GISdevelopment.net ---> AARS ---> ACRS 1992 ---> Land Use 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. Presented at the 13th Asian Conference on Remote Sensing, Ulaanbaator, Mongolia, October 7-11, 1992 A land use map is then produced using the GIS. The boundaries around map units are digitized, producing a factorized land use layer. This is then resterized to form polygonal covers. Relevant attribute data on land use type is then attached to each polygon. Hardcopy maps are then produced and the system calculates the total area occupied by each land use class. An example of a final land use map is shown in Figure 1 and the attached attribute data is given in Table 1. Figure 1. A Section of Land Use Map Table. Land use attribute data for map sheet 5843. Land capability mapping is a more elaborate GIS operation which integrates land use data with geomorphic characteristics of the landscape derived from topographic maps. The topographic maps are digitized to produce a digital elevation model (DEM) which, in turn, yields elevation and slope maps. A soil map of the area is then transferred to the same geographic coordinates and digitized. In all, there are five map layers which are used to generate the land capability map. An overlay operation "compresses" these five thematic maps and the resultant map can then be queried for data on the occurrence of specified sets of conditions, e.g., the extent of areas of specified slope gradient, soil depth and type, vegetation type and existing land use. Any of a number of additional variables can be added or deleted from the analysis such as the spatial distribution of mean annual rainfall or its variability and ground water quality. At present, however, the land capability maps which have been developed for widespread areas in the Northeast comparise the five themes noted above. This land capability classification system is primarlly concerned with crop suitability, agronomic constraints and the risk of soil erosion. It is not a single purpose classification made with regard to land is shown in Figure 2. The conditions which define each of the 14 capability classes shown by the map are given in Table 2. System, i.e., erosion risk, agronomic limitation and suitability, by class. Figure 2. A Section of Land use Map Problems/Issues Analyses of the type described here open new avenues of inquiry into old problems. One scenario in the Northeast is very illustrative of the potential of this new investigative tool, that of population resettlement. Under the Greening of the Northeast Project, which was initiated in 1990 by a host of government agencies with the dual objectives of relocating rural peoples in the Northeast and conserving natural resources, some 4.8 million ral (768,00 ha) of land located in 352 sites across the region and which are classed as Degraded Forest are to serve as resettlement areas for peoples currently living in Conservation Forest, i.e., forest areas designated by the Royal Forest Department exclusively for conservation Approximately 250,000 families, or the equivalent of 2500 villages are affected by the plan. Each new village is to be assigned 150 rai (24ha) for infrastructure development ( e.g. roads, utilities public lands ) and 300 rai ( 48 ha ) of community forest ( e.g., where the villagers serve as custodians of the forest resources while deriving some sustenance from them). There is a six-point rationale behind the resettlement dossier of the Greeting of the Northeast ( Wiwatwanich, 1991): More than 1,000,000 poor people in the Northeast currently live in Conservation Forest; There are numerous conflicts between land occupant; There is widespread destruction of watershed resources; Agricultural productivity in the area is low because the government will not provide relief to lands under illegal occupancy; There is locally extreme poverty in the Northeast; 20% of the population of northeast Thailand lives on Conservation Forest lands. These factors have obvious economic, social and political implications both at the local and national levels. The first contribution which an integrated spatial database can provide in this context is verification of the extent of the Conservation Forest encroachment problem. Up-to-date satellite imagery (TM FCC of band 2,3, and 4) coupled with topographic maps and data on the location of designated forest reserves is a simple Table 2. Land capability attribute combinations for Map 5543 II, for the five attributes: elevation, terrain slope, soil and land cover. Table 3: Land capability class, critical criteria and area occupied by each class. GIS land use application which can keep track of rates of forest encroachment. To date, the rates of encroachment upon total forest resources between 1987 and 1990 in seven provinces ( Changwat ) in the northeast have been compiled. Second, land capability mapping has shown that resettlement has taken place in areas which are less than optimal for agriculture. By virtue of the quantity of data which they present, land capability maps have the potential to identity sites with better agricultural potential. For example, sites in designated areas of Economic Forest, which includes plantation, agroforestry and mixed farming areas and community forests, can be identified and located at optimal distances from the sites to be evacuated, Figure 3. provides an example of the type of sensitivity mapping which could be adapted to these problems. The use of GIS for automated site selection is not a new concept and can be applied in other contexts in the Northeast, such as planning new settlements outside of areas susceptible to seasonal flooding. In the Tung Kula Ronghal areas, Some settlements have ploughed agricultural lands into raised areas to support housing. These types of wasteful land uses could be minimized through zoning based on GIS data. Figure 3. A part of environmental sensitivity map Conclusions Notwithstanding the utility of the methods and data described in this paper, it is clear that these are not the only factors involved in these issues. There are often questions of a strong socio-political or ethical nature attached to the phenomena which are detected and mapped by remote sensing and GIS, These necessitate the intervention of the required, are taken. The practitioners of remote sensing and GIS have no role to play at this level of decision-making. The considerations do not, however, detract from the important contribution which integrated spatial data can make to natural resource management decision-making in northeast Thailand. The perspective offered by this technology is only now becoming available in an operational context and shows much promise. References Mongkolsawat. C, Thirangoon. P., Pongsal. S and Sowana. A. 1991 Land Capability Mapping with Landsat Data and GIS: A Methodological Study for Northeast Thailand, In: Proceedings for he 12th Asian Conference on Remote Sensing Oct,. 30- Nov. 5 1991 Singapore. NESDB, 1987. The Sixth National Economic and Social Development Plan ( 1987-1991). National Economic and Social Development Board, Office of the Prime Minister, Bangkok, Thailand. 373 pp. NESDB, 1991. The Seventh National Economic and Social Development Plan ( 1987-1991). In thal). National Economic and Social Development Board, Office of the Prime Minister , Bangkok, Thailand. 252 pp. Wiwatwanich, W., 1991. Relocation Project in The northeast. In: Proceedings of the Seminar on Applications of Remote Sensing and GIS for Natural Resources and Environment under the 7th National Economic and Social Development Plan (In Thai). KKU, Kasetsaert, NRCT and Royal Forest Department, July.