RUNOFF-ENERGY FACTORS FORMUSLE SEDIMENT-YIELD MODEL FOR SURFACE MINES   总被引：4，自引：0，他引：4  

James V. Bonta 《国际泥沙研究》2000,(2)

1INTRODUCTIONSediment-yieldestimatesarerequiredforsurfacec0al-minepermitsunderFederalandStatelaws-Estimatesareneededfordeterminingtheimpactsofminingandreclamationduringmine0Peration,fordiversi0nandsmallimpoundmentdesigns,andforsizingsedimentpondstocontrolsedimenttransporteddownstfeam0faproposedminesite.Technologiesavailablef0rsediment-yieldestimationsincludetheUniversalSoilLossEquati0n(USLE,WischmierandSmith,l978);theWaterErosionPredictionPr0ject(WEPP,FlanaganandLivingst0n,l995),…  相似文献   

Sedimentation–consolidation modeling with an interaction coefficient     

S. Jeeravipoolvarn  R.J. ChalaturnykJ.D. Scott 《Computers and Geotechnics》2009

This paper examines the use of an interaction coefficient to couple sedimentation and consolidation phenomena with the conventional finite strain consolidation theory. A specific continuous interaction function was implemented and the resulted model was examined. The model was found to able to capture proper sedimentation–consolidation features. It was also determined that the structural and maximum suspension void ratios are the major factors controlling the shape of the void ratio profile. The model was compared with experimental data and other numerical models and qualitatively good agreement was obtained.  相似文献   

Sedimentation model of gravel-dominated alluvial piedmont fan,Ganga Plain,India   总被引：1，自引：0，他引：1  

U. K. Shukla 《International Journal of Earth Sciences》2009,98(2):443-459

The Piedmont Zone of the Indo-Gangetic Plain contains numerous, laterally coalescing small alluvial fans. The Latest Pleistocene–Holocene 30 km long Gaula Fan can be divided into gravelly proximal fan (0–14 km down-stream), gravel-sand rich mid fan (14–22 km) and sand–mud dominated distal fan (22–30 km). The fan succession is composed of two fan expansion cycles A and B. Separated by an undulatory erosional contact of regional extent, cycle A is characterized by river borne clast-supported gravelly deposits, and the overlying fan expansion cycle B by matrix-supported gravely debris flows. The main process behind fan development has been lateral migration of channels over the fan surface probably due to rapid sedimentation caused by increased sediment supply, and the fluctuating water budget in response to changing climate. The water laid expansion cycle A represents a humid phase. The debris flow deposits of expansion cycle B suggest a dry phase. Approximately between 8 and 3 Ka, cycle B also indicates a phase of tectonic instability in the Siwalik Hills forming the mountain front. The tectonic activity caused incision of rivers into the fan surface, and in turn resulted in reduced fan-building activity. At present the fan surface is accreting by sheet flow processes.  相似文献   

三峡库区侏罗系易滑地层沉积特征及其对岩石物理力学性质的影响   总被引：21，自引：7，他引：14  

李守定 李晓张年学  廖秋林 《工程地质学报》2004,12(4):385-389

三峡库区崩滑地质灾害频发 ,其中以侏罗系易滑地层为甚。侏罗系易滑地层特殊的地层结构和岩石物理力学性质是控制崩滑灾害发生的主要因素。本文通过岩相古地理和沉积环境演变两个方面来研究三峡库区侏罗系易滑地层的沉积特征 ,并研究了三峡库区地层的沉积环境和沉积结构对岩层物理力学性质的影响 ,对三峡库区以滑坡为代表的地质灾害频发的原因给出沉积学和物理力学解释  相似文献   

Empirical models for describing recent sedimentation rates in lakes distributed across broad spatial scales   总被引：1，自引：0，他引：1  

Soren Brothers  Jesse C. Vermaire  Irene Gregory-Eaves 《Journal of Paleolimnology》2008,40(4):1003-1019

