Pacific Decadal Oscillation, Local Sea Level and Slope Stability

Sea level rise is to be expected as global warming proceeds and glaciers melt. But linking sea level rise directly to how much glacial ice melts is not so simple. It is complicated by a variety of other factors that must be considered. Stuff like thermal expansion of water, isostatic response of the earth surface as mass (water) is moved around, and local variability based on tides and wind trends.

Weather patterns in the Pacific Ocean over the past decade have suppressed local sea level HERE, but that may change if we move into a cooler Pacific Decadal Oscillation (PDO) period. The chart above shows that over the long term sea level has been rising at San Francisco, but in the last decade actually reversed to to weather patterns.

With wind patterns shifting the west coast will go through a bit of a catch up phase. What this might mean for Washington State and for my work in assessing slope stability is that the frequency of erosive shoreline events along Puget Sound and Salish Sea shoreline bluffs will likely increase causing a greater frequency in shoreline erosion induced landslides. Shifting weather patterns may cause greater frequency of intense storms Bromirski, Flick and Caya (2002).

The PDO cool phase appears to have some impact on overall global temperature and is modeled by climate folks as such. However, the temporary cooling effect is overwhelmed by the CO2 forcing. If anything, a cooler PDO may be masking global warming impacts.

Berini (2010) 

Berini (2010)

Late and Deep Snow Pack

Cliff Mass posted the above plot regarding the snow pack in Seattle's water supply watershed. He notes how rapidly the snow pack recovered to average and beyond this spring with huge accumulations in March and April. In this plot the snow water equivalent (SWE) reached average at the beginning of April after very little net accumulation in January and February. The graph shows that snow has continued to accumulate throughout April when more typically it starts to melt. The current SWE is well over the 10 inches more than average. Very unlikely that Seattle will have water restrictions this year

As Mr. Mass is Seattle centric and I am Bellingham centric here is the Wells Creek station which drains to the Nooksack River in Whatcom County.  

The Wells Creek SWE has followed a bit different pattern than the Cedar/Tolt snow pack in that the SWE never really lagged below average, but it followed a similar pattern from March onward with rapid accumulation that has continued even when on average the snow pack begins to decline. At present Wells Creek has a SWE 25 inches above average.

The Middle Fork Nooksack station is located nearly 1,000 feet higher than the Wells Creek station.

This plot includes only this 2011 (blue) and 2010 (green) as the plotter did not have the average data. The Middle Fork site has a whopping 85 inches of SWE nearly 30 inches more water than last year. Melt began late last year as well so the peaks may coincide. However, snow levels in the North Cascades have continued to dip down to 4,000 feet so more accumulation of SWE may be expected over the next couple of days. Although an average SWE plot was not available for the Middle Fork Nooksack, this is the highest SWE at the Middle Fork Station since 2003 (earliest available data).

I did one more plot for Marten Ridge near the Mount Baker Ski area.  

Precipitation has been about the same as last year, but lots more came as snow with an accumulated SWE 35 inches more than last year. 

How the melt pattern evolves will be interesting for river levels if there is a sudden warm up in late May or early June after continued cool weather. While snow pack levels will be good for hydro power and water supply, there will some farmers on low lying areas along the rivers that may not be able to get crops planted. This may be a year of late spring flooding. 

Iceberg Tracks

Google Earth view of the iceberg marks, North Dakota

A couple of days ago John Freeland at the AGU page agu.org/terracentral/ noted iceberg marks on the former bottom of Lake Agassiz in North Dakota. It is one of those features that is essentially impossible to see from the ground but under the right conditions can be readily seen from say 20,000 feet as in the image above. Lorna Linch provides a short write up and illustration of her research on iceberg marks geog.qmul.ac.uk/staff/linchl.   

The Google Earth view is noteworthy in that the default view emphasises the berg marks. Using other dates in Google Earth the marks are nearly or entirely invisible. The image above is a compilation mosaic with images from different times put together to emphasize pertinent features. The features stand out depending on moisture and possible wind blown snow. Difference in salt concentrations in the soils also plays a role in visibility.

I took a quick amateur look for iceberg marks on the floor of the former Sumas Lake that straddles the border between Washington and Canada in northwest Washington. I saw one possible feature, but I am highly skeptical and believe it is probably an alluvial feature. I suspect there has been far too much sedimentation to preserve any iceberg marks if they ever were present in the first place. I am not aware of any iceberg gouge marks anywhere in Washington. One thing to consider about the berg marks at Lake Agassiz is that the site is incredibly flat and very little sediment has been added to the area since. Any glacial lakes in Washington or glacial tidal areas are not nearly as flat.    

