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881.
水库泥沙淤积量测算方法研究综述及展望 总被引:1,自引:0,他引:1
我国江河大多泥沙量大,所建水库淤积严重,由此带来了一系列的问题。因此,及时、准确地确定其淤积量及淤积位置对工程措施的实施非常重要。首先,介绍了水库淤积量的测量方法,包括经纬仪测记法、SAR法、GPS+测深仪法;然后,针对淤积量的计算方法进行了详尽的述评,如:等深线、规则网格镶嵌法、断面或地形法、基于GIS的DTM法、泰森多边形法及基于库容曲线的泥沙淤积量计算法、输沙量平衡法和水力模型法等;最后,对水深测量误差的控制及淤积体体积计算的改进进行了探讨和展望,指出了需要进一步研究和解决的问题。 相似文献
882.
Irena Ciglenečki Srđan Pichler Esad Prohić Božena Ćosović 《Water, Air, & Soil Pollution: Focus》2006,6(5-6):537-545
Geochemical, mineralogical and sedimentological analyses were carried out to contrast two different sites (respectively characterized
by permanently oxic and anoxic conditions) in a small, meromictic, seawater lake. In fact, due to relatively high organic
matter content, and reduced water exchange, the Rogoznica Lake has almost permanent anoxic conditions below the depth of 12 m,
where sediment can be considered an anoxic–sulphidic sedimentary environment. Different water column and sediments redox conditions
affect the distribution and speciation of major redox-sensitive metals (Fe, Mn, Mo), reduced sulphur species (RSS) and dissolved
organic C (DOC). Trace metals, especially those that accumulate in anoxic–sulphidic environments (Fe, Mo) showed a marked
enrichment in the solid phase, whereas the low solubility of sulphides leads to low porewater concentrations. The relatively
high sedimentary enrichment of Mo (up to 81 mg/kg) also confirms highly anoxic conditions within the Rogoznica Lake sediments.
Results clearly show that chemical species within the sediments will tend towards equilibrium between porewater and solid
phase according the prevailing environment conditions such as redox, pH, salinity, DOC. 相似文献
883.
Cohesive sediments besides their typical heterogeneity are characterised by structural discontinuity. Particularly, organic
consolidated muds are a good example of sediments that consist of vast aggregates, pore water and gaseous products. The texture
of a cohesive sediment bed is a result of a number of mutually affecting factors, such as deposition history, mineral and
organic composition, kind of biota and oxygen uptake. The presented work attempts to quantify the effect of sediment physical
properties and sediments structure on the sediment erosion potential, considering incipient motion and erosion rate. This
quantification is made on the basis of comparative testing of both unremoulded and remoulded samples of a river mud. Due attention
is paid to sediment handling to preserve the delicate structure of the sediment for the laboratory experiments. Mud with two
degrees of consolidation has been examined in a tilting flume under different flow situations. The test results show a typical
increase of erosion strength with dry matter concentration of the mud. It has also been found that the structural properties
increase the erosion strength for the less consolidated mud. An opposite effect has been recorded for a more consolidated
deposit. As a consequence, due to the sediment structure, the original beds differ much less in erosion resistance in relation
to the dry mass concentration than their disturbed analogues. Finally, the erosion resistance of the examined mud is compared
with data from the literature. 相似文献
884.
W. H. Blake R. P. D. Walsh A. M. Sayer K. Bidin 《Water, Air, & Soil Pollution: Focus》2006,6(5-6):615-623
Detailed information on post-logging sediment dynamics in tropical catchments is required for modelling downstream impacts
on communities and ecosystems. Sediment tracing methods, which are potentially useful in extending to the large catchment
scale and longer time scales, are tested in primary and selectively logged rainforest catchments of Sabah, Borneo. Selected
nutrient (P and N) and trace metal (Ni and Zn) concentrations are shown to discriminate surface, shallow subsurface and deep
subsurface sediment sources. Analysis of channel-stored fine-sediment samples and use of an unmixing model allow the relative
importance of these vertical sediment sources to be estimated and erosion processes to be inferred for catchments of contrasting
size. 相似文献
885.
A benthic in situ flume and a 1D biogeochemical sediment model to evaluate solute fluxes across the sediment–water interface have been developed.
The flume was successfully used to determine oxygen and nutrient fluxes at various locations of the Neckar River in Germany.
The experimental results were linked with vertical pore water concentration profiles and independently verified with the model.
By combining experimental and model results we assessed the influence of dissolved oxygen concentrations in the water column
and the availability of degradable organic matter on sediment oxygen demand. The results and the derived relations can be
used to parameterize the sediment module of large scale water quality models, allowing one to assess the influence of sediment–water
interactions on various aspects of river water quality. Moreover, the biogeochemical sediment model can help to improve the
general understanding of the processes governing solute concentrations and fluxes in sediments and across their interfaces. 相似文献
886.
