Nakhon Ratchasima, Resources Atlas
C. Mongkolsawat and NRCT Sub-committee
on landuse, agriculture and forestry
Abstract
The objective of this study is to establish a spatial information system essential for : provincial resources planning. Nakhon Ratchasima, a province in Northeast Thailand was selected for this study. The province covers an area of about 12,778 sq.km. and is 260 kms from Bangkok. The spatial information needed was evaluated in terms of data availability as well as its reliability and compatibility. This includes an analysis of spatial data and its associated attributes as related to system structure. Methods for efficient data conversion have .been developed in consistent with the application scale. Spatial data was georeferenced, based on the Universal Transverse Mercator (UTM) used by the Royal Thai Survey Department. The spatial intonation established was organized by theme into layers. Those layers include administrative boundaries, infrastructure, land resources, digital terrain model, biological .resources and socio-economic aspects. The system developed provides a tool to search spatial information on resources of the province. The hardcopy outputs are also carried out to provide basic spatial information to publics. In addition, with the set of themes and conditions . Identified as related to the problem, spatial modeling can be performed accordingly.
I. Introduction
The 7th National Economic and Social Development plan (1992-1996) called for concommitance of natural resources management and sustainable economic growth (NESDB 1992). The plan describes development issues and problems faced by each natural resource. Natural resource and environmental concerns have been integrated into the regional development master plan. To formulate the plan, it is necessary to gather information in from best suited for management. The information to be collected should include spatial form and its associated attributes. A number of agencies in Thailand have a mandate in establishing information mostly in sectoral and specific form. With regarding spatial information, there exists paper maps with various scales and standards which have significant effect on the creation of spatial databases and ultimately on the integration and modeling. With advancement of technology (remote sensing and GIS), it is now possible to effectively establish spatial information and to formulate the integrated development plan. The National Research Council of 'Thailand (NRCT) then decided to make inventory of resource information
to support the formulation of the provincial resource management plans. The work was
assigned to a study team consisting of a number of government agencies concerned. This is to avoid duplication in setting up database and lowering the expenses. Moreover, the resultant information for each theme will be accordance with the system developed by the agency and provide consistent information to all of the users. In the same time, information can be updated and collected in form and manner suitable for modeling and integration.
2. Objectives
The objectives of this study are:
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to make inventory of resources of Nakhon Ratchasima Province using satellite data.
- to establish spatial resource database for management strategies
3. Study area
Nakhon Ratchasima (NR) Province is situated in the Northeastern part of Thailand (Figure 1 ). The annual rainfall in most part is less than 1000 m.m. Geologically, the area is formed by a thick sequence of Mesozoic sediments, the Khorat group, ranging in age form upper Triassic to Tertiary and Tertiary igneous rock. The Mesozoic sequence has been devided into 5 formations: Phra Wihan, Sao Khua, PhuPhan, Khok Kruat and Mahasarakham. The area is drained by a number of rivers from southwest direction into the Mun River. The central parts of the province are formed by flat to gently undulating alluvial plains with prominent raised margin to the southwest. The land ecosystem of the area can be divided into 2 main systems1:alluvial plains with gently undulating topography and 2) dissected erosion surface and mountain with variation in vegetation density. The former mostly consists of agricultural landuse and scattered remnant tree, the later includes protected forest area, recreation land and different kind of agricultural landuse.
Figure 1
4. Methodology
4.1 Evaluation of existing information
The objectives of this phase are
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To identify all existing databases produced by Governmental agencies its
characteristics, format and reliagility.
- To define data layer for establishing resource atlas and its associated attributes.
This evaluation included the identification of information need. In general, the
information need is defined in relation to the extent and potential of problems. The evaluation was carried out by collecting maps generated by each organization. The characteristics, forms and reliability of map were assessed and assembled. The reliability features of which was adopted in the establishment of spatial database. The classification scheme of themes follows .The organizations that have mandates. The basic features in the map e.g. georeference, contour lines and water resources are in accordance with either the RTSD topographic map or satelliteimagery whichever better .
4.2 Establishment of database
4.2.1 Data collection
The current informations available both in digital and paper map were assembled and
collected. Data for resource atlas could be acquired from the following sources:
- Existing maps
Topographic maps (1 :50,000) : Produced by the Royal Thai Survey Department is among the most important data as geo-referenced map, and basic spatial information.
Thematic maps:
A number of organizations in Thailand have produced thematic maps that can be used as input to the system. These include soil, geology, forest, watershed class quality, protected forest area, water resources and etc.
- Other information
Socio-economic data, e.g. census data from the National .Office forStatistics, national rural development data (NRD2C) can be defined and converted Into digital
spatial form.
Rainfall data from the Meteorological and Royal Irrigation Departments.
- Satellite data
Satellite data offer the most updated information suited to input into the system. Continued development in earth observation satellites has made it possible to collect a
wide variety of spatial data. Analysis of satellite data both analog and digital forms provided
information on current landuse, forest, water resource, landform and etc.
4.2.2 Data conversion
Much of data collected in the study area are available in paper maps which have
various accuracies and standards. Prior to input data in the system, preprocessing was
performed. The preprocessing included auditing, editing, mosaicing and recitifying. The
rectification and other preprocessing related to accuracy based on the topographic map. The updating informations were also undertaken using satellite data and field survey for landuse, .water resources, landform and some features concerned.
4.2.3 Data analysis
Data can be analyzed using a GIS for a number of functions: to establish and manage database ,and to perform modeling. Graphic database and its associated attributes are organized in theme layers. For each layer, the system uses vectors to create line drawing of geographic elements which are rasterized for analysis. The bridging between polygon and its associated database record was performed through Identification numbers. Each polygonal layer has its own database in which to store attributes. Each structure of attribute database permits the user to relate many data tables through a common item.
4.2.4 Spatial data output
A selected theme layer or combination of layers are plotted in either vector or raster form, including a related legend. Graphic and its associated attributes can be accessed from the system.
