Hydro Development-Induced Environmental Impact on River Ecosystem

doi:10.4236/jss.2013.15001

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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

Email: [email protected]

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

Open Access

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

Open Access

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

Open Access

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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Stegner, W. (1992). Where the bluebird sings to the lemonade spring.

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Moyle, P. B. (1988). Fishes: An introduction to ichthyology. Engle-

wood Cliffs, 334, 120-126.

Hughes, F. M. R. (1990). The influence of flooding regimes on forest

distribution and composition in the Tana River floodplain. Applied

Ecology, 27, 475-491.

Rosenberg, D. M. (2000). Global-sca le environmental ef fects of hydro-

logical alterations: Introduction. Bioscience, 50, 746-751.