An Analysis of the Transport of Soil by Rainsplash and an Evaluation of Methods of Measurement

Abstract

Land degradation due to soil erosion continues to be a threat to the maintenance of the productivity of Australia's agricultural and pastoral lands. The development of techniques of predicting soil losses to assist in management decisions concerning these lands is of considerable importance if future management strategies are to maintain long-term agricultural productivity. Deterministic modelling techniques would appear to be the most appropriate research direction to be taken in Australia, as the Universal Soil Loss Equation cannot be directly transferred to Australian soil and climatic conditions, nor is the establishment of the required data basis within financial reach of Australia's soil conservation instrumentalities. The inter-rill erosion component of published erosion models seems to be almost invariably based upon splash cup-based relationships of splash detachment to rainfall kinetic energy or intensity despite published analyses that suggest splash cup and soil tray measurements may be subject to configurational artefact. In view of the potential shown by a number of such analyses of the splash transport process, this aspect was chosen for further research, with a view to improving the predictive performance of the inter-rill component. It was found that inter-rill transport could be validly represented as a drop impact-induced soil particle displacement process. Analysis of this process showed that the transport rate of soil was a function of both the detachment rate and the magnitude and direction of particle displacements. The success of this analysis depended upon strict definition of detachment rate and transport rate as follows.