ALTERATIONS OF RIVER MORPHOLOGY DUE TO VEGETATION ON SLOPES AND FLOOD PLAINS     

Wolfgang MERTENS Prof. Dr.-Ing.  Leichtweiss-Institut fuer Wasserbau  Technical University of Braunschweig  P.O. Box  Braunschweig  Germany 《国际泥沙研究》1997,(3)

LRESEarCHACTIVITIESCharaCtCriedcofunlinedalluvialriVersisthe~linteractionbettVeenwaterflowandmovableriVerbed.Sedimenttransport,bedresistanceandriVermorphologydecisivelydependontheflowconditionsandviceversathesefactorsgovernthehydraulicprocesses.EVenundersimplifiedconditions,e.g.inlaboratorytests,theseillteractionsareeXtremelycomplexandrelldsraliZationmakesengineeringproblemsevenmored~.TomaketheseprocessesmoreunderstandablecomprehensiVeresearchprojectswereconductedatseveralGermanuniv…  相似文献   

Transporting capacity of overland flow on plane and on irregular beds   总被引：2，自引：0，他引：2  

G. Govers  G Rauws 《地球表面变化过程与地形》1986,11(5):515-524

In this paper the transporting capacity of thin flows, in the laminar and transitional flow regime, is studied. Experiments were carried out on irregular as well as on plane beds, using two totally different set-ups. The results of these two types of experiment were convergent. In both cases, sediment concentration was clearly related to grain shear velocity and unit stream power, expressed as the product of mean velocity and slope (Yang, 1973). The data agreed with those of Kramer and Meyer (1969). For a sandy bed, the unit stream power relationship was able to predict reasonably well the sediment concentrations measured on a mulched surface. For laminar and transitional flows, both the unit stream power and the shear velocity are related in the same way to slope and unit discharge. The unit stream power is a parameter which in particular can be very easily measured and might therefore become useful in obtaining a quick estimate of the transporting capacity of a thin flow. However, before a sediment transport equation for thin flows can be developed, more information is needed about the influence of the flow regime and grain size and density.  相似文献   

STREAM-SUBSURFACE EXCHANGE, SUSPENDED SEDIMENT TRANSPORT, AND THE COUPLED TRANSPORT OF COLLOIDS AND CONTAMINANTS IN SEDIMENT BEDS     

Jianhong REN  Aaron I. PACKMAN 《国际泥沙研究》2003,(2)

1 INTRODUCTION Alluvial streams generally have permeable bed sediments that can admit significant pore water flows. Steady flow of surface water over bed roughness features such as sand waves or pools and riffles can then drive water flow into and out of the shallow subsurface. This is often termed hyporheic exchange, and the subsurface region where mixing between stream and ground waters occurs is the hyporheic zone (Hynes, 1983). The hyporheic zone has been shown to be a critical com…  相似文献   

岩土体水力学非线性问题     

柴军瑞 《岩土力学》2003,(Z2)

非线性问题是岩土体水力学研究的主要内容之一。将岩土体水力学非线性问题按非线性性质划分为以下7类:(1)渗流区域非线性问题(具有自由面的无压渗流);(2) 本构关系非线性问题(非达西渗流);(3) 渗透参数非线性问题(非饱和渗流);(4) 流态非线性问题(多相体渗流);(5) 介质非线性问题(多重介质渗流);(6) 相互作用非线性问题(渗流与溶质运移、温度、应力等耦合问题);(7) 多重非线性问题(上述两种或两种以上非线性问题的组合)。对这7类非线性问题的背景、特点、数学性质、解法、应用等方面进行系统的分析与归纳总结。可以看出,对非线性问题的继续深入研究必将推动岩土体水力学的进一步发展。  相似文献   

Geostatistical analysis of the effects of stage and roughness on reach-scale spatial patterns of velocity and turbulence intensity     

Carl J. Legleiter  Tracy L. Phelps  Ellen E. Wohl 《Geomorphology》2007,83(3-4):322-345

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Influence of groundwater on the degradation of irrigated soils in a semi-arid region, the inner delta of the Niger River, Mali     

