By Sid Perkins
Gravel-lined streambeds remain relatively unscathed by many floods, according to a new model. This finding may make ecological and hydrological effects of deluges easier to predict.
The surface layers of gravel-lined streambeds often have higher proportions of large rocks than does the underlying sediment. This armor of stones provides a habitat for aquatic insects and juvenile fish, says Peter R. Wilcock, a geomorphologist at Johns Hopkins University in Baltimore. It also influences how much sediment can be swept away from the streambed as well as the rate at which water is exchanged between the stream and the porous strata beneath and beside it.