- 期刊
林道闢建所可能産生的泥砂量－多納林道的一個個案調查
A Case Study of Soil Excavated by Logging Road Construction
摘要
林試所六龜分所20及22林班內的4段林道經由斷面調查估計其可能產生的土石方量分別為：(1)主林道，365立方公尺/l00m；(2)伐區支線，396立方公尺/100m；(3)森林區支線，4683立方公尺/l00m；(4)集材便道，98立方公尺/l00m。造成森林區支線過多的土石方量的原因是其在陡峻的單一坡面上為了載重的卡車能夠爬昇，而開闢了林道坡度僅約1.1度的林道，因此產生過多的迴頭彎與大量的挖方。此一林道應予以封閉以免產生更多的泥砂災害。 由20林班通往22林班一個伐區的支線在溪谷中沿溪填築了135m，造成直接的溪流泥形來源，林道的闢建對溪流的影響是極為顯著，應當儘量避免。伐區集材便道通常在封閉後4、5年內即可鬱閉，而在這裸露的期間，應該儘量減少林道的長度，伐區的形狀如能配合地形而成為長軸與等高線平行的長方形，應可減少迴頭彎的發生。
並列摘要
Four sections of lagging road in the Liu-Kwei experimental forest were surveyed. The volume of sail excavated was estimated by measurement of the slope profile along the cress section of the road every 20 meters. Sail excavated were 365m^3/100m, 396m^3/l00m, 4683m^3/l00m, and 98m^3/l00m for the main logging road, secondary logging road passing cutover area, secondary logging read passing intact forest area, and temporary logging road in a clearcut area, respectively. The extraordinary amount of excavation along the secondary logging road passing the intact forest area was caused by a very law road gradient (averages only 1.1°). The design of such a low gradient was necessary for uphill climbing of heavily loaded tracks. The enormous amount of soil spilled along the toad plus the read leading directly to the valley bottom is obviously a major source of sediment in the stream. It is recommended that this road should be elated as soon as possible to reduce farther damage to the stream. A 135 meter long road constructed in the stream bed was another major mischief of the road design and should be avoid in the future. Road surface can ha fully vegetated within 4 to 5 years following the close of the road in Liu-Kwei area. Temporary logging road, generally, shows no sign of further gait erosion problems. However, longitudinal alignment of the clearcut unit along contours should be imposed in the future operations to reduce the ores exposed by togging rood surface.