地面浸食による裸地斜面の終局的粒度分布について

Abstract

It is generally difficult to analyze hydraulically the mechanism of water erosion ofland surfaces because of the greatly complicated phenomena. With the developmentof erosion process, characters of sands on the land surface change and especially themedian diameters of sands become large. It is necessary for the considerations on theconservation of land surface to disclose the erosion process and the final stage of landsurfaces.In this paper, changes of size distribution of sands, especially the final size distri-bution, and resistance law of thin sheet flow on land surfaces, which are both signifi-cant problems in solving the phenomena of water erosion, are considered experimentally.The author proposes a rough treatment to estimate the final size distributions, basedon the study of critical tractive forces. It is assumed in the treatment that all of finesand grains less than the critical size calculated by applying the relation of criticaltractive force to the rain water flow, will be transported downstream if sufficient yearsis taken in the erosion process. The treatment is applied to the both experimental andfield data, and it is cleared that the calculated size distributions for final stage agreewell with the observed data and, conclusively speaking, results obtained in the studyof critical tractive forces can approximately be used to such problems for practical use.