Datasets of Strahler Stream Order and Flood Plain Masks in Japan

Abstract

　This technical note introduces the new datasets of the Strahler stream order and flood plain mask covering the entirety of Japan. To obtain the continuous river channel dataset, we first filled the discontinuities in the river channels, which were found in the Digital National Land Information dataset. This filling enabled us to compute the Strahler stream order for all river channels. Because the Strahler stream order is fundamentally limited to the channel merging points in mountainous regions, we developed a new stream order that covers other regions such as urban areas or plains for practical uses. For all river channels of fourth order or higher, a floodplain mask dataset was created by drawing polygons manually on satellite images. The horizontal spatial error of the proposed data is generally within 10 meters when the flood plain boundaries are clear, but it might be larger when the flood plain boundaries are unclear. Our dataset presents benefits for river channel and floodplain identification in greater detail than when using earlier datasets. The developed data are available at http://kaigan.civil.tohoku.ac.jp/kaigan/papers/opendataj.html.