石塊敷蓋對紋溝間土壤沖蝕之影響

The Effects of Mulch Mulch of Rock Fragments on Interrill Soil Erosion

10.29417/JCSWC.200906_40(2).0005

吳明峰(Min-Fon Wu)；范正成(Jen-Chen Fan)；楊智翔(Chih-Hsiang Yang)；鍾宜全(Yi-Chuan Chung)；楊文仁(Wen-Jen Yang)

土壤沖蝕 ； 紋溝間 ； 石塊 ； 敷蓋率 ； 敷蓋方式 ； Soil erosion ； Interrill ； Rock fragment ； Mulch rate ； Mulch type

中華水土保持學報

40卷2期（2009 / 06 / 01）

62 - 74

繁體中文

本文的主要目的在於探討石塊敷蓋率及敷蓋方式對紋溝間土壤沖蝕之影響機制。研究中採集臺北縣林口鄉的紅土，取通過2mm 顆粒，重模於特別設計之詴驗箱，並依序以人工降雨機模擬40 mm•hr^(-1) 及60mm•hr^(-1) 降雨強度分別進行沖蝕詴驗。詴驗坡度固定爲20%。詴驗之敷蓋率計有0、0.1、0.2、0.3、0.45及0.6共六種；敷蓋方式則有全部露出土壤表面及半嵌入土壤表面兩種。詴驗結果發現，土壤表面的石塊，無論完全露出或半嵌入土壤表面，均具有降低紋溝間土壤沖蝕量之效果。其中又以石塊完全露出土壤表面之效果較佳，而且其原因除了因爲石塊完全露出時之滲透性較佳以致逕流量相對較低之故外，本研究亦探討其他可能原因。此外，本研究建立了紋溝間土壤沖蝕率與石塊敷蓋率、降雨強度及石塊嵌入程度之關係式，其判定係數達到0.82。

The main purpose of this study is to investigate the effects of the rates and types of rock fragments used as mulch mulch on the mechanism of interrill soil erosion. The soil used in the soil erosion tests was the lateritic soil from Lin-Kou, Taipei County. After sieved, the soil particles finer than 2 mm were collected and used for the tests. Rainfall simulation were repeated on the soil samples at rainfall intensity of 40 and 60 mm•hr^(-1) continuously. Erosion pans and rainfall simulator were specially designed and fabricated for this study. During the tests, the slope steepness of the erosion pans were kept at 20%. The erosion tests were repeated on soil samples at the mulch rates of 0, 0.1, 0.2, 0.3, 0.45 and 0.6, and on soil samples with the mulch mulch of rock fragments completely exposed on the existing soil surface and half embedded into the soil (i.e. the embedded ratios were 0 and 50%). It was found no matter what the rock fragments were exposed on the existing soil surface or half embedded into the soil, they could effectively reduced the quantity of interrill soil erosion. However, rock fragments exposed on the existing soil surface were found better for reducing interrill erosion. Aside from that the runoff rate of rock fragments exposed on the existing soil surface may be less than that half embedded because of more infiltration, other possible reasons for this are also investigated in this study. Besides, statistical equations for estimating interrill soil erosion rate from the parameters of mulch rate, rainfall intensity and embedding level were established with good correlations (R^2=0.82).