Original Paper Urbanization, Climate Change and Environmental Resilience: Experiences in Sri Lanka

Urbanization in conjunction with climatic change affecting urban life and pose challenges to cities worldwide creating urban residents increasingly vulnerable to extreme weather and other natural disasters. Improvement of urban ecosystems provide cost-effective solution against negative impacts of climate change accelerated with high population pressure and promote resilience of urban dwellers. The cities in Sri Lanka are focused on improving land use planning and management of urban forest ecosystems for adaptation to and mitigation of climate change impacts with the rapid urbanization. This study attempts to ascertain the effects of urbanization, analyze the impacts of urbanization and climate change, and examine the environmental resilience with urban forests in Sri Lanka, reviewing the relevant literature. This paper explore the effects of urbanization in terms of increase population, land use change, rising greenhouse gas emissions and intensity of urban heat island. The impacts of urbanization and climate change are revealed as change of annual rainfall, urban warming, extreme weather events, and urban health hazards. Disaster resilient cities, sustainable urbanization, greening the cities, other environmental resilience strategies as well as institutional and policy setting are discussed for environmental resilience to urbanization and changing climate. Limiting CO2 emission, reducing land surface temperature, and controlling urban heat island effect are discussed under the other environmental resilience strategies. Institutional and policy setting is explained through popularizing urban forestry and developing policy support. Urban forestry strategies incorporating urban planning should be manifested in urban development policy in order to counteract the negative effects of climate change in the process of environmental resilience and sustainable urbanization.


Urbanization
Urbanization has a continuing trend globally which is taking place in conjunction with climatic change affecting urban life and pose challenges to cities worldwide. Evidently, climate change may create hundreds of millions of urban residents increasingly vulnerable to extreme weather and other natural disasters in the coming decades. According to the World Health Organization (WHO), the urban population in the world is expected to grow approximately 1.84 percent per year between 2015 and 2020, 1.63 percent per year between 2020 and 2025, and 1.44 percent per year between 2025 and 2030 (https:// www.who.int/data/gho/data/indicators). South Asia with an area of about 4.5 million km 2 represents 3.31% of the world's land mass and has 22% of the world's population which has increased from 1.13 billion to 1.76 billion from 1990 to 2016 as one of the fastest and leading urbanizing zones in the world (Saparamadu et al., 2018). According to the UN estimates revealed at the World Economic Forum on ASEAN, over half of the population in Asian (4.5 billion) will live in cities by 2026 (World Economic Forum, 2018). Unplanned urbanization face traffic congestion, increased waste resources, limited social services, disorder and confusion in land-use patterns and contribute to environmental challenges including natural disasters and environment pollution. The vulnerability of urban populations to events of higher temperatures, sea-level rise and reductions in freshwater availability in major cities have become a common feature in many locations in the world. The local warming caused by overall tendency of urbanization has induced a proportion of global warming during the last century, as a key issue from the climate change perspective (Paranunzio et al., 2019). The impacts of climate and land use changes driven by urbanization effectively reduce the trade-offs and increase losses of ecosystem services. Hence, urban planning to enhance ecosystem services under future climate change impacts has great importance in ecosystem management and policy making for environment resilience urbanization (Lyu et al., 2018).

Urban Forest Ecosystem
Improvement of forest ecosystems in urban centers can provide cost-effective solution against negative impacts of climate change accelerated with high population pressure. Urban forests such as urban wetlands, nature reserves, urban parks, landscaped and green pathways, river corridors, coastal paths, street trees, woodlots, shelter belts of trees, public gardens, orchards, urban home-gardens etc., are broadly recognized in many different shapes and sizes. Urban forests have a diverse structure, found in stands or arranged in lines or as single trees, remnants of native forests or be deliberately grown vary in composition, diversity age, health status and ownership patterns (Ordóñez et al., 2010). Green elements of urban forests are integral components of the territorial development of urban regions reducing the 47 Lanka Program launched by the Ministry of Environment, Sri Lanka in 2009 (Ministry of Environment, 2012). However, the impacts of climate change on urban centers with rapid urbanization and adaptation of urban ecosystem with urban forestry to climate change are the least studied areas in Sri Lanka.
Planning and designing of urban forest in major cities in Sri Lanka is a challenging task with the rapid urbanization and increasing climate change impacts. Urban-forestry receives limited attention from researchers and policy makers in urban planning and management of natural resources in urban centers (Colgan et al., 2014).

