Modelling the effect of time‐dependent river dune evolution on bed roughness and stage     

Andries J. Paarlberg  C. Marjolein Dohmen‐Janssen  Suzanne J. M. H. Hulscher  Paul Termes  Ralph Schielen 《地球表面变化过程与地形》2010,35(15):1854-1866

This paper presents an approach to incorporate time‐dependent dune evolution in the determination of bed roughness coefficients applied in hydraulic models. Dune roughness is calculated by using the process‐based dune evolution model of Paarlberg et al. ( 2009 ) and the empirical dune roughness predictor of Van Rijn ( 1984 ). The approach is illustrated by applying it to a river of simple geometry in the 1‐D hydraulic model SOBEK for two different flood wave shapes. Calculated dune heights clearly show a dependency on rate of change in discharge with time: dunes grow to larger heights for a flood wave with a smaller rate of change. Bed roughness coefficients computed using the new approach can be up to 10% higher than roughness coefficients based on calibration, with the largest differences at low flows. As a result of this larger bed roughness, computed water depths can be up to 15% larger at low flow. The new approach helps to reduce uncertainties in bed roughness coefficients of flow models, especially for river systems with strong variations in discharge with time. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

A toxicity identification evaluation of silty marine harbor sediments to characterize persistent and non-persistent constituents     

Stronkhorst J  Schot ME  Dubbeldam MC  Ho KT 《Marine pollution bulletin》2003,46(1):56-64

Sediment toxicity in silty marine harbor sediments is frequently dominated by ammonia or sulfide, leaving the adverse effects of persistent toxic substances unnoticed. To investigate the latter, we subjected interstitial water from three contaminated silty sediments to toxicity identification evaluation (TIE) phase I manipulations and tested for toxicity with four bioassays: the amphipod Corophium volutator (survival as an endpoint), the sea urchin Psammechinus miliaris (fertilization, embryo development) and the bacterium Vibrio fischeri (bioluminescence inhibition).The graduated pH manipulations identified the prominent toxicity of ammonia in the amphipod and sea urchin embryo tests, and also sulfide toxicity in the bacterium test. In two of the three samples tested with the amphipods, sea urchin embryos and bacteria, a small but significant reduction in interstitial water toxicity was achieved by removing persistent compounds through C(18) solid phase extraction. EDTA chelation resulted in a slight detoxification of the interstitial water for the amphipods and sea urchin embryos, but this was not related to any measured trace metals. Despite the presence of toxic levels of ammonia and sulfide in the harbor sediments, we established the adverse biological effects of persistent constituents by means of the TIE manipulations and in vivo interstitial water bioassays.  相似文献   

Incorporation and leaching of heavy metals in clay annealed with Pb, Cu and V     

Volker Karius  Petra Bruhns  Kay Hamer  Reinhard X. Fischer 《Environmental Geology》2001,41(3-4):297-304

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Tributyltin release from harbour sediments--modelling the influence of sedimentation, bio-irrigation and diffusion using data from Bremerhaven     

Hamer K  Karius V 《Marine pollution bulletin》2005,50(9):980-992

This study describes the potential release of TBT from harbour sediments based on model calculations for different sediment management scenarios applying a numerical one-dimensional FD-model. A conceptual model was developed focussing on the following processes involved in the transport of TBT: sorption equilibrium, diffusion, irrigation and sedimentation. Assuming TBT-concentration of 292 microg/kg in the sediment, the diffusive release of TBT from sediments into the bottom water was calculated to 7.4 x 10(-7)-6.9 x 10(-6)mol m(-2) after 1 year and 7.4 x 10(-6)-1.6 x 10(-4)mol m(-2) after 100 years. In these scenarios, neither sedimentation nor capping were considered. Assuming a sedimentation at a rate of 1cm/a, the polluted sediments will be covered with TBT-free suspended matter. A diffusive release of TBT will be prevented if no bio-irrigation takes place. Capping with a layer of sand of 50 cm thickness will decrease the diffusive release. If a reactive capping could be applied, the release of TBT into the bottom water would be stopped almost completely. The study shows that our model calculations enables us to compare different scenarios in sediment management based on available data. Additionally, it can provide information for risk assessment in the absence of data.  相似文献   

Discriminant analysis applied to aerial radiometric data and its application to Uranium favorability in South Texas     

