Characterization of Sediment Yield Variation, Little Colorado River Basin Near Saint Johns Arizona.

Abstract

Twenty-one dirt stock-watering tanks in the upper Little Colorado River Basin near St. Johns, Arizona, were surveyed for sediment depth, which, combined with bulk density, contributing watershed area, estimated age, and tank trap efficiency allowed the computation of sediment yield. A Geographic Information System was used to describe the geology, soil, and vegetation for each watershed. Sediment yields varied principally with geology and soil, vegetation, and watershed size. Watershed characterized by Chinle Formation, fluvial soils (AZ078), and the Plains Grassland Biome had the highest sediment yields, whereas basins with other sedimentary rocks, loamy soils (AZ106), and the Great Basin Conifer Woodland Biome had the lowest yields. Computed sediment yields for the 21 tanks ranged from 0.4 to 293.4 (mean of 27.3) tonnes/km²/yr. Sediment yields for the Little Colorado River, Carrizo Wash, and Zuni River drainage basins were 16.9, 41.3, and 25.7 tonnes/km²/yr, respectively.