Planned urban developments – way to improve environment in cities

Rapid urbanization is transforming life throughout the developing world. Urbanization as a process is in itself is the biggest challenge for cities. It is also irreversible process. Urban planners claim that, urbanization is similar to an inevitable evil. The hub of civilization has been cities since the advent of industrial age. The economic process surrounding it is built on exploitation of nature and resources, killing rural outpost, creating inequalities and driving people to high density spaces – leaving rural spaces more exposed to un-controlled exploitation. Cities continue to grow in a haphazard manner. The city crises are many facets but it is only the clogged roads that are seen to be for what they are: impossible to live with. Issues like having enough water and power and getting rid of waste are considered serious.

The biggest challenges for these cities are increase in human density, which leads to problem of food, clothing & sheltering, sanitation, increasing number of slums and so the environmental degradation. Shortage of proper education, better health facilities, and most importantly a gap in demand and supply chain which contribute towards illegal operations getting started in those areas. In addition, low infrastructural and transport facilities in relation to the population growth make living condition problematic. Urban development is the key indicator for information of development indices. Some of the factors and problems to addressed are summerised as: (a) stable political situation, (b) economic strength, (c) corruption issue and public awareness, (d) skilled urban planners, (e) international relations for cultural sharing, (e) most important of all is willingness in the people and government to support for development.

Planned urban development is the key to overcome such problem of urbanization. Good land planning and infrastructure building in developing countries would help to create a perfect base which can be further nurtured with pollution free environment with sufficient greenery, better delivery of basic services like water and sanitation and finally a society with decent living. Research and demonstration are urgently needed if we are to realize our common dream of dynamic, environmentally and use-friendly cities. It is possible to revitalise depressed areas in ways that satisfy the wishes of residents and businesses. Resources such as land and materials can be reused and recycled. The scope for improving the way that buildings are designed, constructed and disposed of is tremendous. In managing the built environment, sustainability must be incorporated at various levels, from regional planning to individual construction sites. Planners, city councils, designers and urban residents all help to determine how cities develop and what construction methods are used.

Environmental issues play a central role in urban planning. However, in emerging megacities, infrastructure growth often takes precedence over the environment. Solving transportation issues has the highest priority in the cities surveyed, and air pollution is seen as the main environmental issue. The environment also plays a major role in the area of energy issues. Thus, alternative sources of energy will have a bright future in megacities. To meet growing demand for mobility, power, energy and water in the long term, megacities must not only build out their infrastructures and use them more efficiently; they must also proactively manage demand. However, city government experts are aware of the fact that efficiency must be improved significantly.

Importance of Urban green cover in improving environmental standard

In the last decade many of the developing countries in Asia, East Europe and Africa have seen rapid growth of industrialization, due to which many of the countries have emerged as economic power house. This rapid growth in industrialization has lead to unplanned development of urban areas by large scale cutting of trees, converting agricultural land into human habitation and deforestation. This has affected adversely on general environment and maintaining ecological balance. Rapid migration and increase in population in the urban areas has also lead to large scale spreading of air & water pollution, garbage etc., and also impairing aesthetic value of area / land. Traffic congestion, water shortages, solid waste, and air, water and noise pollution are common noticeable problems in almost all the urban areas since last few years. The escalated urbanization, associated with environmental degradation, has generated a debate on how much urban green space has been lost due to the urbanization process. Integrated means of addressing the ecological and environmental, economic and social concerns are still neglected in the framework of development. As a result, large areas of urban green space are declining rapidly, and causing numerous environmental problems. However, both environmental awareness and environmental legislation (setting of standards etc.) have advanced considerably in recent years, but enforcement is lagging almost everywhere.

Now, it is well recognized that urban green space plays an important role in the social and natural sustainability of a city. An increase of vegetated surfaces in the urban landscape, provide ecological diversity etc. - can help mitigate several negative effects of urbanization on climate, air pollution, since they contribute to the reduction of the structural differences between the urban area and its rural surrounding. The mitigation processes operated by the vegetation take place both through biophysical and microclimatological properties. Urban green cover form essential structural and functional elements that make cities and urban regions more livable places for their citizens. It is thus, key role of improving the quality of urban life as well as environment. Their imperceptible role in arresting pollution, acting as dust-busters, reducing noise pollution by muffling the sounds of urban living, their cooling effect on the city's temperatures, and how all of this can help keep climate change at bay, are well-known.

Good quality green space enhances the quality of urban life and contributes to wider Government objectives such as improved health, more sustainable neighbourhood renewal and better community cohesion, especially in more deprived communities. Neglected parks attract anti-social behaviour and have the potential to undermine regeneration of deprived neighbourhoods.

Urban green spaces provide a wide range of outputs, however, due to their multi-functional characteristics, the development and management of parks and green spaces is becoming a more and more complex planning issue that needs careful consideration, if green spaces are to be successful places, accepted and appreciated by citizens.

