Rates of erosion and sediment transport in Australia

Abstract

Soil erosion is a serious issue in Australia and this paper attempts a continental synthesis of erosion, fluvial sediment transport and sediment delivery to the coast. Continental soil erosion is estimated to be 28 × 109 t year-1 of which about 50% is from sheet and rill erosion and the remainder from gully and river channel erosion. The rill and sheet erosion is 19% of Pimentel's global estimate from 5% of the world land area. Modern rates of erosion have increased by a factor of up to 145 compared to the natural rates before human disturbance. River transport rates are relatively low due to inefficient sediment delivery in keeping with the arid and low lying nature of the continent. Much of the river sediment is derived from gully sources and while sheet and rill erosion are high, little of this material is delivered to rivers. The modern flux to the oceans is about 302 × 106 t year-1 or 2% of the estimated global flux (Milliman & Syvitski, 1992) which appears approximately double that pre-human disturbance. The continental sediment delivery ratio is 3%. Show more