Effect of vegetation and waterbody on the garden city concept: An evaluation study using a newly developed city, Putrajaya, Malaysia

https://doi.org/10.1016/j.compenvurbsys.2016.03.005Get rights and content

Highlights

  • Combined cooling effects of vegetation and waterbodies caused a daily temperature decrease of 0.53 °C.

  • Each km2 of vegetation and waterbody added to Putrajaya city induced a cooling effect of 0.047 and 0.024 °C, respectively.

  • Vegetated areas showed more cooling effect than those with waterbodies.

  • Waterbodies exhibited a rather undesirable effect in warming the area during mornings and nights.

  • The adopted garden city concept has been successful to an extent.

Abstract

The garden city concept was adopted in the development of a new tropical city, Putrajaya, aimed at mitigating the effect of urban thermal modification associated with urbanisation, such as urban heat island (UHI). WRF/Noah/UCM coupled system was used to estimate the urban environment over the area and the individual thermal contributions of natural land use classes (vegetation and waterbody). A control experiment including all land use types describing the urban conditions of Putrajaya city agreed well with the observations in the region. A series of experiments was then conducted, in which vegetation and waterbody were successively replaced with an urban land use type, providing the basis for an assessment of their respective effect on urban thermal mitigation. Surface energy components, 2-m air temperature (T2m) and mixing ratio (Q2m), relative humidity (RH) and UHI intensity (UHII) showed variations for each land use class. Overall, an increase in urban surfaces caused a corresponding increase in the thermal conditions of the city. Conversely, waterbody and vegetation induced a daily reduction of 0.14 and 0.39 °C of T2m, respectively. RH, UHI and T2m also showed variations with urban fractions. A thermal reduction effect of vegetation is visible during mornings and nights, while that of water is minimally shown during daytime. However, during nights and mornings, canopy layer thermal conditions above waterbody remain relatively high, with a rather undesirable effect on the surrounding microclimate, because of its high heat capacity and thermal inertia.

Section snippets

Introduction and background information

At present, approximately 3.9 billion of the world population live in urban areas, which is expected to increase rapidly (United Nations, 2014). This could be due to the rapid rural-to-urban migration of people in developing countries (e.g. China, Brazil, India, Indonesia, Nigeria and Mexico). Urban areas occupy < 3% of the Earth surface (Liu et al., 2014) and the increase in the population of urban residents has exacerbated problems (e.g. waste management, increase in energy consumption,

Study area

Putrajaya is located in the Klang Valley region in Southeast Asia at 2°55′00″ N 101°40′00″ E and 25 km south of Kuala Lumpur (Fig. 1) with an approximate area of 49 km2 previously covered by vegetation, that is, rubber and oil palm plantation. To the east, PC is bordered by Bangi, Cyberjaya to the west and Dengkil to the north. Located few degrees north of the equator with an average elevation of 30 m, PC is a typical tropical city. Rainfall averages 2–3 m per year and falls heavily during the

Methodology and model evaluation

In order to assess the performance of the GCC in mitigating the effect of thermal positive feedback (such as UHI) on the urban and surrounding environment induced by urbanisation, a control case (case 1), two different experiments (cases 2 and 3) and an ideal case (non-urban) were successively simulated. Case 1 represents up-to-date ground truth of the city, while cases 2 and 3 represent scenarios with waterbody and vegetation of PC replaced with high-intensity residential urban surfaces,

Results and discussions

Model results and analyses are conducted for d03 only, except otherwise stated. Presented results are averaged over 513 grid cells (Fig. 3a) within PC for a 24-h temporal scale. Fig. 4a shows a graphical representation of reclassified land use and land cover for the three scenarios investigated. Vegetated land use classes were reclassified to greenery, while urban classes were reclassified to urban. Waterbodies and sparsely vegetated regions are left as originally classified. It is worth noting

Conclusions

Coupled WRF/Noah/UCM was used to simulate the urban environment of Putrajaya using a one-way downscaling approach to investigate the effectiveness of the GCC adopted during the development of PC. Simulated results compared well with observational data. Surface energy balance analysis indicates that direct solar radiation predominates urban exchange of momentum, heat and water vapour during daytime. However, exchange of fluxes during night and early hours was controlled by reradiated absorbed

