The population of Japan has declined since 2008. In the future, it is predicted that varied areas will experience depopulation. Especially in the residential suburbs of Japan, imbalanced age structures are major problems. Therefore, management strategies for diversity of age structure are currently required. In this study, we focused on coal mining city as an example of advanced shrinking area. In this study, we aimed to clarify transformations of age structure according to changes of company housing areas in the point of housing type in Omuta city, Fukuoka prefecture.
Methods are as follows. First, we studied the location and transformation of company housing area primarily by using maps, literature materials and aerial photographs. Second, we investigated housing type composition and age structure mainly by questionnaire data of National Cencus. Finally, we analyzed and evaluated the diversity of age structure by defining "Age Structure Similarity Rate".
Through this study, we made the following things clear; 1)In Omuta city, there were 87 company housing areas of Mitsui group and they were located in DID in 1960. Therefore, we could suggest that the urban area of Omuta city was developed based on company housing areas. Furthermore, Omuta city has a characteristic of the monotonous depopulation, compared to Shiranuka town which experienced the sharp population decline along with the end of coal mining industry.
2)In Omuta city, there are various types of current uses in company housing sites. Regarding housing use, we could confirm detached houses, sold compnay houses, employment promotion houses, improved houses, prefectural and municipal houses, apartments, condomiums and company houses.
3) i) When detached housing areas were developed for coal mine workers based on support system for house ownership by coal mining company, the sharp population aging and imbalanced age structure happened in M town. ii) When detached residential areas were normally developed and company houses were sold for workers, the populatopn aging has advanced with the passing of the years both in redeveloped areas and sold company housing areas, and finally imbalanced age structure happed in K town. Additionally, it appears that private rental houses constructed in company housing sites contribute to diversity of age structure in K town. iii) When developments of detached housing areas and constructions of detached houses happened in phases and employment promotion houses were constructed, the balanced age structure was implemented in N town. iv) When varied housing supplies in company housing sites such as continuation of company houses, constructions of detached houses in phases and constructions of various public houses (employment promotion houses, improved houses and prefectural houses) were conducted, the more balanced age structure was implemented in H town than M town, K town and N town.
From these results, we demonstrated that combination of various housing supplies can contribute to diversity of age structure. Moreover, we found that not only housing type, but support system for house ownership also influenced age structure. In Omuta city, the support system for house ownership caused sharp population aging in M town. Therefore, we need to consider not only housing type but also support system for house ownership in order to form the diversity of housing stocks and age structures. Additionally, this study’s methodology can be applied for study of other residential areas and can be important to as a current state analysis by local government.