FA2 Activity for CBSE syllabus, Grade X.

1. Advantages & Disadvantages of
Multipurpose Projects
Ebad ur Rahman X-B1

2. Multipurpose Projects
A multipurpose project is a large scale hydro project often including dams for water retention ,
canals for irrigation, water processing and pipe lines to supply water to cites and power
generation.These often include transportation improvements and industrial growth.They are
also developed to reduce the dangers of flooding. Some of the multipurpose projects in India
are:
• Bhakra-Nangal Projects
• Hirakud Dam Projects
• Mayurakshi Project
• DamodarValley Project
• Sardar Sarovar Project
• WesternYamuna Canal
• EasternYamuna Canal
• PeriyarVagai Project

7. Purpose of large dams
Dams and reservoirs are usually built to serve at least one of the following purposes:
 Hydropower generation: The most prominent use of large dams is for hydroelectric power generation,
combined with a hydropower plant.Compared to other renewable sources, hydropower produces the most
cost-efficient energy at costs as low as 2 US¢/kWh.
 Irrigation for agriculture: Water stored in a reservoir is used to irrigate agricultural crops. It is estimated that
30-40% of irrigated lands worldwide, which contribute 12-16% of global food production, rely on dams.
 Water supply: Especially in urban areas, reservoir storage capacities are used to supply drinking water or
water for industrial purposes.
 Flood control: As a positive side effect, dam structures often offer flood protection by regulating water
discharge and balancing runoff differences.
 Inland navigation: The navigability of a water system enabled through the regulation by the dam may
provide an impetus for trade and development. Inland navigation is the most cost effective and least polluting
means of transportation.
 Recreation: Finally, the lakes created through water storage can additionally serve recreational and touristic
purposes.

8. Issues to consider regarding large multipurpose dams
Sustainability
Adaptation to climate change

9. Sustainability
 Large dam projects are subject to widespread criticism due to their social and environmental impacts.The
construction of dams and the creation of reservoirs often lead to the resettlement of a high number of people,
as well as to major changes in the river ecosystem.This criticism equally applies to multi-purpose dams.
 Sustainable development of dams is therefore pivotal to ensure that dams provide true development benefits
without worsening the overall situation of the population affected by the dam. Negative social and ecological
impacts are to be mitigated or compensated; the participation of all relevant stakeholders, including the
affected communities, at an early stage is an important prerequisite.
 For multi-purpose dams, careful consideration and coordination of the interests of the different users are
additional prerequisites in order to avoid conflicts.While hydropower typically generates maximum output
from maximum storage levels in the reservoir, it is necessary for flood protection to keep the water level low
at certain times in the year. Further trade-offs between effectiveness and productivity may arise if irrigation or
water supply is combined with hydropower when water levels are low.

10. Adaptation to climate change
 Combined with political and institutional strategies, multi-purpose dams offer important solutions to climate
change adaptation needs, especially in vulnerable regions.Though climate change predictions are still subject
to a high degree of uncertainty on a local scale, rivers in dry areas of the tropical zone are expected to carry
10-30% less waterin the future, while humid areas are predicted to contain 10-40% more water.Therefore, in
regions likely to experience water stress, e.g. Southern Africa, increased water storage will make an important
contribution to improve sustainable access to safe drinking water and sanitation (a target defined in the
Millennium Development Goal #7). On the other hand, improved flood control is necessary to safeguard the
lives of millions of people in regions with increased precipitation and runoff, e.g. parts of Southeast Asia.
 Changing climatic and hydrological conditions are also challenging technical concepts of dam projects. If
economic viability analyses rely only on the historical time series of annual water levels, then dams may fail to
perform as desired when a water flow regime in the future substantially deviates from the past norms. In
addition to technical solutions, information exchange and coordination between different institutions and
sectors remains a key component for multi-purpose dams.To develop effective strategies to address climate
change, it will not suffice to treat individual dams in an isolated way. Basin-wide coordinated approaches for
all dams on a river system, although a challenging task, can be an important way to sustain ecosystems and
the overall benefits generated by dams.

11. Advantages of Multipurpose Projects
 Eliminates or reduces flooding.
 Impounds water for later use - irrigation, human consumption, industrial consumption.
 Lake fisheries
 Checking floods
 Power generation
 Navigation
 Recreation
 Habitat improvement
 Generation of Hydroelectricity.
 Improves transportation as part of a canal system.
 From a macroeconomic perspective, multi-purpose dams provide multiple benefits from a single investment.

12. Disadvantages of Multipurpose projects
 Inundation of thousands of acres of forests and agricultural land, a devastating blow to human lives and
biodiversity.
 Large forests get submerged under water.
 Due to anaerobic respiration by the plants submerged, Methane (CH4) is released causing the water to
become poisonous.
 Displacement of millions of people.
 Excessive sedimentation of the reservoir.
 Can cause flood.
 Stoppage of aquatic fauna migration.
 Can be the cause of water-borne diseases.
 Loss of arable land and salination of irrigated land.
 Disrupts existing infrastructure.

14. Challenges
 Most multi-purpose dams are funded by governments, with possible international donor support. Attracting
private investors to finance more multi-purpose projects is desirable but difficult due to the inherent
complexity. Conflict of interests among the individual uses, e.g. hydropower requiring maximum storage
levels and irrigation causing lower levels, result in complex and potentially vulnerable contract structures.
Often, promoting a single purpose dam, such as hydropower, is more economically attractive as it promises
secure returns on investment.
 Regulatory demands are more complex for multi-purpose dams as compared to projects serving only a single
function.Water rights and allocation quotas have to be distributed among the users, with potentially
competing demands and impacts usually spread over a large portion of the river basin.As a consequence,
inter and cross-sector coordination demands are much higher, requiring relatively strong institutional
capacities.
 The impacts of climate change may further intensify competition among the different users as the overall
water availability decreases.

15. Conclusion
Multi-purpose dams, if well planned and managed, provide an important option to meeting some of today’s
major development challenges. By providing clean and reliable energy, storage volume to improve drinking
water supply or agricultural food production, and enhanced flood control, they contribute to energy, water and
food security - and to human security in general. In vulnerable regions, multi-purpose dams can also be an
appropriate response to the impacts of climate change.Yet, as many new multi-purpose projects are expected
to be realized in the future, the sustainability of large dams and reservoirs will remain a key issue.