Earth surface processes and landforms vol:32 issue:10 pages:1475-1490
Sugarcane is grown on the floodplains of northern Queensland adjacent to the Great Barrier
Reef lagoon. Sediment and nutrient loss from these sugarcane areas is considered a potential
threat to coastal and marine ecosystems. To enable sugarcane cultivation, farmers have
structured the landscape into different elements, comprising fields, water furrows, ‘headlands’
and drains. In order to apply appropriate management of the landscape and reduce
export of sediment, it is important to identify which of these elements act as sediment
sources or sinks.
In this study erosion and deposition rates were measured for the different landscape
elements in a subcatchment of the Herbert River and used to create a sediment budget.
Despite large uncertainties, the budget shows that the floodplain area is a net source of
sediment. Estimated sediment export varies between 2 and 5 t ha−1 y−1. The relative importance
of the landscape elements as sediment sources could also be determined. Plant cane is
identified as the most important sediment source. Water furrows generate most sediment,
but are a less important source of exported sediment due to their low connectivity. Headlands
and minor drains act as sediment traps.