LAND COVER CHANGE MONITORING OF TYPICAL FUNCTIONAL COMMUNITIES OF SICHUAN PROVINCE BASED ON ZY-3 DATA

According to the function, land space types are divided into key development areas, restricted development areas and forbidden development areas in Sichuan Province. This paper monitors and analyses the changes of land cover in different typical functional areas from 2010 to 2017, which based on ZY-3 high-score images data and combined with statistical yearbook and thematic data of Sichuan Province. The results show that: The land cover types of typical key development zones are mainly composed of cultivated land, forest land, garden land, and housing construction land, which accounts for the total area of land cover 87%. The land cover types of typical restricted development zone mainly consists of forest land and grassland, which occupy 97.71% of the total area of the surface coverage. The land cover types of the typical prohibition development zone mainly consist of forest land, grassland, desert and bared earth, which accounts for the total area of land cover 99.31%. * Corresponding author


INTRODUCTION
Land space in Sichuan province is divided into key development zones, restricted development zone and prohibition development zone (Liu, 2016a andFan, 2015a).The main functional areas is an important area protecting natural and cultural resources in Sichuan province, is important soil and water conservation area and important drinking water source protection area.Under the premise of strict protection of the ecological environment, rational develop advantages and characteristics of tourism resources, develop eco-tourism industry, control strictly the interference of human factors on the natural ecology, prohibit the development activities which does not comply with the main functional areas targeted, guide population transfer gradual and orderly, reach the achievement of pollutant "zero emissions", improve environmental quality, enhance capacity for sustainable development (Pei, 2010a).This paper takes the main functional area of Sichuan Province as the research object, based on the ZY-3 image, combined with statistical yearbook and special data, to monitor the changes of surface coverage of key ecological function areas in Sichuan province, which is very important significance for us to learn about the current situation of regional ecological civilization, maintain regional ecological security, prompt the relationship between environment and economic development policies and promote the construction of the main functional area of the national construction pilot demonstration (Wang et al., 2017a).

RESEARCH AREA OVERVIEW
Key development zones include 89 counties (cities, districts) of the 19 cities (districts) in Chengdu plain, the southern of Sichuan, and the northeast of Sichuan, and the western of Sichuan, as well as the connected 50 punctate development towns (Zhang et al., 2010a).Among them, Chengdu plain is a national level key development zone, which main function positioning is the important economic center in the West, the national comprehensive transportation hub, the business logistics center and the financial center, and a base of advanced manufacturing industry, scientific technological innovation industrial base and agricultural products processing base.
Restricted development zone includes ecological function areas and agricultural products producing areas.Among them, the national level key ecological function areas includes Ruoergai prairie wetland ecological function areas, Sichuan-yunnan forest biodiversity and ecological function areas, qinba biodiversity ecological function areas and others, a total of 25 regions.There is no doubt that such wide coverage is of rich biodiversity.
Prohibition development zone is an important protection area of natural and cultural resources, is also a key ecological function area needing special protection, which prohibits any other industrialization and urbanization development, including national level and provincial level two parts (Wang et al., 2017a andSun et al., 2015a).The national prohibition development zone include national nature reserve, world cultural and natural heritage, national scenic area, national forest park, national important wetlands, national wetland park and national geological park; The provincial prohibition development zone include provincial and lower levels of various types of natural and cultural resource protection area, important drinking water sources, and other prohibited development area which to be determined by provincial People's Government (Nie et al., 2010a andLi et al., 2013).

Method
Based on the ZY-3 orthographic image, surface coverage data production is performed by means of full manual acquisition or human-computer interaction interpretation.The results showed that: The type of surface cover varies greatly；The largest change in arable land occurs, and the main flow is arable land to the garden, house construction land, artificial excavation sites and structures.

Figure
Figure 1.Regional location 3. DATA AND METHOD 3.1 Data Source ZY-3 high resolution remote sensing image data are derived from the first national survey of national geographical conditions, DEM, DOM, 1:5 million scale, the administrative division and other data are derived from the Sichuan geo information bureau.

Table 1 .
The surface cover type of key development zonesThe monitoring results show that: the surface cover types of typical key development zones are mainly composed of cultivated land, forest land, garden land, and housing construction land, which accounts for the total area of land cover 87%.The area of cultivated land and forest land reduced significantly from 2010 to 2017, and the area of garden, grassland, housing construction land and construction land increase greatly.

Table 3 .
The land cover type of prohibition development zone The cover types of the typical important prohibition development zone mainly consist of forest land, grassland, desert and bared earth, which accounts for the total area of land cover 99.31%.From 2010 to 2017, the area of cultivated land, grassland, desert and bared earth decreased greatly, but the area of forest land, housing construction land and structure were increased greatly.Land cover transfer matrix is mainly used to show the mutual transformation between land cover types.The statistics of land cover transfer are shown in the following table:

Table 4 .
The land cover transition matrix of key development zones

Table 5 .
The land cover transition matrix of restricted development zone