Hillslope soil erosion estimated from aerosol concentrations, North Halawa Valley, Oahu, Hawaii

Concentrations of aerosolic quartz and137Cs were used to estimate rates of hillslope soil erosion during 1990–1991 in the North Halawa Valley on the island of Oahu, Hawaii. Fluvial transport of quartz was estimated to be 6.1 Mg in 1990 and 14.9 Mg in 1991. Fluvial transport of137Cs from North Halawa Valley was estimated to be 1.29 × 109 pCi in 1991. Results were used with quartz contents,137Cs activities, and bulk densities of hillslope soils to compute rates of basinwide hillslope soil erosion ranging from 0.1 to 0.3 mm yr−1. These rates are within the range of previous estimates of denudation computed for drainage basins on Oahu. The aerosol-concentration approach, therefore, is a useful method for assessing basinwide soil erosion.