Spatial land use/land capability data for northeast Thailand a new challenge resource planning
C. Mongkolsawat, P. Thirangoon
Computer Centre, Khon Kaen University, Thailand
P. MacLean, A. Sowana
Dept. of Geography, McGill University, Canada
Abstract
Natural resource management in northeast Thailand has traditionally relied upon disparate sources of mapped information. The introduction of Geographic Information Systems (GIS) is changing the way spatial data are assembled and analyzed. The methods used to generate several types of map are described with examples and the potential applications of GIS-produced data are viewed in the context of typical natural resource management problems encountered in the Northeast. This new perspective sets the stage for planners and decision-makers.
Introduction
For many years, the economic development of Thailand was based on the exploitation of natural resources. As a result, extensive forest areas were encroached upon to increase agricultural productivity and to alleviate poverty. These natural resources are now being depleted with a number of serious consequences.
The sixth and Seventh National Economic and Social Development Plans were formulated to ensure the sustainable use of resources ( NESDB, 1987;1991). Sustainable development in this sense can be defined as development which ensures that the utilization of resources and the environment today does not damage prospects for their use by future generations. A key element in sustainable development is the linkage between conservation strat4egy and the optimal use of resources. The main trust of the NESDB Plans is to reconcile economic growth with resource conservation. In th4e past, the Plans have run into implementation problems specifically, difficulties in achieving coordination between organization and in the acquisition of Information.
Previous plans for the management and use of each natural resource or group of resources had been formulated separately, with the result that each plan had adverse effects upon the others, It has become evident, for example, that forest clearing in the Northeast has led to soil erosion, soil salinization, silting of waterbodies and flooding.
In order to reduce conflicts arising from the use, or abuse, of natural resources, systematic and integrated management plans are necessary. However, in order to implement such & systematic approach, know-how and practical skills in the methodology for integrating spatial data are required. Through the use of Geographic Information Systems (GIS), spatial information on natural resources can be systematically integrated. In addition, access to satellite image data along with competent interpretation, makes it possible to periodically update the spatial database. Land use/land capability mapping provides a good example. Land capability maps can constitute the spatial basis for sustainable resource development by ensuring land use which is suited to its capability for sustained economic production. In the past, land capability mapping for agriculture was carried out using traditional methods because there were no effective tools for merging information from diverse sources and of different scales. GIS technology and remote sensing present ways of overcoming these difficulties by enabling the simultaneous analysis of a number of variables in order to obtain criteria for optimal land use management.
This paper briefly describes the methodologies behind development of a natural resource spatial database for northeast Thailand through the use of GIS and remotely - sensed data and discusses some natural resource-related problems / issues which arise from these data. Completed land use and land capability maps,/ issues, which hitherto was not possible, should become a key element in formulating a plan for sustainable natural resource development.
Methodologies
Establishment and monitoring of spatial information
Land use maps combine static spatial data and dynamic spatial data. An example of static data is soil type; quaststatic data are roads, natural water courses and irrigation canals; dynamic data include changes in the extent of urban areas or of agricultural lands and changes in cropping patterns. Both types of data need to be established but only those which are subject to change over time ( In the short-term) need to be monitored through periodic updating from satellite imagery.
- Land use maps for the Northeast are produced from two primary sources of information:
- Landsat Thematic Mapper ™ Imagery, usually colour composite images of band 2, 3 and 4;
- Topographic maps from the Thal Royal Survey Department
The TM imagery is visually interpreted and a hierarchical interpretative scheme is devised which consists of the following steps:
- Directly - observable features such as water bodies, water channels, roads and urban areas are identified;
- Stratification of the target, based on colour, texture and pattern of the imagery is carried out and general features of the area being mapped are noted Sampling sites for field verification are also identified at this stage;
- Delineation of terrain is inferred from soil moisture conditions and vegetation cover through an analysis of the image elements lone, texture, pattern. Previously-defined generic terrain or landform types for the Northeast are adopted;
- Land use patterns are identified with particular reference to the terrain units identified in step (3) by incorporating additional features. These additional features include the spatial distribution of vegetation and soil moisture condition.
- Field surveys, to sample and verify relationships between terrain-soil vegetation, are carried out.
