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Hydraulic head

About: Hydraulic head is a research topic. Over the lifetime, 2449 publications have been published within this topic receiving 43923 citations. The topic is also known as: piezometric head.


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Book ChapterDOI
26 Oct 2015
TL;DR: In this paper, the conductivity of the soil to water is measured and the data are used for analysis of any saturated-soil water-flow system, which can provide indirect information about the structure and structural stability of soils.
Abstract: The rate of movement of water through soil is of considerable importance in many aspects of agricultural and urban life. The entry of water into soil, the movement of water to plant roots, the flow of water to drains and wells, and the evaporation of water from the surface of soil are but a few of the obvious situations in which the rate of movement plays an important role. An important soil property involved in the behavior of soil water flow systems is the conductivity of the soil to water. Qualitatively, the conductivity is the ability of the soil to transmit water. Measurements of conductivity of saturated soil have long been made. The data are of use in analysis of any saturated-soil water-flow system. These include drainage of soils for agricultural as well as engineering purposes. Drainage of highways, airports, and construction sites, and seepage below dams are among the latter. The data also provide indirect information about the structure and structural stability of soils.

360 citations

Journal ArticleDOI
TL;DR: In this article, a distinction is made between water-pressure and effective pressure in the chamber, and the stability of the tunnel face is controlled through the combined effects of these two entities.

358 citations

Journal ArticleDOI
TL;DR: In this article, the authors used InSAR measurements of the typically small-magnitude, generally recoverable deformations of the Las Vegas Valley aquifer system occurring at seasonal timescales.
Abstract: Analyses of areal variations in the subsidence and rebound occurring over stressed aquifer systems, in conjunction with measurements of the hydraulic head fluctuations causing these displacements, can yield valuable information about the compressibility and storage properties of the aquifer system. Historically, stress-strain relationships have been derived from paired extensometer/piezometer installations, which provide only point source data. Because of the general unavailability of spatially detailed deformation data, areal stress-strain relations and their variability are not commonly considered in constraining conceptual and numerical models of aquifer systems. Interferometric synthetic aperture radar (InSAR) techniques can map ground displacements at a spatial scale of tens of meters over 100 km wide swaths. InSAR has been used previously to characterize larger magnitude, generally permanent aquifer system compaction and land subsidence at yearly and longer timescales, caused by sustained drawdown of groundwater levels that produces intergranular stresses consistently greater than the maximum historical stress. We present InSAR measurements of the typically small-magnitude, generally recoverable deformations of the Las Vegas Valley aquifer system occurring at seasonal timescales. From these we derive estimates of the elastic storage coefficient for the aquifer system at several locations in Las Vegas Valley. These high-resolution measurements offer great potential for future investigations into the mechanics of aquifer systems and the spatial heterogeneity of aquifer system structure and material properties as well as for monitoring ongoing aquifer system compaction and land subsidence.

342 citations

Journal ArticleDOI
TL;DR: In this paper, the authors analyzed unsaturated flow in heterogeneous soil with an arbitrarily oriented mean hydraulic gradient using spectral solutions of the stochastic perturbation equation which describes the capillary pressure head ψ.
Abstract: Steady unsaturated flow in heterogeneous soil with an arbitrarily oriented mean hydraulic gradient is analyzed using spectral solutions of the stochastic perturbation equation which describes the capillary pressure head ψ. The unsaturated hydraulic conductivity is related to ψ by K = Ks exp (−αψ), where Ks is the saturated hydraulic conductivity and α is a soil parameter, and both Ks and α are treated as three-dimensional statistically homogeneous, anisotropic random fields. Analytical results are obtained for the capillary pressure head variance and the effective (mean) unsaturated hydraulic conductivity. The head variance depends upon the degree of anisotropy of the ln Ks covariance; when α is random, the head variance increases with mean capillary pressure head. The effective hydraulic conductivity for arbitrary orientation of the mean hydraulic gradient J is shown to have tensorial properties, but its components depend on the magnitude and direction of J and the orientation of the stratification in the soil. When α is random, the degree of anisotropy of the effective conductivity depends strongly on mean capillary pressure.

334 citations

Book
28 Sep 1999
TL;DR: In this paper, the fundamental principles of head loss in pipe networks are discussed and a general method for Rigid-Column Unsteady Flow in pipeline networks is presented. But this method does not consider the effect of air entrainment on wave speed.
Abstract: INTRODUCTION REVIEW OF FUNDAMENTALS The Fundamental Principles Head Loss Formulas Pump Theory and Characteristics Steady Flow Analyses MANIFOLD FLOW Introduction Analysis of Manifold Flow A Hydraulic Design Procedure PIPE NETWORK ANALYSIS Introduction Equations Systems for Steady Flow in Networks Pressure Reduction and Back Pressure Valves Solving the Network Equations Concluding Remarks DESIGN OF PIPE NETWORKS Introduction Large Branched Systems of Pipes Looped Network Design Criteria Designing Special Components Developing a Solution for any Variables Higher Order Representations of Pump Curves Sensitivity Analysis EXTENDED TIME SIMULATIONS AND ECONOMICAL DESIGN Introduction Extended Time Simulations Elements of Engineering Economics Economic Network Design INTRODUCTION TO TRANSIENT FLOW Causes of Transients Quasi-Steady Flow True Transients ELASTIC THEORY OF HYDRAULIC TRANSIENTS (WATER HAMMER) The Equation for Pressure Head Change ?H Wave Speed for Thin-Walled Pipes Wave Speeds in Other Types of Conduits Effect of Air Entrainment on Wave Speed Differential Equations of Unsteady Flow SOLUTION BY METHOD OF CHARACTERISTICS Method of Characteristics, Approximate Governing Equations Complete Method of Characteristics Some Parameter Effects on Solution Results PIPE SYSTEM TRANSIENTS Series Pipes Branching Pipes Interior Major Losses Real Valves Pressure Reducing Valves Wave Transmission and Reflection at Pipe Junctions Column Separation and Released Air PUMPS IN PIPE SYSTEMS Pump Power Failure Rundown Pump Startup NETWORK TRANSIENTS Introduction Rigid-Column Unsteady Flow in Networks A General Method for Rigid-Column Unsteady Flow in Pipe Networks Several Pumps Supplying a Pipe Lilne Air Chambers, Surge Tanks and Standpipes A Fully Transient Network Analysis TRANSIENT CONTROL DEVICES AND PROCEDURES Transient Problems in Pipe Systems Transient Control Each chapter also includes problems REFERENCES APPENDIX A: NUMERICAL METHODS APPENDIX B: PUMP CHARACTERISTIC CURVES APPENDIX C: VALVE LOSS COEFFICIENTS

276 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202395
2022172
202199
2020115
2019103
2018111