Methodology
This study therefore attempts to ascertain the effects of urbanization in major cities, analyze the climate change impacts of rapid urbanization and examine the resilience of urban environment to sustain and improve health and well-being of the urban dwellers. This study is based on a review of literature considering urbanization, climate change and environmental resilience of urban forestry with special reference to Sri Lanka. This paper discuss the effects of urbanization; impacts of urbanization and climate change; and environmental resilience to urbanization and changing climate in urban areas in Sri Lanka.

Increase Population
Rapid growth of urban population due to natural growth, migration and expansion of cities integrating rural areas declines the quality of urban environment has become serious concern of the urban planners.
It is difficult to make international comparisons of urban population because the countries are using very different urban definitions. The urban landscape of Sri Lanka consist of 6 cities with more than 100,000 population, 34 intermediate or medium-size towns with 20,000~100,000 population, and 94 small towns of fewer than 20,000 (The World Bank, 2012). An alternative projection of the urban population is based on agglomerations of more than 20,000, 50,000, 100,000 or 500,000 in ranking a list of towns and cities by the size in each country (Bocquier, 2005).
Compared to the United Nations estimated 60 percent urban population in Asia, the urban population in Sri Lanka will remain 40 percent by 2050 along with marginally dropped percentage of urban population of the country during last three decades (Gasimli et al., 2019 There is a disagreements from different conceptual models of urbanization derived from a statistical perspective. Urbaneness is defined in India concerning the legal boundaries of urban jurisdictions other than population density, areal contiguity, and the total population of sufficiently dense adjoining areas (Balk et al., 2019). Analysis of population growth rate with urbanization has also become a complex and challenging task. According to The World Bank (2012), the compounded annual growth rate of urban population is comparatively and positively high in Colombo (4.9 percent), Galle (3.8 percent) and Gampaha (3.2 percent) while negative in Anuradhapura (-0.4 percent) and Kurunegala (-0.6 percent), the major cities in Sri Lanka during the period from 2001 to 2009 (Table 2) Vol. 4, No. 1, 2021 and benefits are not distributed equitably among urban communities where the urban poor living in unacceptable conditions (George & Leeson, 2018).

Land Use Change
Connecting land use pattern with urbanization process under the changing climate has become an important attempt to explore and quantify urbanization. Urban concepts and measures undergo frequent revision as there is no well-established, consistent way to measure either urban land or density of population. For the comparison urban structure and its changes, land that is more than 50 percent built-up and people living are classified as urban while less than 30 percent built-up areas classified as suburban and peri-urban according to urban proxies for the US (Balk et al., 2018). According to a spatial analysis, the urban built-up area in Colombo the capital city of Sri Lanka increased from 41 km 2 in 1995 to 281 Km 2 in 2017 diminishing the non-built up areas from 125 Km 2 to 10 Km 2 (UN-HABITAT, 2018). Another study has proved that the land use change where built-up area has increased by 29.36 km 2 while decreased in other cultivation (-11.75 km 2 ), paddy (-8.46 km 2 ), boggy (-5.11 km 2 ), water (-1.74 km 2 ), and sand land use (-1.51 km 2 ) in Colombo city from 1990 to 2015 (Saparamadu et al., 2018) (Table 3). The green space in Colombo city in Sri Lanka has remarkably change with "annual reduction rate of 0.46km2 (1980-1988), 0.39km2 (1988-1997), 0.37km2 (1997-2001), 1.37km2 (2001-2011) and 0.71km2 (2011-2015)" due to a higher rate of increasing population density and economic development of the country (Li & Pussella, 2017).
Urbanization in Sri Lanka has converted large area of agricultural lands to housing and commercial use.
Urbanization induce land scarcity through anthropogenic interference related to forest degradation for 52 www.scholink.org/ojs/index.php/uspa Urban Studies and Public Administration Vol. 4, No. 1, 2021 urban agricultural expansion, urbanization on formerly agricultural land, or the competition for the use of urban space (Froese & Schilling, 2019). Change of land use pattern with urbanization process and climate change has become critical knowledge gap in enhancing and managing the tradeoffs between agricultural production, food security, and environmental goals in urban areas. The urbanization processes in Sri Lanka is the main driven force leading the land use/land cover (LULC) change particularly the trend of demands and pressure on agricultural land to become non-agricultural land.
With rapid urbanization, the built-up area of Nuwara Eliya, the capital city of up-country in Sri Lanka,

Rising Greenhouse Gas Emissions
Rapid urban population growth, increased vehicle ownership and higher consumption of fuel, make contribution to rising greenhouse gas emissions in Sri Lanka. The transport sector in Sri Lanka consumed 50 percent of the total fossil fuel consumption and contributes 30 percent of the total urban air pollution in the country (Ministry of Environment, 2012). Although CH4 and N2O are commonly found in urban areas, the most prominent anthropogenic greenhouse gas is CO2. It has been measured that Methane gas emission was 1507.681 m 3 and CO 2 gas emission was 9474.516 m 3 in Colombo

