Pre-development denudation rates for the Great Barrier Reef catchments derived using ¹⁰Be

Area of Science:

• Earth Science
• Environmental Science
• Geomorphology

Background:

• Baseline denudation rates delivering sediment to the Great Barrier Reef (GBR) remain poorly understood.
• Sediment input significantly impacts GBR health and ecosystem dynamics.
• Cosmogenic isotopes provide valuable long-term averages of erosion and sediment yield.

Purpose of the Study:

• To quantify pre-development, baseline denudation rates and sediment yields for GBR catchments.
• To compare modern sediment yields with long-term background rates.
• To identify areas with accelerated erosion impacting the GBR.

Main Methods:

• Analysis of cosmogenic beryllium-10 (¹⁰Be) in sediment from 71 sites across 11 catchments draining to the GBR.
• Calculation of background sediment yields using ¹⁰Be data.
• Comparison of modern suspended sediment loads with ¹⁰Be-derived yields to compute an Accelerated Erosion Factor (AEF).

Main Results:

• ¹⁰Be data provided background sediment yields for 80% of the GBR catchment area.
• The Accelerated Erosion Factor (AEF) identified significant increases in modern sediment yields for 58% of the studied basins.
• Denudation 'hot-spots' with higher-than-background sediment yields were highlighted.

Conclusions:

• The AEF is an effective tool for prioritizing erosion remediation efforts in GBR catchments.
• The study provides crucial empirical data to support and improve predictive models of sediment dynamics.
• Understanding long-term denudation rates is essential for effective management and conservation of the Great Barrier Reef.