Western Washington Sees Pattern of Severe Flooding
Climate change, developers, and logging are blamed
Since the winter of 2006, when a state of emergency was declared for 18 counties in the state, Western Washington has experienced increasingly dramatic annual flooding episodes creating a state of emergency in growing numbers of counties each year.
For the past three years here, the number of roads, farms, buildings, and houses damaged or destroyed increased—helped along by the landslides that usually follow in the wake of such flooding. Although with this year the number of landslides has been somewhat constrained, the total area of flooding has increased from the previous two years (several sections of Interstate 5 remained shut down as of Saturday night, Jan. 10), and tens of thousands of people have had to be evacuated over the past 10 days. The governor declared a state of emergency in late December, which has only abated in the past couple of days.
It would seem that a “trifecta” of reinforcing factors is to blame: climate change (an extra heavy dose of snow, followed by several days of heavy rains), upland forest clear-cutting (leaving less vegetation to soak up water and hold the soil in place), and over-development in flood plane areas (leaving too many people’s houses too low in the face of rising rivers) …all of which set the stage for the current state of emergency. The damage is still being tallied, and although the heavy rains have largely abated, repairs to roads and highways will take months if not a full year (and with state budgets so tight) or more.
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Scientists have been voicing concern over clear cutting and over-development for years—a concern that has grown more vocal since 2001. But as a seventeen year resident of this region, I’ve been hearing and reading ecological warnings since practically the day I arrived by bus. Back then, in the early 1990’s, the argument was that clear-cutting hurt the valuable salmon industry by causing excess soil run off into streams (a process known as siltation), and development was also contributing through the filling in of stream habitat and spawning ground. But those who voiced such concerns were labeled “tree huggers” (”salmon huggers” ?) and were largely assigned to the radical, environmental fringe. But now, formerly less-than-environmentally concerned folks are starting to realize that sound forest management (including preservation of ‘buffer zones’ around streams) and preserving marshland and green space might just be good for people too.
Although current data indicates climate change is happening faster than is predicted by many computer models, from a scientific viewpoint, it is difficult to point to any one storm and say that was caused by global warming (which is believed to facilitate climate change by creating greater extremes of weather, and so also the potential for catastrophic, natural events). The reality is more like an emerging pattern of increasingly worse conditions and storms which seem to point clearly to climate change. It is a globally distributed phenomenon. Locally, we see a patchwork of different effects (depending upon types of environment—dessert, forest, mountain, plane, coastline, etc.) that exist in complex inter-relationships with each other. For this reason, we can not predict all the possible effects and impacts of climate change.
But, as Chief Sealth (Seattle’s namesake) once said: “Whatever man does to the web, he does to himself.”
photo credit: Michael Brunk
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Here’s a link to a flood report in the Seattle Post-Intelligencer:
Blame recurring floods on a triple whammy
More environmental news from the Pacific Northwest at:
Sightline Daily – Northwest News that Matters
A rusty pickup in the middle of a flooded field is an interesting photo, but not evidence of increased flooding. It is symptom of the real problem: that is people and development moving into floodplains. The flood plain is the area where water goes when it rains hard like it of the does on the west side of he Cascades and has for millions of years. The snow melting lowland winter storms makes for more water. That is why we have these great deltas along the margins of Puget Sound. Those deltas were for the fish, but now they have become the preferred place to develop. Weather happens it always has. If you look real science you will see that forest management, including clearcuts, have very little to do with the impact of flooding in these big events. Read “Effects of Forest Practices on Peak Flows and Consequent Channel Response: A State-of-Science Report for Western Oregon and Washington” Gordon Grant et.al. Pacific Northwest Research Station General Technical Report PNW-GTR-760. May 2008.
What you will find in this the “state-of-the-science synthesis of the effects of forest harvest activities on peak flows and channel morphology in the Pacific Northwest.” The conclusion is “The magnitude of effects of forest harvest on peak flows in the Pacific Northwest, as represented by the data reported here, are relatively minor in comparison to other anthropogenic changes to streams and watersheds.”
What this means is that flooding is worse because of damming, diking, dredging, filling and building in flood plains not clearcutting. The real environmental issue in the western Washington is loss forest. Managed, productive, lumber producing forest included. The loss is not from harvesting and growing more trees, but from development that permanently removes trees and replaces them with roof tops and pavement.
I agree with the general conclusions of the study, but, these “conclusions” are constantly being modified as new data (and theory) appear. I know of no study that is definitive on this topic.
The blog post speaks plainly of a confluence of factors, only one of which is clear-cutting (and it clearly mentions over-development in/near rivers and streams, hence the photo). But you’ll note that the trees in the background are quite tall, at least 30-40 years old or more. Flooding tends to rot and kill trees that come in contact with excessive water on a regular basis. Point being: it’s been a long while since flooding hit this particular area of Chehalis, WA.
Regarding clear-cutting’s impact on flooding, granted, this is difficult to determine precisely (and its effects are indirect), but this is because the practice occurs in various topologies, and to different degrees. Clear-cutting along mountain sides has demonstrably led to siltation of streams, which, in time, fills the stream and prevents the stream from doing its job (channeling water to a river, and providing shallow water habitat for spawning salmon). Also, clear-cutting of forested mountains promotes loss of vegetation and erosion, and this demonstrably leads to landslides (one of the co-effects of flood-producing storms).
I recognize the tendency of web media to distort information for increase traffic (not much different than print) and I strive for balanced writing (note the last paragraph). Blog posts, due to their brevity, tend to simplify.
Regards, M.R.
Almost every year, many parts of the country are plagued with flooding from heavy rains in the early Spring, but this unfortunate episode can be eased and possibly totally prevented by taking some very basic precautions in the previous years. Admittedly,
Some Sure Ways of Preventing Local Flooding