森林集水區坡地逕流路徑之研究

Pathways of Hillslope Runoff in the Fushan Watershed No.1

夏禹九(Yue-Joe Hsia) ； 王立志(Lih-Chi Wang) ； 黃正良(Jeen-Lian Hwong) ； 金恆鑣(Hen-Biau King)

《台灣林業科學》 11卷4期 (1996/12) Pp. 481-486

https://doi.org/10.7075/TJFS.199612.0481

摘要

沿著山坡側向的地中逕流是上游森林集水區暴雨時期主要的逕流路徑之一。集水區內降雨成為溪流水流出的路徑，不僅關係到溪流對降雨時間上的反應，亦與溪流水質及營養鹽的輸出有關。沿著福山1號集水區溪岸所設置的兩個側向逕流水收集試區，在1993年4月至1994年8月總共收集了43次側向逕流水。各層側向逕流水佔總量的比率由表層(0~2cm)、2~10cm、10~40cm、40~80cm到底層(80~120cm)依序為20.1、6.9、8.2、19.7、45.1%。除了表層外，此一逕流水在土壤較深處反而增加，顯示其為化育較不完全的崩積土，貢獻於溪流之水，可能含有更多比例入滲到此深度土層的逕流水。地表層的逕流水隨著前置降雨指數的增加而增加，深層的逕流水則有相反的減低趨勢，顯示可能有部分的坡面上，在大雨時會產生地表逕流或飽和地表逕流。

關鍵字

森林集水區 ； 森林水文 ； 地表下逕流

並列摘要

A study of routes of hillslope runoff was carried out in the Fushan watershed No.1 located upstream of the Harpan Creek. Soil at the study site is not well developed and consists mainly of loose colluvia with more than 30% gravel. A pair of 2-meter-wide trenches was excavated along the hillslope near the creek. Based on the changes in soil texture and color, five collection troughs were placed in the soil profile with plastic sheeting and infilled with silica sand. Surface and subsurface flow from the hillslope were then collected after each storm. Data from a total of 43 runoff events were collected from April 1993 to August 1994, The results show that contributions of runoff from 0-2, 2-10, 10-40, 40-80, and 80-120 cm soil layers were 20.1, 6.9, 6.2, 19.7, and 45.1%, respectively. The increasing trend of runoff contribution with depth below the soil surface layer indicated that runoff percolating into deeper soil profile might account for a significant portion of streamflow. Runoff contribution from the surface layer increased with the antecedent precipitation index, whereas the portion of subsurface runoff from the deepest layer decreased with the antecedent precipitation index. This suggests that surface runoff or saturation overland flow which occurred at least in some area of the hillslope as the storm prolonged.

並列關鍵字

forested watershed ； forest hydrology ； subsurface runoff