rates of fluvial bedload transport in glacier connected steep mountain valleys in western norway erdalen and bodalen Drainage Basins
Geomorphology, 2015Co-Authors: Achim A Beylich, Katja LauteAbstract:Abstract Contemporary fluvial bedload transport rates are still very difficult to measure and, as a result of this, in many sites only quantitative data on suspended and solute transport are included in sediment budget studies carried out for defined Drainage basin systems. The presented analysis of fluvial bedload dynamics in different defined subsystems of the glacier-connected Erdalen (79.5 km 2 ) and Bodalen (60.1 km 2 ) Drainage Basins in the steep fjord landscape of western Norway provides insights into (i) detectable relevant sediment sources, (ii) instream channel storage of bedload material, (iii) spatiotemporal variability and controls of bedload transport rates and bedload yields, and (iv) the absolute and relative importance of fluvial bedload transport within the sedimentary budgets of these steep cold climate mountain valleys. Rockfalls, snow avalanches, stream channel bank erosion, and fluvial transfers through small tributaries draining slope systems are relevant sediment sources for fluvial bedload transport in the main stream channels, whereas the main outlet glaciers in both Drainage Basins are not of importance as all bedload material delivered directly from these outlet glaciers is trapped within proglacial lakes. Narrow valleys within both Drainage basin systems are characterized by a higher intensity of slope-channel coupling and display higher rates of sediment supply from slopes into the main stream channels than wider valleys. Snow avalanches are the most important sediment source in Erdalen, whereas fluvial transfers through small tributaries followed by snow avalanches are most important in Bodalen. Longer term, instream channel storage is not of great importance in the steep Bodalen Drainage basin but currently plays an important role within the Erdalen Drainage basin, which is characterized by a stepped longitudinal main valley bottom profile favoring deposition of bedload material within less steep main channel reaches. The mean annual bedload yields (2010–2013) are 2.4 t km − 2 y − 1 for the entire Erdalen and 13.3 t km − 2 y − 1 for the entire Bodalen Drainage basin, which are comparably low values for steep and partly glacierized Drainage basin systems. Because of supply-limited conditions, the intensity of fluvial bedload transport is generally much more related to the availability of sediments than to channel discharge. Fluvial bedload transport accounts for about one-third of the total fluvial transport and accordingly plays an important role within the sedimentary budgets of both Drainage basin systems.
Katja Laute - One of the best experts on this subject based on the ideXlab platform.
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contemporary suspended sediment dynamics within two partly glacierized mountain Drainage Basins in western norway erdalen and bodalen inner nordfjord
Geomorphology, 2017Co-Authors: Achim A Beylich, Katja Laute, Joep E A StormsAbstract:Abstract This paper focuses on environmental controls, spatiotemporal variability and rates of contemporary fluvial suspended sediment transport in the neighboring, partly glacierized and steep Erdalen (79.5 km 2 ) and Bodalen (60.1 km 2 ) Drainage Basins in the fjord landscape of the inner Nordfjord in western Norway. Field work, including extended samplings and measurements, was conducted since 2004 in Erdalen and since 2008 in Bodalen. The distinct intra- and inter-annual temporal variability of suspended sediment transport found is mostly controlled by meteorological events, with most suspended sediment transport occurring during pluvial events in autumn (September–November), followed by mostly thermally determined glacier melt in summer (July–August), and by mostly thermally determined snowmelt in spring (April–June). Extreme rainfall events (> 70 mm d − 1 ) in autumn can trigger significant debris-flow activity that can cause significant transfers of suspended sediments from ice-free surface areas with sedimentary covers into main stream channels and is particularly important for fluvial suspended sediment transport. In years with occurring relevant debris-flow activity the total annual Drainage-basin wide suspended sediment yields are strongly determined by these single extreme events. The proportion of glacier coverage, followed by steepness of slopes, and degree of vegetation cover in ice-free surface areas with sedimentary covers are the main controls for the detected spatial variability of suspended sediment yields. The contemporary sediment supply from glacierized surface areas and the Jostedalsbreen ice cap through different defined outlet glaciers shows a high spatial variability. The fact that the mean annual suspended sediment yield of Bodalen is with 31.3 t km − 2 yr − 1 almost twice as high as the mean annual suspended sediment yield of Erdalen (16.4 t km − 2 yr − 1 ) is to a large extent explained by the higher proportion of glacier coverage in Bodalen (38% of the Drainage basin surface area) as compared to Erdalen (18% of the Drainage basin surface area) and by a significantly higher sediment yield from the glacierized area of the Bodalen Drainage basin compared to the glacierized surface area in Erdalen. When looking at the total annual mass of suspended sediments being fluvially exported from both entire Drainage basin systems, the total amount of suspended sediments coming from the ice-free Drainage basin surface areas altogether dominates over the total amount of suspended sediments coming from the glacierized surface area of both Drainage Basins. Drainage-basin wide annual suspended sediment yields are rather low when compared with yields of other partly glacierized Drainage basin systems in Norway and in other cold climate environments worldwide, which is mainly due to the high resistance of the predominant gneisses towards glacial erosion and weathering, the altogether only small amounts of sediments being available within the entire Drainage basin systems, the stable and nearly closed vegetation cover in the ice-free surface areas with sedimentary covers, and the efficiency of proglacial lakes in trapping sediments supplied by defined outlet glaciers. Both contemporary and long-term suspended sediment yields are altogether supply-limited. Contemporary suspended sediment transport accounts for nearly two-thirds of the total fluvial transport and, accordingly, plays an important role within the sedimentary budgets of the entire Erdalen and Bodalen Drainage Basins.
