1887

oa Civil Engineer in South Africa - Soil moisture flow theory : technical paper

 

Abstract

Vertical flow of soil moisture, in situations with water application, drainage and evapo-transpiration, is investigated through theory in which the dynamic effects of both water and air are taken into account. The hydro-pneumatic properties of two model soils - a fine-grained loam and a medium-grained sand - are derived from publications by investigators worldwide. A system of equations for defining soil characteristics is described, which can be applied to any soil tested in a specified manner. Lacking sophisticated laboratory service, complete data for a project soil, for which two specific readily determined properties are known, can be estimated from those of the model soils by interpolation. A method of analysis utilizing finite differencing is developed and its application demonstrated by numerical examples in aquifer recharge and irrigation. The complex analytical problems arising from the hysteresis phenomenon in matrix potential, in situations where there is cyclic change in soil moisture content, are solved.

Vertikale vloei van grondvog, in omstandighede met watertoediening, dreinering en evapotranspirasie, word deur teorie ondersoek, waarin die dinamiese uitwerking van beide water en lug in aanmerking geneem word. Die hidro-pneumatiese eienskappe van twee modelgronde - 'n tynkorrelrige leem en 'n medium sand - word van wereldwye publikasies van wetenskaplike werkers afgelei. 'n Stelsel vergelykings vir grondkarakteristieke word beskryf, wat op enige grond wat op 'n voorgeskrewe wyse getoets is, toegepas kan word. Waar 'n gesofistikeerde laboratoriumdiens ontbreek, kan volledige gegewens vir 'n projekgrond, waarvoor twee spesifieke geredelik bepaalbare eienskappe bekend is, deur interpolasie van die van die modelgronde beraam word. 'n Ontledingsmetode waarin eindige elemente-berekenings aangewend word, word ontwikkel en die toepassing daarvan op numeriese voorbeelde in grondwateraanvulling en besproeiing gedemonstreer. Die ingewikkelde analitiese probleme wat voortspruit uit die histereseverskynsel in matrikspotensiaal, in omstandighede waar daar sikliese verandering in grondvog voorkom, word opgelos.

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/content/civeng1/32/3/EJC25098
1990-03-01
2016-12-04
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