Region (CMR) in 2003
(http://www.climatechange.lk/Documents/Project_Terminal_Report.pdf). The carbon emission is changed with the changes of urbanization level particularly in response to the changes in energy consumption, and economic levels. A study in Sri Lanka confirm that urbanization has significant effect on carbon emissions in the long term as well as in the short term with increase of the energy consumption (Gasimli et al., 2019). Urban areas are mainly responsible for more than 70 percent CO 2 emissions related to global energy consumption and increase with the continuous trends of urbanization (Hegazy et al., 2017 (Ministry of Environment, 2012). A long-term relationship between carbon emissions and urbanization together with energy consumption, income level, and trade openness has found in Sri Lanka (Gasimli et al., 2019). The impact of urbanization level on carbon emission is significant in the long or short term, until the continuously increased GDP and technology advances make the stable decline in per capita carbon emission (Zhang et al., 2015).

Intensity of Urban Heat Island
The Urban Heat Island (UHI) effect in a large cities in Sri Lanka are experiencing with rapid urbanization resulted in a tremendous land cover change dynamics and consumed vast areas of land adjacent to the cities. The phenomenon of Urban Heat Island (UHI) is that the temperature in urban areas is higher than the surrounding rural areas, which is a critical issue in the cities with rapid urbanization. Gradual enhancement of the effect of Urban Heat Island (UHI) is usually noted an increasing trend of Surface Air Temperature (SAT) in local observation series, in comparison with nearby rural stations as the urban environment develops (Yan et al., 2016). The Urban Heat Island (UHI) is caused by the heat-storing structures that increase the heat capacity of the cities with rapid urbanization and create relative warmth of the urban areas with respect to the rural surroundings (Argüeso et al., 2014). An empirical finding on Nuwara Eliya a mountain city in Sri Lanka a renowned   Vol. 4, No. 1, 2021 temperature between the urban and rural areas shows an increasing pattern from 1.0 0 C in 1996, 1.3 0 C in 2006 and 3.5 0 C in 2017 .
The warmer temperatures in urban areas in Sri Lanka due to high-rise buildings, concrete structures, poor air quality and limited shade and green space adversely contribute to Urban Heat Islands (UHI) effect.
Although large areas of Colombo city in Sri Lanka remain low rise, a significant urban warming has been recorded with high-rise development. Even though a large area of Colombo city remains "low-rise" blocks, the Urban Heat Island (UHI) is intensified by the mixture of 'mid-rise' and 'high-rise' blocks (Herath et al., 2018). The greatest difference in Urban Heat Island intensity (UHI) of the Colombo city However, Colombo, the capital city of Sri Lanka is highly humid area and with this higher temperature values ranged the average between 23 0 C-32 0 C. The city is suffering from Urban Heat Island (UHI) intensities of 0.090C-4.40C compared to surround rural and suburb areas creating undesirable living condition and poor thermal comfort (Herath et al., 2018). More than 60 percent of agricultural lands in Kesbewa Urban Council area was converted to residential areas by 2012 for the expansion of boundaries of Colombo Metropolitan Region (Mohamed & Gunasekera, 2014). Land cover changes from natural or agricultural lands to build-environments due to rapid urbanization increase air and surface temperatures in the urban area as compared to its rural surroundings, transform cities into urban heat islands (UHI) (Middel et al., 2015). The empirical finding of a study indicate the reductions in green space in high-density residential areas and town centers in 10 percent will increase surface temperatures by 7-8.2°C by 2080 (Dulal, 2017). Any occupational health hazards caused by UHI has not been reported yet in Sri Lanka. UHI has a significant adverse health experiences in elsewhere depending on duration of working in the city, and being in high-rise and high-density buildings (Wong et al., 2017)