A. Valenza  J. C. Grillot  J. Dazy 《Hydrogeology Journal》2000,8(4):417-429

The problem of soil degradation through alkalinization/salinization in an irrigated area with a semi-arid climate was examined in the inner delta of the Niger River, Mali, by the study of groundwater hydraulics and hydrochemistry in an area recharged by irrigation water. On the basis of data analysis on various scales, it is concluded that the current extent of the surface saline soils is due to a combination of three factors: (1) the existence of ancient saline soils (solonchaks) resulting from the creation of a broad sabkha west of the former course of the Niger River, now called the Fala of Molodo. These saline crusts were gradually deposited during the eastward tilting of the tectonic block that supports the Niger River; (2) the irrigation processes during the recent reflooding of the Fala of Molodo (river diversion in 1950). These used very poorly mineralized surface water but reintroduced into the alluvial groundwater system – generally of a low permeability (K=10–6?m?s–1) – salts derived from the ancient solonchaks; and (3) the redeposition of the dissolved salts on the surface due to the intense evapotranspiration linked to the present Sahelian climate. In this context, only efficient artificial draining of subsurface alluvial groundwater can eliminate most of the highly mineralized flow and thus reduce the current saline deposits.  相似文献   

酸化液压技术在地热增产中的应用分析   总被引：3，自引：0，他引：3  

王平  程万庆  宗振海  田光辉 《城市地质》2011,6(2):49-54

本文介绍了酸化液压技术在天津地热增产中的应用和经验。应用该技术应重视对基础地质资料和酸化前抽水试验资料的分析,弄清酸化液压技术应用的条件。  相似文献   

UNSTEADY MOVEMENT OF FRESH WATER IN THICK UNCONFINED SALINE AQUIFERS     

MAHDI S. HANTUSH 《水文科学杂志》2013,58(2):40-60

Abstract

Fresh-water lenses are formed in unconfined saline aquifers in response to deep percolation from rainfall, artificial recharge, and seepage from irrigation waters and/or in response to injecting fresh water through vertical or horizontal wells. An approximate differential equation is derived in terms of the depth of the fresh-salt water interface below the initial position of the saline-water table. This equation is analogous to that of the ground-water motion in two dimensions. The wealth of knowledge available from solving the latter equation is used to obtain approximate expressions for the movement of the fresh-salt water interface in several flow systems wherein this interface does not reach the bottom of the aquifer. These approximate solutions as well as others for related quantities of interest may afford useful tools for rationally planning the extraction of usable waters from such flow systems.  相似文献   

波浪作用下曲面防波堤水力特性及波能损耗研究   总被引：1，自引：1，他引：0  

蒋学炼  郭少龙  李炎保 《海洋工程》2012,30(3):59-67

执行了一系列规则波与曲面防波堤相互作用实验。采用π定理确定了两种曲面防波堤(半圆堤和圆弧堤)反射透射水力特性的三个主要影响因素,包括入射波陡、相对水深和堤顶相对超高。基于实验数据对比分析了两种曲面防波堤的反射和透射特性,从能量守恒角度计算了波浪与曲面防波堤相互作用过程中的能量损耗率,并利用数值模拟探讨了波浪越堤过程中两种曲面防波堤波能损耗差异的机理,表明圆弧堤背浪面更强的尾涡区使得其局部能耗总体上高于半圆堤。  相似文献   

Seasonal variation of river and tide energy in the Yangtze estuary,China   总被引：1，自引：0，他引：1       下载免费PDF全文

Min Zhang  Ian Townend  Yunxuan Zhou  Huayang Cai 《地球表面变化过程与地形》2016,41(1):98-116

In many large estuaries there are significant variations in flow conditions due to the interaction between tide (with spring–neap changes) and river discharge (with wet–dry seasons), which is key to understanding the evolution of the morphology and the resultant equilibrium state. To explore whether there exists an equilibrium state, and what might control such a state in such a dynamic environment, both numerical and analytical methods have been used to investigate the relative importance of tide and river contributions to the work done locally and globally over a wide range of discharge conditions in the Yangtze estuary. In particular, we have quantified the contributions from the tidal flow, the river flow and the tide–river interaction in terms of energy and its dissipation under different river discharge conditions. Model results suggest that there is a state of minimum tidal work for the case representing the wet season, when river and tide are doing uniform work locally and minimum work globally, within the bi‐directional tidal reach for tide and along the whole estuary for river. We also observe that the system is not optimized for other conditions (peak discharge and low flows during the dry season), but the system would tend to do the minimum work possible given the constraints on the system (e.g. imposed forcing conditions and available sediment supply). Results, therefore, are consistent with the use of these two energetic optimization principles, and the proposed method could be applicable to other alluvial estuaries. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献