Kettles in the Columbia Valley

Kettle lake or pond, Columbia Valley, Whatcom County, Washington

Kettles are a common feature along former glacial ice margins. Blocks of ice that get buried or partially buried in gravels and other debris melt creating pits in the landscape. There are numerous kettle areas in Washington State along former glacial margins.  

I took a trip out to the Columbia Valley in Whatcom County with David Tucker to check out some of the kettles on the valley floor. First, the Columbia Valley in question is in Whatcom County and should not be confused with the Columbia River. In fact this valley currently has no river. It formerly had a very large river during the late stages of the last glacial period.

These particular kettles stand out as the area is very flat and around at least a few of them there are no trees. As noted kettles are a common feature along ice margins where ice is melting back. There are numerous kettle areas in Washington State as well as along former ice margins where glacial ice was melting back. These areas tend to be lumpy landscapes of debris left behind by the ice. The Columbia Valley kettles formed within a former large river channel and as such the topography of the area is fairly level except for old river channel banks and the kettle depressions. 

Not all of the kettle depressions contain water. Only the ones that are deep enough that they intersect the ground water contain ponds or lakes. I have seen one of these kettles in the summer and the water was a fair bit lower. However, the Columbia Valley contains a fairly productive aquifer within the old gravel and cobble river valley. 

Two kettle lakes or ponds, Columbia Valley, Whatcom County, Washington

Columbia Valley in north Whatcom County

Columbia Valley showing former river flow path in blue

The LiDAR image of the valley shows the former river channels as well as numerous kettle depressions within the former river channel. The kettle depressions, are concentrated in only one area and are all located only within the deepest and most recent channel.  

LiDAR of Columbia Valley, blue arrows show flow direction of former river.

A major river flowed down the Columbia Valley during the late stages of the last glacial period approximately 12,000 years ago. The ice margin was located a few miles to the north in Canada. Multiple channels can be seen in the LiDAR image. I have always been intrigued by the fact that for at least a period of time some of the water escaped to the west and flowed down what is now Saar Creek and down through an area called South Pass. The LiDAR indicates that the river channel where the kettles are located is the deepest channel. A number of geologist have scathed their heads trying to figure out the timing of the events associated with this old river not only in Columbia Valley but downstream well. And the problem has some practical applications regarding landslides, slope stability, faulting, current river processes on the Nooksack River and Samish River and gravel resource areas in Whatcom County. The kettles provide some clues as to the history of water flow through this valley during the late glacial period.

Besides the great views of the kettles the former river bank channels are readily apparent not only on the LiDAR but out on the ground as well.

River channel edge as viewed looking from the former river channel

Road traversing up former river bank.

The valley floor is very rocky with lots of cobbles and boulders. Streams flowing off of the mountain sides disappear into the gravel and cobbles shortly after flowing off the mountain sides. Except for the kettles there are no surface water bodies in this portion of the valley. We enjoyed the short New England style rock wall with trees near one of the kettles.



National Conservation Area and San Juan Islands

Ken Salazar, the head of the U.S Department of Interior, visited Anacortes last week to hear more about a proposal to designate Bureau of Land Management (BLM) land in the San Juan Islands. The BLM controls huge swaths of land in the Great Basin and desert areas of California. In Washington State the BLM has approximately 450,000 acres with only approximately 1,000 acres in western Washington.

A group of San Juan Island leaders have been working toward having the BLM lands in the San Juans designated as a National Conservation Area (NCA). The San Juan County Council passed a resolution of support with a unanimous vote. The properties in San Juan County are described HERE and are scattered around the San Juan Islands. The sites include small islands, points, light house sites or former light house sites that have remained owned by the U.S. government. All together approximately 1,000 acres encompassing 60 separate sites. The largest island is Patos Island and a fair bit of the southern end of Lopez Island is controlled by the BLM. The designation would be Washington State's first NCA.

The designation would allow for local input on how the lands would be managed for conservation purposes. Given that the BLM regional office is in Spokane, local involvement may provide efficiency in managing the lands. Mr. Salazar made a point of commenting on Washington State's commitment to land conservation. Local land conservation in the San Juans would likely provide the partnerships needed to develop a NCA from the San Juan BLM lands. There already is significant cooperation in management of these lands but local volunteer groups as well as Washington State. For example, a volunteer group has taken care of the light house on Patos Island and Washington State Parks operates a campground on the island.

