This project was carried out to identify the major processes involved in the delivery of sediment and nutrients to rivers within the Herbert River Catchment. The loss of sediment and nutrients from the land can degrade freshwater and marine ecosystems by reducing water quality and degrading aquatic habitat. It is also acknowledged that a loss of sediment and nutrients from agricultural landscapes can lead to a decline in the productivity of local farming systems. For individual catchments, a spatially-explicit understanding of both the magnitude of these sediment and nutrient losses from different parts of the landscape, and the erosional and hydrological processes controlling them, is essential to plan, implement and monitor improved land management practices with reduced impacts. With support from the Herbert River Catchment Group (HRCG), this project was carried out to:(1) identify the major sources from which sediment and nutrients in rivers and streams of the Herbert River Catchment were generated;(2) determine the total sediment and nutrient loads for the Herbert River Catchment; and,(3) predict likely changes in these inputs associated with a number of scenarios in which changes to current land management practice were implemented.

The Herbert River Catchment covers an area of approximately 10,000 km 2 and is characterised by complex patterns of geology, terrain, soils, vegetation type and land use, together with steep climatic gradients (especially for rainfall). There have been numerous studies investigating the movement of sediment and nutrients in the Herbert River Catchment, and a review of the relevant aspects of this previous work is presented in the report. However, only a limited number of these studies have examined the major sources of sediment and nutrients, and fewer still have assessed these from a ‘whole of catchment’perspective.