Landsat -5 Tm Data Analysis and Slope Mapping
by GIS and Computer Technique, Showing Topographic Gradient of Li
and Thung Hua Chang Districts, Lamphun Province, Thailand
Manasan Kantontong
Geographician (cartographer)
Forest Resource Analysis Division, Forest Research Office
Royal Forest Department, Bangkok, Bangkok 10900, Thailand.
Abstract
This study is to identify and then employ forest types, natural distribution of flora, forest land-use patterns as factors to produce forest map, forest land-use and topologically slope map within Li and Thung Hua chang Districts of lamphun Province. The study area is approximately 1,406,362.50 rais (2,250.18 square kilometers). Landsat -5 TM imageries (FCC : FCC : Falsi Color composite imageries) have been visually interpreted to identify different land-use land-use patterns comparing with black-and -white aerial photographs which have also been interpreted to identify different patterns of forest types, and data from toplogical maps to be further incorporated in details for the study. Then, check and correct the interpreative outcomes with ground data. The study has indentified data into 9 different categories as paddy field, agricultural cropland, mixed species orchared and natural stand, forest plantation, degraded and cleared forestlands, dry dipterocarps forest, mixed deciduous forest, hill evergreen forest and water catchment area. Enter data into computer system and then analyzing spatial data to be utilized later on for the production of the study map. Utilize thecomputerized SPANS programme version 6.0 which has been operated on OS/2 system in Windows 95 to interpret and identify the data, then save and bring them up to organize spatial database and finally create topological slope map of the study area. From the overlay analysis of different layers of data, especially the forest types layer and the 1997 land-use pattern layer (which has been visually analyzed) which have been overlaid upon the topologically slope layer, the study has successfully fixed forested and non-forested areas onto the topological different sloping positions of the study area. The study outcomes usefully help create understandings of the nature of topological slopes in Li and Thung Hua change Districts in relationships with natural distribution of flora. Most forested areas lie upon high slopes and possess few agricultural potentiality. These high slopes cause severe landslides and illegal land denudation. So, they should be preserved as forested areas and should be reforested urgently within cleared and degraded patches where water catchment ability of the land is potentially high.
1.Introduction
Presently, large areas of Li and Thung Hua Chang forests in Lamphun province have been extensively cut, partly occupied and agriculturally developed by local people. In order to follow -up and limit the mentioned illegal occupation, Royal Forest Department (RFD) should possess updated database and a mapping system of Li and Thung hua Chang Districts. Such databases should be used to plan the budget - saving law enforcement and land surveying efforts. Economically GIS, computerized techniques, and topologically slope maps are effectively employed to monitor the changing data of Li and Thung Hua change forest resources. By these high techniques, the forest resources conservation can be sustainably maintained.
2. Objectives
2.1 to assess the existing forest land in the study areas (Li and Thung Hua Chang Districts) by employing Landsat - 5 TM imageries, data interpreted from aerial photographs and ground check.
2.2 to produce forest map and forest land -use of Li and Thung Hua Chang Districts overlaying by slope map.
2.3 To test the functional feasibilities and efficiency of the PC software SPANS package version 6.0 in terms of its processing and overlay techniques.
2.4 To generate the topological slope map for RFD use.
