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099		9	_aAIT Thesis no.NR-91-04
100	0		_aNokeo Ratanavong
245	1	0	_aAssessing potential salt-vulnerable areas through terrain analysis using remote sensing and GIS - the Vientiane Plain case study
260			_aBangkok : _bAsian Institute of Technology, _c1991
300			_a119 p.
490	1		_aThesis ; _vno. NR-91-04
500			_a A thesis submitted in partial fulfillment of the requirement for the Degree of Master of Science, School of Environment, Resources and Development
502			_aThesis (M.Sc.) - Asian Institute of Technology, 1991
520			_aSalt-affected areas in the Vientiane Plain have been created by a salinization process operating primarily via saline groundwater. They are characterized by the occurrence of highly saline barren patches with few halophiles, surrounded by apparently less or non - saline areas. The saline patches show an uneven distribution within t he topographically low-lying terrains. Salt- affected areas can be observed o n remotely-sensed images with the help of secondary indicators and verified by ground truth surveys. Besides soils affected by salt at present, potential salt-vulnerable soils must also be distinguished. Soils considered potentially salt-vulnerable are those that are not, or only to a mi n o r degree, saline at present, but with environmental changes could become salt-affected. Potential salinity classes are based on a combination of factors rather than t he presence of surface salt occurences only. Highly salt- vulnerable areas are located within low- lying areas with shallow watertables, of saline quality, underlain by the Tha Ngone salt-bearing Formation, with fine textured soils a nd inefficient drainage, and covered with sparse vegetation. A sandy soil is rarely a salt- affected soil because t he soil is well drained a nd the salt can be leached out easily. A clayey soil is likely to be salt-affected if t he salts are introduced by surface water. A loamy soil is likely to be affected if t he ground water is saline because the capillary rise is higher than in other soils. Paddy fields may favor the development of salinization. These fields need poor drainage conditions for rice cultivation, which is one of the factors favoring salinization if combined with other environmental factors. Potential salt-vulnerable areas could be assessed at a reconnaissance level by integrating and analyzing the necessary environmental data and information. Further field and analytical data are needed for more adequate modeling.
650		0	_aSalinization _xVientiane Plain
650		0	_aSalinization _xRemote sensing
650		0	_aGIS (Computer program)
700	1		_aLukens, John E., _eChairperson
700	0		_aPrinya Nutalaya, _eExamination Committee
700	1		_aMotti, Etienne, _eExamination Committee
710	2		_aSIDA ( Swedish International Development Agency),
810	2		_aAsian Institute of Technology. _tThesis ; _vno. NR-91-04
856			_3Full-Text _uhttp://203.159.5.9/ait-thesis/detail.php?q=B17692
907			_a.b10098331 _bmnait _cs
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