Resistance of Cohesive Soil to and Amount of Erosion by Surface Sheet Flow Characteristics of soil erosion caused by rain water flow (II)

• Published in: Transactions of The Japanese Society of Irrigation, Drainage and Reclamation Engineering Vol. 1981; no. 92; pp. 1 - 7,a1
• Main Authors: KUSAKA, Tatsuro, TANAKA, Kohei, FUJITA, Noriyuki, SHIKASHO, Shiomi
• Format: Journal Article
• Language: Japanese
• Published: The Japanese Society of Irrigation, Drainage and Rural Engineering 25.04.1981
• ISSN: 0387-2335; 1884-7234
• DOI: 10.11408/jsidre1965.1981.92_1

Erosion of soil by rain water flow is considered as the result of interaction between erosion and carriage of soil layer caused by spattering erosion from rain drop energy and the tractive force of water flow. The erosion mechanism of soil grains from the soil layer that comprises cohesive soil containing fine particles, unlike the case of a moving floor of sand, is complicated by the influence of grain-size distribution, compaction, water content, content of organic matters, etc. Provided the natural contents of organic matter and water in the soil are maintained on as uniform a level as possible, the grain size distribution in the soil layer (clay ratio*), the degree of compaction (dry density), etc, are considered to constitute the principal factor for the resistance of soil layer that is closely associated with soil erosion. An experiment was conducted to investigate erosion by the tractive force of surface sheet flow, on several types of soil such as granite, volcanic ash soil and calcareous soil systems extensively distributed in western Japan after regulating the soil conditions with clay ratio* and dry density. For systematic expression of the experiment results, the dimensional quantity of qe/u*dk, u*2/(γd/ρ) gdk were used as the pysical indices to obtain general tendency of experiment wherein the amount of erosion is represented by qe, the friction velocity by u*, the average clod size that shows the roughness of soil layer, by dk, the dry density by γd, the water density by ρ and gravity acceleration by g. Through an investigation into the relationship among the tractive force of surface sheet flow, soil resistance and amount of erosion, on the basis of the above quantitative data being performed, the general susceptibility of cohesive soil to erosion, especially the amount of erosion of soil, was analyzed.