Basin-scale transport of suspended sediment and associated nutrients.

摘要

Suspended sediment has been identified by numerous researchers as an important agent in the transport of nutrients, herbicides, toxics, and metals (Knopman and Smith, 1993; Smith et al., 1987; Smith et al., 1994). The time scales over which sediment moves through a watershed, however, remain unclear (Wolman, 1971; Wolman, 1977; Meade, 1982). In this research, the transport of suspended sediment and associate contaminants is studied at the basin scale. Sediment and nutrient transport in major East Coast rivers are analyzed using the NASQAN data set. The relationship between large sediment producing events and high contaminant loads is explored. Travel distance and residence time of suspended sediment in a small watershed in northern Mississippi (the Goodwin Creek watershed) are also studied. Sediment budget analyses and numerical modeling are used to identify channel features which are important determinants of the suspended sediment regime in Goodwin Creek. Analyses show that in Goodwin Creek, a deeply incised stream with limited active floodplains, fine-grained sediment can be stored for long periods of time. In the 21.4 km