| The Karst rocky desertification becomes the third ecological problem of our country after the desertification in northwestern area and the soil erosion in the loessial area. In this paper, on the base of the former achievements, according to the practical needs of the survey, monitoring, prevention and control of Karst rocky desertification in the northwestern area of our country, referring to the study experience of the desertification in northern area, by the study of Mabie-river watershed of Guizhou province, the features and impact of Karst rocky desertification were systematically summarized and the meaning of rocky desertification was disclosed; by use of the advanced 3S technique, the key technique and technical flow of remote sensing evaluation for Karst rocky desertification were put forward; the result of remote sensing evaluation and the other materials were spatial analyzed to discuss the forming mechanism of Karst rocky desertification in the watershed; the basic contents and scientific mode for the prevention and control of Karst rocky desertification were systematically summarized; the projection and suggestion of Karst rocky desertification in the Mabie-river watershed of Guizhou province were put forward. The following achievements were made in the study:1. The study of the basic theory of Karst rocky desertification:The conception of Karst rocky desertification was collated and stipulated again and the features and impact of Karst rocky desertification, the index system of the evaluation and standards of classification and level, the spectral feature and the characteristics of RS image were systematically summarized.2. The method and technology of remote sensing evaluation of Karst rocky desertification:1) The content and the system of method and technology which the method and technology of remote sensing evaluation(investigation and monitoring) of Karst rocky desertification were put forward; 2) the technology and method of RS information enhancing of Karst rocky desertification were summarized and combined with the study practice, the mending model of enhanced vegetation index(GEVI) were put forward; 3) by the contrast study, the thought, method and step of the extraction of RS information of Karst rocky desertification based on the statistics and classification of image featurewere discussed in detail; 4) 5 important quantity indexes evaluating the status and change of Karst rocky desertification; 5) the data of remote sensing evaluation of Karst rocky desertification of Mabie-river watershed in the year of 1987 and 1999 were got.3. The study of forming mechanism of Karst rocky desertification:There are complex reason and multiple influencing factors for Karst rocky desertification and they can be reduced to two factors: the human factor and the nature factor. On the basis of the systematic study of the mutual action and relationship between the factors and Karst rocky desertification, the genetic model of Karst rocky desertification was put forward.4. The study of the prevention and control of the Karst rocky desertification: The work of the prevention and control of Karst rocky desertification should bedone in three aspects-the ecology, the economy and the society to achieve the continual development of the ecology, the economy and the society of the Karst area, according to the practical condition of rocky desertification of the Karst area and surrounding the problem of rocky desertification. The basic content and the present scientific model to prevent and control the Karst rocky desertification were systematically discussed. Comb ined with the Karst ecosystem status in the Mabie-river watershed of Guizhou province, on the basis of reasonable developing and using the available resources in the watershed, complying with the natural law, depending on the advanced technological method and using the effective technique, the suggestion to prevent and control the Karst rocky desertification in the watershed were put forward.
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