Abstract:

In recent years,the social economic development of Erhai basin has been rapid,the process of urbanization has been accelerated,and the land use has been changed greatly.It is of great significance to study the long-term evolution of land use in the upper reaches of Erhai and to analyze its correlation with urbanization.Based on the remote sensing images of the upper reaches of Erhai in 1975,1985,1995,2005 and 2015,the land use patch information of each period was extracted and the land use transfer matrix was calculated.With the help of the dynamic model of land use,information entropy model and fractal model,the evolution of land use in the upper reaches of Erhai was quantitatively described and analyzed.The results show:(1) In the recent 40 years,the forest land,farmland and shrub-grassland in the upper reaches of Erhai were the dominant land.The area of the construction land continued to increase,and the overall level of land use is at a moderate level.(2) In terms of transfer change,the main features are the outflow of shrub-grassland and the transfer of construction land.The change of dynamic degree of single land use type is small,of which the dynamic change of construction land is obvious and the area is in an increasing trend.The land use system is characterized by the outflow of shrubs and the transfer of construction land.Single dynamic degree change is small,the dynamic degree of the construction is obvious and the area is increasing.(3) Information entropy,equilibrium and stability of land use patches in the upper reaches of Erhai also changed correspondingly during the period from 1975 to 2015.Analyzing the evolution of land use in the upper reaches of Erhai under the background of urbanization can provide an important guiding significance for enhancing the degree of land intensification,planning and managing land resources reasonably,formulating economic development policies scientifically,promoting land science and sustainable utilization,and accelerating the sustainable development of towns.

Key words: urbanization, land use dynamic degree, information entropy, fractal dimension, upper reaches of Erhai