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woodlands; 1986-2000, the order would become construction,
lawn, unused land, farmland, woodland, water. From 2 periods
of the changes, all the type of comprehensive dynamic content
increased. ©The state index: in 1972-1986, the state index of
construction land and farmland is closer to -1.00. It illustrated
the input speed was big than the output speed of this two
categories, internal two-way conversion have large area to turn
out very few but very unbalanced states. The state index of
Waters, woodland and undeveloped land was larger, were
0 .97,0.83 and 0.76. Note that the output speed of the three
kinds of categories is much larger than the input speed, size
reduction, in the "cuts" state; Grassland index for the state was
0.56, in a relatively unbalanced state, and the output speed was
bigger than input speed. 1986-2000, construction sites than the
output speed, extreme "expansion" state; Grassland index for
the state was -0.38, describing its input speed was faster than
output speed. Although lawn state of absolute index was small,
its input speed and output speed was large, the internal two-way
conversion obvious. In the State index greater than zero, the
state index of unused land was close to 1.00. Note the output
speed was bigger than input speed, many areas of the category
turned into other categories; the state index of waters is 0.46,
Note the output speed was bigger than input speed, which was
the relative imbalance in the state; the state index of woodland
and farmland were 0.16 and 0.18, closer to zero, the output
speed was slightly bigger than the input speed, but both the two
speeds were large, the internal two-way conversion Obviously,
which was based on the t high turn in and turn out the
circumstances of a state of equilibrium.
4. ANALYSIS OF LAND USE / COVER DRIVING
CHANGE FORCE IN THREE GORGES RESERVOIR
AREA AT NEARLY 30 YEARS
Land use / cover dynamically change of Three Gorges
reservoir area affected by the natural elements and human
factors at nearly 30 years. Policy, economic development,
population and other human factors play a leading role, while
climate, soil, topography and other natural elements were the
minor. Following is the lead role of human factors analysis.
4.1 policy-driven
Nearly 30 years, the land use / cover change of Three Gorges
reservoir area relatived with major national macro-policies.
1970s to the 1980s, large-scale irrigation and water
conservancy basically completed, and, since the 1950s and
1960s large clearing, So in this time suitable for cultivation in
the region have decreased, reducing land clearing, the farmland
area increased to slow down; After the 1980s countries have
implemented the upper reaches of the Yangtze River Water
Conservation Forest, upper reaches of the Yangtze River
Protection Project and the returning farmland to forest or
grassland Project, the cultivated land on steep slopes of Three
Gorges reservoir was part returned into woodland and grassland,
the destruct of woodland and grassland were in a certain degree
kept within limits; Meanwhile the mid-1990s after the progress
of the Three Gorges Project is the most tense five years, the
dam closure, the river closure, resettlement and urban relocation
to varying degrees, causing a decrease in the amount of
farmland.
4.2 Economic development driven
Three Gorges reservoir area is agricultural, 70's to the 80's as
well as destroyed forest and wasteland in order to develop
economic, But more appropriate or suitable for the cultivation
of land has been rare, so 70's to the 80's cultivated area
increasing trend towards relaxation; the late 1980s to the late
1990s,with the economic development, people farming
technology continues improved, also people began to
understand improve farming land is not the only means of
income, this means the use of farmland started increasing
diversification, factories and construction sites of the increase
was the main way. After the 1980s, particularly in 1997 after
the establishment of Chongqing municipality, with Three
Gorges reservoir area's rapid economic development, a large
number of high quality arable lands were occupied for
construction projects.
4.3 Population growth drives
The infection of population in the land use / cover change
performs the change of the increase or minus in population lead
to less food, clothing, shelter, transportation needs, population
has been growing was one of the major pressure in regional
sustainable development process, the conflict of high
population density and the lack of per capita cultivated land of
the Three Gorges reservoir area had become more prominent.
70's to the mid-80, population increased, but the amount of land
reclamation reduced, One can only cultivated at steep, but the
growth rate slowed significantly; 1980s to 2000, construction
sites have become increasing rapidly. The areas of cultivated
land were occupied continue increased. Nearly 30 years, the
population growth of reservoir was the important reason of the
construction increasing sustained, rapid.
5. RECOMMENDATION
Analyzing the land use / cover changing of Three Gorges
reservoir area from the mid-1970's to the end of last
century ,nearly 30 years , could found that the reservoir quality
of the ecological environment in urgent need of improvement.
However, the ecological environment restoration and
reconstruction has a long way to go, ensuring the upper reaches
of the Yangtze River land sustainable use of resources,
quickening the pace of the ecological environment restoration
and reconstruction, given the following recommendations:
(1) People should control the size of the population and
improve the quality of population, develop the economy of the
reservoir area. Three Gorges reservoir area had many people on
too little land, coupling with the construction of the Three
Gorges Project reservoir resettlement, Resettling
Area returning farmland to forest and grassland in the
implementation of the project, the obvious contradiction
between people and land, for all the factors above should
strictly control the size of the population; while the low quality
of the population have resulted in a lack of backward
technology, production methods primitive, the value of the
ecological environment of ignorance for the development of
chaos, extensive development, which should vigorously
improve the quality of the population; In addition to the
destruction of the ecological environment is largely caused by
poverty, only to solve the problem of poverty in order to restore
the ecological virtuous circle.
(2) Scientific planning of urban construction, strictly control
urban land. No one-sided pursuit of "high, and new and
comprehensive", resulting in the building of things on too much,
wasting a lot of land resources, This requirement will be strictly
in accordance with the relevant regulations, strictly control the
