Geoscience Reference
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located in the Karst Rock Hill areas take up more than 30% of the administrative areas. RD
in Guangxi has become a main cause of disaster and poverty, which constrains the regional
economic and social development.
In China, studies on RD have been paid a lot of attention by many researchers since 1980s.
Remote sensing and GIS technique always plays an important role in this research field.
Landsat TM image, topographic map, geological map and GPS in-situ data were applied to
produce a RD classification distribution map in Du'an Yao Autonomous County of Guangxi
(Jiang et al., 2004) and to monitor the RD area in Wenshan County of Yunnan Province (Wu,
2009). ASTER image was used to study the situation of RD and its change trend from 2000 to
2005 in the Karst area of Guizhou Province (Chen et al., 2007). In addition, NOAA/AVHRR
and MODIS data were used to monitor land desertification (Liu et al., 2007), in which
humidity index was used to define the desertification area and two suitable classification
methods were established to monitor the desertification dynamics from 1995 to 2001.
MODIS data was first applied in the western Guangxi of southwest China to monitor the
rocky desertification with the change of land cover types from 2000 to 2010. The study area
covers 30 counties in the western Guangxi. The study tends to give some suggestions to the
local governments on the reconstruction of the rocky desertification and defense on new
desertification in order to sustain the balance of the whole eco-geo-environment in western
Guangxi of southwest China in the near future.
2. Study area
The study area is located in the western Guangxi province of southwest China (see Fig. 1),
which is adjacent to Vietnam. The study area contains 30 counties with the total area of
about 7.4×10 4 km 2 , 31% of the whole province's area of Guangxi (23.76×10 4 km 2 ). Its
geographic location is north latitude 21°36′N to 25°40′N, and east longitude 104°20′E to
108°31′E. The area is mountainous region and belongs to subtropical zone with enough
rainfall and rich natural resources.
The conflict between human and land in Guangxi is very sharp, but in the western
Guangxi, it is even more severe. The land resources in this area have the following
characteristics:
a. the area of land is large but the farmland is very limited due to mountainous and rocky
landform;
b. a high density of population in Guangxi results in the small farmland per capita, which
is less than 0.1 hm 2 . In the study area it is much smaller;
c. the land cannot be utilized adequately as the whole agricultural productivity with a
very low land quality. Most of the farmland belongs the second or third class.
Moreover, the land is difficult to be utilized in the Karst area;
d. soil fertility was lost due to a serious soil erosion.
The study area is mainly composed of carbonate rocks, granite, purple sandstone and shale
with weak anti-erosion properties. Climate in the study area is complex and changeable, and
sunlight and rain is abundant all over a year, which may accelerate soil erosion.
Additionally, with the increasing population and development of economy, human
activities impact the probability of soil erosion. All of the characteristics of the study area
made the Karst rocky desertification more seriously.
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