Ester Heath Nives Ogrinc Jadran Faganeli Stefano Covelli 《Water, Air, & Soil Pollution: Focus》2006,6(5-6):605-614
To reconstruct a history of polycyclic aromatic hydrocarbon (PAH) pollution in the Gulf of Trieste, one of the largest urbanized
areas in the Adriatic Sea, we analyzed three long sediment cores collected between 1996 and 1997. Concentrations of total
PAHs, the sum of 16 PAH compounds and six of their methylated analogues, in all three cores show a decrease from 600–800 ng
g−1, at the surface, to levels below 250 ng g−1 in deepest layers (down to 3 m). The same trend was shown with separate representative pyrogenic PAHs (pyrene, benzofluoranthene
and phenanthrene). Using Hg as a recent geochronological tracer, we observe an increasing input of PAHs since the beginning
of the 20th Century and, especially, after the Second World War coinciding with increasing industrialization and urbanization
of the region. This correlation is supported by PAH ratios that are indication of combustion processes and represent a marker
for anthropogenic inputs. No correlation exists between PAHs and black carbon within the core profiles, indicating two different
fractions of the ‘black carbon continuum’. 相似文献
887.
Rasmus B. Lauridsen Brian Kronvang Nikolai Friberg 《Water, Air, & Soil Pollution: Focus》2006,6(5-6):423-432
In a total of 189 water samples collected from Danish streams no traces of the pyrethroid esfenvalerate were detected. However,
pyrethroids have previously been found in sediments in 9 out of 30 streams investigated. We found that the shredding activity
of the Trichopteran Sericostoma personatum and the amphipod Gammarus pulex was significantly reduced with increased concentration of the pyrethroid lambda-cyhalohtrin adsorbed to the leaves on which
they fed. Predation rate on the Plecopteran Leuctra nigra by the leech Erpobdella octoculata increased significantly with increasing concentration of lambda-cyhalothrin on the leaves on which L. nigra was fed. Our results clearly indicate that the ongoing monitoring of pesticides is likely to underestimate pyrethroid occurrence
and that sediment-bound pyrethroids have a potential negative impact on ecosystem function and biotic interactions in streams. 相似文献
888.
ESTIMATING TMDL BACKGROUND SUSPENDED SEDIMENT LOADING TO GREAT LAKES TRIBUTARIES FROM EXISTING DATA1
Peter J. Whiting 《Journal of the American Water Resources Association》2006,42(3):769-776
ABSTRACT: The total maximum daily load (TMDL) for suspended sediment is the maximum quantity of suspended sediment that can enter a waterway without affecting the beneficial uses of the waterway. It is calculated as the sum of permissible allotments of point sources of suspended sediment, permissible allotments of nonpoint sources of suspended sediment, background (natural) loading of suspended sediment, and a margin of safety. The goal of this project was to develop methods for estimating background levels of sediment loads in tributaries of the Great Lakes. Such quantification is key to determining permissible TMDL in waters that do not meet water quality standards under the Clean Water Act of 1972. Suspended sediment loading for 46 rivers was estimated from data collected at U.S. Geological Survey (USGS) gages. Land use and physiographic attributes were estimated for these gaged basins with a geographic information system (GIS). Basin attributes and sediment yield data are the basis for examining two approaches to estimating background suspended sediment loads. One method, based upon envelope curves of sediment yield and drainage area, will be shown to have considerable merit. A second method, based upon correlation of sediment yield to various basin attributes such as drainage area and land use, will be shown to be fraught with difficulties. 相似文献
889.
Steven W. Effler David A. Matthews Josef W. Kaser Anthony R. Prestigiacomo David G. Smith 《Journal of the American Water Resources Association》2006,42(6):1697-1710
Abstract: The impacts of runoff events on external suspended solids loading to Schoharie Reservoir, New York, and patterns of light scattering and sediment deposition in this reservoir are assessed. The assessment is based on monitoring of suspended solids concentrations in the reservoir's primary tributary, detailed vertical profiles of optical backscattering (a surrogate measure of light scattering) in the reservoir water column, and analysis of sediment trap collections, over a seven-month interval of high runoff. These impacts are reported to be tightly temporally coupled and strongly positively related to the magnitude of runoff events. The primary tributary entered the reservoir as a plunging inflow during runoff events, causing conspicuous subsurface peaks in light scattering, with vertical patterns that varied strongly for different events. Deposition quantified by near-bottom trap deployments is reported to be more representative than results from metalimnetic deployments that were generally within, rather than below, the turbid layers. Direct inputs of sediment, transported by density currents, are found to drive deposition, rather than resuspension/redeposition. More than 50 percent of the reported deposition occurred in less than 15 percent of the study period, associated with the four largest runoff events. 相似文献
890.
A. N. Macgregor D. R. Keeney 《Journal of the American Water Resources Association》1973,9(6):1153-1158
ABSTRACT: Renewed (de novo) synthesis of methane gas was shown to occur when samples of lake sediment were dispersed on glass beads and incubated in a helium atmosphere at 23°C. Under the above conditions, sediment samples from hardwater and softwater lakes generated up to 440 nanomoles and 80 nanomoles per ml of sediment per two days, respectively. At the time of collection, sediment samples possessed approximately similar amounts of “native” methane. Nitrate, sulfate, and acetylene were shown to suppress methane synthesis by sediment incubated as described. 相似文献