環境整備目標設定のための過去・現在の水域生息空間ネットワークの比較
キーワード:
Historical comparison,
Habitat networks,
Paddy and ditch network,
Cadastral map,
Graph theory,
Network analysis
2009 年 15 巻 p. 25-30
詳細
2009 年 15 巻 p. 25-30
Using geographic information on cadastral maps in 1890s, we quantitatively estimated structures of the aquatic habitat networks (AHN), which were composed of a river, ditch networks and paddy fields, by Geographic Information System (GIS). Also we quantitatively calculated the current velocities and water depths of the channel networks by hydro accounting and then evaluated the influences of differences of AHN between present and past on the spawning behavior of catfishes. The results indicated that the past AHN had the following characteristics compared with the present one: (1) catfishes were able to move easily into paddy fields from ditches as fragmentation between the ditches and the paddy fields was small; and (2) the frequency of catfish migration into the ditches, which were disconnected to the paddy fields, was lower because there were fewer branch structures of irrigation canals.