Importance of Forests:

Importance of Forests:

A forest is an area with a high density of all types of trees, shrubs, vegetations. Forests cover considerable areas of woodland. The word forest eventually came to mean wooded land more generally. Forests can be found in all regions capable of sustaining tree growth. Forests sometimes contain many tree species within a small area (as in tropical rain and temperate deciduous areas), or relatively few species over large areas (e.g., arid region). Forests are often home to many animal and plant species, and other vegetations. This emphasis on trees reflects their ecological, biological, and cultural importance. Also, trees are critical to the classification of forests. Trees represent some of the oldest living organisms on the planet. Trees are instrumental in the development and support of civilizations. They form important links in the earth's geological, chemical, and hydrological cycles by:

• Taking in CO2 and releasing oxygen;
• Releasing carbon and mineral elements such as nitrogen and phosphorus (important in plant growth) as they decay;
• Absorbing moisture for growth and releasing it as vapor through transpiration;
• Preventing erosion by reducing the force of rainfall at the soil surface and by intercepting and absorbing water, rather than allowing it to run off directly;
• Harboring a diversity of wildlife;
• Acting as windbreaks;
• Providing us with shade and beauty on a largely agricultural and urban landscape.

At present unfortunately, the forest environment has been impaired heavily by natural processes or by human activities resulting large scale deforestations. Deforestation is the conversion of forested areas to non-forest land by cutting of trees for urban use. Deforestation results from removal of trees without sufficient reforestation.

Impact on the environment by deforestation:

• Generally, the removal or destruction of significant areas of forest cover has resulted in a degraded environment with reduced biodiversity. In many countries, massive deforestation is ongoing and is shaping climate and geography.

• ·Deforestation, to be precise, responsible for Global warming.

• · Deforestation affects the amount of water in the soil and groundwater and the moisture in the atmosphere. Forests support considerable biodiversity, providing valuable habitat for wildlife.

• Moreover, forests foster medicinal conservation and the recharge of aquifers.

• ·Deforested areas become sources of surface water runoff, which moves much faster than subsurface flows. That quicker transport of surface water can translate into flash flooding and more localized floods than would occur with the forest cover.

• ·Long-term gains can be obtained by managing forest lands sustainable to maintain both forest cover and provide a biodegradable renewable resource.

• ·Forests are important stores of organic carbon, and forests can extract carbon dioxide and pollutants from the air, thus contributing to biosphere stability and probably relevant to the greenhouse effect.

• Forests are also valued for their aesthetic beauty and as a cultural resource and tourist attraction.

Water pollution by power plants – affects marine life adversely

Water pollution by power plants – affects marine life adversely:

Power plants use water for cooling. The quantity of water required by any fossil fuel fired power plant is huge - up to a billion gallons each day! As this water is discharged back to the river, thermal (heat) pollution occurs. This huge quantity of warmer water can create ice-free pockets in winter of cold countries, which can attract and then trap many species when the flow slows or stops. In summer, the hot water can add to oxygen-deficiency in the river water, choking fish and aquatic life. Heavy metals and chlorine in cooling water discharges are also having a negative effect on aquatic life in rivers and other water bodies.

Rivers which act as estuarine type nursery of ocean fish species are badly affected by such polluted water from power plants. There are millions of tiny fish eggs, larvae, and very young fish essentially adrift in the water, and hence extremely vulnerable to power plant cooling water intakes. These small animals are often killed by the passage through a plant’s cooling system. In some cases, about 60% mortality of newborn fish stock have been reported due to power plants. Moreover, Adult fish are also trapped and pinned to intake screens by the force of the suction.

Use of Fly ash - in cement making etc.:

Use of Fly ash - in cement making etc.:

Fly ash is the mineral residue resulting from the combustion of powdered coal in power generating plants. Fly ash consists of mostly of silicon dioxide, aluminum oxide and iron oxide. It is pozzolanic in nature, meaning it reacts with calcium hydroxide and alkali to form cementitious compounds. In the coal fired power plant the fly ash is collected by using electrostatic precipitators or filter bags. Initially, this collected ash was disposed of in ash ponds or landfills. Once its pozzolanic properties were discovered however, it became useful as a replacement of Portland cement in concrete. Fly ash can replace up to 50% by mass of Portland cement. Generally less expensive than Portland cement, it also presents advantages in a host of applications.

• Fly ash can be used to improve workability and pumpability of concrete. Due to its generally slower rate of hydration, fly ash also lowers the heat of hydration and is important in mass concrete structures, such as large foundations, bridges, and piers.
  


• High fly ash concrete shows less bleeding and shrinkage than straight cement mixes.
  Fly ash is also used as a component in the production of flowable fill, which is used as self-leveling, self-compacting backfill material in lieu of compacted earth or granular fill.

