Luas Hutan Kota Optimal Berdasarkan Kebutuhan Air Di Kotamadya Bogor

Abstract

Introduction. Water constitutes the basic need for all living creatures, including plants. Plants need water and also serve as important agent for water regulation process. On the other hand, a city, which was identical with densely populated area, had great need for water. The usefulness of urban forest are among other things as water catchment area and as air quality control. Development of urban forest constituted an ideal plan to fulfill the need for open green space in the city. Hopefully, urban forest could serve as water catchment area to increase the supply of ground water. For achieving harmonization between real condition of a city and the actual need for urban forest, there is a need for calculating the optimum size of urban forest, which was performed in this research by using the need for water as its basis. Research Method. The research was conducted from May through August 2008, in Bogor City. Data collection was conducted through observation, data / archive collection from relevant agencies and literature study. The collected data were among other things, size and growth rate of human population, number of industry units, number of livestock, ground water potency, water supply capacity of Local Drinking Water Company, rainfall data, and spatial data (which comprised land cover, city administration map, and soil type map). All of these data were processed and analyzed, so that the following information were obtained: total need for water, total water supply, capacity of urban forest in absorbing water, optimum size of urban forest, capacity rate of infiltration well, and number of infiltration wells which were needed. Results and Conclusion. Based on calculation results, the total amount of water needed in Bogor city was 81.150.693,72 m3 / year, and the total supply of water was 79.442.512,81 m3 / year. Therefore, the water deficit of Bogor city was 1.708.180,91 m3 / year. With the ability of forest to absorb water per year, as much as 1.127,70 m3 / ha / year, then the optimum size of needed urban forest was 1.514,78 ha or 12,78% of the city area size. The existing urban forest at present was only 141,50 ha. The available land for developing urban forest was in the form of scrubland and vacant land, which if being forested, the area size of urban forest would become 933,09 ha. Such available area size of urban forest could not be able to eliminate the deficit of water. For overcoming such problem, designing of infiltration well constituted the appropriate solution. Bogor city had two types of soil, namely Latosol and Regosol. Based on calculation, number of infiltration wells needed in Regosol was as many as 53, whereas that in Latosol was 2.166, therefore, the total number of infiltration well needed in Bogor city was 2.219 infiltration wells. Keywords: The Need for Water, Urban Forest.

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