Change of Annual Rainfall
Sri Lanka is experiencing in increasing trend of percentage change in annual rainfall and predicted several extreme weather events with very heavy rainfall in the future. The analysis of long-term trends of rainfall as climatic variables in Colombo city of Sri Lanka indicate that the average annual dry days (193.41) and average annual wet days (171.84) are changing with large standard deviation annually (Chen & De Costa, 2017). High intensity and frequent rainfall has been recorded in wet-zone cities particularly Ratnapura, Ratmalana, and Colombo by El Niño-Southern Oscillation (ENSO) as the primary climate driver in Sri Lanka (Naveendrakumar et al., 2018). The long-term trend of the annual rainfall records in Colombo the capital city of Sri Lanka for the 30 years from 1981 to 2010 shows that there was an increase (R 2 = 0.146) slightly from the average annual rainfall of 2302 mm with some recorded high rainfall values ( Figure 2). Further analysis with simulated rainfall data from 2011~2099 of Colombo city in Sri Lanka has revealed that very heavy rainfall as an extreme weather event may occur in the future particularly during 2080~2099 (Lo & Koralegedara, 2015). Contrary, a study has shown that the periphery of urban areas experienced a higher probability of heavy rainfall while the urban areas have decrease in rainfall with climate change impacts (Niyogi et al., 2017).

The analysis of rainfall has shown a strong increase trend of monsoon rainfall in Batticaloa Municipal
Center (28 percent) and Negombo Municipal Center (34 percent) and increase of minor floods during the last two decades (Ministry of Environment, 2012 climate change pose significant threats for flooding in urban areas with increased rainfall (Miller & Hutchins, 2017).

Urban Warming
Urban warming with anthropogenic heat emissions is a profound impact of urbanization process and The impacts of climate change in the in Batticaloa Municipal Center in Sri Lanka shows that the recorded daily temperature during the last two decades has a trend of increasing in 0.4-0.5 0 C compared to the previous two decades (Ministry of Environment, 2012). The trend of temperature in Colombo city of Sri Lanka is increasing with 0.0164 0 C/year and R 2 =0.67 with the change of micro climate conditions due to increasing population and rapid urbanization (Chen & De Costa, 2017). Increases of high heat stress in urban areas as an impact of climate change dependent on urban density and the climatic setting of the city (Oleson et al., 2013). However, urbanization-induced warming in urban areas is greatly complicating in the determination of actual climate change (Ren, 2015). 1981 1984 1987 1990 1993 1996 1999 2002 2005 2008 Year 4000 Vol. 4, No. 1, 2021 The results from the interaction of urban human activities and local climate change contribute to human-induced heat emission. The rising trend of temperatures in urban areas is more apparent with the transformation of rural landscape and its natural vegetation to urban landscape, under urban land expansion together with climate change impacts. Changing temperatures may negatively impact on terrestrial forest cover near urban settlements and the flora and fauna they contain as Sri Lanka is a biodiversity hotspot. www.scholink.org/ojs/index.php/uspa Urban Studies and Public Administration Vol. 4, No. 1, 2021 The annual cost of energy consumption in residences in Colombo Metropolitan Region (CMR) under conventional design options is estimated at US$ 3 million per square km (at domestic electricity rate of US$ 0.08-0.10/kWh) with significant increases in the cooling load due to urban warming (http://www.climatechange.lk/Documents/Project_Terminal_Report.pdf). Socially and economically disadvantaged populations within urban areas are vulnerable to the adverse effects of climate change and expose to higher extreme temperatures and also less able to take adaptive actions (Fagliano & Diez Roux, 2018).