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sediment sources spatiotemporal variability and rates of fluvial bedload transport in glacier connected steep mountain valleys in western norway erdalen and bodalen Drainage Basins
Geomorphology, 2015Co-Authors: Achim A Beylich, Katja LauteAbstract:Abstract Contemporary fluvial bedload transport rates are still very difficult to measure and, as a result of this, in many sites only quantitative data on suspended and solute transport are included in sediment budget studies carried out for defined Drainage basin systems. The presented analysis of fluvial bedload dynamics in different defined subsystems of the glacier-connected Erdalen (79.5 km 2 ) and Bodalen (60.1 km 2 ) Drainage Basins in the steep fjord landscape of western Norway provides insights into (i) detectable relevant sediment sources, (ii) instream channel storage of bedload material, (iii) spatiotemporal variability and controls of bedload transport rates and bedload yields, and (iv) the absolute and relative importance of fluvial bedload transport within the sedimentary budgets of these steep cold climate mountain valleys. Rockfalls, snow avalanches, stream channel bank erosion, and fluvial transfers through small tributaries draining slope systems are relevant sediment sources for fluvial bedload transport in the main stream channels, whereas the main outlet glaciers in both Drainage Basins are not of importance as all bedload material delivered directly from these outlet glaciers is trapped within proglacial lakes. Narrow valleys within both Drainage basin systems are characterized by a higher intensity of slope-channel coupling and display higher rates of sediment supply from slopes into the main stream channels than wider valleys. Snow avalanches are the most important sediment source in Erdalen, whereas fluvial transfers through small tributaries followed by snow avalanches are most important in Bodalen. Longer term, instream channel storage is not of great importance in the steep Bodalen Drainage basin but currently plays an important role within the Erdalen Drainage basin, which is characterized by a stepped longitudinal main valley bottom profile favoring deposition of bedload material within less steep main channel reaches. The mean annual bedload yields (2010–2013) are 2.4 t km − 2 y − 1 for the entire Erdalen and 13.3 t km − 2 y − 1 for the entire Bodalen Drainage basin, which are comparably low values for steep and partly glacierized Drainage basin systems. Because of supply-limited conditions, the intensity of fluvial bedload transport is generally much more related to the availability of sediments than to channel discharge. Fluvial bedload transport accounts for about one-third of the total fluvial transport and accordingly plays an important role within the sedimentary budgets of both Drainage basin systems.
Shusen Wang - One of the best experts on this subject based on the ideXlab platform.
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long term water budget imbalances and error sources for cold region Drainage Basins
Hydrological Processes, 2015Co-Authors: Shusen Wang, Jianliang Huang, Daqing Yang, Goran PavlicAbstract:This study assessed the long-term (1979–2008) water budget closures for 19 large cold region Drainage Basins in Canada using recently developed datasets for precipitation (P), land surface evapotranspiration and water surface evaporation, and observed streamflow. Total water storage (TWS) trends from the GRACE satellite observations were also used to assist the assessment. The objectives are to quantify the magnitudes and spatial patterns of the water budget imbalance (e) and its source of errors for these cold region Basins. Results showed that the water budget was closed within 10% of the P on average for all the Basins. The e showed a general pattern of positive values in the south and negative values in the north and mountainous regions over the country. Basins with large e values were mostly found in the north. Uncertainties in the water budget variables, particularly P, were found to play a major role in the e. Significant trends in TWS were found over 11 Basins, which accounted for 31% of their e on average. Improvements in the observation network, data quality assurance, and spatial models for P are critical for further improving the water budget closure for the cold region Drainage Basins. © 2014 Her Majesty the Queen in Right of Canada. Hydrological Processes. © John Wiley & Sons, Ltd.