Another significant motivation articulated in letters to the BLM, and congress by proponents and the San Juan County Council is the risk that at some future date the land would be sold. Scenic headlands, an entire island (Patos) and the land at the southern end of Lopez Island would be very desirable real estate and the capacity of local county government or land trusts to buy the land would be a challenge. San Juan County went through a similar process when the Washington State Department of Natural Resources decided for efficiency to divest from trust lands they managed within the San Juan Islands. With the regional BLM office  located in Spokane, so few BLM lands in western Washington and the occasional calls from leaders in Washington DC to sell public lands, the concern over management and possible selling of BLM land by San Juan leaders is real.

A few years ago the BLM withdrew 276 acres of BLM land in western Washington from potential mining. The withdrawal is to last 20 years and would then need to be renewed. Hence, besides sale of the land outright, some parcels could at some future date be subject to mining. Perhaps this scenario is unlikely given the sensitive nature of the locations, but NCA designation would provide long term clarity to the status of this properties. 
The withdrawal of BLM land from mining included three parcels that are in the island area but that are outside of San Juan County. Lummi Rocks, a set of rocky islands off the west shore of Lummi Island, the very southern tip of Lummi Island (Carter Point) as well as Chuckanut Rock are BLM land in Whatcom County. Perhaps it would make sense to include these sites within the NCA designation as well.

Glimpse of the South Fork Nooksack Elk Herd

South Fork Nooksack elk

Last week I was out in the South Fork Nooksack River valley checking out a riparian area along the river and got a glimpse of part of the South Fork Nooksack elk herd. I have been told the herd that frequents the valley numbers approximately 70 animals. Elk need a fair bit of room and the presence of this herd is testament to a great deal of cooperation between Washington Fish and Wildlife, tribal hunters, Washington Department of Natural Resources, U.S. Forest Service, Seattle City Light, Whatcom County, Skagit County, non profits, and land owners including some South Fork farmers.

Over the weekend the purchase of land along the South Fork Nooksack River by the Whatcom Land Trust was announced. The Whatcom Land Trust has been taking a leadership role in cobbling together properties in the South Fork Valley for habitat and open space and has worked in a remarkable cooperative manner with Whatcom County and local tribes and property owners. 

 see/click  whatcomlandtrust.org/maps/ for more information.

The unique thing about this latest purchase announcement is the land is in Skagit County - off the above map. But the purchase ties in well with the series of land acquisitions concentrated along the South Fork Nooksack as can be seen in red on the above map. The South Fork Nooksack River is like many Cascade River valleys extends low elevations deep into the mountains. But in the case of the South Fork development does not extend up the valley and thus there is significant opportunity to develop viable habitat areas. Add the cooperation in the farmed section of the valley and one can have a viable elk herd. 

As for my adventures along the river, I appreciated the trail building the elk do to ease passage through the brush areas along the river banks. I came out of this venture with less thorn pokes than I typically have. 

Elk trail leading through the brambles

Dunite - Decorative, Heat Resistant and CO2 Sequestration

Visiting a local office in Bellingham today I noted the counter of the reception area was made from slabs of dunite.

Dunite counter top.

Later walking to the post office and courthouse for mail and research I saw a dunite bench along the Whatcom Creek trail.

Dunite bench along Whatcom Creek trail

Dunite is the from the earth's mantle and consists primarily of olivine. Dunite and other rocks with high iron and magnesium content are called ultramafite. The Twin Sisiters range in the Northwest Cascades consists almost entirely of dunite. The range is essentially a huge block of the earth's mantle somehow exhumed and thrust up into the Northwest Cascade Range (twin-sisters-range-and-dunite). A quarry on the lower slopes of the range extracts dunite as a liner for high temperature incinerators as olivine has a high melting temperature (its from the mantle of the earth). The rock is attractive so is also commonly used as a decorative stone. The downside of its use as decorative rock is that it is very hard and very massive with a specific gravity approximately twice that of average rocks. 

Ultramafic rocks such as dunite have gained interest as a means of sequestration of CO2 by the reaction Mg2SiO4 (Mg Olivine) + 2CO2 ---> 2MgCO3 (magnesite) + SiO2.  See Danae and others (2009) for an over view of site selection and Koukouzas and others (2009) for a bench study.  

In both examples above I like the orange weathering rind left on the edge of the counter and bench. This is the same color as the Twin Sisters range when the range is not mantled in snow as it was last week when I saw the range from near the South Fork Nooksack Valley. 

Twin Sisters viewed from Saxon