Extreme Weather Events
Rapid urbanization increases in demand and use of urban resource while the urban dwellers exposed to climate change and climate induced extreme weather events. Expansion of cities with complex and interdependent structural systems under urbanization to accommodate increased population and in response to increases in greenhouse gas emissions, make cities extremely vulnerable to threats from natural hazard. The Global Climate Risk Index 2019 has listed Sri Lanka as one of the most affected country from extreme weather conditions with significant increase in vulnerability especially urban communities to climate change (Karunanayake, 2019). Vulnerability to high intensity rainfall, frequent and prolonged droughts, increased storm activity and sea-level rise have been identified as significant impacts of climate change to the coastal city habitats and thus the whole economy of Sri Lanka. The following maps shows the exposure indices for floods, droughts, landslides, and sea level rise respectively in the planned mega cities and urban centers in Sri Lanka (Map-1~4) (http://www.climatechange.lk/Documents/Project_Terminal_Report.pdf).
Likelihood of flooding becomes higher in many urban areas in Sri Lanka and also exacerbated by higher rainfall intensities. Rainfall extremes with high intensity and frequent rainfall causing flash floods in urban areas has been frequent during recent years particularly in wet-zone cities in Sri Lanka mainly Ratnapura, Ratmalana, and Colombo (Naveendrakumar et al., 2018). The analysis of historical rainfall data and simulated rainfall data of Colombo city in Sri Lanka has predicted several very heavy rainfall in the future particularly during 2080~2099 causing excess runoff, and potential overflow and urban floods as a result of the Climate change impacts (Lo & Koralegedara, 2015). There are more dry days than wet days even within the highly changing dry and wet days in Colombo city of Sri Lanka rising more frequent flooding particularly in lower part of Kelani River causing flash floods (Chen & De Costa, 2017). Balangoda town which is strategically and economically importance in the central hilly region of Sri Lanka experiencing severe flooding during heavy rains over recent years (https://www.fukuoka.unhabitat.org/projects/sri_lanka/detail20_en.html). The largest flood occurred in the Batticaloa MC during December 2009-January 2010 for the last 100 years loosed lives and properties while damaging the tourism industry emerging in the coastal city (Ministry of Environment, 2012). Frequency and magnitude of urban flooding in many regions of the world has substantial increased as the urban drainage systems have ineffective to collect and convey increased storm water and wastewater due to rapid urbanization and changing climate (Zhou, 2014). 60 www.scholink.org/ojs/index.php/uspa Urban Studies and Public Administration Vol. 4, No. 1, 2021 With the rapid urbanization, around 80% of national economic infrastructure as well as 70% of the population of Sri Lanka are concentrated in cities located in coastal and hilly areas have become highly vulnerable to disasters of climate change and predicted impacts. Sea level rise, salination of water resources, storm surges, floods and landslides as climate change impacts together with malaria and dengue epidemics of coastal cities and cities in disaster prone hilly areas in Sri Lanka create constraints achieving the Millennium Development Goals in terms of productivity of cities and delivery of service especially for the urban poor (https://www.fukuoka.unhabitat.org/projects/sri_lanka/detail20_en.html).
Climate change have significant impacts increasing episodic (e.g., storm events) and chronic (e.g., sea level rise) hazards on the cities in coastal zone in Sri Lanka where a large percentage of population is located and also the areas making significant contribution for the economic growth of the country (Hettiarachchi & Samarawickrama, 2012). The climate change impacts on coastal zone in Sri Lanka which accounts for about 43% of the GDP make substantial impacts on the national economy (Nayanananda, 2007). The studies have revealed that the sea level rise in coastal cities in Sri Lanka may inundate and displace low lying wetland and coastal areas; erode coastal and degrade shoreline; salinize freshwater aquifers and estuaries, and relocate fresh water intakes; and change and migrate coastal habitats and eco-systems (Hettiarachchi & Samarawickrama, 2012).

Urban Health Hazards
Incidence and the level of exposure of wide range of vector-borne diseases are increased with the increased temperatures, changes in precipitation together with urban waste in major cities in Sri Lanka. relatively higher temperature (Udayanga et al., 2020). Urban residents in selected urban area tested in 2010 reported a significantly higher prevalence of coughs, phlegm and wheezing than those living in the rural area (Perera et al., 2010). Rapid urbanization and increase in extreme weather events lead to human health consequences such as heat stress, cardio-respiratory and infectious diseases (Paranunzio et al., 2019). Rapid urbanization with the growing migrant population, dramatic changes in the natural landscape and unprecedented impacts from climate change create infectious diseases as a major cause of morbidity and mortality (Tong et al., 2015).
Colombo Municipal Council area shows relatively higher exposure level (0.89: higher exposure level) for climate change compared to Kandy Municipal Council area (0.79: higher exposure level) (Udayanga et al., 2020). Rapid urbanization in relatively high-risk areas need special concern because development should be concentrated not only on people and assets but also on increasing vulnerability to climate-change impacts (Garschagen & Romero-Lankao, 2013   The overcrowded populations with rapid urbanization in Sri Lanka are vulnerable to climate change impacts and make additional stresses on urban services and public health services. The deepening stress on the water resources are experiencing in major cities in Sri Lanka mainly due to ever increasing demand for human needs and also due to impacts of natural disasters including the climate change.
Urban households generally consider water quantity which is more important than its quality even contaminated water supplies during droughts.
Although the urban households are better off than their rural counterparts, the community living in poor urban areas can be among most life-threatening environments. Rapid urbanization and rural-urban transmigration pushes more and more people into the major cities in Sri Lanka while pushing more poor urban people living in hazard-prone areas in major cities with exposure and vulnerability to climate and disaster risk.

