Large Dam Construction:A Global Problem in Perspective

Source: Deutsche Welle, 2015 <http://www.dw.com/en/china-blocks-yangtze-river-dam-project/a-18371157>

GEOG 211 Term ProjectFall Semester, 2016

Lone Corianne Mokkenstorm

#70567169

Word count: 3000

Introduction

Dams have contributed to the development of societies throughout history, for example by providing

drinking water, facilitating irrigation and generating hydropower (Brown et al., 2009). Currently,

approximately two-thirds of the largest rivers in the world are fragmented by dams and reservoirs

(Nilsson et al., 2005). This does not only alter the flow of the rivers; it has impacts on the environment,

local populations and politics (Tilt, Braun and He, 2009). This paper will assess the problems associated

with large dam construction, using the DPSIR framework. The main focus will lie on hydro dams built for

irrigation and energy generation, as these are the two major purposes for which large dams are built

(Oud, 2002; Chen, Chen and Fath, 2014).

Context

Hydroelectricity

Hydropower is an energy source that has been exploited for centuries (Oud, 2002; Sternberg, 2008;

McCully, 2001). Early power plants were designed to generate motive power, until the first hydroelectric

plant was built in 1880. As technology improved and demand increased, the scale of hydroelectricity

projects increased as well. Most major projects were constructed between 1955 and 1985, after which

the activity decreased again due to financial, environmental and social reasons (Oud, 2002). In 2010,

hydroelectricity constituted 16% of global annual energy generation (Chen, Chen and Fath, 2014).

Currently, China is the largest producer of hydroelectricity, with a total production of 662.2 TWh in 2014

(Mao et al., 2016).

Because of the natural water cycle, hydropower is considered a renewable energy source. Therefore, the

current growth in (sustainable) energy demand will likely revive the construction of large scale dams

(Sternberg, 2008; Oud, 2002; Mao et al., 2016). However, associated with the construction of hydro

dams are many socio-environmental concerns that challenge the sustainability of hydroelectricity

(Sternberg, 2008; Chen, Chen and Fath, 2014). Inadequate environmental impact assessments and

insensitivity to local populations often fuel local opposition (Sternberg, 2008).

Irrigation

Eight thousand-year-old irrigation canals have been found in the area that used to be Mesopotamia. The

farmers in this area were likely the first builders of dams, using natural material to divert water from

streams into these human-made structures. The first irrigation dams that were found originate from

3,000 BC, and were situated in modern-day Jordan (McCully, 2001).

Irrigation works became the very first public works, protecting societies from flooding and distributing

the water among the society (Koch, 2002). In 2001, an estimated 272 million ha of land was under

irrigation. Approximately 60-80% of all water used globally is currently used for irrigation purposes

(Gerbens-Leenes et al., 2009).

Methods

The DPSIR Framework is a framework used to develop integrated environmental assessments

(Kristensen, 2004). It helps to understand what is happening to the environment, what the reasons are

behind this, what the consequences of the changed environment are and what is being done about it

(Pinter et al., 1999). An analysis with the DPSIR framework includes an investigation of driving forces,

pressures, states, impacts (both on the environment, human health and functions) and political

responses (Kristensen, 2004). The framework has proven to be useful in breaking down complex,

widespread problems and evaluating the policies connected to it.

It is important to clarify that dam construction does not necessarily have to be a problem. Impacts can

be mitigated if dams are designed and constructed adapting to the particular environment and situation.

For the purpose of this study however, we will define the problem as follows: “The increasing

construction of large dams has proven to have detrimental socio-environmental impacts.” Through a

literature review, a DPSIR analysis will be conducted.

Analysis

Driving forces

Driving forces are overarching, socio-economic factors capable of creating pressures on the state of the

environment (United Nations Environment Programme, 2012). Thus, one could describe them as the

causes behind the human activities that (can) affect environment and climate. In the context of our

hydro dam problem, the main driving forces are those forces that indirectly lead to more demand in

hydro dams for irrigation or power generation.

The primary drivers of this problem are population growth, economic growth and climate change. These

lead to the secondary drivers: a growing (renewable) energy demand, technological innovations and an

increasing water consumption (Table 1).

A growing, wealthy population leads to increasing demands in water and energy (Brown et al., 2009).

