After reading this article you will learn about:- 1. Objective of Green Belt Development 2. Suggested Scheme for Future Green Belt Development around Industrial Area 3. Choice of Plant Species 4. Planting Pattern 5. Current Status of Green Belt Development in India.
Objective of Green Belt Development:
It is an established fact that vegetation plays an important role in cleaning the atmosphere by absorbing certain toxic air pollutants from its surroundings. Thus Green Belts are recommended for containment of air pollution in the human environment, especially in urban and industrial environment.
In addition, there were a number of other benefits like aesthetic improvement, climatic amelioration, biomass generation, and enhancement of biodiversity are the bones derived through the presence greenery in the concerned areas.
Green Belt (GB) development envisages the multiplicity of objectives encompassing the micro level air pollutant abatement to enhancement of socio-economic value of the region. The prime objective of GB is attenuation of air and noise pollution.
It comes to the immediate rescue during accidental release/explosion minimising the risk to quite a considerable level. GB can also serve as a measure for soil protection for erosion losses, enhance the aesthetic value and beautify the landscapes.
GB also improve the soil quality in degraded landscape. Development of GB can help generate the employment avenues and thus involve the mass participation in environmental protection activity. On the whole, Green Belt can also act as a backup technology for pollution abatement measures which could substantially reduce pollution hazard.
Suggested Scheme for Future Green Belt Development around Industrial Area:
As per the air quality monitoring data around Industrial area, the particulate pollutant concentration is fairly higher during winter, and in few cases SOX and NOX level are greater than 30 µg/ m3. So major emphasis of Green Belt development will be given on particulate pollution abatement in and around industrial area.
In fact there is not much computable data available for measuring the total air pollutants emitted by the power plant on annual basis, as such accurate computation of effective Green Belt requirement through predicted theoretical model could not be possible.
However, for the design of GB around pollution source certain basic algorithms are used from Gaussian plume diffusion approach and settling rate concepts for air pollutants. In addition parameters considered for compulation of optimum width of GB depends on plants own pollutant sink efficiency and various morphometric features like height, canopy size, foliage stomatal distribution etc. along with atmospheric conditions like wind speed, solar radiation, humidity temperature of air etc.
Choice of Plant Species:
Air pollution tolerance index of plants species (trees and shrubs) are required at the initial stage. This is calculated by the formula proposed by Singh and Rao (1983).
APTI = A(T+P) + R/10
where, A = Ascorbic acid content of leaf T = total chlorophyll of leaf (mg/gm fresh wt); P = pH of leaf extract (cell sap); R = Relative water content of leaf (%).
On the whole selection of appropriate plant spectes is very important factor as they are the sink sites. In general, the plants should be fast growing with thick canopy cover to act as- a mechanical and biological barrier,
1. Perennial and evergreen plants having large leaf area index (LAI),
2. Preferably indigenous, resistant to specific air pollutants and should maintain regional ecological balance for soil and hydrological regimes of the region.
A list of pollution tolerant plants thus selected for the better Green Belt development in and around any industrial settlement (Table 13.8).
However, tree plantation with the objective of pollution attenuation is very site specific activity as it depends on the source strength, meteorological conditions of site and interaction with indigenous flora of the area.
However, a few generalizations can be made for GB plantation as follows:
1. Tall trees, with height more than 8 to 10 meter should be planted around the source,
2. Planting of trees should be in appropriate encircling rows, each rows alternating the previous one to prevent further fauning and horizontal pollution dispersion.
3. Since tree trunks are normally devoid of foliage, it would be appropriate to have small shrubs (Table 13.9) in front and in between the tree spaces.
4. The open areas between the process installations where trees cannot be planted should be covered with lawn grasses (Table 13.10) for effective trapping and absorptions of air pollutants.
5. Fast growing trees with thick canopy and perennial foliage should be selected so that the effective tree height with envisaged objective will be attained in minimum span of time.
Planting Pattern:
A standard horticultural practice involving planting of saplings in pits of substantial dimensions i.e. 1 m x 1 m x 1 m for big trees and along half of these dimensions for smaller trees and shrubs. The pits are then filled with earth, sand, silt and manure in pre-determined proportions. Saplings planted in such pits are watered regularly during dry months.
The growing plants are then cased at-least for the first two years under favourable conditions of climate and irrigation. Nutrients in pits are supplemented and the juveniles provided protection. Hence it is safe to assume that trees and bushes grow as green belt components.
For effective removal of pollutants it is necessary that:
(i) Plants grow under conditions of adequate nutrient supply,
(ii) Absence of water logging and
(iii) Are well exposed to atmospheric conditions (light and breeze).
For roadside avenue plantation, both automobile pollution and pollutants from power plant need to be considered. Components of Green Belts on roadside hence, should be both absorbers of gases as well as of dust particles, including lead particulates.
Thus the choice of plants should include pollution tolerant plant (shrubs of height 1 to 1.5 m and trees of 3 to 5 m). The intermixing of trees and shrubs should be such that the foliage area density in vertical almost uniform.
Current Status of Green Belt Development in India:
Govt. of India has made it mandatory to have Green Belt around the new as well as existing industries. However, no specific norms regarding the width of GB and pollution potential activity have been promulgamated so tar.
In many countries width of the Green Belt varies from 50 to 500 meter depending on pollution potential of the Industry. Moreover land availability becomes a major constraint in GB development around any source of pollution in India. By and large, in practice depending on space availability for mega industries 200m to 500m wide GB was suggested around pollutant emitting sources.