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September 2003 |
Assessing land resource by using the GIS technique
Evaluating and grading land is made on the map with the scale of 1:50,000 and the level of adaptability is graded into 4 levels named as Very suitable (S1), Suitable (S2), Less suitable (S3) and Non suitable (N). Through interviews, data collection, examination, treatment and document perusal, we identified land characteristics as shown in Table 3 and Table 4. Based on definite criteria grading system, the data in Table 2 and Table 3 was classified and the landscape in the Nam Dong
district was divided into 196 land units. The land units were mapped and displayed on a specialized map of 1:50,000 scale. We applied information overlaying method to output the land unit map (Fig. 2).[5].
Selecting, Arranging Criteria and Mapping
Comprehensive information of natural resources and the environment is essential for sustainable planning and management. With the availability of satellite remote sensing data, information generation has acquired new dimensions and momentum. Worldwide, Geographical Information Systems have become a powerful organizational and analytical tool for resources planning and decision making. The GIS and satellite remote sensing technology have a wide scope of application, acting as an integrative framework to support the decision-making processes -- from generation, storage and display of thematic information to impact prediction and finally for their evaluation for planning and decision making. The use of Remote Sensing and GIS for land resources valuation constitutes an area of substantial interest and development in Vietnam. We use the Pascal and MapInfo softwares for drawing land unit map. A calculated program is written for assigning a value to land units as shown in Table 4 [Select DVD_ND.PAT].
The Result of Evaluating and Grading
In principle, the gradation is made from a combination of limited factor with the highest limited level to conclude land adaptability, since, any land use adaptability of per land unit depends on the lowest level of a particular factor.
Adaptability is identified by comparing land use demand of plant groups with each land unit quality. The result of land adaptability gradation in Nam Dong district shows:
- The appropriate area for two crops wet rice in 9,715 ha (in which 5,239 ha is suitable - S2 level; 4,476 ha is suitable - S3 level and there is no land with S1 level); 55,889 ha is not suitable (N).
- The area of short-term upland plant 9,767 ha is suitable (in which 5,376 ha is suitable with S2 level; 4,391 ha is suitable with S3 level and there is no land suitable with S1 level); 55,847 ha is not suitable (N).
- The appropriate area for long-term industrial trees and fruit trees is 8,367 ha (in which 3,496 ha is suitable with S2 level; 4,871 ha is suitable with S3 level and there is no land suitable with S1 level); 57,247 ha is not suitable (N).
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