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REMOTE SENSING AVAILABLE IN ECOLOGICAL MONETARY VALUE
ASSESSMENT OF SAND BEACH
Xie HongYu?,
“ Wuhan Environmental Protection Bureau Information Center, Wuhan China
bubblefatcat@163.com
KEY WORDS: Remote sensing, Hydrology, Environment, Ecology, Ecosystem
ABSTRACT:
Sand beach ecological monetary value assessment is an important part of ecosystem monetary value assessment, because it plays an
important role in Ecosystem being a type of wet land. The area of Sand beach is an important data in assessment, but its measure
very difficult by traditional means because it is affected by climate, season and flow of river etc. In this paper, the author discusses
how to measure the area of sand beach by remote sensing technology in this assessment. Above all, spot images of rainy season, dry
season and midst season been selected according to local climate. After then, sand beach image feature been extracted and calculated
area form these spot images after image process. At last, the average area of sand beach been calculated after different weight been
set for area of different season according to local climate and environment factor. As a result, the area of sand beach calculated by
remote sensing more efficiently than traditional means
1. INTRODUCTIONON
Sand beach (only means sand beach and sand island of river in
this paper), being a type of wetland, plays an important role in
Ecosystem. Its ecological monetary value assessment is an
important part of ecosystem monetary value assessment,
because it has very high ecological value. The area of Sand
beach is an important elementary data in this assessment (Liu
NianFeng, 2002), but its measure is very difficult by traditional
means because its area depend on the water level of river is a
variable directly affected by local climate and season transfer. It
is thought that obtaining the average water level in different
season and climate is the key in this measure
2. ANALYZE AND SOLUTION
2.1 Hydrology data analyze
In one year, the water level of river can be divided three
seasons, rainy season, dry season and midst season, in
according” to flow of river that is depend on rainfall and
evaporate rate in this year. This is means that the area of sand
beach has three values correspond to the average water level in
different season. There is dry season area and midst season area.
Except that, the maximum area of sand beach must be account
in this measure.
f. Dry season area: the area of sand beach exposed in
river when water level is.the average dry season
water level. It is obtained by emerged area of sand
beach in average dry season water level minus
emerged area in average rainy season water level.
Midst season area: the area of sand beach exposed in
lriver when water level is the average midst season
water level. It is obtained by emerged area of sand
beach in average midst season water level minus
emerged area in average rainy season water level.
ta
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'Corresponding Author. E-mail: bubblefatcat@163.com
447
3 The maximum area: the area of sand beach exposed
in river when water level is the lowest water level in
history. It is obtained by emerge area of sand beach in
lowest water level minus emerge arca in highest
water level.
2.2 Measure solution
After analyzing data of hydrology, the dates of above water
level occurring were chosen. The satellite images would be
chosen in according to these date. Unfortunately, the image of
water level occurring often can’t be obtained, because satellite
had no been invented at all in these dates. In general, the images
in that time of approximate to these water levels would be
chosen to be replacement.
In addition, the river need to been divided many section
because length of river is too longer so as to can’t be
represented by ones.
After chosen image, all of image must be complete geometry
correction and image improvement. And then, polygons that
represented sand beach were generated after riverside and
boundary of sandbank were extracted from these images. At last,
area of sand beach obtained by calculated area of polygons
3. EXPERIMENT
The example is about how to measure sand beach area of Han
River XiangYang section. Its dry season from October to
February, midst season form March to May and rainy season
form June to September.
3.1 Water level data analyze
Appropriate water level time need to been determined by
analyzing hydrology data. The next three tables are Han River
XiangYang section month average water level, annual average
and maximum and minimum of year from 1989 to 1999(Huang
Sea Height/ meter)(XiangFan city Hydrology Bureau,2000).
