SOURCE IDENTIFICATION OF SUSPENDED SEDIMENT FROM GRAIN-SIZE DISTRIBUTIONS - I - APPLICATION OF NONPARAMETRIC STATISTICAL TESTS

Suspended sediment flux (SSF) supplied from sediment generated by logg ing and deposited on hillslopes, and that from unpaved road surface, w ere obtained in the Hiyamizusawa Brook basin, Hokkaido, Japan. The rat io between SSF from deposited sediment fines (DSF) and that from suspe nded sediment in the road surface flow (SSR), i.e. the ratio DSF:SSR, was estimated from grain-size distributions of the river-suspended sed iment based on nonparametric statistical tests. The grains supplied fr om DSF were sorted while they were being transported to the river; thu s the ratio between the weight percentages of two subdistributions rep resenting the grain-size distribution of DSF (i.e., the ratio S(d)1:S( d)2) was considered to estimate the grain-size distribution of grains supplied from DSF into the river. The compounded grain-size distributi on with various S(d)1:S(d)2 ratios was again combined with the grain-s ize distribution of SSR at the various DSF:SSR ratios, and the twice c ompounded distribution, which was most similar to the grain-size distr ibution of river-suspended sediment was found. Each of the DSF:SSR rat ios of the most similar distribution was all within 10% of the each ac tual ratio. (C) 1997 Elsevier Science B.V.