Tensiometers for Measuring the Capillary Tension of Soil Water<sup>1</sup>

Richards, L. A.; Gardner, Willard

doi:10.2134/agronj1936.00021962002800050002x

Cited by 59 publications

(19 citation statements)

References 1 publication

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“…In Figure 5.5a, the unsaturated soil sample is placed on a porous membrane (or porous plate) which has very small openings, such that air cannot be sucked through them into the manometer, even through the largest openings (recall that Pc = 2aaw1r*) at the range of suctions planned for the experiment. The instrument used for measuring the capillary pressure in an unsaturated soil is called a tensiometer (a name introduced by Richards and Gardner, 1936). After some time, eqUilibrium is reached between the water in the soil and in the manometer.…”

Section: Capillary Pressurementioning

confidence: 99%

Modeling Groundwater Flow and Pollution

1987

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PrefaceGroundwater constitutes an important component of many water resource systems, supplying water for domestic use, for industry, and for agriculture. Management of a groundwater system, an aquifer, or a system of aquifers, means making such decisions as to the total quantity of water to be withdrawn annually, the location of wells for pumping and for artificial recharge and their rates, and control conditions at aquifer boundaries. Not less important are decisions related to groundwater qUality. In fact, the quantity and quality problems cannot be separated. In many parts of the world, with the increased withdrawal of groundwater, often beyond permissible limits, the quality of groundwater has been continuously deteriorating, causing much concern to both suppliers and users. In recent years, in addition to general groundwater quality aspects, public attention has been focused on groundwater contamination by hazardous industrial wastes, by leachate from landfills, by oil spills, and by agricultural activities such as the use of fertilizers, pesticides, and herbicides, and by radioactive waste in repositories located in deep geological formations, to mention some of the most acute contamination sources.In all these cases, management means making decisions to achieve goals without violating specified constraints. In order to enable the planner, or the decision maker, to compare alternative modes of action and to ensure that the constraints are not violated, a tool is needed that will provide information about the response of the system (the aquifer) to various alternatives. Good management requires the ability to forecast the aquifer's response ,to planned operations, such as pumping and recharging. The response may take the form of changes in water levels, changes in water quality, or land subsidence. Any planning of mitigation, clean-up operations, or control measures, once contamination has been detected in the saturated or unsaturated zones, requires the prediction of the path and the fate of the contaminants in response to the planned activities. Any monitoring or observation network must be based on the anticipated behavior of the system.The necessary information about the response of the system is provided by a model that describes the behavior of the considered system in response to excitation. The model may take the form of a well posed mathematical problem, or that of a set of algebraic equations, referred to as a numerical model, solved with the aid of a computer. For most practical problems, because of the heterogeneity of the considered domain, the irregular shape of its boundaries, and the nonanalytic form of the various source functions, only a numerical model can provide the required forecasts.However, given a certain problem, one cannot go directly to the computer, pick Xl xii PREFACE up a program, push some buttons, and expect a solution to the problem. A most important part of the modeling procedure is a thorough understanding of the system, and the processes that take place in it. It is impo...

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Section: Capillary Pressurementioning

confidence: 99%

Modeling Groundwater Flow and Pollution

1987

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“…Techniques for measuring matric suction include tensiometers (Richards and Gardner 1938), electrical/ thermal conductivity sensors and contact filter paper techniques. High-capacity tensiometers are used to directly measure negative pore water pressure up to 15 MPa (Ridley and Burland 1993;Mongiovi 2001, 2003).…”

Section: Soil Water Retention Curvesmentioning

confidence: 99%

Laboratory Hydraulic Testing in Unsaturated Soils

Masrouri¹,

Bicalho

Kawai

2008

Geotech Geol Eng

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This paper synthesizes the state-of-the art of the various laboratory testing techniques presently available for measuring the water hydraulic constitutive functions of unsaturated soils. Emphasis is on the laboratory testing techniques for measuring the soilwater retention curves and the water hydraulic conductivity functions of unsaturated soils. The significant recent advances in the investigation of the hydraulic behaviour of unsaturated swelling soils, are also presented. Comprehensive recent references on each measurement method are listed and discussed.

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“…A porous cup when filled with water and connected to a suitable gage may be used for measuring the pressure in soil water (1,5). This pressure may be either greater or less than atmospheric pressure, which is ordinarily taken as the pressure reference.…”

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“…At points below a water table the pressure is positive, but in unsaturated soil the water in a porous cup must be under negative or vacuum pressure in order to be in equilibrium with the water in the soil. The combination of a porous cup and a vacuum gage for measuring the equivalent negative pressure3 or tension of water in unsaturated soil has been called a "tensiometer" (1).…”

mentioning

confidence: 99%

Soil Moisture Tensiometer Materials and Construction

Richards¹

1942

Soil Science

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Tensiometers for Measuring the Capillary Tension of Soil Water¹

Cited by 59 publications

References 1 publication

Modeling Groundwater Flow and Pollution

Modeling Groundwater Flow and Pollution

Laboratory Hydraulic Testing in Unsaturated Soils

Soil Moisture Tensiometer Materials and Construction

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Tensiometers for Measuring the Capillary Tension of Soil Water1

Cited by 59 publications

References 1 publication

Modeling Groundwater Flow and Pollution

Modeling Groundwater Flow and Pollution

Laboratory Hydraulic Testing in Unsaturated Soils

Soil Moisture Tensiometer Materials and Construction

Contact Info

Product

Resources

About

Tensiometers for Measuring the Capillary Tension of Soil Water¹