本研究では，多様な流域からなる北海道の渇水比流量を説明する領域モデルを構築し，現在および将来の渇水比流量分布を推定する．代表115流域の渇水比流量を再現する線形回帰モデルを，降水量，気温，地形，地質，植生，土壌，土地利用の44説明因子を用いた部分最小二乗法により決定する．その際，冬の降水中の雪・雨割合は月平均気温による指数近似式を用いて推定する．その結果，冬の降雨量と降雪量，秋の降水量，冬と夏の平均気温，標高の標準偏差と平均勾配および，集水域中の火山噴出物，第四紀火山岩，森林，湿原の面積割合の11因子からなるモデルを推定誤差と因子数の点から最良と判断する．領域モデルを北海道全1122流域に適用し，非観測流域を含む渇水比流量の現在分布を推定するとともに，気候変動シミュレーション結果と併せて将来分布を予測する.
This study evaluates the regional modeling of drought river discharges in a unit area for a variety of watersheds, Hokkaido Island, Japan, and illustrates its present and future maps under the climate change condition. An initial linear model for drought discharge data in 115 watersheds consists of 44 parameters covering the areas of precipitation, temperature, geomorphology, geology, vegetation, soil, and land use. The parameters are extracted step by step in terms of parameter numbers and residuals in partially least squares. As a result, the regional model is obtained with 11 parameters; total snowfall in winter, total rain-falls in winter and autumn, temperatures in winter and summer, standard deviation of elevation, averaged surface slope, areal ratios of Quaternary volcanic deposits and rocks, and of forests and wetlands. The coefficients in the regional model contribute to interpret the factors controlling drought discharges in the snowy cold island. The present drought discharges at 1152 watersheds are calculated by the regional model, and are mapped in the GIS procedure. The prediction map of drought discharge when the global mean temperature would increase by 2K is also illustrated by inputting previous simulation results of precipitation and temperature into the regional model.
積雪寒冷地における領域モデルを用いた渇水比流量の分布推定―現在と将来―
JSCE_72_5_I253_I264
(1.57MB)
