Contribution of diffuse sources to the sediment and phosphorus budgets in Ben Chifley Catchment, Australia

• Published in: Environmental earth sciences 2010-04, Vol.60 (3), p.463-472
• Main Authors: Rahman, A. K. M. Mostafizur, Bakri, Dhia Al
• Format: Article
• Language: English
• Subjects: Agricultural land; Alluvium; Biogeosciences; Earth and Environmental Science; Earth Sciences; Earth, ocean, space; Environmental Science and Engineering; Erosion control; Eutrophication; Exact sciences and technology; Fertilizers; Freshwater; Geochemistry; Geology; Gullies; Hydrology/Water Resources; Land use; Marine and continental quaternary; Nutrients; Original Article; Pasture; Phosphorus; Quaternary; Reservoirs; Riparian vegetation; Sedimentary geology; Sediments; Soil and rock geochemistry; Stream banks; Surficial geology; Terrestrial Pollution; Water quality; Water resources management; Watercourses
• ISSN: 1866-6280; 1866-6299
• DOI: 10.1007/s12665-009-0187-1

Relative contribution of different diffuse sources to the sediment and phosphorous (P) budgets in the Ben Chifley Reservoir was estimated using a multivariate mixing model and geochemical indices and tracers. The influence of the underlying geology on land use characteristics and the dynamics of sediment and P in the catchment were discussed. Sediments currently in transport to the reservoir are derived mainly from areas underlain by Quaternary alluvium, accounting for 33% of the reservoir sediment budget. A major portion of the sediments from the Quaternary alluvium originates from pasture land which also contributes about 60% of sediment-bound P in the reservoir, followed by cropland (30%) and forest area (10%). Phosphorus-based fertiliser contributes more than 50% of the soil P in pasture and cropland and more than 60% in forest plantation area. The remaining P reaching the reservoir originates from natural soils (native sources). Phosphate from both fertiliser and native sources are transported to the water courses and ultimately the reservoir as a consequence of gully, stream bank and surface erosion. Erosion control, trapping of fertiliser runoff, establishing riparian vegetation and reducing application of P-based fertiliser by increasing native pasture cultivation in the risk areas should be considered as management options for controlling the impact of P and sediment in the reservoir.