Disaster Resilient Cities
Urbanization and climate change cause natural disasters within urban spaces directly and indirectly.
The urban disaster risks are increasing in Sri Lanka with high population density and concentrations of vulnerable people in urban areas together with intensification of adverse impacts of climate change.
Urban planners and policy makers have shifted towards inclusion of disaster risk reduction in development practices with the increasing frequency of disasters induced by climate change. Disaster resilient city minimize disasters by building resilience to adverse environmental changes including climate change. The Disaster Resilient City Development Project in Sri Lanka attempted to develop disaster resilient cities and townships in disaster prone regions of Sri Lanka to adapt to climate change, and mitigate its risks (Ministry of Environment, 2012). The concept disaster resilient city aims to develop the urban resilience, the ability to overcome natural disasters particularly climate change that the urban areas face. Resilience is the ability to reduce the impact, damage, or stress inflicted on a city and the ability to recover the city to its previous or better state (Park et al., 2021 government is holding the legislative power by the country's Disaster Management Act (Malalgoda et al., 2013).
Urban planning and development in Sri Lanka draw attention for climate change impacts and related disaster risk in cities as well as urban ecosystems components of resilience framework for cities.
Removal of vegetation and climatic changes can possibly increase the vulnerability of an urban areas and its coping capacity in Sri Lanka. Therefore, understanding of the broad issues regarding urban fringe zones, urban ecosystems and climate change, and inclusion of these issues have to be included in the overall urban planning process. Efficient urban disaster management on threat of heavy rainfalls causing urban floods in many parts of Sri Lanka is considered for the implications of climate change.
Re  Transition from unutilized urban land to urban forest in Sri Lanka attempts to assure cities with urban green tree cover and provide environmental services by promoting the capacity of ecosystems.

Map 5. Development of Disaster Resilient Cities in Sri Lankan
Enhancement of multi-stakeholder resilience and culminate in a multi-purpose green belt were aimed by the "UN-HABITAT Climate Resilient Action Plans for Coastal Urban Areas" (Hettiarachchi & Weeresinghe, 2014). Batticaloa Municipal Council has established 12 km in length of multi-purpose green belt to restore mangrove eco-systems and coastal bio-diversity in protecting the lagoon and coastal areas https://fukuoka.unhabitat.org/programmes/ccci/pdf/SRL4_Climate_Reslient_Action_Plans.pdf. Green areas are highly resilient and are more able to cope with and systematically manage climate change impacts in vulnerable urban areas (Park et al., 2021 Vol. 4, No. 1, 2021 Urbanization Strategy in 2016 support for sustainable, inclusive and resilient cities in the developing countries (Kazak, 2018). Sustainable urbanization respond to rapid urbanization in developing countries and its consequences that are relevant to achieving the SDGs in cities and urban areas for sustainable development (UNDP, 2016b). The urban based crisis-ridden economic development has underscore the need to pay attention to urbanization thus overall urban metabolism has become totally unsustainable (UN HABITAT, 2012). It is difficult to interpreted sustainable urbanization without climate change related themes. Sustainable urbanization taking urgent action to combat climate change and its impacts is critical to achieve the Goal 13 of Agenda 2030 (UNDP, 2016b). Adaptation actions in the context of accelerating climate change patterns should be incorporated into the process of urban planning for sustainable urbanization (Kazak, 2018).   Vol. 4, No. 1, 2021 Development in 2030 concern sustainable cities and community well-being and climate actions. Green mechanisms is a great effort in urban design for sustainable urbanization in order to enhance the quality of life of urban communities (Hegazy et al., 2017). Supply of drinking water in major cities in Sri Lanka has become a deepened stress on the water resources mainly due to ever increasing demand for human needs and also due to impacts of man-made and natural disasters including the climate change.
Urban forests help in storing water in soil profiles which increase resilience to drought exacerbated by climate change. The existing storm-water and sewer systems in the urban areas in Sri Lanka are often inadequate to handle peak flows in impervious surfaces dominating urban cores with rapid urbanization.
Urban forest trees often decrease the amount of storm-water runoff by capturing and storing rainfall in the canopy and, reduce sediment and pollutants through the roots improving water quality before reaching urban water streams. Trees in urban forest absorb gaseous pollutants and intercept particulate matter including dust and smoke in the urban areas. Rehabilitating and re-connecting productive green spaces by urban forestry and urban agriculture throughout the cities reduce surface flows and enhancing infiltration reduces urban flood risks while contributing substantially to urban household nutritional needs. Urban Forest in home-gardens return a multitude of environmental services and economic benefits to the urban households continuously. Green roofs combined with urban agriculture turned into urban forests reduce urban heat islands and cool the city heat created by climate change impacts. Urban agriculture through food on rooftops produce part of the food requirements for growing urban communities in a more sustainable manner (Chan, 2017). Maintaining the food security of rapidly growing urban populations is greatly affected by climate change, which is a main challenge for an active and healthy urban life. The Sri Lanka Climate Fund (SLCF) under the Ministry of Mahaweli Development and Environment, restores abandoned paddy lands to a crop producing areas and provides resources for households to start their urban home gardens, as market based instruments to deal with urbanization challenges and mitigate climate change (https://cdkn.org/resource/integrating-urban-agriculture-and-forestry-into-clima). Integrating elements of urban forestry, urban agriculture, and agroforestry is a multifunctional approach to improve food security and nutritional status, and sustainability of urban landscape (Clark et al., 2013). sustainable urbanization to extend urban agriculture, urban forestry and eco-parks to achieve food sovereignty and promote food production as a climate change adaptation strategy (Kekulandala at al., 2012). Urban green spaces is a key component of urban sustainability enriching human life by providing social and psychological benefits and improving the quality of life of the city dwellers (Rostami et al., 2015).

