Estimation of wetland area using multi-temporal topographical map

In the nature restoration project, it is important to decide the aimed environment. Therefore, it is necessary for develop the multi-temporal database. The topographic maps are useful information in the development of the multi-temporal database, because they have been maintained for a long term. In this study, we estimated the wetland area using multi-temporal topographic maps in Kushiro Wetland and Sarobetsu Mire and evaluated the change of wetland area. Kushiro wetland decreased about 13,000 ha from 1920s. Sarobetsu mire decreased about 4,500 ha from 1920s. These results indicated that it is necessary in effective conservation and restoration planning to comprehend the long-term wetland change and the cause. Furthermore, we discussed the problems on the estimation of wetland area using topographic maps