Using a criterion to define a zone of potential impact of where the water quality value exceeds the 80 th percentile of the baseline value for turbidity-based metrics or the 20 th percentile for the light based metrics, effects were observed predominantly up to three km from dredging, but in one instance up to nearly 20 km. Using an extensive collection of in situ water quality data (73 sites) from three recent large scale capital dredging programs in Australia, and which included extensive pre-dredging baseline data, we describe relationships with distance from dredging for a range of water quality metrics.

It is also important for public perception of risks associated with dredging. There is little detailed observational time-series data on the spatial effects of dredging on turbidity and light and defining likely footprints is a fundamental task for impact prediction, the EIA process, and for designing monitoring projects when dredging is underway. Proceedings of the 2nd International Conference on Dredging and Dredged Material Placement.Dredging poses a potential risk to tropical ecosystems, especially in turbidity-sensitive environments such as coral reefs, filter feeding communities and seagrasses. International Conference on Dredging and Dredged Material Placement National Spatial Data Infrastructure and its usefulness to the dredging community Efforts have been made by the Federal Geographic Data Committee (FGDC) and the creation of a National Spatial Data Infrastructure (NSDI) as an element of the National Information Highway has helped in solving some of the problems of the unavailability and unacceptability of data needed to support the applications. New data are becoming available to allow the examination of the consequences of dredging in a manner not done before. The solution to understanding the dredging impacts is the type of scenario that lends itself to new approaches to understanding interrelationships between multiple variables within a dynamic environment.

Dredging data