More and more fly ash is being used beneficially as a recycled material, although it is still far from fully utilized as more than 75% of fly ash produced from coal power plants is disposed in landfills. This amounts to hundreds of megatons in India and China, creating environmental problems. Though it is costly to retrofit older coal-fired power plants to filter fly ash from the atmosphere, over time the economic incentive of selling the captured fly ash pays for the initial expense of installation.

Nuisances of fly-ash generated by coal-fired power plant:

Nuisances of fly-ash generated by coal-fired power plant:

Thermal Power plants using pulverized coal or lignite as fuel generate large quantities of fly-ash as a by-product. With the increase in commissioning of several super thermal power plants with large capacity and with the increasing use of low grade coal of high ash content, the amount of generation of ash from them is becoming very large. This poses serious ecological problems. Most of the ash generated from the power plants is disposed off in the vicinity of the plant as a waste material covering several hectares of valuable land. Looking into the nuisances poses by fly-ash; it has been well appreciated by everybody and various Government agencies, the need for the safe disposal and effective utilisation of fly-ash. The properties of fly-ash depend on several variables such as coal source, degree of pulverization, design of boiler unit, loading and firing conditions, handling and storage methods etc.

At present in the under-developed country like India, the focus is on demonstration of coal ash related technologies - these include fly-ash characterisation, Hydraulic Structures, Handling and Transportation, Agriculture related studies and Application, Ash Ponds and Dams, Reclamation of Ash Ponds for Human Settlement, Roads and Embankments, Underground Mine Fills etc. Only a small quantity of the total ash produced is utilized in concrete, brick making, soil-stabilization treatment etc. The bulk utilization of ash is yet to begin in full swing.

Fly-ash characterization: - The physical, geotechnical and chemical parameters to characterize fly-ash are the same as those for natural soils, e.g., specific gravity, grain size, Atterberg limits, compaction characteristics, permeability coefficient, shear strength parameters and consolidation parameters.

Fly-ash disposal in Ash Ponds: - Fly-ash is mostly disposed off using either Dry or Wet disposal procedure. (a) In the case of dry disposal method, the fly-ash is transported by truck, chute or conveyor from the power plant to the site of disposal where these are disposed off by constructing a dry embankment (dyke). (b) In wet disposal, the fly-ash is transported as slurry through pipe and disposed off in impoundment called "ash pond". Most of the power plants use wet disposal system.

Environmental concerns: - The ash produced in thermal power plants cause all three environmental risks, such as, air, surface water and groundwater pollution. . Directly related to these concerns is the additional environmental goal of aesthetically enhancing ash disposal facilities. Air pollution is caused by direct emissions of toxic gases from the power plants as well as wind-blown ash dust from ash mound/pond. The air-borne dust can fall in surface water system or soil and may contaminate the water/soil system. The wet system of disposal in most power plants causes discharge of particulate ash directly into the nearby surface water system. The long storage of ash in ponds under wet condition and humid climate can cause leaching of toxic metals from ash and contaminate the underlying soil and ultimately the groundwater system. The environmental aspects of ash disposal should be taken care of in order to minimize air and water pollution. Most of the above environmental problems can be minimized by incorporating engineering measures in the design of ash ponds and continuous monitoring of surface and groundwater water systems.

Coal-fired power plants and pollution

Coal-fired power plants are the single largest stationary source of air pollution in any country. The toxins these coal fired power plants produce severely damage both human health and the environment and contribute to a reduced quality of life. Cleaning up these plants and finding cleaner, alternative energy sources is the overall objective to achieving clean, healthy air in every country.

Air pollution consists of a mixture of chemicals with various harmful effects on the human body, wildlife, plants, and climate. The main ingredients of air pollution are the following:

* Ozone Smog: Formed at ground level when sunlight mixes with nitrogen oxides and hydrocarbon vapors emitted by power plants, vehicles, and industry. It contributes to airway irritation, coughing, wheezing, asthma attacks, and immune suppression.

* Sulfur Dioxide (SO2): Gas emitted through burning coal and oil, that converts into acid gases (sulfuric acid) and sulfur particulate matter (pm). Health effects include: airway irritation, heart rhythm destabilization, and asthma attacks.

* Nitrogen Oxide (NOx): General term for NO/O2 hazes formed from burning coal, oil, natural gas, and gasoline. It is a main ingredient in acid rain and ozone smog.

* Particulate Matter (PM): Soil, soot, SO2, and NOx particles from power plants, cars, and factories that are tiny enough to penetrate indoor spaces and deep into the lungs. They can trigger premature death from heart attacks, lung diseases, and cancer in adults; and stunted lung growth, low birth weight, neurological impairment, and SIDS in children.

* Mercury (Hg): Toxic metal particles settle in water, contaminate fish, and move up the food chain. Mercury ingestion can result in premature birth, low birth weight, structural defects, learning disorders, heart and neurological defects.

It would be our prime objective, not only for the general public, but for govt. concerned to prepare effective means / legislations to control such hazards immediately.