Open Journal of Social Sciences
2013. Vol.1, No.5, 1-4
Published Online October 2013 in SciRes (http://www.scirp.org/journal/jss) http://dx.doi.org/10.4236/jss.2013.15001
Open Access 1
Hydro Development-Induced Environmental Impact
on River Ecosystem
Qingran Wang
State Grid Xinyuan Company Ltd., Beijing, China
Received June 2013
Based on the analysis of river ecosystem characteristics, the external problem of hydropower develop-
ment is detailedly analyzed. Dam plays the important role in regulating regional water resources, reducing
the storage of flood disaster, producing clean energy. However, the river system of morphology, topogra-
phy, water quality and ecological environment are adversely affected. The controlling countermeasures of
ecological compensation mechanism, the artificial cultivation of ecological system are proposed.
Keywords: Reservoir; Ecosystem; Environmental Impact; Externalities
Introduction
Hydropower development is an important engineering meas-
ure for dealing with water, and is an important way to protect
the ecological environment (Shiklomanov, 2005). However, hy-
dropower development will bring negative impacts on river
basin. The paper analyzes the adverse effects of hydropower
development on river ecological system. At the same time, the
measure of reducing adverse effects of river ecological system
is present.
River Ecosystem Composition
River ecosystem is the complex biological communities in
the river and river environment interaction, the system is the
series of subsystems from land riparian ecosystem, aquatic
ecosystems, and wetlands to marsh ecological system which is
open and continuous (Stegner, 1992).
From the endwise perspective, the river ecosystem includes
upstream, middle, lower ways from the analysis of the vertical
angle (Moyle, 1988). Most of the river originate in the moun-
tains, flows through the hills, and is through to the estuary allu-
vial plain. The meteorological, hydrological and geological
condition is very different which formats different mainstreams,
tributaries, wetland, alluvial plain and flood plain.
From the horizontal perspective, the river ecosystem includes
rivers, floodplains, riparian zone, and marshes. The river is the
main body of the aquatic ecosystem, and is the main river eco-
logical system. Floodplains are the river flood periodic region
which includes shallow, shallow lakes and wetlands. Floodplain
flood plays an important role in absorbing the flood, keeping
the soil. Forests, grasslands, wetlands and marshes can maintain
soil, prevent sediment into river.
From the vertical perspective, the aquatic ecological system
of river ecological system can be divided into superficial, mid-
dle, bottom layer and the substrate. On the surface, oxygen is
rich in water. Due to the flow of the river, the atmosphere of the
large contact area and good gas exchange which is in favor of
the decomposition for microbial survival and aerobic aquatic
organisms. This is the main primary production water of aqua-
tic ecosystem. In the lower layer, plankton is gradually reduced
due to oxygen, sunlight is weakened. The basal rivers contain
pebble, gravel, sand, clay and so on, which is the habitat for
many organisms. At the same time, the aquatic ecological sys-
tem carry out energy exchange continuously with the land bank
system, wetland with material, which constitute the river eco-
system integrity.
From the time perspective, the river ecological system is
changed with the passage of time, precipitation change, human
disturbance, temperature fluctuation. The river is a living, in
morphology, channel change may need very long time, but
human disturbance effects on the river do not need too long
time, such as water pollution, excessive water etc.
Hydropower Development Affect
on River Ecosystem s
Impact of hydropower development on river basin ecosystem
environment is mainly reflected in two aspects which are river
ecosystem impact on non-ecological factors and river ecosys-
tem impact on ecological factors. River ecosystem impact on
non-ecological factors are the characteristics of watershed hy-
drological, water, water, sediment, water, landforms, river
morphology, the lower strata, regional climate. River ecosystem
impact on ecological factors is primary production and higher
trophic production which is interrelated and interacted. This
change can be divided into three levels according to the effects
of the depth (Hughes, 1990), as shown in Figure 1. The effects
of hydropower development on river ecological system start
from the influence on non-ecological factors. And then, chang-
ing is happened in the higher trophic level. The complexity of
this interaction process is gradually increased from the first
grade to the third grade.
River Ecosystem Impact on
Non-Ecological Factors
1) Impacts on river systems in hydrological regime. Hydro-
power development is the controlling mode of flow change

Q. R. WANG
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2
The effects of
hydropower
development
River ec osystem
impact on non-
ecological factors
River ecosystem
impact on ecological
factors
Hydrology, water
River sedim ent
Wate r qua lity
Primary bio logical ,
phytoplan kton, macrophytes,
algae
Landform, river morphology,
lower bottom structure,
regiona l climate
Fi sh, invertebrates
Birds, mammals
The first level of influence
The second level of influence
The third level of influence
Figure 1.
