Green city model of Bandung Regency West Java

Abstract

Urban development in Bandung Regency has been responsible for the urban heat island effect and increased of air temperature due to increased CO2 emissions from motor vehicles, human population and industries. Other then these, urban heat island was also caused by increasing built ups and declining green open spaces leading to decreased albedo while in turn raised the air temperature. Urban heat island should be managed through studying the related variables. The purpose of this study was to assess the heat island city and create a green city model. This green city model is expected to be the basis to make policy for green growth based development to create Bandung regency as a green city. The research was conducted by collecting secondary data (socio-economic conditions, number of vehicles, industry, population), and primary data through field’s measurements of micro climate, crowns density, quantities of motor vehicles, direct interviews with residents of Bandung Regency, and analyzing the distribution of air temperature. The results of this research, especially the study of the conditions of heat island effect, indicated that Bandung Regency has experiencing urban heat island effect, where the air temperature in urban centers (27,0 °C) were higher than in rural areas (20,0 °C). The difference between the highest and lowest air temperature was 7 °C. The research also suggested that higher percentage of land built ups would result in lower percentage of green open spaces, thus higher CO2 emissions which would caused an increase of areas with high temperature. Research Area I has the highest percentage (60%) of develop area and the lowest percentage (29%) of green open space and also high CO2 emissions (503,987 tons CO2/year). This causes the region has most extensive area (161.59 ha) with high temperature (air temperature > 27 º C) in comparison with Research Area II and III. Urban heat island problems can be solved by building a green open space. Based on the measurements of micro climate in several types of green open space, it can be concluded that green open spaces including urban forest are very important in overcoming urban heat island, because they can lower the air temperature. Urban forest is known to be more effective in resolving urban heat island issues than any other types of green open spaces. Based on the results of simulations model, green scenarios can be used as a tool to determine alternative policies to address urban heat island issue. Green scenario could hold back the occurrence of ≥30°C air temperature. The temperature would occur on 2054 in Research Area I, after 2058 in Research Area II, and on 2056 in Research Area III. Although the factors which influence heat island had been well managed (using green scenario), nevertheless urban areas which already had high percentage of developed area, low percentage of green open space, and high CO2 emissions, would still generate a condition of ≥30°C air temperature on a faster rate (for example Research Area I).

Masalah lingkungan global yang dihadapi banyak negara saat ini adalah terjadinya pulau bahang kota (urban heat island) di beberapa kawasan perkotaan di dunia termasuk kota-kota di Indonesia. Pulau bahang kota menyebabkan heat island effect (efek pulau bahang) yang dicirikan dengan suhu udara di wilayah perkotaan yang lebih tinggi dibandingkan dengan suhu udara di sekitarnya. Beberapa kota di dunia yang sudah mengalami efek pulau bahang adalah Los Angeles, London, Bogota, beberapa kota di Swedia, Philadelphia, dan Guangzhou. Beberapa kota di Indonesia juga sudah mengalami efek pulau bahang yaitu Jakarta, Surabaya, Semarang dan juga Kota dan Kabupaten Bandung. Terbentuknya pulau bahang kota disebabkan oleh tingginya gas rumah kaca (CO2, N2O, CFC, CH4) dan lahan terbangun di area perkotaan. Berbagai aktivitas di perkotaan (transportasi, industri, sampah), menghasilkan gas rumah kaca dan menyebabkan terjadinya akumulasi gas-gas rumah kaca di atmosfer sehingga menyebabkan pancaran radiasi balik gelombang panjang terperangkap oleh gas-gas tersebut sehingga menyebabkan terjadinya efek rumah kaca. Efek rumah kaca di kawasan perkotaan ini membentuk pulau bahang kota dan menyebabkan suhu udara di kota lebih tinggi dibandingkan dengan daerah sekitarnya. Lahan terbangun di area perkotaan menyebabkan albedo menurun sehingga semakin banyak radiasi yang diserap sehingga dapat meningkatkan pemanasan dan peningkatan suhu udara. Kabupaten Bandung merupakan salah satu kota di Indonesia yang sudah mengalami efek pulau bahang. Kabupaten Bandung juga merupakan kawasan penyangga Kota Bandung yang terus berkembang dan menyebabkan jumlah penduduk, lahan terbangun dan jumlah kendaraan roda dua dan kendaraan roda empat terus meningkat dengan peningkatan masing-masing sebesar 1,95%; 7%; 4,3%; dan 2,3% . Total emisi CO2 dari berbagai aktivitas tersebut, diperkirakan sebesar 4.563.174 ton/tahun. Sebaliknya ruang terbuka hijau terus menurun (4,3%). Tingginya emisi CO2 dan kurangnya ruang terbuka hijau khususnya di area perkotaan, menyebabkan terjadinya efek pulau bahang sehingga suhu udara di wilayah perkotaan lebih tinggi dibandingkan wilayah perdesaan. Kondisi ini menyebabkan kenyamanan di area perkotaan menurun.