# Stochastic Characteristics of Cobble-Gravel Bed Load Transport

*by*Shuyou Cao, San Diego State Univ, United States,

Fang Duo, San Diego State Univ, United States,

Chuanyi Zhang, San Diego State Univ, United States,

**Document Type:**Proceeding Paper

**Part of:**Hydraulic Engineering

**Abstract:**

Prototype tests of stochastic characteristic of cobble-gravel bed load transport have been done in Dujiangyan reach of Minjiang River in China in 1977-1985. All of 718 sample data from 20 set tests show that the maximum transport rates of cobble-gravel bed load are often hundreds to ten thousands times as much as the minimum rates, and the maximum transport rates are 5-25 times greater than that of time-average on the constant external conditions. The transport rate of cobble-gravel bed load is influenced by a rather large number of factors which form a series of random variables. Those factors cause the rate to be a random variable. In this paper the rate is verified by the Central Limit Theorem of probability theory as a random variable which satisfies the lognormal probability distribution. Kolmogorov-Smirnov Test was used to judge the theoretic probability distribution function. The test shows that the theoretical probability distribution can be accepted at a 95% level of confidence.

**Subject Headings:**Stochastic processes | Bed loads | Gravels | Probability distribution

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