title: Statistical power of detecting trends in total suspended sediment loads to the Great Barrier Reef.
abstract: The export of pollutant loads from coastal catchments is of primary interest to natural resource management. For example, Reef Plan, a joint initiative by the Australian Government and the Queensland Government, has indicated that a 20% reduction in sediment is required by 2020. There is an obvious need to consider our ability to detect any trend if we are to set realistic targets or to reliably identify changes to catchment loads. We investigate the number of years of monitoring aquatic pollutant loads necessary to detect trends. Instead of modelling the trend in the annual loads directly, given their strong relationship to flow, we consider trends through the reduction in concentration for a given flow. Our simulations show very low power (<40%) of detecting changes of 20% over time periods of several decades, indicating that the chances of detecting trends of reasonable magnitudes over these time frames are very small.
authors.affiliation: CSIRO Mathematics, Informatics and Statistics, Ecoscience Precinct, GPO Box 2583, Brisbane, QLD 4001, Australia. ross.darnell@csiro.au
authors.forename: Ross
authors.initials: R
authors.lastname: Darnell
authors.forename: Brent
authors.initials: B
authors.lastname: Henderson
authors.forename: Frederieke J
authors.initials: FJ
authors.lastname: Kroon
authors.forename: Petra
authors.initials: P
authors.lastname: Kuhnert
mesh_terms: D003247:Conservation of Natural Resources; D057894:Coral Reefs; D004784:Environmental Monitoring / Q000379:methods*; D058735:Environmental Policy; D019015:Geologic Sediments / Q000032:analysis*; D006078:Government Programs; D011793:Queensland; D013223:Statistics as Topic; D014872:Water Movements; D014876:Water Pollution / Q000706:statistics & numerical data*