Classification of effects of dam construction on riverine ecosystem.
artificially. The hydrological changes mainly happen in the
rivers flow into the lake, sea water, river water, groundwater
level variation. a) Changes in river flow, water level. The dam
can change the natural flow pattern, has the capacity of flood
storage and discharge. Reasonable regulation of river flow in
the reservoir can reduce the peak flow of the river, flood con-
trolling through to the combined use of river engineering
downstream. The dam impounding water can make the seasonal
rivers into a perennial River, which is more stable and adequate
water irrigation to farmland, improve food production. Hydroe-
lectric power generation makes by the river water level which is
not only due to precipitation change, also will change because
of power demand factors changing. b) The change of ground-
water level. Surface water and groundwater in the basin is
closely related. The river hydrological conditions changing will
affect the level of groundwater, water quality. The dam up-
stream reservoirs make the surrounding groundwater level ele-
vation, thus expanding the scope of the reservoir, leading to
salinization and marsh land. At the same time, damming the
river also reduces the source of groundwater recharge in the
lower reaches of the dam base, resulting in a lowering of the
groundwater level, large tracts of the original groundwater
gravity irrigation districts lose gravity conditions, reducing the
downstream area of water resource utilization which makes the
adverse effects of irrigation.
2) Effects on the river morphology, relief system. a) Changes
of river morphology. The river flows through the area of soil
and rock by erosion, transportation, the part of sediment is de-
posited in front of the dam, the formation of backwater delta,
the reservoir capacity is greatly reduced. The river bed rises
gradually because of scouring substance in the local deposition
of more downstream. b) Changing of delta and coast line. Delta
is caused by the accumulation of sediment for hundreds of
thousands of years, and is formed in the sediment compaction
and marine erosion under the interaction of. The interception
effect on sediment dam has deeply influenced the Delta and
coastal area. Sediment reduction will make the coastal areas
seriously eroded, and the effect from the estuary along the
coastline extends far away.
3) Influence on water quality of the river system. Chemical,
physical and biological changes in river and experience for the
dam will greatly change the original water quality which is the
reservoir water salinity increasing, reservoir water temperature
stratification, library increased algal blooming. a) Salinity
changes. Dam water will form the reservoir area wide, com-
pared with the natural river, greatly increasing the exposure to
the sun’s surface area. In the arid regions in the hot climatic
conditions, a large number of evaporation of water will lead to
increase salinity in water. b) Changes of acidity. The dam up-
stream is reservoir submerged vegetation, dissolved oxygen
consuming water, releasing large amounts of greenhouse gases
and carbon dioxide, which will increase the water acidity, dis-
solve mineral accelerated Lake. c) Change of temperature.
Usually, discharge from the reservoir depth of water, the water
temperature is low in summer than in winter than in the river
water, and release export from the reservoir near the top of the
water, all the year round than the high water temperature. Out-
let water discharges from the reservoir near the top, all the year
round than the high water temperature. d) Change of algae.
Dam traps sediment and nutrient retention, these nutrients are
more susceptible to the reservoir water body eutrophication
phenomenon. When the temperature is higher, the algae may be
overbearing in the reservoir with rich nutrition, so that the wa-
ter body smell bad.
River Ecosystem Impact on Ecological Factors
River ecosystem impacts on the ecological factors are re-

Q. R. WANG
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3
flected in Table 1. 1) The impact on the ecological environ-
ment of the river. Dam construction provides good condition
for the development of aquaculture, makes many reservoir be-
come the aquatic product supply base. However, at the same
time, flooded vast tracts of land also hindered the valley life
network connections, influence of wild plant ecological envi-
ronment of survival, reproduction of the original. a) Habitat and
reproduction environment changes. The dam destroys part of
terrestrial plant habitat and changes to rely on these terrestrial
plants living resources. The dam was also blocked with the
migration routes of migratory fish, affects the species exchange,
and changes the reservoir downstream aquatic plants and ani-
mals. The river water level changes with the electric power
demand pattern which will cause some adverse consequences
on the aquatic ecological environment. In addition, the living
environment and life cycle of the river water tem perature chang-
ing will change the aquatic organisms, because of changes in
larval breeding, hatching and metamorphosis often depending
on the temperature. b) Changing in the number and species. The
dam has weakened the peak, adjusted the water temperature,
reduced the dilution effect of downstream river, and the
plankton greatly increased the number, and distribution signi fi -
cantly changed. Due to the large number of pebbles and sand
dam, the river bottom invertebrates lost survival environment,
such as insects, shellfish and animal (Rosenberg, 2000).