The increase in water consumption is mostly due to food consumption, as an approximate 70% of global

water usage is linked to agricultural practices (UNESCO-WWAP, 2009). As the climate is changing and

fossil fuels are being depleted, the demand for renewable energy in particular is likely to grow (Brown et

al., 2009). Moreover, turbine efficiency increases and large-scale structures are made possible by

technological innovations. These secondary drivers will lead to an increase in dam construction, as dams

can be increasingly used to manage water supply, irrigate farmlands and provide hydroelectricity.

Table 1: Drivers of large dam construction

Primary drivers Secondary drivers

Climate change Growing demand in (renewable) energy

Population growth Increasing water consumption

Economic growth Technological innovations

Pressures

The building of large dams to meet energy and water demands puts certain pressures on the

environment, which will be outlined in this section.

Upstream intervention in river regime

Dam construction is always subject to governmental approval because it concerns both energy and

water policies (Koch, 2002) and often has impacts on the international scale. Rivers cross national

boundaries, and the creation of a reservoir in a country or region upstream has widespread effects in the

regime (and associated with this, ecology) downstream (Brown et al., 2009).

River fragmentation

Damming of rivers fragments them into smaller sections, putting pressure on biotic and abiotic

components throughout the river system (Chen, Chen and Fath, 2014). It has ecological, morphological

and political impacts that exceed the mere obstruction of the natural water flow (Zhai et al., 2010; Wang

et al., 2012; Chen, Chen and Fath, 2014), which will be elaborated on later in this work.

Need for reservoir

A benefit of hydroelectricity over other forms of renewable energy, is that water can be stored in

reservoirs during low demand, which in turn increases the water (thus generated energy) available

during peak hours (McCully, 2001). Large areas are inundated to create these reservoirs.

States

Fluctuations in downstream regime

Intervention in the river regime through damming may lead to fluctuations in the downstream regime.

Especially when ‘peak generation’ is applied -where water is stored in periods of low demand and

released during peak hours- dam construction can lead to extreme fluctuations in stream flow

downstream (McCully, 2001).

Lower water availability downstream

When water is diverted from dam reservoirs for irrigation, water availability downstream decreases.

Increased evaporation rates from reservoirs may add to this (Von Sperling, 2012), as will be explained

later in this paper.

Sediment deposition upstream of dam

Hydro dams trap sediment from the flowing river in the reservoir behind the dam. Here, it deposits on

the reservoir bed. Sediment trapping occurs the most in larger reservoirs (Zhai et al., 2010). When the

water is released to the river again, it is depleted of sediment (Kondolf, 1997).

Obstructed fish migration routes

The fragmentation of rivers by dams fragments the habitats for fish as well. This is both an

environmental as it is a social issue, as it affects fish populations as well as fisheries (Koch, 2002). It has

serious impacts on migratory species, as spawning and breeding areas as well as their habitat in general

is disturbed or made inaccessible (Wang et al., 2012).

Community displacement

Hydropower projects can have some positive social effects, such as poverty alleviation through the

sharing of revenues with the local community, or the creation of recreation facilities for example.

Moreover, it can provide water resources to the community (Koch, 2002; Odermatt, 2004).

However, the construction of hydro dams and associated creation of a reservoir frequently leads to the

displacement of local communities from the reservoir area as well (Koch, 2002). Through modern

communication technology, their voices are made heard more easily, which has led to greater public

sympathy for these people (Koch, 2002).

Inundation of natural area

As mentioned before, a significant area of (vegetated) land must be flooded to create the reservoirs-

large stagnant bodies of water. This has widespread impacts on ecology, environment and public health.

Reduced navigation and transport capacity

Of course, river fragmentation will prevent access per water to some sections of the river (Von Sperling,

2012). However, as dams are often constructed in large-relief upstream areas, this state is less of a

concern.

Impacts

Hydro dam construction can have adverse social and environmental impacts which need to be

considered in planning processes. However, it is important to emphasize that each dam project is

unique, in the sense that environments can react differently to the construction of a hydro dam (Koch,

2002). Major occurring impacts are assessed in this section.

