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TEMPORAL-SPATIAL DYNAMIC CHARACTERISTIC OF VEGETATION IN THE 
AREA OF CASCADE HYDROPOWER STATION CONSTRUCTION IN THE UPPER 
REACH OF THE YELLOW RIVER 
Dan Wang, Cheng Zhao, Hongguang Cheng*, Li Gong, Fanghua Hao, Xuying Shi 
School of Environment, State Key Laboratory of Water Environment Simulation, Beijing Normal University, Beijing, 
100875, China 
Working Group IV/2 
KEY WORDS: Temporal-Spatial Dynamic; Eco-environmental Impact; Hydropower Development; Yellow River 
ABSTRACT: 
The hydropower station construction produced serious impacts on the regional eco-environment. The most obvious characteristics of 
the impacts caused by the cascade hydroelectric development are progressive, cumulative and regional. In this paper, the study area 
of Yellow river section from Longyangxia to Liujiaxia reservoir locates in the northwest Loess plateau of China. The remote sensing 
data of 1977, 1996 and 2006 were selected to analyze the temporal-spatial dynamic characteristic of regional vegetation coverage in 
last 30 years. The result indicated that : a) The vegetation coverage in study area was gradually improving, the main cause of the 
vegetation decrease was the hydropower plant construction, especially annual regulating reservoir, because of which many land use 
types were converted to water and the vegetation coverage decreased, b) With the increase of the altitude, vegetation increase rate 
rose firstly and then declined, while the change trend of vegetation decrease rate was opposite, c) The vegetation increase rate rose 
gradually as the distance to roads goes farther, while the nearer the vegetation was to the roads, the higher the vegetation decrease 
rate was. d) The decrease rate was relative to the population density and residents; but in some districts the decrease rate rose 
contrarily with distance to resident went farther, e) The vegetation change was highly related to the activities of human beings in the 
study area, f) This research demonstrated that there was no obvious evidence proved that there was correlativity between the cascade 
hydropower development and the regional vegetation coverage. 
1. INTRODUCTION 
China's rapid economic development has left deep marks on 
energy availability, and a further development hydropower 
energy resource will be an inevitable choice for China’s 
resource strategy (Zhe-Ren Dong, 2006).The Yellow River, 
with its own advantages, has played an important role in the 
country’s hydropower development. The cascade construction 
from Longyang gorge to Liujia gorge is the most concentrated 
area in the Yellow River, which is located on the northeastern 
Qinghai-Tibet Plateau, across Qinghai and Gansu provinces. In 
2000, the total generating capacity is 20.101 billion kw-h, 
accounting for 24.1% of the Northwest Power Grid (Zhen-ke 
Zhang, 2004). But the natural ecological environment is fragile 
as grassland degradated and desertification intensified. As a 
double-edged sword, the regional hydro-power exploitation 
promotes the development of local economy; meanwhile, it also 
has an adverse influence on the eco-environment such as the 
regional vegetation and landscape pattern. Due to its severe 
impact on local natural and geographical conditions, once the 
vegetation is damaged, it will not be easy for restoration. 
Therefore, it is necessary to analyze the temporal-spatial 
dynamic characteristic of vegetation in the area of cascade 
hydropower station construction. 
The most obvious characteristics of cascade hydroelectric 
development are progressive, cumulative and regional (Anna 
Brismar. 2004), which can be described by application 
advantages of remote sensing technology from the perspective 
of space-time. The Landsat series of sensors are the most 
Hongguang Cheng. E-mail: chg@bnu.edu.cn. 
Foundation item: project 40771191 supported by National Natural Science Foundation of China 
popular ones in collecting regional environmental data for 
comparison analysis (W. Ouyang, 2007; F.H. Hao, 2007). The 
Multi-spectral Scanner (MSS), Thematic Mapper (TM) and 
Enhanced Thematic Mapper Plus (ETM+) sensor series can 
provide continuous high spatial resolution images. Since 1972, 
plenty of such images captured by Landsat series of sensors 
have been used in the retrospective assessment of the regional 
environmental quality (W. Ouyang, 2007). Now, remote sensing 
is an effective way for regional construction disturbance 
observations, and satellite images have been applied widely, 
especially in long-term monitoring of vegetation responses to 
environmental change. 
Spectral indices of vegetation, based on satellite observations in 
the near-infrared and visible (usually red) wavebands are widely 
employed as measures of green vegetation density. Vegetation 
indices have been identified by many authors with measures of 
the vigor and productivity of vegetation and applied at all scales 
of operation, ranging from continental scale vegetation 
dynamics, global studies of plant responses to climate change, 
to regional crop yield predictions and precision farming. 
Vegetation index was a simple and effective parameter, which 
was used to indicate the vegetation cover and growing condition 
in RS fields (N Guo, 2003; J. W. Rouse., 1974). NDVI has a 
good linear relationship with the condition of vegetation cover, 
vegetation productivity, etc., which was the important index to 
study the vegetation change. In this paper, we choose NDVI and 
f N ovi as an indicator to measure the change of regional 
vegetation density.