林野火災とマツ枯れによる森林の衰退が流出量と流況曲線に及ぼす影響 : 岡山市竜の口山量水試験地の場合  [in Japanese] Influence of Forest Decline by Forest Fire and Pine Wilt Disease on Discharge and Discharge Duration Curve : In the Case of Tatsunokuchi-yama Experimental Forest  [in Japanese]

岡山市竜の口山量水試験地を対象に,林野火災,マツ枯れによる2回の森林の衰退が,流況曲線に及ぼす影響を対照流域法によって検討した。北谷,南谷両流域の流況曲線を,森林健全期の36年間について比較し,回帰直線を求めた。森林衰退期の19年間に対して,森林健全期に求めたこの回帰直線から算出される日流出量計算値と日流出量観測値を比較した。その結果,ごく一部を除いて,ほぼ全ての日において日流出量観測値の方が大きかった。この増加割合は,1〜40日目で約15%,140〜320日目で約35%,320日目以上で約43%と,日数が大きいときほど大きかった。

The influence of two forest declines caused by forest fire and pine wilt disease on the discharge duration curve was estimated with a paired catchments experiment in Tatsunokuchi-yama Experimental Forest (34°42'N, 133°58'E). The regression lines between the discharge duration curves from Kitatani and Minamitani catchments were calculated during the control period (36 years). The observed discharge and calculated discharge with this regression line during the treatment period (19 years) were compared. Except for a few dozen days, the daily discharge was judged to be increased by disturbance on almost all days. The increased ratio on the observed discharge was around 15, 35 and 43% on the 1〜40 th, 140〜320 th, and 320 th〜day, respectively, in the discharge duration curve.