| The variation characteristics on slope spectrum and information entropy of cultivated land in the crossing zone of Tibetan-Qiang settlement |
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| DOI：10.7606/j.issn.1000-7601.2018.04.34 |
| Key Words: slope spectrum information entropy cultivated land Tibetan-Qiang settlement crossing zone |
| Author Name | Affiliation | | ZHANG Shu-jie | School of Environment and Resource, Southwest University of Science and Technology, Mianyang, Sichuan 621010, China | | GUO Ya-lin | School of Environment and Resource, Southwest University of Science and Technology, Mianyang, Sichuan 621010, China | | FAN Min | School of Environment and Resource, Southwest University of Science and Technology, Mianyang, Sichuan 621010, China | | WANG Qing | School of Environment and Resource, Southwest University of Science and Technology, Mianyang, Sichuan 621010, China |
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| Abstract: |
| The study takes the Tibetan-Qiang settlement as the research unit and extracts the local spatial information of the cultivated land of the zone in 1999, 2009 and 2014, and quantifies the slope differentiation characteristics of the cultivated lands through geo-info spectrum and information entropy technologies to clarify the reasonability of cultivated land utilization system in the Tibetan-Qiang crossing zone across the upper reaches of Min River. The results reveal that: (1) during the three study periods (1999~2014), the total amount of cultivated land decreased significantly and the slope spectrum curves of cultivated land descended significantly when the slope is over than or equal to 24°, meanwhile the cultivation rate of steep cultivated slope land also has dropped dramatically from 83.67% in 1999 to 71.97% in 2009 and to 55.03% in 2014. However, the spectrum curves in the range of the slope less than or equal to 14° showed an ascending variation trend and the rate of gentle slope cultivation is 16.33%, 28.03% and 44.97% for 1999,2009 and 2014, respectively, indicating that the distribution of cultivated land moved gradually toward the regions with gentle cultivated slope land and it will gradually become the local concentrated distribution area of crops. (2) Under the influences of the implementation of the Grain for Green Project, the occurrence of 5·12 earthquake and the secondary geological hazards derived from the earthquake, the information entropy of slope spectrum for cultivated land increased from 1.253 in 1999 to 1.515 in 2009, and further reached 1.707 in 2014, showing an increasing trend in the Tibetan-Qiang settlement crossing zone. Therefore, the gap between area percentage of gentle cultivated slope land and area percentage of steep cultivated slope land has narrowed. It suggests that the allocation of cultivated lands in different hierarchical slope sections tends to be uniform, which is conducive to local conservation of water and soil. The research results can provide the basis for the reasonable planning, utilization and scientific management of cultivated lands in the crossing zone of Tibetan-Qiang settlement across the Upper Reaches of Min River. |
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