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Mapping without the sun
Zhang, Jixian

Sun xiaoxia, Zhang jixian, Liu zhengjun
Chinese Academy of Surveying and Mapping, 16#,Beitaiping Road, Haidian District,Beijing, P.R.China, 100039-
(sunxx, zhangjx, zjliu)@casm.ac.cn
KEY WORDS: Three Gorges Reservoir Area, Land Use/Cover, Change, Analysis
The eco-environment in Three Gorges Reservoir Area was given a lot of attention due to the construction of the three gorges
hydropower station. The land use / cover change (LUCC) is one of the causes of ecological environment changes. In this paper, we
monitored the temporal-spatial landscape dynamic change from 1978 to 2005 in the Three Gorges Reservoir Area, based on the
multispectral scanner (MSS) and thematic mapper (TM) images of remote sensing of 1978, 1988, 1995, 2000 and 2005. Using the
monitoring data, we studied on the changes in several analysis indexes and techniques. The results indicated that: in the recent 30
years, cropland, woodland, grassland reduced continuously, at the same time, water body and built-up areas increased obviously on
the dynamic degree 1.918% in 2000-2005 period, and 2.894% in 1995-2000 period respectively; built-up area changed in the most
ratio and greatest speed which is at the cost of cropland, woodland, grassland.
The construction of three gorges hydropower station in China is
a large hydropower project. It will give great benefits to human,
such as preventing or controlling flood, generating electricity
and shipping, but at the same time, it will bring some effect to
the entironment, for example, land use change caused by
migration, water pollution and geological disaster brought by
rising water line(Q. Wang,2006). A lot of attention was paid to
entironment in Three Gorges Reservoir Area. The land use/
cover is an important part of the natural environment. LUCC is
one of the focuses in global entironment change research since
the new century and one of the important reasons of environment
changes(Liu J Y. and Shi P J.,1996; Ding F,2004; Zhao S
H ,2003). Here we used remote sensing data gathered between
the end of 1970S to 2005, to analysis the magnitude and pattern
of land use changes in Three Gorges Reservoir Area, and to
reveal the driving forces on the changes, which will be helpful
for the land resource protecting, utilizing, and management in
Three Gorges Reservoir Area.
Locating at latitude 29°16TSi-31 0 25'N and longitude 106°16'E -
111°28'E, central China, lower section of the upper reaches of
the Yangtze River, linking section of central China and
southwest China, the Three Gorges Reservoir Area consists of
submerged portions and resettlement involved in 23 counties
and cities. The total land area with 20 million people is about
58 000 km 2 in the whole reservoir area (Meng J J, 2005). This
region has many cross and deep valleys and rich water
resources. Most of the countries are poor and low productivity
level in the reservoir area (Z. Q. Huang, 2006).
With the image data in five special history times for the entire
Three Gorges Reservoir Area: MSS for 1977, Landsat-TM for
1988, 1995, 2000, and 2005, we monitored the land use change
between each two sequence periods by man-computer interactive
interpretation (Fig. 1). Based on one time period type map of land
use/cover, we obtained the land use/cover type maps of the rest
periods by using ARCGIS analysis techniques.
Figure 1. LUCC map in Three Gorges Reservoir Area from
1977 to 2005
We used classification system developed by the Chinese
Academy of Sciences, which is a hierarchical classification
system of 25 land-cover classes. In order to suit the convenience
of the study. The 25 classes of land cover were grouped further
into 6 aggregated classes of land cover - croplands, woodlands,
grasslands, water bodies, built-up areas and unused land (J. Y.
Liu, 2005).
Using the monitoring data we studied on the spatial-temporal
changes of land use for 5 different time in Three Gorges
Reservoir Area. In order to reveal the change synthetically and
accurately, we analysed the land use data in several analysis
indexes and techniques, including the area ratio of land use /
cover change, the dynamic degree of land type area change, and
land transformation matrix.
3.1 the Area Ratio of Land Use / Cover Change
The area ratio of land use / cover change refers to the proportion
of the changed area in the total areas. It is a simple and effective
way for weighing the relative quantity of area change for a land