2) Effects of dams on the environment in the flooded area. a)
The wetland landscape reduced. Ecological environment deg-
radation of wetland functions is pejorative due to hydropower
development changes the hydrological situation of wetland a nd
water circulation. b) The wetland biodiversity loss. Blocking
the river channel change and animal habitat environment will
make the quantity of birds and mammals changed. The dam has
changed the hydrological and hydrodynamic conditions, the
ecological environment system of floodplain wetland is de-
structed, which leads to the deterioration of regional ecological
environment.
Control Measures on Negative Externalities of
Hydropower Development
Ecological Compensation Mechanism
According to the changing of river ecosystem service value,
Table 1.
Effects of dams on river ecological system.
The first level of influence Hydropower development affects energy and material flowing into the river and related ecosystems.
1) Hydrology
The river flow is reduced due to evaporation and dive r sio n.
In addition to unnatur al flow fluctuation caused by the operation of the external (such as power pulse discharge),
flow rate decreases.
Flooding scope, duration and frequency are decreased.
2) Water quality
Thermal regulation.
Salinization due to evaporation.
Changing the content of dissolved oxygen and nitrogen content.
pH value.
Nutrients, hydrogen s ul fide, manganese and iron content.
3) River sediment Because of sedi ment deposit ion in the reservoir and the sed i ment reduction.
River turbidity.
The second l evel of influence The first stage effects caused by the change of local conditions, which cause abiot i c and biol ogical c hanges
in ecosystem structure and primary biological, also depend on variation of rive r dam characteristics.
1) Plankton Because the dam can reduce flood, adjusting the water temperature, reduce water turbidity and reducing
downstream dilution of sewage, so that great l y increa sed the number of plankto n.
2) Aquatic organisms Because the dam can increase the low water flow, reducing the flood and flood frequency, lower turbidity,
adjusting energy situation and reduce the base erosion, so that the number of aquatic organisms attached.
3) Aquatic macrophyte
The number of plants with r oot will increase, because the dam can reduce flood and grass-roots blunt turbidity,
increased deposition of eutrophication of fine sediment.
Because of the dam can reduce the peak flow, so that the river can not sand, increase in the number of floating plants.
4) Riparian vegetation Due to flooding can decrease the dependence on flood change species.
Sediment deposition decreases and the flood area in nutrient supplement can decrease the soil fertility decrease.
The third level of influence Due to the combined effect of all the first and second stage of change, biological, including near the top of the
food chain species were affected (such as invertebrate community and fish, birds and mammals cha nge).
1) Invertebrate Hydrologic al and phys i cochemical conditions (such as temperature, turbidity and d i s solved hydrogen) changes,
the number and distribution of macroinvertebrates will change remarkably (usually reduce the types).
2) Fish
Because of migration channels blocked and w ater regim e, physical and chemical conditions (such as temperature,
turbidity and dissolved oxygen ) , the primary biological and the riverway change, so that the number of fish change.
3) Birds and mammals That will make the number of birds and mammals to change due t o t he floodplain animal habitat environment
improvement and rive r channel bl ocking.

Q. R. WANG
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we can take the measure of ecological compensation. In general,
the hydropower development of ecosystem service includes
power generation, water supply, irrigation, hydropower devel-
opment, the owners are the main beneficiaries, the persons of
the river flows through the city and rural areas also get signifi-
cant irrigation and water supply benefit. Therefore, the benefi-
ciaries of the river flows through the area should pay compen-
sation in the amount of benefit ratio.
Building Dams Using Modern Technology
In the planning, design, construction and operation process,
we should use modern science and technology and modern
engineering technology. In the planning stage, we obtain in-
formation environment, using modern geophysical technology
to fully understand the dam foundation and the reservoir natural
conditions, analysis of the changes before and after c ompletion
of environmental factors with the mathematical model and
physical model.
Strengthening Environmental Impact Assessment of
Dam Construction
In the development of construction, evaluation and prognos-
tic evaluation value changing by the dam with the natural ecol-
ogy, social ecology and the environment, reducing the adverse
impact on the environment to a minimum, maximizing the
overall benefit of project.
Conclusion
The designers, builders and managers should be the ultimate
goal to improve the ecological environment and sustainable de-
velopment, through the application of modern technology, car-
rying out environmental impact assessment, to develop means
of dam operation mode for the ecological environment. Careful
study of negative environmental impacts of dam may bring
fully demonstrating the feasibility of a dam construction project
environment, changing analysis humanities, social, ecological,
natural resources, climate change, land resources, river sedi-
ment and other factors may occur, distinguishing the favorable
and unfavorable elements, adhere and mitigate the adverse ef-
fects of dams on river ecosystem environment, so that every
project construction will not only has great economic benefits,
but also will promote the sustainable development of economy
society, and promote harmony between man and nature.
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Hughes, F. M. R. (1990). The influence of flooding regimes on forest
distribution and composition in the Tana River floodplain. Applied
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