URBAN HEAT ISLAND
City of Johannesburg (CoJ)
M ARCH 1st SEMESTER
GSA, GITAM UNIVERSITY
The study of this paper involves what changes the City experience with the rapid Climate Change in temperatures, longer summer periods, uncommon winter and heavy rainfalls. With the rapid climatic changes in the City becoming more evident and have the potential to increase the vulnerability even in the livelihood.
It provides an insight on how to tackle vulnerability, disaster risk and climate change and adaptation efforts to be taken to share awareness of the issues in society.
1.1 URBAN HEAT ISLAND:
The term “urban heat island” (UHI) refer to the observed temperature difference between urban environments and the surrounding areas. Temperature in a heat island can be 5 – 12°C higher than the surrounding natural environment (Guay and Baudouin, 2005) (Voogt, 2002)
Urban heat island is a metropolitan area which is hotter that it’s surrounding rural areas due to human built environment. The main reason or cause for the UHI in the cities are due to the concentration of buildings, roads which absorb more heat than the suburb and rural areas during the day. After the urbanization the use of materials in urban areas for roofs, pavements, concrete and asphalt, which have thermal conductance and radiative properties than the rural areas. Other major reason for UHI is lack of evapotranspiration in urban areas. This is due to the lack of vegetation, shade and cooling effect of trees and increase in the carbon dioxide levels in the atmosphere.
1.2 Types of Urban Heat Islands
Urban Heat Islands can be broadly classified into two types – Surface heat islands and Atmospheric heat island:
1. Surface urban heat islands
2. Atmospheric urban heat islands
· Canopy layer Heat Islands
· Boundary layer Heat Island
Fig.1.Urban heat island profile
Johannesburg is South Africa’s most populated city in an area of 1645 km2. With rapid urban growth and environmental changes, increase need on resources have also multiplied. The direct impact of Urbanization has an in?uence on the natural spaces and surfaces are replaced by man-made structures, many harmful gasses are emitted into atmosphere resulting in the development of urban heat islands (UHIs) within the city and informal settlements.
2. LITERATURE REVIEW:
The urban landscape and topography is not a homogeneous surface is comprised of many different materials and structures; surface properties, thermal characteristics. The location such materials and natural features such as rivers and hills describe the urban form of CoJ.
The urban function and seasonal changes affect the amount of energy used and the increase levels of gas emission.
This report also makes a start to the process of assessing the relative prioritisation of adaptations. CoJ management has to identify and collating the data’s necessary for determining the foundation of future projected costs/benefits.
The world health organisations say that the gases the get released like carbon dioxide, nitrogen oxides, volatile organic compounds trap the dust which is the major cause for pollution. As Johannesburg is always ranked top in the most polluted city in the world. The regions is most effected with heat storms, pollution in the air, toxic water system which is causing health and environmental issues in the city.
Below are the listed risk identified with rapid changes
· Increase in Heat-Related Deaths
· Increased Energy & Water Demand
· Biodiversity Impacts
· Urban Flood Risk – Damage to Property, Personal Injury and Impacts on Livelihood
· Climate-Change-driven Refugees and Migrants
It shows that the climatic changes of CoJ will become hotter and humid in future Temperatures for the CoJ may increase by around 2.3oc by the near future (2056 – 2065) and additionally CoJ will experience increase in annual rainfall and storm events.
The Landsat classi?cation map was used to identify measurements points’ representative of the seven land cover class’s identi?ed. The urban heat island intensity (UHII), which is described by the equation ?Tu?r = Tu?Tr, was calculated by subtracting the mean temperature of the non-urbanized class from the mean temperature of the each of the other land use classes for each day represented in the satellite data dataset.
‘A National Climate Change Response Strategy for South Africa’. Was formed in 2004 to fulfil the strategy which is aimed at government and their associated institutions, including all public sector funding and implementing agencies, requiring that they access appropriate funds – such as investment through the Clean Development Mechanism (CDM) and financing institutions linked to government – for the implementation of the climate changes.
5. MITIGATION STRATEGIES
The government has decided on the mitigation strategies to overcome the climate change in the summers by making the city green and increase the mass transportation instead of single drive cars. The parking lots can both be used as urban forests and gardens and even thought to implement the sustainable gardens and landscape in the city.
Awareness and encouragement was done by the government to make their roofs green and grow vertical gardens. Large bus systems and cycle lanes were introduced to decrease the carbon emission. The government has planned to grow dense forest in the form of parks and sports areas around the city as a wrap to make the citizens to spend less time in the air-conditioning at office and homes. This decreases the emission of greenhouse gasses which is also a major element of urban heat island.
The storyline of this entire report the future is uncertain it is not possible to predict climate change with complete accuracy including the driving forces of future greenhouse gas (GHG) emissions, from demographic development, socio-economic development to technological change and economic developments.
Factors to be taken in consideration:
· Keeping cities cool – urban development to save energy and reduce waste heat;
· Promotion of flood control measures to adapt to effects of climate change;
· Promotion of water leakage prevention and provision of technical information;
· Integrating concepts for mitigating the Urban Heat Island effect into strategic urban planning
Effective implementation of these and other risk- specific adaptations will require commitment from both the planning and resource level from a broad range of CoJ departments, municipal entities and other stakeholders.
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