The purpose of this study is to produce a landslide susceptibility map for the lower Mae Chaem watershed, northern Thailand using a Geographic Information System (GIS) and remotely sensed images. For this purpose, past landslide locations were identified from satellite images and aerial photographs accompanied by the field surveys to create a landslide inventory map. Ten landslide-inducing factors were used in the susceptibility analysis: elevation, slope angle, slope aspect, lithology, distance from lineament, distance from drainage, precipitation, soil texture, land use/land cover (LULC), and NDVI. The first eight factors were prepared from their associated database while LULC and NDVI maps were generated from Landsat-5 TM images. Landslide susceptibility was analyzed and mapped using the frequency ratio (FR) model that determines the level of correlation between locations of past landslides and the chosen factors and describes it in terms of frequency ratio index. Finally, the output map was validated using the area under the curve (AUC) method where the success rate of 80.06% and the prediction rate of 84.82% were achieved. The obtained map can be used to reduce landslide hazard and assist with proper planning of LULC in the future.

This study evaluated environmental factors affecting on sediment and nutrient loads in Lam Takong River basin, Northeastern region of Thailand, using the results of SWAT (Soil and Water Assessment Tool) model. The simulation from 2007-2009 showed that mean annual sediment, NO3-N and TP at the outlet were 8.134 t/ha, 0.879 kg/ha and 1.213 kg/ha, respectively. Seven factors were significantly related to soil erosion including slope, elevation, agriculture, wetland, deciduous forest, evergreen forest and orchard. In addition, two factors were significantly related to NO3-N including surface runoff and urban area. Finally, four factors were significantly related to TP including surface runoff, elevation, deciduous forest and orchard. Modification of these factors can reduce sediment and nutrient loads in this basin.

ABSTRACT:The main objective of this study is to evaluate the land suitability for cultivation of some economically important energy crops, which are sugarcane and cassava, in Kanchanaburi province, Thailand. To achieve this goal, multicriteria decision making (MCDM) integrated with the 1976 FAO framework for crop plantation was used to assess suitable areas for growing these crops. Several biological and economical factors involved in the analysis were selected based on the FAO framework and experts' opinions. Their data were kept, displayed, and used as individual and combined GIS layers. Each factor received a weight and a score which represented its relative importance in the suitability evaluation by using the analytical-hierarchical process method which is one of the widely used MCDM techniques. A land suitability map for each crop selected was produced based on the linear combination of weight and rating score of each factor involved and classified into 4 suitability classes according to the FAO standard. The proportion of the area highly suitable or moderately suitable for cultivation of sugarcane was 52%, and for cultivation of cassava, 45%. Only a small percentage of the area was not suitable. Typically, the most suitable areas for both crops were located in the eastern and lower part of the province having highly fertile soil and abundant water resources available therein. It was also found that most parts of the suitable area of both crops were located in the existing agricultural land (but being used for other crops/plants).