The hydrology and form of spring-dominated channels

The form of channels that receive the bulk of their flow from springs differs in a number of ways from channels receiving direct runoff from rain and snowmelt. Spring-dominated channels tend to have poorly developed bars, and logs and aquatic vegetation may clog the channel. The organic-rich floodplain soils of spring-dominated channels are very moist. Channel beds lack a cover of fines indicating that sediment transport occurs frequently enough to flush fine sediment even though the drainage area of channels is very small. These differences in form reflect the distinctive hydrology. The range of discharge in spring-dominated channels is narrow. Spring-dominated channels often flow at bankfull or above 20 percent of the time while the typical value for runoff-dominated channels is 2–4 percent. At Browns Creek, an example of spring-dominated channels, the ratio of baseflow to bankfull flows is 0.65, whereas the respective value for runoff-dominated channels is 0.10. Peak flows often occur in late summer or fall whereas peak flows in runoff-dominated channels in the study areas occur with the spring snowmelt. Bankfull flows occur with a recurrence interval of about 1.67 years which is roughly equivalent to values for snowmelt- and runoff-dominated channels.