Acknowledgements

The authors would like to thank the Ministry of Science, Technology and Innovation (MOSTI) of Malaysia for providing financial support for this research work. This work is sponsored under contract number 06-02-12-SF0346. The authors also wish to thank the University of Nottingham for access to the University of Nottingham High Performance Computing Facility as part of the numerical calculations. The research work also forms part of The Seven South-East Asian Studies Mission (7SEAS) under the

References (70)

  • I. Middle

    Integrating community gardens into public parks: An innovative approach for providing ecosystem services in urban areas

    Urban Forestry & Urban Greening

    (2014)
  • K.I. Morris

    Computational study of urban heat island of Putrajaya, Malaysia

    Sustainable Cities and Society

    (2015)
  • K.I. Morris

    Numerical study on the urbanization of Putrajaya and its interaction with the local climate, over a decade

    Urban Climate

    (2016)
  • S. Moser

    Putrajaya: Malaysia's new federal administrative capital

    Cities

    (2010)
  • B.A. Norton

    Planning for cooler cities: A framework to prioritise green infrastructure to mitigate high temperatures in urban landscapes

    Landscape and Urban Planning

    (2015)
  • A. Onishi

    Evaluating the potential for urban heat-island mitigation by greening parking lots

    Urban Forestry & Urban Greening

    (2010)
  • G. Papangelis

    An urban “green planning” approach utilizing the Weather Research and Forecasting (WRF) modeling system. A case study of Athens

    Greece. Landscape and Urban Planning

    (2012)
  • K. Perini et al.

    Effects of vegetation, urban density, building height, and atmospheric conditions on local temperatures and thermal comfort

    Urban Forestry & Urban Greening

    (2014)
  • M. Santamouris

    Cooling the cities — A review of reflective and green roof mitigation technologies to fight heat island and improve comfort in urban environments

    Solar Energy

    (2014)
  • M.F. Shahidan

    An evaluation of outdoor and building environment cooling achieved through combination modification of trees with ground materials

    Building and Environment

    (2012)
  • L. Shashua-Bar et al.

    Quantitative evaluation of passive cooling of the UCL microclimate in hot regions in summer, case study: urban streets and courtyards with trees

    Building and Environment

    (2004)
  • L. Shashua-bar et al.

    Vegetation as a climatic component in the design of an urban street: An empirical model for predicting the cooling effect of urban green areas with trees

    Energy and Buildings

    (2000)
  • G.J. Steeneveld

    Refreshing the role of open water surfaces on mitigating the maximum urban heat island effect

    Landscape and Urban Planning

    (2014)
  • S.K.S.O. Thani et al.

    The Influence of Urban Landscape Morphology on the Temperature Distribution of Hot-Humid Urban Centre

    Procedia - Social and Behavioral Sciences

    (2013)
  • B. Vidrih et al.

    Multiparametric model of urban park cooling island

    Urban Forestry & Urban Greening

    (2013)
  • A.Q. Ahmed

    Urban surface temperature behaviour and heat island effect in a tropical planned city

    Theoretical and Applied Climatology

    (2015)
  • M.J. Brown et al.

    An Urban Canopy Parameterization for Mesoscale Meteorological Models

  • T. Bunnell

    Multimedia Utopia? A geographical critique of high-tech development in Malaysia's multimedia super corridor

    Antipode

    (2002)
  • F. Chen

    The integrated WRF/urban modelling system: development, evaluation, and applications to urban environmental problems

    International Journal of Climatology

    (2011)
  • F. Chen et al.

    Coupling an advanced land surface–hydrology model with the Penn State–NCAR MM5 modeling system. Part I: Model Implementation and sensitivity

    Monthly Weather Review

    (2001)
  • L. Chen et al.

    Impacts of urbanization on future climate in China

    Climate Dynamics

    (2015)
  • R. Cox et al.

    A mesoscale model intercomparison

    Bulletin of the American Meteorological Society

    (1998)
  • J. Dudhia

    Numerical study of convection observed during the winter monsoon experiment using a mesoscale two-dimensional model

    Journal of the Atmospheric Sciences

    (1989)
  • J. Dudhia et al.

    A new method for representing mixed-phase particle fall speeds in bulk microphysics parameterizations

    Journal of the Meteorological Society of Japan

    (2008)
  • EPA

    Reducing Urban Heat Islands : Compendium of Strategies — Green Roofs

  • Cited by (0)

    View full text