Diggings logo

WSU/Pend Oreille Extension introduced the Sense of Place series in 1999, with a focus on place-based stewardship education. Since 2001, a partnership with the Kalispel Tribe of Indians Natural Resources Department (KNRD) has supported this newsletter and allowed us to expand class offerings through EPA funding. Further staff support comes through Renewable Resources Extension Act (RREA). Our newest partner, sponsor of the Rain Garden Challenge, is the Pend Oreille Conservation District. Many thanks to our partners and to you, our readers, for your continued enthusiasm for "digging" into the natural history and culture ofthis part of the world.

A River's Job


by Carol Mack

Geologists say that the life work of a river is to transport the mountains to the sea, one particle at a time. Spend a lazy summer afternoon watching water trickle from a hose onto a sandy slope and you can observe the process. The tiny streambed it forms as it travels downhill illustrates many of the same earthmoving processes common to river systems—but over a period of minutes rather than millennia. Before your very eyes, the trickle alternately picks up sediment and then deposits it on point bars, forming a meander pattern. Soon the meanders begin shifting places as the growing deposits direct the erosive energy of the water to a new spot. Ox-bows form as channels are abandoned, and gradually, as the shifting stream cuts downward, a floodplain is created. If you turn the faucet up a tad (imitating a different climate regime) the more energetic stream will cut a new, lower floodplain, leaving the old one high and dry as a terrace along the river. If you “armor” a bit of the stream bank with small pebbles to slow the erosion, there may be a larger blowout below as the stream adjusts.

For real rivers, these processes may take enough lifetimes that it is easy to forget that rivers are dynamic, ever-changing systems. We build houses, bridges and roads assuming the river will continue to flow along the same course. Often we find ourselves fighting natural geological processes to protect our riverside investments. How successful we are at delaying the work of the river may depend on how well we understand the dynamics of the system—as well as the workings of weather, climate and blind luck. In the long term, though, the best bets are on the river.

<----previous article...Diggings Spring 2008...next article---->