| Based on changing data of land use and charts correlative to land use in Gansu province from 1997 to 2004, the land use structure of total province and fourteen cities in Gansu province were analyzed with the theory of Shannon entropy and fuzzy comprehensive assessment. The results showed as following:(1) With the development of economic and urbanization, contradiction between cultivated land and building land in Gansu province is quiet prominent during past eight years(from 1997 to 2004) and agricultural land areas had decreased while non-agricultural land areas had increased. Cultivated land and grassland areas reduced gradually; Woodland, garden plot, traffic land, residential and industrial land and unused land areas showed a increasing trend; Water area was basically steady.(2) The entropy value of land use structure had been rising in general since 1997, indicating decrease in orderliness of the land use system in this district; being compared with the total country, the East, Central and West of China (1999), the entropy value of Gansu province is far less than the national, East and Central of China, which was slightly higher than the West. It accounted for the entropy value of Gansu province was lower and its land use system maintained at a low level in an orderly state. In 2004, the entropy of land use structure varied significantly with the city. The entropy value in Pingliang city was the highest which was 1.6296; The smallest one was 0.7922 in Jiuquan city. The biggest was 0.8374 higher than the smallest.(3) Land use types whose areas showed increasing trend had a positive correlation with the entropy while those that had decreasing trend were adverse. The former were garden plot, woodland, traffic land, residential and industrial land and unused land respectively; the later were cultivated land, grassland and water respectively. Woodland and cultivated were main influential factors because of their largest relativity. Under the condition of no change in total land area and land use types, the land use structure entropy value was closely related to the land use types which changed greatly. However, it was less related to the land use types which changed litter or did not change. (4) On the whole, expect for high grade, land use structure grade of fourteen cities dispersed other five grades. Jiayuguan city was high, Dingxi city, Lanzhou city, Linxia canton, Longnan city, Pingliang city, Qingyang city and Tianshui city were middle, Baiyin city,Jinchang city,and Wuwei city were low, Jiuquan city and Zhangye city were lower, and then followed by Gannan canton.(5) The rational grade of land use structure in Gansu province took on well-regulated distribution. The cities which were assessed for the middle grad were mostly distributed in the central, eastern and Longnan area of Gansu province. However, the cities of low grade were mainly distributed in Hexi area and Gannan plateau. The results were closely related to the geographic location and partially coincide with five natural geographical climes. It had a great relationship with the weights were got in according to five natural geographical climes.(6) It had great advantages to assess land use structure rationality by fuzzy comprehensive assessment, but from the above concluded results, the judge of results still had certain deviations, for example Jiayuguan city. Not only according to resources but also land use status-quo, there was still a certain warp between the results and the actuality. It should be amended in terms of actual situation to ensure accurate results and the method should be perfected so that it can be widely used for land use structure assessment. |
PDF Full Text Request