Greening the Cities
Greening the cities develop a high proportion of forested land within the city borders. Greening city spaces are advised by UNDP to create and manage urban protected areas and implement green infrastructure solutions (UNDP, 2016b). Greening the cities in Sri Lanka help to mitigate negative impacts of unplanned and rapid urbanization creating pockets of forests, landscapes and green areas in the main urban areas thus make them more resilient to the climate changes. Rapid urbanization and migration to cities create land more precious, and convert urban green and public spaces to residential housing and businesses (UNDP, 2016b). Green elements including street trees, gardens and parks support the connectivity creating a network which allows ecological processes tackling environmental challenges, including climate change in urban areas (Grădinaru & Hersperger, 2019). Green spaces mitigate the impact of urban heat islands and improve air quality through the uptake of pollutants and reduce of energy costs for the cooling of buildings (Froese & Schilling, 2019).
Kandy city in Sri Lanka covers 28.53 Km 2 with 150,000 residence living population where 15 percent of the land and has been designated as three forest reservations, the UdwattaKalle Rainforest Reserve, Dulumadalawa Sanctuary and Hantanne Forest Area (Ministry of Defense and Urban Development, 2014). Udawattha Kele is an urban forest located in Kandy city in Sri Lanka which was declared as a sanctuary in 1938 under the forest department. Colombo city area in Sri Lanka had maintained a good rate of per capita green space which is used to evaluate the environmental sustainability, satisfying the UN, WHO and EU standards until 2011 (Li & Pussella, 2017). Shading by vegetation of urban green areas and forests keeps the temperature tend to equalize between urban areas to neighboring areas by acting as a solar radiation interceptor that reflects and absorbs radiant energy temperature (Kazak, 2018). Urban forestry has become a valuable part of urban life helping the urban dwellers for physical and mental health, better community cohesion, livelihood development and improved quality of life.  Vol. 4, No. 1, 2021 mental, spiritual, and emotional states of harmony within healthy urban environments to achieve livable cities and the well-being of urban dwellers to achieve main goals of sustainable urban policy (Rostami et al., 2015).
Association between percentage green space and the population density particularly the low income city dwellers are critical in the utilization within densely built urban environments in Sri Lanka.
Unauthorized occupation of low income city dwellers in urban green areas including traditional forest and natural conservation areas and fertile agricultural lands, and climatic changes have increased the vulnerability of an urban areas for natural disasters and its coping capacity. Colombo city area is not presently maintaining its green spaces a quantitative measurement where the per capita value of green space 7.16m 2 recorded in 2015 is below the WHO standard of 8m 2 (Li & Pussella, 2017). Greening city is asses based on environmental indicators and enhance the understanding and decision-making on environmental performance. Implementing "the Urban Vision" by the government of Sri Lanka was aimed at improving connectivity and "Green City" initiatives in the Colombo metropolitan and its suburban cities (Ministry of Environment, 2012 (Rostami et al., 2015). Urban tree planting program with native species withstand climate changes. A city wide Tree Planting Campaign with native trees have been proposed by the

Federation of Environmental Organizations (FEO) in both public and private lands in the greater
Colombo area creating resilient and sustainable urban landscapes. Commencement of tree planting in a large land area available at the urban public palaces is planning in the first week of July 2020 with the seasonal rains (https://feosrilanka.org/projects/greening-the-city-of-colombo/).  Vol. 4, No. 1, 2021 (Mahogany-685995, Robarosia-685995, Kottamba-685995, Acacia-1371990, Teak-914660 and Mara-914660) required to sequester emitted CO2 to reduce CO 2 emission (50352.05 ton CO 2 ) annually through urban forestry in Pettah division of Colombo city in Sri Lanka (Table 8). Source: Sugathapala and Jayathilake (2012) Increase of the average green area per person under the urban planning can reduce urban emissions and enhance climate change mitigation and adaptation benefits (Dulal, 2017). A study has suggested urban vegetation design for physical comfort in urban environment in Colombo where 80% of air pollution is due to vehicular emission (http://www.climatechange.lk/Documents/Project_Terminal_Report.pdf).

