Event-driven sediment transport in a highly responsive lowland river as influenced by climate and land-use change, Haw River, North Carolina.

摘要

Anthropogenic activities have dramatically altered river systems from their natural state. Not only has population growth enhanced the magnitude of human impacts such as contaminants, it has also led to an increasingly direct link between a river and its basin. Land-use change has increased available material by mobilizing large quantities of sediment, while impervious surfaces and storm drains have intensified discharge events by more efficiently directed runoff to stream channels. In central North Carolina, the hydrologic response to precipitation events has intensified 22-91 percent. Yet, this change is shown to have occurred during a period when precipitation and temperature remain normal compared to historical baselines.;Sediment is an efficient vehicle for transporting contaminants, which are known to decouple and become bioavailable upon deposition in these reservoirs. This is particularly problematic because of the increasing number of reservoirs built along rivers and utilized for drinking water. Sixty-one suspended sediment samples were collected between April 2008 and June 2010 in the Haw River, a lowland river located in a high-population growth area of the Piedmont of North Carolina. Radioisotope measurements identify excess sediment from human impacts (construction) present primarily during peak discharge of a hydrologic event. Such human impacts have implications not only for ecosystems and public health but also for the utilization of radioisotopes to elucidate sediment transport. While there is a global focus on climate change, this study illustrates how land-use change is already having significant consequences that will only be exacerbated by the intensified hydrologic cycle predicted to result from global warming.