LAND DEGRADATION ANALYSIS IN THE ONGI RIVER BASIN
Tungalag.Aa * * , Tsolmon.Ra , Bayartungalag.Ba
a
National University of Mongolia, School of Physics-Electronics, Laboratotay for Remote sensing/GIS
NUM-ITC-UNESCO, Ulaanbaatar, Mongolia
tungalag86@yahoo.com; tsolmon@num.edu.mn; b_tungalag_b@yahoo.com
CommissionVII, WG VII/5
KEY WORDS: Socio-economic, Mineral Resources, Degradation, Biodiversity, MSAVI2, NDVI,
ABSTRACT:
During Mongolia’s transition to the free market, socio-economic factors such as poverty and profit-seeking have greatly increased
small to large-scale mining, as well as illicit activity resulting in the exploitation of the country’s mineral resources. This has
subsequently contributed to the deterioration and loss of regional biodiversity and increased levels land degradation. This study aims
to monitor land degradation processes in the study area of the Ongi River Basin. This area is affected by mining activities and
desertification processes. The vegetation indexes MSAVI2 and NDVI from SPOT data were applied in this area in order to determine
vegetation cover change in the time period of 1998 to 2006.The result from both vegetation indexes described that there is a
vegetation decrease due to mining activities in the study area.
1
INTRODUCTION
There are a limited research works in Mongolia particularly
developing the necessary facilities and science for monitoring
the socio-economic change and environmental impact derived
from country’s mining sector. During Mongolia’s transition to
the free market, socio-economic factors such as poverty and
profit-seeking have greatly increased small to large-scale
mining, as well as illicit activity resulting in exploitation of
country’s mineral resources. Thus, the society and environment
problems in Mongolia interact in such a way where poor
environmental policy and regulation is linked to land
degradation and environmental contamination, which therefore
increases the society’s vulnerability. Lake, river and pond in
Mongolia is dried up and lost ecological balance caused by
human wrong activities and mineral extraction. Furthermore, it
is caused damage on environment and people’s lifestyle in
Mongolia.
This study aims to determine vegetation condition in Ongi river
basin. A great concern for the environmental officers Ongi river
basin is mining. Mining is done legally by companies that have
large concessions, but also illegally by so called "Ninjas",
individuals and families that literally dig for gold without a
license. The mining companies use heavy equipment to remove
the top layer and vegetation. Vegetation and pasture land most
important for the nomadic people living in the river basin.
Therefore this study is analyzing vegetation change in the river
basin in last years between 1998-2007.
2
2.1
the world bigger fresh watershed point and starts form Khangai
Range then crossed 3 kinds of areas which are Mountain &
Wooded area, steering plain area, gobi desert area. It is one of
the important rivers in the area for the lifestock breeding for the
local people (“Ongi” movement). Main environment concern is
the river is drying up and starting to interrupt since 1998 (Figure
2).
The length of the river is 437km, site is 175 square km and
1000-3000m above the sea level. The main reason of drying up
Ongi river is to the mining of gold placer deposit and never
making technical and biological reclamation (Mijiddorj.R,
Bayasgalan.Sh, 2006).
2.2
VEGETATION SPOT 4 1km data from April to October 19982006, LANDSAT ETM+ data for 23 July, 1999 and 20
September, 2000 were used in this research. Two kinds of
vegetation indexes NDVI and MSAVI 2 were used for the
monitoring vegetation change in the study area.
