Survey of shape and area of Lake Izunuma-Uchinuma, Miyagi Prefecture, Japan using aerial photographs taken in 2007

Abstract

Various environmental preservation activities are being conducted to conserve endangered species in Lake Izunuma-Uchinuma located in northern Japan. In order to facilitate these activities, 1/25,000 topographic maps surveyed by Geospatial Inform- ation Authority of Japan in 1968, 1981 and 2001 had been used as base maps of the lake. However, the shoreline of the lake has been changed due to various factors such as feeding damage by swans and flooding and erosion by wave. To enhance the effect- iveness of conservation activities, a precise map based on the assessment of the present status of the lake has been needed. In this study the precise delineation of the water surface of Lake Izunuma-Uchinuma was established using the latest aerial photographs (taken in November 2007) and from this we calculated the area of the water surfaces of the lake. From this information we found that the sizes of water surfaces of the lake Izunuma and Uchinuma were 357 and 119 ha, respectively. These results indicated that the water surface of Izunuma and Uchinuma expanded by 110 and 113 % from 1981 to 2007. Based on the 1/50,000 vegetation map surveyed by Ministry of the Environment in 1985, 88 % of the area of expanded water surface of the lake was dominated by common reed Phragmites australis and Indian rice Zizania latifolia. These results demonstrated that the expansion of the water surface of the lake caused by the loss of plant comm- unities along the lakeshore.