Changing geomorphology

Upstream regulation of river regimes has far reaching downstream effects on geomorphology, and

connected to this, ecology. In general, the range of flows decreases and the suite of flows simplifies as

downstream flow is regulated. This leads to a reduction in active flood plain, islands and bars, and

abandonment of high flow channels. Riparian habitats can shrink because of this, and the array of

habitat types can decrease (Graf, 2006; Von Sperling, 2012).

Increased erosion

Trapping of sediments upstream leads to sediment depleted, ‘hungry water’ downstream. This is water

with an extreme erosive power due to a tendency to balance the sediment load again. It can degrade

river banks and coarsen bed material, sometimes leading to loss of spawning gravel for certain fish

species (Kondolf, 1997).

Terrestrial and aquatic biodiversity loss

Biodiversity loss after large dam construction can occur for several reasons next to changes in

morphology. Firstly, river fragmentation can make migratory species slowly transform into lake fishes as

spawning and rearing areas are blocked. These species can also become endangered if environmentally

sensitive. The numbers and types of fish present in dammed rivers will therefore change (Wang et al.,

2012).

Moreover, impacts of the inundation of the reservoir area include species loss through flooding, habitat

loss and local climate change (Wang et al,., 2012). These factors can threaten certain species that are

already endangered or change the biodiversity in the area.

Health risks

The formation of a large body of stagnant water can be associated with health risks that need to be

taken into account in the planning process. Especially in tropical areas the risk on water-borne diseases

can increase (Koch, 2002). Two big health risks imposed by dam construction are increasing occurrence

of schistosomiasis (Jackson and Sleigh, 2000; Lerer and Scudder, 1999) and malaria (Keiser et al., 2005;

Von Sperling, 2012), as the snails and mosquitoes that transfer these diseases benefit from slowly

moving water (Von Sperling, 2012). Impoverishment, lack of medicinal services and malnutrition after

relocation can also pose significant health risks to the population (Jackson and Sleigh, 2000).

Social issues

As mentioned before, there are many social issues associated with community displacement. Excessive

local opposition can lead to a halt in construction or funding, which happened for example with the

Sardar Sarova dam in India (Morse and Berger, 1992).

In many cases, evicted people might be appointed a plot of land in a different city or region. However,

often the host communities are inhospitable or hostile. This is especially apparent in areas where job

opportunities are scarce and poverty is apparent (Jackson and Sleigh, 2000). Moreover, agricultural

farmlands may be flooded, leading to a decrease in food production in a mountainous area where arable

land is scarce (Jackson and Sleigh, 2000). Displaced farmers might not be able to find resumption of

former occupations, or arable land with the same productivity levels as their former plots.

Eutrophication and reduced soil fertility

Many nutrients accumulate in dam reservoirs: natural ones as well as those originating from flooded

biomass. This does not only reduce soil fertility downstream, it also promotes algae growth in the

reservoir (Wang et al., 2012; Von Sperling, 2012). When these algae die, they are consumed by

heterotrophic bacteria. This creates an oxygen depleted environment which could lead to suffocation of

many desirable fish species. Moreover, eutrophication deteriorates water quality (Munyati, 2015),

increasing costs for water purification (Von Sperling, 2012).

Greenhouse gas emissions and increased evaporation

There is increasing evidence that dam reservoirs, especially in tropical regions, are large greenhouse gas

(GHG) emitters. The gases form through decomposition of flooded biomass (Beck, Claassen and Hundt,

2012). Although the exact numbers are currently poorly understood, it is clear that under certain

conditions GHG emissions may be higher than those of conventional thermal generation plants (Von

Sperling, 2012).

Large dam reservoirs may alter local climate, for example through increased evaporation rates (Von

Sperling, 2012). The surface area of water exposed to the sun is larger in a reservoir than in a flowing

river. This leads to water salinization and a smaller water availability downstream. Upstream water

diversion also adds to the latter (Pottinger, 2009).

Responses

Ecological and environmental issues

By conducting an extensive EIA (environmental impact assessment) prior to construction and an EIPA

(Environmental impact post-assessment) after construction, most of the impacts illustrated here can be

mitigated or avoided in the future (Wang et al., 2012).

Problems associated with the fragmentation of migratory fish habitat are aimed to be solved with

measures like ‘fish ladders’ or similar structures (Von Sperling, 2012). Although not always suitable for all

local species, these structures can facilitate movement between river sections upstream and

downstream of the dam.