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assessment of water budget for sixteen large Drainage Basins in canada
Journal of Hydrology, 2014Co-Authors: Shusen Wang, Jianliang Huang, Alfonso Rivera, Daniel W Mckenney, Justin SheffieldAbstract:Summary This study represents the first attempt to examine the spatial and seasonal variations of the surface water budget by using state-of-the-art datasets for sixteen large Canadian Drainage Basins with a total area of 3.2 million km2. The datasets used include two precipitation grids produced using measurements and reanalysis models, land surface evapotranspiration and water surface evaporation estimated using the EALCO model, streamflow measured at hydrometric stations, and total water storage change derived from GRACE satellite observations. The monthly water imbalance resulted from these datasets varied from 7.0 mm month−1 to 21 mm month−1 among the studied Basins, which was 30% on average of the corresponding monthly precipitation. The accumulated water budget imbalance over the 7 years of 2002–2008 varied from close to zero to ±10 mm month−1. The positive and negative imbalances among the sixteen Basins were largely offset and the all-basin imbalance was very close to 0. The uncertainties in precipitation, streamflow, evapotranspiration and total water storage change all contributed to the water budget imbalance and their relative magnitudes were found to vary with basin and season. In most cases, precipitation showed the largest uncertainties, which had similar magnitudes to the water budget imbalances. While improvements are noted in comparison with previous water budget studies over the regions, the water imbalance obtained for some Basins is quite large, suggesting that considerable improvements in both the observation networks and models are necessary before the water budget closure can be substantially improved over this region.
Nicolas Massei - One of the best experts on this subject based on the ideXlab platform.
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Classification of worldwide Drainage Basins through the multivariate analysis of variables controlling their hydrosedimentary response
Global and Planetary Change, 2011Co-Authors: Julie Raux, Yoann Copard, Benoît Laignel, Matthieu Fournier, Nicolas MasseiAbstract:Quality and amount of waters and sediments conveyed within large Drainage Basins are crucial for human societies and biodiversity concerns. This work aims to determine the factors controlling the hydrosedimentary response (water discharge and sediment load) of 24 worldwide large Drainage Basins. In this respect, eleven geomorphologic and climatic variables routinely used in the literature were considered and others as fractal dimension, elongation and mean channel slope are novel for such an issue. In addition, two variables, land cover and lithology indexes, somewhat different from the literature in terms of calculation principles, were also included. All these variables were then subjected to multivariate statistical analyses (CA and PCA) and confronted in a matrix correlation. On the whole, our results display that water discharge is controlled by runoff, precipitation, basin area, elongation and fractal dimension while sediment load is governed by runoff, precipitation and maximum elevation. Mean channel slope and land-use have a minor role while other parameters (hypsometry, lithology, length, slope, mean elevation and temperature) do not play a significant role in the hydrosedimentary response. Such statistical analyses also bring out a classification of these Drainage Basins, comprising five to six main clusters which are ranged according to the main variables ruling their hydrosedimentary response. Two clusters are essentially governed by geomorphometric parameters (area, elongation, fractal dimension, mean elevation and hypsometry) while one cluster is rather controlled by transfer processes (runoff) and by active tectonic (maximum elevation). Hydrosedimentary response of arctic and continental rivers is controlled by low temperature while two Drainage Basins show any trend. A comparison of our results with other previous works dealing with this same issue points to some significant disagreements essentially based on the number of Drainage Basins considered, the number of nature of variables used and the analytical methods carried out. Despite their obvious influence, anthropogenic impacts are not considered in this study. In foreseeable works dealing with such issue, anthropogenic parameters would be required for a better description of hydrosedimentary responses of these large Drainage Basins.
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Classification of worldwide Drainage Basins through the multivariate analysis of variables controlling their hydrosedimentary response
Global and Planetary Change, 2011Co-Authors: Julie Raux, Yoann Copard, Benoît Laignel, Matthieu Fournier, Nicolas MasseiAbstract:International audienceQuality and amount of waters and sediments conveyed within large Drainage Basins are crucial for human societies and biodiversity concerns. This work aims to determine the factors controlling the hydrosedimentary response (water discharge and sediment load) of 24 worldwide large Drainage Basins. In this respect, eleven geomorphologic and climatic variables routinely used in the literature were considered and others as fractal dimension, elongation and mean channel slope are novel for such an issue. In addition, two variables, land cover and lithology indexes, somewhat different from the literature in terms of calculation principles, were also included. All these variables were then subjected to multivariate statistical analyses (CA and PCA) and confronted in a matrix correlation. On the whole, our results display that water discharge is controlled by runoff, precipitation, basin area, elongation and fractal dimension while sediment load is governed by runoff, precipitation and maximum elevation. Mean channel slope and land-use have a minor role while other parameters (hypsometry, lithology, length, slope, mean elevation and temperature) do not play a significant role in the hydrosedimentary response. Such statistical analyses also bring out a classification of these Drainage Basins, comprising five to six main clusters which are ranged according to the main variables ruling their hydrosedimentary response. Two clusters are essentially governed by geomorphometric parameters (area, elongation, fractal dimension, mean elevation and hypsometry) while one cluster is rather controlled by transfer processes (runoff) and by active tectonic (maximum elevation). Hydrosedimentary response of arctic and continental rivers is controlled by low temperature while two Drainage Basins show any trend. A comparison of our results with other previous works dealing with this same issue points to some significant disagreements essentially based on the number of Drainage Basins considered, the number of nature of variables used and the analytical methods carried out. Despite their obvious influence, anthropogenic impacts are not considered in this study. In foreseeable works dealing with such issue, anthropogenic parameters would be required for a better description of hydrosedimentary responses of these large Drainage Basins
