| After the collection of land sat ETM+ image data and the precision as 1:50000 image, this paper takes it as the main source of information. After the preliminary remote sensing interpretation of rocky desertification in the study area, the geological interpretation of remote sensing was divided into middle area(Ⅱ), poor area(Ⅲ) and generated the rocky desertification distribution diagram of remote sensing interpretation. Combined with my participation in the China geological survey issued to Chengdu University of Technology in April 2013 by "Guizhou 1:50000 Xiangshui, Baina,Dafang, Linquan, Niuchangpo, Shawo geological investigation of karst mountain region" of the project of the field survey data, the map the rocky desertification distribution diagram in the study area, draw diagram of the distribution of rocky desertification and classified rocky desertification rated into six units: ①non-rocky desertification area;②no rocky desertification area;③slight rocky desertification area;④minor rocky desertification area;⑤moderate rocky desertification area;⑥Severe rocky desertification area. Compared with rocky desertification diagram of remote sensing interpretation, it can be seen that it can be seen that the main development area of the distribution of rocky desertification is in the central region(Dafang and Linquan). While in brief rocky desertification remote sensing map, it is in the south(Niuchangpo and Shawo). The distribution of rocky desertification of the two pictures shows good agreement of one another. Based on the actual survey results and the characteristic of the distribution of rocky desertification, three aspects consisting of geological factors, climate factors and human factors are used in this paper to were used to analyze causes of rocky desertification in the study area. Among these, geological factors include landform, lithology, structural factor, slope factor; Climatic factors includes the rainfall factor, vegetation factor; The man-made factors includes unreasonable development, unreasonable farming and over plantations. Finally, this paper discusses the formation mechanism of rocky desertification. Through the research, the following understandings were achieved:1.According to the current situation of the study rocky desertification area, the non-rocky desertification areas covers an area of 2395.49km2 which is about 87.24% of the whole study area; the potential rocky desertification areas covers an area of 91.41km2 which is about 3.32% of the whole study area; the slight rocky desertification areas covers an area of 155.9km2 which is about 5.68% of the whole study area; the moderate rocky desertification areas covers an area of 76.55km2 which is about 2.79% of the whole study area; the serious rocky desertification areas covers an area of 26.65km2 which is about 0.97% of the whole study area; and the rocky desertification areas covers an area of 350.51km2 which is about 12.74% of the whole study area. After comparing with the remote sensing interpretation of rocky desertification, as well as comparing the current development degree of rocky desertification with the one 12 years ago, it’s concluded that the rocky desertification has been effectively controlled and the rocky desertification area has dropped to 350.51km2 from 2749km2, especially in the Niuchangpo and Shawo where the rocky desertification degree has been improved apparently, which is because the efforts that Guizhou province payed to control the rocky desertification gained remarkable results.2. The effects of landscape on rocky desertification: mainly play an instruction role, through on-the-spot reconnaissance found that its physiognomy types in the area with deep landscape region landform areas are more likely to happen than shallow cut rocky desertification. In peak cluster and hoodoo depression incidence, the rocky desertification landscape is easy to be formed, which are moderate-severe area. Relatively flat terrain basin, hilly areas are non-rocky and slight rocky desertification area.3. Lithology effects of rocky desertification: it mainly due to lithologic difference weathering, also the essence reason of rocky desertification formation, the quality of a material is pure, bedding face continuous carbonate rocks in the area is the main development of rocky desertification area, with limestone and among them continuously exposed to severe main area of the development of rocky desertification degree of rocky desertification in limestone regions are significantly higher than dolomite region; Carbonate rocks of clastic rocks of rocky desertification probability is small; Clastic rock area is non-rocky desertification area.4. The effects of structure on rocky desertification: mainly lies in the control of tectonic units of rocky desertification development scale, the distribution, trend, etc. Southwest China new tectonic movement is mainly characterized by periodic rise, cause early planation surface after strong cutting, transformation, form the plateau on the background of deep ravines; Rugged broken plateau landform and steep terrain, provides a potential energy base of soil and water loss and soil erosion. As a result, new tectonic stage uplift is one of the geological factors that affect rocky desertification.5. The effects of gradient on rocky desertification: different degree of slope for the development of rocky desertification played an important decisive role. Ground slope in the area of 0 ° ~ 5 °, rocky desertification occurring probability is small, rocky desertification in the study area are mainly in the slope for the regional development of 5 ° ~ 20 °, high slope region especially in the area of 10 ° above the main development in moderate, severe rocky desertification, and rocky desertification mainly severe rocky desertification, slope in more than 30 ° area while within the area proportion of small and relatively scattered, rocky desertification, but occurs mainly severe rocky desertification.6. Climate factors on the rocky desertification in the study area: the influence of rainfall on soil erosion provides a dynamic conditions, the karst mountainous region under the heavy rain washed the basic do not leave the thin layer of surface layer soil, thus formed the bedrock exposed rocky desertification landscape. Vegetation and rocky desertification is a dynamic relationship, that is, the higher vegetation coverage, the lower the degree of rocky desertification.7. The influences of human factors on rocky desertification: s The serious development area of rocky desertification mainly concentrated in the areas of densely populated and economic backward as well as having the prominent contradiction between human and land. Especially in nowadays, human activities to a great extent, affect the growth of the rocky desertification degree.8. Analysis of rocky desertification formation: the study area belongs to shallow cover or bare karst mountainous area, where vegetation degradation and human unreasonable use of land, make the surface soil further eroded. Moreover, the earth’s surface loses its soil further, causing large areas of exposed bedrock and accelerating the weathering rate of carbonate rock, thus the rocky desertification forms. The different regional geomorphic types in the study area caused by neotectonics formed different layers of the slope transition interface. On the topography and geomorphology, group composition of the carbonate formation such as peak cluster, high mountains, low vegetation coverage area are rocky desertification areas, and under the unreasonable human interference, the environment deteriorates further. Factors affecting the formation of rocky desertification include natural factors and human factors. Natural factors is the precondition of the occurrence and development of rocky desertification., while human factor is the dominant factor. |
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