| Abstract: | ABSTRACT: The important ecological and hydrological roles of wetlands are widely recognized, but the geomorphic functions of wetlands are also critical. Wetlands can be defined in geomorphic, as well as in hydrological or biological terms, and a geomorphic definition of wetlands is proposed. An analysis of fluvial sediment budget studies shows that wetlands typically serve as short-term sediment sinks or longer-term sediment storage sites. In ten study basins of various sizes, an estimated 14 to 58 percent of the total upland sediment production is stored in alluvial wetland or other aquatic environments. Of the sediment reaching streams, 29 to 93 percent is stored in alluvial wetland or channel environments. For basins of more than 100 km2, more than 15 percent of total upland sediment production and more than 50 percent of sediment reaching streams is deposited in wetlands. The data underestimates the magnitude of wetland sediment storage due to the lack of data from large river systems. A theoretical analysis of river channel sediment delivery shows that wetland and aquatic sediment storage is inevitable in fluvial systems and systematically related to basin size. Results suggest that wetlands should be managed in the context of drainage basins, rather than as discrete, independent units. |
