2.3. Cuap within the unit area (1 m2)
The estimated quantity of CUAP, which will be produced from the total urban agricultural area if the Seoul metropolis implements urban agriculture was calculated as in Eq.(2) by converting the quantity into the unit area (m2) of urban agriculture. In addition, to be calculated CUAP when cultivating square meter of urban agriculture by multiplying the occupation area within the square meter by CUAP. The study calculated the occupation area by CUA by applying the occupation ratio of CUA. The occupation ratio by CUA was calculated using the ratio of the sum of the area needed for producing the city of Seoul's food imports by urban agriculture and the ratio of the area needed for producing the food imports of the relevant CUA. The statistical data on the city of Seoul's carry-in was obtained from the Seoul Agriculture and Marine Products Corporation, and the area needed for calculating the carry-in was obtained by applying the output data per unit area by crop to the carry-in data.
equation(2)
In-unit area CUAP=In-unit area occupation area of CUAi (m2)× CUAiPi output per unit area (kg/m2))In-unit area CUAP=In-unit area occupation area of CUAi (m2)× CUAiPi output per unit area (kg/m2))
where In-unit area occupation area of CUAi = In-Unit Area Occupation Area ratio of CUAj × 1 m2, In-unit area occupation area ratio of CUAi = Area needed for CUAiPi carry-in/Area needed for total CUAiPi carry-in.
2.4. The area of the space available for urban agriculture
Because of the nature of land use in Korean cities, there is little land available for agricultural production. Given such a situation, the smallest instead of minimum available spaces for urban agriculture are primarily small pieces of land, gardens, rooftops, verandahs, and unused land belonging to residential and commercial areas. Beyond these possibilities, there exist landscaped, amenty green land around public buildings and natural environment conservation areas; however, these areas are designated for urban eco-system function maintenance and conservation and are thus not available for agricultural use (Fig.1). Targeting the space available for urban agriculture, we calculated the area of buildings with flat roofs and the green area within residential and commercial districts using the Seoul metropolis’ urban ecology status map. We estimated that 30% of the flat rooftop area and 50% of the green area are available for urban agriculture. In the city of Tokyo in Japan, the city government makes it compulsory to afforest more than 20% of a building rooftop and more than 30% of a large-scale building. In Seoul, the area that supports rooftop greening ranges from 30% to 80%; therefore, referring to this figure, we suggested 30% of the flat-roof rooftop as the space for urban agriculture. For interior areas such as verandas within apartment housing, the study assumed the available area for urban agriculture as square meter per dwelling in more than five-story apartment housing. To determine the number of households within apartment housing, we used 2009 data from the Seoul Metropolis Housing Status (stat.seoul.go.kr).
Fig. 1.
The distribution chart of available area for CUA.
• Area for detached housing and apartment housing: the residential area
• Educational facilities, administrative agencies, hospitals and medical care institutions, and research institutions: the facility area for commerce and business, the mixed area for residence and commerce
• Research Institute, sewage disposal plants, and purification plants: the area for public use and the facility area for city support.
Source: Extracts using the Seoul Metropolis Urban Ecology Status Map (2010).