Over the last 20 years there has been a surge of interest in paleolimnology and as a result a large accumulation of lake sedimentation records. This emerging archive has allowed us to develop empirical models to describe which variables explain significant variation in sedimentation rates over the past ∼150 years across large spatial scales. We hypothesized that latitude would be a significant explanatory variable of profundal zone lake sedimentation rates across a temperate to polar gradient. We further hypothesized that along a more longitudinally-constrained dataset (i.e. east coast of North America), latitude would explain a greater proportion of the variance. To test these hypotheses, we collated data from 125 natural, average-sized lakes (with surface area <500 km²) by recording authors’ estimates of sedimentation rates (measured as mm/year) or by digitizing recent sediment profiles and calculating sedimentation rates over the past ∼150 years. We found that, at both scales, latitude was the strongest predictor of lake sedimentation rates (full dataset: r ² = 0.28, P = 0.001, n = 125; east coast dataset: r ² = 0.58, P < 0.001, n = 43). By conducting a multiple linear regression analysis, we found that 70% of the variance in sedimentation rates from the east coast transect was explained by latitude and elevation alone. This latter model is of sufficient strength that it is a robust predictive tool. Given that climate and land-use strongly co-vary with latitude and that both of these factors have previously been shown to influence lake sedimentation rates, it appears that latitude is a surrogate measure for climate and land-use changes. We also show support for land-use as an important variable influencing sedimentation rates by demonstrating large increases in recent versus Holocene accumulation rates. These results indicate that it is possible to make generalizations about sedimentation rates across broad spatial scales with even limited geographic data.  相似文献   

Experimental Study for the Allocation of Ground-Sills Downstream of Check dams     

Bing-Shyan LIN  Chao-Hsien YEH  Hui-Pang LIEN 《国际泥沙研究》2008,23(1)

The main purpose of this study is to understand the stabilizing effect of ground-sills on the riverbed through a series of flume model experiments.From results,although check dams have the ability to control upstream sediment transport,the mass energy produced by the free fall of the overtopping discharge still causes strong local scour downstream of the structure,and this Scour lcads to the instability of the check dam.Therefore,this study conducted model experiments on various types of serial ground-sills to determine the appropriate spacing to best protect the downstream bed.Based on the observations and analysis of channel geomorphology and sedimentation,this study concluded the following results:1)Serial ground-sills reduces the sediment transport ability perfectly,especially under a mild channel gradient equipped with 2-4 times the average channel width interval.But for steep slopes,it is suggested that the proper spacing should be shortened to 1-2 times the average channel width.2)Ground-sills can effectively protect the streambed from scouring under a suitable equipped condition and the concepts of guiding scour and riverbed inertia were used in the analysis of optimal ground-sill spacing.  相似文献   

Removal mechanisms of nitrogen in waste stabilization ponds     

《Physics and Chemistry of the Earth》2014

The aim of this research work was to determine the major nitrogen transformation and removal mechanisms in primary and maturation ponds. To accomplished this objective, nitrogen mass balance in waste stabilization pond system was determined using a dynamic mathematical model in order to elucidate the biological nitrogen transformation mechanisms that are effective for removal of nitrogen in this pond system. Results show that nitrogen removal efficiency in a primary facultative pond unit was 13.2%, which was largely due to net loss of organic nitrogen to sediments (9.76%) and denitrification (3.42%). On the other hand, maturation pond removed 15.2% of nitrogen received in the influent with denitrification (13.55%) being the major pathway for nitrogen removal. Ammonia volatilization was not a predominant mechanism for nitrogen removal in both primary facultative and maturation ponds. The major nitrogen transformation routes were mineralization and ammonia uptake in the primary facultative pond, but ammonia uptake by microorganisms was a predominant nitrogen transformation mechanism in maturation pond.  相似文献   

Improving age-depth models of fluvio-lacustrine deposits using sedimentary proxies for accumulation rates     

