Reference :

Appui methodologique a l'application d'une politique agricole : utilisation de la teledetection pour caracteriser les sols en vue de la gestion des ressources en eau de la Plaine Centrale de Thailande
Ph.D. Thesis (in French)
Year : 1996

Authors :

Pongsant Srijantr

Summary :

The objective of the present research is to find out the methodological image processing of raw data Landsat Thematic Mapper in order to determine the soil characteristics in the Central Plain of Thailand for water resources management prospective, and on behalf of testing the advantage of remote sensing in the framework of agricultural policy. We used a Landsat TM image of the Central region, taken at the end of the dry season (8th of  April 1991).

The numerical data of six bands Landsat TM were processed without the band TM6 and without the sampling of test areas by the principal component factors analysis (PCA) to study the soil moisture behaviors. The classification of surface stages had been carried out by the stepwish discriminant analysis with the seven bands of Landsat TM numerical raw data in order to classify the bare soils according to the soil textures and the soil moisture stages. The results of image processing were displayed in the form of classified images. We processed the PCA directly so as to obtain the first three linear components of a PCA which explained more than 95 % of variance.

The result images of the third component permitted to elaborate the soil moisture index. We can classify the various surface stages corresponding with the agro-ecological landscapes and the spectral graphics of radiometric reflectance values of the training areas. The obtained map of surface stages shows : kinds of crops cultivation, soil moisture stages, stages of crops growing, kinds of soil textures and different water surfaces. The classified images and the obtained maps may be used to determine the suitable areas of rice production, and to mark off the hydromorphic soils with high moisture retention. These images and information can contribute to improve soil maps, water resources management and soil management. They can also provide a better orientation and organization of new agricultural policy of Thai government.

Keywords :

Landsat Thematic Mapper / Central Plain of Thailand / Principal composant of factors analysis / Stepwise discriminant analysis / Cartography / States of surface / States of soils moisture / Soil texture / Irrigation / Behavior of soil humidity / Agricultural development / Agricultural policy