Other Environmental Resilience Strategies
However, dedication of lands for trees are least competitive in urban core areas due to the high competition for non-tree-based land uses, and required also to sort alternative remedial measures.  Vol. 4, No. 1, 2021 highlighted the ability of urban forest to improve thermal comfort associated with its tree canopy reducing temperature and regulating microclimate (Jamei. & Rajagopalan, 2017). Vegetation of urban forests reflect more heat than absorb heat and allows heat to be transferred upwards into the atmosphere through the process of transpiration (Chan, 2017).
The urban trees provide shade below the canopies avoiding sunlight reaching the surface and intercept greenhouse-gas-emitting from fossil fuels and other sources in urban areas, cooling the local environment. Vegetation abundance urban green space offers significant potential to retain and enhance carbon stocks and help adapt to climatic extremes, such as heat waves by counteracting urban heat island effects in controlling land surface temperature (Dulal, 2017). Carbon sequestration remove CO 2 that can retain heat by the vegetation of trees reduce heat of the microclimate directly and indirectly.
The roof temperatures and indoor heat gains with turf roof is at a minimum compared to the bare roof slab tops and tile roof roof-tops. According to a study conducted in Colombo urban area in Sri Lanka shows that the green roof record the minimum highest slab top temperature (37 0 C) compared to the bare roof slab top (61 0 C) and tile roof roof-top (63.6 0 C). The minimum highest indoor temperatures is recorded under the green roofs (32.7 0 C) compared to the tile roofs (34.50C) and bare roofs (35.90C) (Halwatura, 2013). Urban forests reduce the cost of energy needed to cool buildings in urban areas by adapting to higher temperatures and reducing greenhouse gases emissions through carbon dioxide sequestration. Perera et al. (2013)  percent and combination of all options, reported a reduction of day time peak temperature in 1.87 0 C, 1.79 0 C, 1.76 0 C, 1.86 0 C and 1.9 0 C, respectively. Thus, the greenery and vegetation would improve the human thermal comfort by reducing air temperature and reflected radiation (Herath et al., 2018). Green roofs are considered as the most suitable Green Infrastructure (GI) in urban areas with limited open spaces (Berardi et al., 2014). High density green areas as green infrastructure help mitigate the problem of the UHI and reduce the thermal stress as it does not heat up as much as the built-up area (Kazak, 2018).

Popularizing Urban Forestry
With the growing awareness of climate change and environmental protection the relationship between urbanization and greenhouse emissions has become a heated topic in rapid urbanization process in Sri Lanka not only serve as a biodiversity hub and enhance resilience to environmental changes but also educate and spread their knowledge to preserve and restore urban ecosystems required for sustainable urban development.  Vol. 4, No. 1, 2021 Strengthening and supporting the children for tree planting in urban schools to cope with risks and adversity associated with climate change draw attention of their families and the communities.
Community Based Disaster Response Teams (CBRDTs) of UN HABITAT in Sri Lanka enhanced community awareness of climate change impacts and disaster preparedness, demonstrating best practices including tree planting and created social harmony and community to be motivators in effective decision making to build urban resilience (UNDP, GEF/SGP) (2016). Educate the public on the thermal benefits of trees and create incentives for the urban people to engage in urban forestry as they have limited understanding of the importance of the urban forest (Middel et al., 2015). Promotion (https://www.climatelinks.org/sites/default/files/asset/document/Sri%20Lanka%20Fact%20Sheet%20-%20rev%2010%2012%2016_Final_0.pdf).
Greenhouse gas emissions reduction through urban forestry is an important strategy in sustainable urbanization thus identifying possible enhancing or restricting conditions to be considered in policy actions. The integration of Disaster Risk Reduction (DRR) in Town and Country Planning Ordinance is considered beneficial in multi-hazard risk assessments for resource security and adoption of non-structural and structural mitigation measures in planning and development activities (Hettiarachchi & Weeresinghe, 2014). The urban development policies and institutions need to undertake action to create more sustainable urban forestry and to better adapt to climate change and environmental 75 www.scholink.org/ojs/index.php/uspa Urban Studies and Public Administration Vol. 4, No. 1, 2021 extremes in order to develop more sustainable human settlements. Strengthening policy and institutional capacity is vital for improving urban climate resilience in cities that recognize urban climate change risks and impacts through carefully design urban planning and developing appropriate