Green Eastern Washington and Palouse Falls Lineup

There is a short window of time every Spring when eastern Washington turns brilliant green. With deep snows and plenty of rain, this year the scrub steppe lands are particularly green as new grass growth covers over the brown grasses of the year before.

Horse Heaven Hills with green and more rain showers in the distance

Devil's Canyon was brilliant green

and in sharp contrast to the last time I visited

Devil's Canyon late January 2017

With the heavy snow and cool Spring, word was out that Palouse Falls was putting on a show. Since I was passing by on a Saturday, the crowds were lined up. The State Park employee at the entrance said folks were having to wait close to 2 hours as the park was full.

Lineup to see the falls

  

Slide Causing Highway 530 Closure

The landslide that caused the closure of the State Highway as well as evacuations of a few homes is labeled in the LiDAR imagery below at the Montague Slide (my name as it is located just west of a creek by that same name).

I had initially presumed that the Skaglund Hill slide had moved as it has caused road problems in the past. The Montague slide is not a new slide. LaHusen and others (2015) estimated that the Montague slide was less than 500 years old based on surface roughness from LiDAR combined with carbon dates from several locations on nearby slides. The recent sliding on part of the Montague slide area will add some new roughness.

The slide itself has not impacted the highway; the highway is below the slide area. The concern is that the slide may become very active and slide down onto the valley floor and the highway. Hence, some monitoring of slide movement before any further decisions regarding the highway. 

Swift Creek Landslide and Creek Update

The Swift Creek landslide  continues to present challenges to Whatcom County Public Works (Click on the tag at the bottom of this post to get all the previous posts). The bridge at Oat Coles Road has been removed. The bridge was removed to prevent it from being damaged and to minimize the flooding that would be caused by the bridge causing a blockage of the sediment filled creek. The County is planning to put a one lane bridge with a control light to allow access for local traffic.

Flood waters can cause problems, but at Swift Creek the problem is even worse because the sediment carried by the creek contains asbestos form minerals. Hence, the effort to minimize the flood potential. The bridge is located nearly 2 miles from the landslide.

Swift Creek with landslide area outlined in red

Dredge spoils on both sides of the creek viewed from the north

It is hard to capture the scale of this problem. And it is a problem that will not be going away. The slide shows little sign of stopping. Linneman (2016) estimates that the main body of the slide is moving at 2 to 4 meters/year.

The Washington State Senate has included $5.5 in its current budget for Swift Creek. Two years ago the money was in that State Budget proposal but got pulled at the last minute by the local State Senator Doug Ericksen in favor of directing money elsewhere. The budget process is not over for the state, but for Whatcom County the news is so far good.   

The English Channel and Eastern Washington

A few news outlets have had fun with a new geology paper and Brexit. Gupta and others (2017) used high resolution sonar imagery as well as seismic line investigations to support a theory about the formation of the Dover Strait and the formation of Great Britain as an island. Hence, the term Brexit being applied by news stories about the paper. The resemblance to eastern Washington landscapes of the sonar imagery is striking.

From Gupta and others (2017)

Smith (1985) proposed that the Strait of Dover was carved by a large glacial age flood event. That idea has gained strong support (see for example Gibbard (2007) and Gupta and others (2007)).

Gupta and others (2017) further support the idea of a huge ice-age flood using far higher resolution data than what was available to Smith (1985), and their recent work helps refine the idea. They noted similarities between the topography in the Dover Strait and the landscape of eastern Washington's Channeled Scabland, "We interpret the amphitheater-shaped channel heads as abandoned cataracts formed by focussed knickpoint popagation similar to those formed by high-magnitude floods in the Channeled Scabland, Snake River Plains and Iceland".

Channel Shifting on an Alluvial Fan

Four hazards are typically present on alluvial fans: 1) debris flows, 2) debris floods, 3) flooding, and 4) erosion. The debris flows and floods are the most worrisome because of their suddenness and violence. In many cases they are rare events which makes them more dangerous particularly in areas that have no previous recorded history of debris flow or debris flood events.

Another hazard on alluvial fans is the tendency for the stream channel to become filled with sediment and the stream then moving to another location on the fan. The new flow path causes flooding but also can cause significant erosion as the stream erodes into its new channel. This hazard can be mitigated, but in some cases it is a too costly a fight. 

Last week I got some experience on an alluvial fan stream that has left its old channel of many decades and has begun the process of establishing a new channel on the fan surface.     

Uncertainty and Public Officials

I am giving a short talk to some public (elected) officials on a particular geology hazard in Whatcom County. I included the following picture that I lifted from a talk given by the someone else on a similar subject. Alas this science/public policy problem can be applied to more than just my subject. 

More on the talk itself at some later date.

Breckenridge Creek Flooding, Whatcom County

After a visit to the Sumas Valley in north Whatcom County, I headed south via Telegraph Road, Sorenson Road and Goodwin Road. Lots swampy ground is present along the Sorenson and the north end of Goodwin. Water was pouring over Goodwin Road.

Road erosion at the head of the spill over is thus far minor

The water is from Breckenridge Creek. The creek is having a hard time passing all of its water under Goodwin Road and my general sense looking into the brush is that the stream may be going through a bit of a channel change upstream. The problem for the creek, and the Public Works folks, is that the gradients in this area are very low and the creek is flowing onto a landform area not of its own making.

Breckenridge Creek is flowing into an area of large glacial river outwash channels and late ice age moraines associated with what has been termed the Sumas Stade. That is the ice front lingered in the Sumas area leaving behind a landscape that has very little to do with the current streams.

DEM of part of the west edge of the Sumas Valley

Moraine features are evident north of the Kinney Creek label

Note also that the glacial outwash contains several gravel mines

In the DEM image above Kinney Creek and Breckenridge Creek flow off the north slopes of Sumas Mountain and encounter an old glacial outwash channel that flowed out of the ice front, the moraine of that ice front can be seen just north of the Kinney Creek label. Kinney Creek has somehow managed to flow north opposite the former outwash flow path. Brekenridge Creek flows west across the old channel then flows southwest along the base of an elevated area of outwash before turning west and joining the Sumas River. The west path of Brekenridge is intriguing in that it makes a narrow cut through a ridge of elevated glacial sediment. Just how that happened would be a rather difficult exercise that requires pulling back further and thinking through a lot of factors. And for that matter, Why is there such a narrow ridge of glacial sediment at that location?

The main take-a-way is that this is an area where the existing streams are flowing across a landscape that was formed by other processes. It does not take much for these creeks to fill their channels and spill over and find new courses. Brenkenridge Creek is actively eroding its incised valley upstream of the low lands. That sediment load will readily fill its channel on the low lands. Breckenridge is not the only creek posing flooding problems in this area. Most of the streams entering the Sumas Valley pose flooding problems and many have long histories of sediment management issues. Any large change in sediment flux in these streams poses a big challenge (hint: look at the DEM at Swift Creek).