Spatio-temporal Changes Of Landscape Patterns And Water-toward Expansion Of Built-up Urban Areas In Mengzi Basin,Southeast Yunnan

Yunnan province is a large mountainous province in China,and the mountainous area(including plateaus)account for about 94% of the total land area in the province.Various basins have become the center of polities,economy and culture.They have also become agricultural production base throughout the province and the region with dense population,densely populated areas and major traffic lines.This study took Mengzi Basin for example,and used the Landsat images of 1992,2000,2009 and 2017,try to analyze the area of land use types in the four periods.We used various methods to analyze the spatio-temporal changes of landscape pattern and built-up areas in Mengzi Basin.The results showed that,(1)From 1992 to 2017,the area of wetlands and cultivated land in the Mengzi Basin decreased;the area of construction land and woodland increased;the bare land increased at first beginning and then decreased;the area of grassland is basically unchanged.Among them,the proportion of wetland decreased from 10.72% to 7.41%;the proportion of cultivated decreased from53.66% to 33.01%;the proportion of construction land increased from 10.92% to25.84%;woodland increased from 10.60% to 22.86%;and the grassland accounts for about 10.50%.(2)There were 9949.78 ha,19472.75 ha,16669.71 ha land transferred in the three stages of 1992-2000,2000-2009,2009-2017,respectively.The cultivated land had the largest output areas in all three stages,and the output rates were 40.73%,65.64% and 44.90% respectively,which were transferred to construction land,woodland and grassland.And the cultivated land,woodland and construction land had the largest input area respectively in the three stages.It indicated that the development and utilization of cultivated land in the basin was frequent.(3)The human activities in the Mengzi Basin greatly interfered with the landscape pattern,and the degree of landscape fragmentation and heterogeneity both showed an upward trend,and the type of landscapes developed towards diversification.The change of landscape pattern was influenced by many factors,such as topography,climate,population,social economy and policies.(4)From 1992 to 2017,the total area of built-up areas in the Mengzi Basin has increased year by year.In the five main regions,Wenlan Town is the location of the municipal government,it had the fastest growing area and the greatest expansion strength,and followed by the town of Xin'ansuo.The growth rate of Yunguopu Town,Datun Town and Shadian Town were relatively slow.(5)Therefore,we considered that urbanization had a profound impact on the basin's landscape pattern.Under the background of regional development policy,population and per capita GDP had become the major driving forces of landscape pattern changes,but terrain was the major constraint factor.These factors together prompted the built-up areas expand towards water area.