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Lecture

Hydraulic Head Determination in Unsaturated Soil

Description

This lecture covers the determination of hydraulic head in unsaturated soil using tensiometers and mercury manometers, explaining the principles behind the measurement of pressure load and suction. It also discusses the relationship between suction and water content, characteristic soil moisture curves, and the influence of soil texture on the function. The presentation explores the hysteresis effect on the suction-water content relationship, the presence of trapped air causing hysteresis, and the experimental methods for measuring water content in soil samples. Additionally, it delves into the concept of capillary capacity and provides examples of retention functions based on water content saturation and residual values.

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Instructors (3)

Géraldine Michèle Bullinger

Gabriele Manoli

David Andrew Barry

Research InterestsSubsurface hydrology, constructed wetlands, ecological engineering, in particular contaminant transport and remediation of soil and groundwater; more generally, models of hydrological and vadose zone processes; application of mathematical methods to hydrological processes; coastal zone sediment transport, aquifer-coastal ocean interactions; hydrodynamics and modelling of lakes.

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Related concepts (21)

Water content

Water content or moisture content is the quantity of water contained in a material, such as soil (called soil moisture), rock, ceramics, crops, or wood. Water content is used in a wide range of scientific and technical areas, and is expressed as a ratio, which can range from 0 (completely dry) to the value of the materials' porosity at saturation. It can be given on a volumetric or mass (gravimetric) basis. Volumetric water content, θ, is defined mathematically as: where is the volume of water and is equal to the total volume of the wet material, i.

Soil salinity control

Soil salinity control refers to controlling the process and progress of soil salinity to prevent soil degradation by salination and reclamation of already salty (saline) soils. Soil reclamation is also called soil improvement, rehabilitation, remediation, recuperation, or amelioration. The primary man-made cause of salinization is irrigation. River water or groundwater used in irrigation contains salts, which remain in the soil after the water has evaporated.

Soil physics

Soil physics is the study of soil's physical properties and processes. It is applied to management and prediction under natural and managed ecosystems. Soil physics deals with the dynamics of physical soil components and their phases as solids, liquids, and gases. It draws on the principles of physics, physical chemistry, engineering, and meteorology. Soil physics applies these principles to address practical problems of agriculture, ecology, and engineering.

Millimetre of mercury

A millimetre of mercury is a manometric unit of pressure, formerly defined as the extra pressure generated by a column of mercury one millimetre high, and currently defined as exactly 133.322387415 pascals or exactly 133.322 pascals. It is denoted mmHg or mm Hg. Although not an SI unit, the millimetre of mercury is still routinely used in medicine, aviation, and many other scientific fields. One millimetre of mercury is approximately 1 Torr, which is 1/760 of standard atmospheric pressure (101325/760 ≈ 133.

Pressure measurement

Pressure measurement is the measurement of an applied force by a fluid (liquid or gas) on a surface. Pressure is typically measured in units of force per unit of surface area. Many techniques have been developed for the measurement of pressure and vacuum. Instruments used to measure and display pressure mechanically are called pressure gauges, vacuum gauges or compound gauges (vacuum & pressure). The widely used Bourdon gauge is a mechanical device, which both measures and indicates and is probably the best known type of gauge.

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Unsaturated Soils: Water Retention and Mechanical Behavior

Explores unsaturated soil behavior, emphasizing water retention and mechanical properties.

Retaining Structures: Geomechanics

Explores the design and analysis of retaining structures, lateral earth pressure, and unsaturated soils.

Critical State Concept: Unsaturated Soils

Explores the critical state concept in geomechanics, focusing on unsaturated soils and Terzaghi's effective stress validity.

Soil Science: Water in Soil Log in to Mediaspace to watch this video