坡面漫地流之土粒分離現象初步探討

Preliminary Study on the Phenomenon of Soil Detachment in Overland Flow on Slopeland

唐琦(Chi Tang) ； 游繁結(Fan-Chieh Yu)

《中華水土保持學報》 25卷4期 (1994/12) Pp. 191-197

https://doi.org/10.29417/JCSWC.199412_25(4).0002

摘要

土壤受漫地流之沖蝕作用，首先會造成土粒分離之現象，而土粒分離量多寡將會影響土壤沖蝕量之推估，故爲了解土粒分離現象，本文利用室內渠槽在不同供水量（0.5、1、2、3、4、5 l/min）下，形成漫地流後，觀測三種粒徑之土粒（粗砂、中砂、細砂）在不同坡面傾斜度（5°、15°、25°），供水時間（5 min）及可蝕面長度（3 cm）的條件下，對土粒分離量之影響，並找出相互間之關係，以提供研究土壤沖触之參考。茲將試驗結果分述如下：（1）坡面漫地流之土粒分離量與坡度及水流剪力呈正變相關，與糙度則略呈負變相關。（2）土粒於緩坡時，均一粒徑較混合粒徑易發生土粒分離作用；於陡坡時，坡度增加使水流剪力提高而克服混合粒徑中粘粒所產生內聚力之影響，致使細砂之混合粒徑者較均一粒徑易發生土粒分離。（3）土粒分離量可由土粒分離強度參數（Φ）及水流參數（Ψ）所建立的理論推估式得到合理估測。

關鍵字

土壤沖蝕 ； 土粒分離量 ； 漫地流

並列摘要

Running overland flow will cause surface soil detachment on slopeland. The results of previous studies had indicated that soil detachment is a primary factor to induce soil erosion on slopeland. Therefore, this research was undertaken to investigate the effect of overland flow and various influence factors on the phenomenon of soil detachment. The study was performed using a flume in laboratory. The investigated conditions included six flow discharges (0.5, 1.0, 2.0, 3.0. 4.0, 5.0 litter per minute), three types of soils (coarse sand, medium sand. clayey fine sand), and three slope angles (5°, 15°, and 25°). The inflow period was five minutes, and the length of erodible bed was 3 centimeters. The results of the investigation pertained the following conclusions: (1) The increase of shear stress of overland flow and slope angle would increase the phenomenon of soil detachment. (2) The increase of ground roughness would slightly decrease the effect of soil detachment. (3) The phenomenon of soil detachment due to overland flow is more significant for uniform grain soil than that of mixture grain soil on mild slope. However, on steep slopeland, in the condition that the increase of shear stress of overland flow due to steep slope overcomes the cohesion pertaining to clay particle, the phenomenon of soil detachment .would be more significant for mixture grain soil than that of uniform grain soil. (4) The correlation between soil detachment, sedimentation parameters, and flow parameters was formulated as a rational function. The formulated function can be used to predict soil detachment due to overland flow. The results of the investigation also can be used as an useful reference for study of soil erosion.

並列關鍵字

Soil Erosion ； Soil Detachment ； Overland Flow