Impact Of Green Spaces On Environmental Pollution And Use Of And Accessibility To Urban Green Spaces

Urban Expansion with an alarming rate has been created a number of social,cultural,environmental and economical problems,specially,in the developing countries.With the intention to provide adequate facilities to the growing population,natural environments are converting into artificial structures such as buildings,roads and railways etc and as a result the extents of urban green spaces are decreasing day by day.Urban green spaces perform multiple functions in order to mitigate the terrible consequences of the urban sprawl.They provide an esthetically pleasing environment and give sustainable solutions for several environmental issues.They mitigate the global warming scenario and reduce the environmental pollution and provide habitats for animals.Further,natural parks provide the spaces for social and cultural gatherings for residents and provide facilities to engage in the physical exercises and create necessary platforms to release the mental stress created by unplanned urbanization.Therefore,it is very important to allocate a considerable portion of the city area for green spaces in the city planning processes.It has been introduced a number of standards on natural green spaces/natural parks which should be maintained by the urban administrators to reduce the environmental injustice.These standards are based on the physical extent,population density,accessibility to general public,coverage,spatial distribution,location based parameters and spatial characteristics.This study was designed with the intention to assess the reduction of green spaces and its consequences and use of and accessibility to urban green parks by the general public related to Colombo city which is the main economical hub of the Sri Lanka.Further,it was attempted to determine the role of urban green spaces on environmental pollution.In the study,it was firstly analyzed the use of urban parks by the general public.In this,the data were mainly collected from the residents in the Colombo urban area through a semi structured questionnaire under categories:non park users,park users who visit to the nearest park from their residence place and park users who do not use the nearest park regularly.These data were analyzed statistically through SPSS software.Study found main difficulties in the parks as the security problems,unclean environments,unwillingness to go to these spaces and privacy problems.The driving forces for the use of and accessibility to urban green parks in Colombo was identified and assessed by using the Analytical Hierarchical Process（AHP）based indicator approach.This conceptual model was built up based on 50factors under 08 main indicators through a semi structured questionnaire with the responses of regular park users in Colombo.Further,this approach was utilized to rank04 green parks in the district.The role of urban green spaces on air pollution and noise pollution was analyzed in the study.In this,concentrations of air pollutants（NO₂and SO₂）were directly taken from the Central Environmental Authority of Sri Lanka.It was found the relationship between the NDVI values and the NO₂and SO₂concentrations of each and every pixel using tools in GIS.In order to understand the relationship between spread of noise and vegetation of the urban environment,the study used a participatory approach to get the noise measurements using a mobile application at pre-scheduled time intervals.Finally,from these data,the noise spread map was prepared and it was analyzed with the NDVI map to understand the relationship between the two parameters.Study thoroughly emphasizes that the current practice of land use and the way of handling the natural environment in Colombo are not in the acceptable status.The results of this study can be used to prepare a sustainable and comprehensive city plan for Colombo city to achieve the millennium goals with economically strength and socially,culturally and environmentally stable.In addition to that,the conceptual model which was introduced in the study to assess the use of and accessibility to urban green parks can be enrich by altering the parameters of the model to assess green parks.Also,it needs to adapt the general public to the rules and educate them on the roles of green spaces on environmental processes.Further,study recommends to introduce the ratio of green to brown where green represents the forest coverage of the city and brown represents the total extent of the respective city to be used in city ranking scale.And as a practical solution to overcome this issue,it can introduce a tax paying system to get the motivation of the land owners to keep their lands greener and encourage them to make their territory into green in the process of making a healthy and wealthy city.