Urban Forestry for Sustainable City
Environment and Climate Change
Thursday September 20 2012 22:25:46 PM BDT
Md. Zahidur Rahman and Saeed Ahmed Siddiquee
The global population pressure has increased in urban areas for passing better life. According to the UN Population Division, about 44% of the total populations in developing countries are living in urban area. There is no doubt that the urbanization will proceed to have significant impact on the ecology, economy and society at local, regional, and global scales.
The great impact have observe in the urban green spaces includes urban forest, parks, playground, urban domestic garden, roadside avenue and urban vegetation.
World Health Organization (WHO) stated that per city dwellers should have 9 sq. meter green spaces for ensuring better life. In developed countries, normally, have more trees (more than 20 sq. meter green spaces per city dwellers) to meets the ecological balance of human well-being compared to cities in developing countries, which often fall below the minimum standard of open green spaces set by WHO. For example, most of the cities of China have more than 30% and 6.52 sq. meter green coverage which is questionable for betterment of human life.
Now we have to look over the capital city in Bangladesh. What is the scenario really we enjoy in Dhaka city? It is one of the fastest growing mega cities in the world. The metropolitan city of Dhaka has an area of 131 sq. kilometer with more than 15 million populations. Currently, unplanned urbanization resulted ecological imbalances in the city. FAO (2008) pointed out that Dhaka city has 21.57% open space where city parks belong to 0.89% and 0.02% for urban forest, garden for 0.90% and 12.12% for agriculture to meets the ecological balance of the city dwellers. The green space has been reducing gradually by increasing building number without considering environmental protection. According to the Chief Town Planner of Dhaka City Corporation (2003), an ideal city needs 20% areas covered by trees but there is only 8% vegetation in the city. Currently, almost 15 million dwellers of Dhaka city enjoy limited ecological services from Ramna Udyan, Sohrawardy Udyan, Dhaka University campus, National Parliament Bhaban, Ganobhabon, Chandrima Park, Bahadur Sah Park, Botanical Garden and National Zoo etc. which can be regarded as important urban green resources.
Hence, green space in Dhaka city is now questionable in the context of entire global standard. Inadequate tree coverage in Dhaka city resulting many environmental hostility as well as human health related problem. Since 14 years, highest temperature has experienced in Dhaka city. Bangladesh Meteorological Department (BMD) reported that the maximum and minimum temperature of Dhaka city have gradually increased, adding hotter summers and cooler winters. In 27 April 2009, highest temperature was showed at 42.3 degree Celsius in Dhaka city. The urban heat has sharply increased in the recent few decades also with dust storms and the wind speeds has reduced in Dhaka city.
Department of Environment (DoE) pointed out that air pollutant (SOx, NOx and CO2) levels in Dhaka city are about 4 to 5 times higher than the levels prescribed in Bangladesh of Air Quality Standard (AQS). Such kind of pollutants remains and persists with air due to lack of tree coverage. Several research in US shows that trees can remove pollution by intercepting airborne particles. Another study of BAPA (2002) pointed out that these air pollution causes headache, burning of eyes, pain in throat, bronchitis, breathing problems, heart disease, anemia, mental problems, kidney disease and even cancer. According to expert of WBB (2002), about 33% of Dhaka dwellers suffer hearing problems due to noise pollution. In US one research estimate suggests that 7db noise reduction is achieved for every 33 meter of forest. Therefore, vegetation can play an important role in attenuating noise and absorbing sound energy.
Another important hydrological function of urban is growingly distressed as protection of drinking water resources in order of reducing woodland and trees. Undoubtedly it is true that increasing the area of green space will increase the volume of pure water of city authority. The limited trees in the parks and streets in Dhaka are unable to infiltrate and recharge of this rainwater. As consequences, drinking water becomes deflowered. Considering importance of woodland for water purification, Denmark has demonstrated woodland close to the cities.
Forthrightly, we should emphasize urban forestry and incorporate it into the urban planning and development. Two main reasons are for betterment of our healthy life in cities and second one is catching global agenda due to the present development scenario which forwarding towards sustainable development. Generally, we can do this in narrower scale beside the river bank and cannels around the cities, government office space, both private and public universities, school and college, park and beside the play ground, private open spaces, roof considering herb trees and slums in Dhaka city. The sum of total can present a remarkable contribution in the urban forestry for building green city, which will make important role for green job generation, improving health, environmental quality as well as aesthetic value of urban landscapes.
Apart from that, the master plan of Dhaka city should consider remarkable green space for ensuring urban dwellers healthy life in future. Rajdhani Unnayan Kartripakkha (RAJUK) should emphasize housing with garden strategy for the planned area under the master plan of Dhaka Metropolitan. A research is crucial for introducing types of tree in the open area of Dhaka city. Along with concrete coordination among forest department, Dhaka City Corporation (DCC), RAJUK and other stakeholders is needed to extend the urban forestry. Yet, the forest policy didnít consider urban forestry. Hence, possible sensitization of policy makers through this issue is urgent in recent days. Considering all the advantages of urban forestry, a holistic approach is needed for representing Sustainable city in future.
Md. Zahidur Rahman works in the field of Environment and Climate Change of Prodipan.
Reach them at firstname.lastname@example.org and email@example.com respectively.