Other issues with biodiversity loss could be predicted with a survey of species in the area and their

reliance on a certain regime variability. This regime could then be mimicked to an extent, for example by

focusing less on energy demand and allowing a more natural flow of water.

Greenhouse gas emissions from reservoirs can be mitigated by forest clearing in the reservoir area prior

to inundation (Von Sperling, 2012).

Social issues

Public acceptance has grown into a huge issue for the energy industry, especially since local communities

can make their voices heard and find support through new forms of media (Koch, 2002). The consulting

process is therefore expected to require more time and money in the future. Research on the factors

that determine social acceptance of hydropower projects in Switzerland found that ecological impact

and local ownership explained approximately 70% of the respondents’ choices on whether or not to

support a hydro energy project (Tabi and Wüstenhagen, 2017).

It is often seen as the duty of the developers to ensure the host communities as well as the displaced

communities are not worse off than prior to dam construction. An effective measure to incentivize

voluntary resettlement is the offering of compensation payments (Jackson and Sleigh, 2000). However,

some factors restricting voluntary resettlement might have no monetary value, such as loss of culture

and indigenous grounds.

Political issues

Large scale hydro dams are often an international concern. International collaboration and agreements

are therefore key in every stage of the planning process.

Run of the river

Many countries are currently subsidizing small-scale run of the river hydroelectricity, as it is perceived as

being more environmentally and socially acceptable (Koch, 2002). These dams do not store the water in

large reservoirs (Kumar and Katoch, 2017; Von Sperling, 2012), which means that certain pressures

associated with reservoirs do not apply to these dams. However, run of the river damming can bring

about its very own hazards and impacts, such as landslides and illegal dumping of debris (Kumar and

Katoch, 2017).

Changing strategies

Renewable energy sources are exploited to combat climate change, but the sources themselves are

vulnerable to climate conditions as well (De Queiroz et al., 2016). Flow variability is likely to increase

according to future climate scenarios and dam developers should take this into account in any future

project planning and investments (United Nations Environment Programme, 2012; De Queiroz et al.,

2016). The changes are due to increasingly variable precipitation, river runoff and rising reservoir

evaporation (Boehlert et al., 2016). Moreover, increased droughts in certain areas might mean that less

water can be stored upstream to provide sufficient water in downstream areas or countries. Risks on

malaria might increase due to an increase in temperature as well. In general, hydropower generation is

likely to increase under most greenhouse gas mitigation scenarios (Boehlert et al., 2016) due to the need

for renewable energy sources.

Conclusion

This paper consisted of a DPSIR-analysis of the problem of large dam construction. An overview of the

driving forces, pressures, states, impacts and responses can be found in Table 1 and Table 2. Whereas

hydropower is considered a renewable energy source, there are many environmental impacts associated

with dam construction that should be considered.

It was found that each of the DPSIR components differs per case, as social and natural environments

differ per hydro project as well. For example, evaporation rates and the number of malaria incidences

are likely to be larger for dams and reservoirs in tropical environments.

Furthermore, climate change is likely to impact the potential of hydroelectricity and the impacts of

hydropower projects. Regimes will be more variable, water availability will be lower in some regions and

the risk on malaria might increase. Due to the long lifespan of most hydro plants, long-term climate

predictions should be taken into account in the planning processes.

Table 2: Pressures, states, impacts and responses of large dam construction. US = upstream and DS = downstream

of dam.

Pressures States Impacts Responses

Upstream intervention in

river regime

Fluctuations in DS stream

flow

Biodiversity loss DS

Changed geomorphology

DS

EIA and EIPA, mitigating through

altering stream flow

Lower water availability DS Political tensions Agreements, collaboration

River fragmentation Sediment deposition US Increased erosion DS,

‘hungry water’

EIA and EIPA

Obstructed fish migration Biodiversity loss Fish ladder construction

Reduced navigation and

transport capacity

Political tensions Agreements, collaboration

Need for reservoir Community displacement Social issues Public involvement, financial

compensation

Reservoir formation Decreased agricultural

production

Increased evaporation

GHG emissions

Eutrophication

Biodiversity loss

Health risks

EIA and EIPA, forest clearance, run of

the river dam construction.

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