David A. Patterson  Fredric L. Pirkle  Mark E. Johnson  Thomas R. Bement  Newton K. Stablein  C. Kay Jackson 《Mathematical Geology》1981,13(6):535-568

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The Public's View of National Parks     

Kay L. Booth 《New Zealand geographer》1987,43(2):60-65

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Alkaline magmatism from Kutch, NW India: implications for plume–lithosphere interaction     

N.R. Karmalkar  Sonal Rege  W.L. Griffin  Suzanne Y. O''Reilly 《Lithos》2005,81(1-4):101-119

Geochemical data are presented for primitive alkaline rocks from the Kutch region, north–northwest of Deccan Volcanic Province (DVP) of west central India, which is generally regarded as related to the Reunion Plume. The trace element systematics of these rocks are similar to those of ocean-island basalts, but there is considerable compositional variation, which is related to a strong overprint from the lithosphere on plume-derived magmas. This subcontinental lithospheric mantle (SCLM) component has geochemical characteristics that overlap those observed in spinel lherzolite xenoliths entrained in these rocks. Phlogopite and apatite in the SCLM are of metasomatic origin attributed to the infiltrating fluids and/or melts derived from rising mantle plume material. The composition of the alkaline rocks is consistent with a regional upwelling of deep mantle related to marginal rifting and with OIB-type geochemical characteristics. Thermal inhomogeneities within such plume swath resulted in small diapirs, which may have undergone melt segregation at the base of the lithosphere (100 km) and incorporated varying amounts of SCLM during ascent.  相似文献   

Development of hypoxia in well-mixed subtropical estuaries in the Southeastern USA     

Peter G. Verity  Merryl Alber  Suzanne B. Bricker 《Estuaries and Coasts》2006,29(4):665-673

Esturies throughout much of the South Atlantic Bight (southeastern U.S.) have been considered to be relatively pristine, but are now experiencing elevated concentrations of both organic and inorganic nutrients. As is true in many parts of the world, this eutrophication is correlated with coastal population growth. These estuaries have been assumed to be immune from extended hypoxia, in large part because they are well mixed and do not generally exhibit the water column stratification that is traditionally associated with low concentrations of dissolved oxygen. data presented here show long-term (19 yr) decreases in dissolved oxygen in surface waters of the Skidaway estuary, a pattern that is occurring throughout coastal Georgia. More limited data from bottom waters exhibit the same trend. The decreases in dissolved oxygen occurred at the same time as observed increases in inorganic and organic nutrients and in bacteria concentrations, implying an increase in heterotrophic activity. These observations suggest that traditional paradigms long applied to stratified estuaries, wherein the cycle that leads to hypoxia is initiated by the uptake of inorganic nutrients by autotrophs that are then decomposed below the pycnocline, may need revision for well-mixed estuaries. Heterotrophic community metabolism, stimulated by anthropogenic loading of organic and inorganic nutrients, can overwhelm even vigorous vertical mixing and horizontal exchange to gradually cause declining oxygen concentrations and eventually hypoxia.  相似文献   

Uncertainty analysis for estimating flood frequencies for ungauged catchments using rainfall-runoff models     

David A. Jones  Alison L. Kay 《Advances in water resources》2007

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Aquifer-yield continuum as a guide and typology for science-based groundwater management     

Suzanne A. Pierce  John M. Sharp Jr.  Joseph H. A. Guillaume  Robert E. Mace  David J. Eaton 《Hydrogeology Journal》2013,21(2):331-340

Groundwater availability is at the core of hydrogeology as a discipline and, simultaneously, the concept is the source of ambiguity for management and policy. Aquifer yield has undergone multiple definitions resulting in a range of scientific methods to calculate and model availability reflecting the complexity of combined scientific, management, policy, and stakeholder processes. The concept of an aquifer-yield continuum provides an approach to classify groundwater yields along a spectrum, from non-use through permissive sustained, sustainable, maximum sustained, safe, permissive mining to maximum mining yields, that builds on existing literature. Additionally, the aquifer-yield continuum provides a systems view of groundwater availability to integrate physical and social aspects in assessing management options across aquifer settings. Operational yield describes the candidate solutions for operational or technical implementation of policy, often relating to a consensus yield that incorporates human dimensions through participatory or adaptive governance processes. The concepts of operational and consensus yield address both the social and the technical nature of science-based groundwater management and governance.  相似文献