Estimating soil erodibility for the RUSLE with rainfall simulation in central Queensland, Australia

B. Bosomworth; B. Yu; A. E. Elledge

doi:10.1071/SR25008

RESEARCH ARTICLE (Open Access)

Previous Next Contents Vol 63(4)

Estimating soil erodibility for the RUSLE with rainfall simulation in central Queensland, Australia

B. Bosomworth

^A ^B ^* , B. Yu ^A and A. E. Elledge ^B

+ Author Affiliations

- Author Affiliations

^A School of Engineering and Built Environment, Griffith University, Nathan, Brisbane, Qld 4111, Australia.

^B Queensland Department of Environment, Tourism, Science and Innovation, PO Box 3130, Rockhampton, Qld 4701, Australia.

^* Correspondence to: Bronwyn.Bosomworth@qld.gov.au

Handling Editor: Stephen Anderson

Soil Research 63, SR25008 https://doi.org/10.1071/SR25008

Submitted: 21 January 2025 Accepted: 17 May 2025 Published: 23 June 2025

© 2025 The Author(s) (or their employer(s)). Published by CSIRO Publishing. This is an open access article distributed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND)

Abstract

Context

Land use change in central Queensland has led to increased sediment and nutrient loads in the Great Barrier Reef (GBR) lagoon, impacting water quality. Accurate soil loss prediction is essential for managing these impacts, necessitating improved erodibility estimates for grazing lands.

Aims

The objective of this study was to advance the prediction of fine sediment exports to the GBR lagoon from hillslope sources. It specifically aims to enhance hillslope erosion modelling by refining the Revised Universal Soil Loss Equation (RUSLE) soil erodibility estimates (K-factors) for grazed lands.

Method

An integrative approach was employed, combining the empirical RUSLE with the process-based Water Erosion Prediction Project (WEPP). This study leverages observed soil loss data from simulated rainfall experiments to calibrate WEPP and produce an annual average soil loss to substitute into RUSLE. Prevalent soil types in the Fitzroy Basin were studied.

Key results

The WEPP was calibrated with observations and shown to be able to simulate observed sediment loss with good performance indicator values (R² = 0.9, PBIAS = 1.9%, and NSE = 0.87). The study identified that the existing RUSLE nomograph-derived K-factors would overestimate soil erodibility by up to 63% for the soils evaluated. Traditional methods predict higher erodibility; however, results from this study classify these soils as having low to moderate erodibility, attributed to local soil consolidation and limited erosion detachment processes typical in grazed areas.

Conclusions

Findings suggest that the conventional RUSLE erodibility nomograph does not adequately reflect the erodibility of consolidated or highly aggregating grazing soils found in the GBR catchments, leading to overestimated K-factor values and, subsequently, overestimated contribution of hillslope erosion to the sediment budget for the GBR catchments.

Implications

This research contributes to delivering a cost-effective, measurement-based method for K-factor estimation to improve hillslope erosion prediction for grazing lands in central Queensland.

Keywords: erosion, grazing, Great Barrier Reef, hillslope erosion, rainfall simulation, RUSLE, soil erodibility, WEPP.

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