Nokeo Ratanavong creator Lukens, John E. Chairperson Prinya Nutalaya Examination Committee Motti, Etienne Examination Committee SIDA ( Swedish International Development Agency) text th Bangkok Asian Institute of Technology 1991 monographic eng

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119 p. Salt-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. A thesis submitted in partial fulfillment of the requirement for the Degree of Master of Science, School of Environment, Resources and Development Thesis (M.Sc.) - Asian Institute of Technology, 1991 Salinization Vientiane Plain Salinization Remote sensing GIS (Computer program) Asian Institute of Technology. http://203.159.5.9/ait-thesis/detail.php?q=B17692 http://203.159.5.9/ait-thesis/detail.php?q=B17692 060798 20260817163438.0