《Quaternary Geochronology》2016

Lacustrine fills, including those of oxbow lakes in river floodplains, often hold valuable sedimentary and biological proxy records of palaeo-environmental change. Precise dating of accumulated sediments at levels throughout these records is crucial for interpretation and correlation of (proxy) data existing within the fills. Typically, dates are gathered from multiple sampled levels and their results are combined in age-depth models to estimate the ages of events identified between the datings. In this paper, a method of age-depth modelling is presented that varies the vertical accumulation rate of the lake fill based on continuous sedimentary data. In between Bayesian calibrated radiocarbon dates, this produces a modified non-linear age-depth relation based on sedimentology rather than linear or spline interpolation.The method is showcased on a core of an infilled palaeomeander at the floodplain edge of the river Rhine near Rheinberg (Germany). The sequence spans from ∼4.7 to 2.9 ka cal BP and consists of 5.5 m of laminated lacustrine, organo-clastic mud, covered by ∼1 m of peaty clay. Four radiocarbon dates provide direct dating control, mapping and dating in the wider surroundings provide additional control. The laminated, organo-clastic facies of the oxbow fill contains a record of nearby fluvial-geomorphological activity, including meander reconfiguration events and passage of rare large floods, recognized as fluctuations in coarseness and amount of allochthonous clastic sediment input. Continuous along-core sampling and measurement of loss-on-ignition (LOI) provided a fast way of expressing the variation in clastic sedimentation influx from the nearby river versus autochthonous organic deposition derived from biogenic production in the lake itself. This low-cost sedimentary proxy data feeds into the age-depth modelling. The sedimentology-modelled age-depth relation (re)produces the distinct lithological boundaries in the fill as marked changes in sedimentation rate. Especially the organo-clastic muddy facies subdivides in centennial intervals of relative faster and slower accumulation. For such intervals, sedimentation rates are produced that deviate 10–20% from that in simpler stepped linear age-models. For irregularly laminated muddy intervals of the oxbow fill – from which meaningful sampling for radiocarbon dating is more difficult than from peaty or slowly accumulating organic lake sediments – supplementing spotty radiocarbon sampling with continuous sedimentary proxy data creates more realistic age-depth modelling results.  相似文献   

钱塘江河口周边钻孔磁性地层学研究及意义   总被引：1，自引：0，他引：1       下载免费PDF全文

彭杰  杨小强  强小科  刘春莲  李剑  林清龙  翁元忠  周绮娴  丁洁莹 《地球物理学报》2016,59(8):2949-2964

长江三角洲地区的沉积历史和特征,是揭示我国东部沿海区域新生代以来构造演化与地理格局形成过程的重要窗口.本文基于磁性地层学方法,结合AMS14 C和光释光测年数据以及该地区硬质黏土标志层,对分布于钱塘江河口两侧的五个钻孔建立年代地层框架.结果表明,除河口北部一个钻孔底部年龄至高斯正极性期外,其余钻孔显示南部地区约200ka BP以来才开始沉积,最南端晚至约60ka BP.与该地区已有钻孔磁性地层学资料进行对比,认为长江三角洲部分区域沉积年龄超过百万年和"北厚南薄、东厚西薄"的特征,主要是受早期区域构造背景的影响,而长江三角洲大范围的沉积发生自约200ka BP以来,受构造缓慢沉降和海平面变化控制的细颗粒(黏土-粉砂粒级)从晚更新世才开始沉积,约60ka BP以后扩大至整个三角洲区域.  相似文献   

东坪铅锌矿构控特征及矿床成因   总被引：1，自引：0，他引：1  

罗家贤 《云南地质》2003,22(3):304-312

东坪铅锌矿是巧家～小牛栏铅锌成矿亚带上一个有代表性的铅锌矿床,与处在同一成矿带上的其它铅锌矿床(点)有许多相似之处。不同的是该矿床由层间剥离空间或顺层挤压破碎带控制的矿床规模较大,并随上震旦统灯影组第二段赋矿层位延伸较远,显示较典型的层控加构控、与岩浆成因无关的沉积叠加中低温热液矿床类型。经对该区进一步物探与地质勘查证实：矿区SE边缘的巧家～小牛栏断层与派生的次一级NW向断层交汇部位,存在厚大的铅锌矿体,其深部也存在一定范围和宽度的“低阻高激化异常体”,应是该区今后找矿重点。  相似文献