Advantages & Disadvantages of Multipurpose Projects

Ebad ur Rahman X-B1

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• Damodar Valley Project• Sardar Sarovar Project• Western Yamuna Canal• Eastern Yamuna Canal• Periyar Vagai Project

Purpose of large damsDams 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.

Issues to consider regarding large multipurpose dams

SustainabilityAdaptation to climate change

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.

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 water in 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.

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.

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.

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.

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.