APPROACHES
Study area
The study are is, Ongi River basin is situated in the central part
of Mongolia, is located on E101044’24’’-E104030’00” and
N44022’48”-N46041’24” (Figure 1). The Ongi river is one of
*
Data used
corresponding author
1021
Figure1. Study area : Ongi river basin
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part B7. Beijing 2008
0.022675
0.099066
21-30 July, 1998
21-30 July, 1999
21-30 July, 2000
0.175456
0.251847
0.328237
0.404628
21-30 July, 2001
21-30 July, 2002
21-30 July, 2003
0.481018
0.557409
0.633800
21-30 July, 2004
21-30 July,2005
21-30 July, 2006
Figure 3. Change of vegetation using MSAVI2 index between
years 1998-2006 in the study area
0.01
0.12
Description:
21-30
July,
21-30 July, 1999
21-30 July, 2000
0.23
0.34
(Ongi river interruption in south part: from imagery LANDSAT ETM+
data for 23 July, 1999 and 20
0.45
September, 2000)
21-30 July, 2001
21-30 July, 2002
Figure 2. Location of the Ongi river
21-30 July, 2003
0.56
0.67
0.78
2.3
Method
0.89
21-30
Vegetation indices NVI and MSAVI 2 from the SPOT satellite
for vegetation period from April to October 1998-2006 years
used in the study area. Spectral bands Near Infrared 0.78-0.89
μm, Short wave Infrared1.58-1.75 μ m were selected for the
3
(1)
NIR − RED
* (1 + L)
NIR + RED + L
MSAVI 2 = ⎡2 NIR + 1 −
⎢⎣
21-30 July, 2006
RESULTS AND DISCUSSION
We made vegetation change analysis on for identifying of land
degradation using remote sensing tools in Ongi river basin in
Mongolia.
Huete (1998) suggested a new vegetation index, which was
designed to minimize the effect of the soil background, which
he called the soil-adjusted vegetation index (SAVI) (2)
developed of an iterated version of this vegetation, which is
called MSAVI2 (3)
SAVI =
21-30 July, 2005
Figure 4. Change of vegetation using NDVI index between
years 1998-2006 in the study area
analysis.
NDVI is normalizad ratio of the NIR and RED bands (1).
NIR − RED
NDVI =
NIR + RED
July,
(2)
(2 NIR + 1)2 − 8(NIR − RED )⎤⎥ / 2
⎦
(3)
As a results from the figure 5 and 6 of Onggi River basin’s
vegetation loss has been increasingly 12000 square km. (since
1998 year). Vegetation has a decreasing trend from both
vegetation indexes MSAVI and NDVI (figure 5 and 6). This
analyzes was compared with the results from the “NGO
Ongiinhon” (www.onggiriver.com) research team which used
ground truth data in recent years.
Concluding that this number will be keeping to increase in the
future. Future study should be focused not only on vegetation
condition but should take analysis connected with socio
economic data.
MSAVI varies from 0.022675 to 0.633800 while NDVI values
for vegetation is from 0.01 to 0.89. There is less greenness in
south part area where is interruption river and mining activities
(Figure 3 and 4).
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The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part B7. Beijing 2008
80000
70000
60000
y = -620.4x + 44068
50000
Area
40000
Linear (Area)
30000
20000
10000
0
1998/07
1999/07
2000/07
2001/07
2002/07
2003/07
2004/07
2005/07
2006/07
Area 53046.4
37513.3
31835.1
38680.4
31476.5
71621
35983.2
27899.3
40641.7
Year
Figure 5. Change of vegetation area between years 1998-2006
in the
Onggi river basin /MSAVI/.
45000
40000
35000
y = -1052.4x + 32442
30000
25000
Area
20000
Linear (Area)
15000
10000
5000
0
1998/07 1999/07 2000/07 2001/07 2002/07 2003/07 2004/07 2005/07 2006/07
Area 40640.6 27403.2 23171.5 29169.8 14780.7 37807
24531.1 18196.2 28921.2
Figure 6. Change of vegetation area between years 1998-2006
in the
Onggi river basin /NDVI/.
REFERENCES
Heute, A.R., 1998, A soil-adjusted vegetation index (SAVI).
Remote Sensing of Environment, 25, 295-309
Mijiddorj, R., Bayasgalan, Sh., 2006, “Integrated Assessment
on Drying Process in the Ongi River Basin”, Ulaanbaatar,
Mongolia
“NGO ONGIINHON”: http://www.onggiriver.com/
SPOT-VEGETATION: http://www.free.vgt.vito.be/
ACKNOWLEDGEMENTS
We would like to thank SPOT /VEGETATION
(www.free.vgt.vito.be) data center for providing satellite data
and “NGO ONGIINHON” in Mongolia for their contribution to
ground truth collection.
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