Wednesday, February 24, 2016

another giant passes...Doug Inman

Look at these guys studying 1948! We are all just poorly-dressed copy-cats. Dr. Inman on the left, looking dapper. Photo from The San Diego Union Tribune

This article in the New York Times is a really nice summary of the massive contributions that Doug Inman made to coastal science, science diving, nearshore sediment transport and more.

I love this one..."this is not the approach recommended by Doug Inman". Photo from

Friday, February 12, 2016

Kalaloch Beach

A few weeks ago while surveying Kalaloch Beach I was struck by the loss of wood from the upper beach. Below, for example, is a 12 March 2014 photo of a pile of large wood pressed up against an old wooden bulkhead that protects the trail running down from the lodge to the beach. In this photo Casey Nattinger, who I was working with alongside some students from the North Olympic Peninsula Skills Center, stands atop a pile of large wood, which is itself perched on a pile of accreted sand:

and below is a photo of the same feature (from a slightly different perspective), taken on 16 January 2016. Use the wooden fence for reference. The wood, and much of the sand, has been removed:

The loss of the wood from this beach is either a cause or a consequence (or perhaps a bit of both), of erosion of the beach and bluff. Here is a profile collected just south of the wooden bulkhead:

which suggests meters of erosion of both the beach and bluff in the two years since the photo above from 2014 was shot. Its hard to say how big a deal this is...its likely that this beach erodes and recovers each year, and I've never surveyed this beach in January before. But the loss of the wood likely is important. Here is why: The video at the very top of this post was shot yesterday, 11 February 2016 at 3:30 pm, when the tide gauge in La Push was reading a still water level of about 2.9 m above MLLW. The water, driven by set-up due to large waves, was easily working away at the base of the bluff, which sits somewhere around 4.0m above MLLW. Presumably, in past years, some wood would have remained along the base of the bluff to helped to dissipate some of the energy prior to it striking the base of the bluff. So where did the wood go? Here is the water level time-series from La Push for the last month:

which suggests that yesterday's high tide (the last high tide in the time-series) really wasn't all that high compared to those that have happened over the last month (and indeed the whole winter). In other words, it is likely that the ocean has been spending a good bit of time on the upper beach. Note in the video at top how easily those large pieces of wood are moved by the combination of water level (floating the log) and wave energy. The mass of large wood that had been loaded against the upper beach here was floated away. Probably as a result, here is what the base of the bluff looks like as of 11 February 2016:

That sort of cupping at the base of bluff will precede failure, and as happens in all too many cases on the coast, there is investment (the cabins at the iconic Kalaloch lodge) in the way:

how long this site has isn't clear, but bluff erosion doesn't grow back...

Wednesday, February 3, 2016

A real flood season at Elwha

The plot above of river flow from the McDonald Bridge gage on the Elwha River looks so very different then that from previous winters. We've had multiple flows above 10K cfs, three that have exceeded 20K, and one that went above 30K cfs. The river has spent a good bit of time above the median flow based on records dating back >100 years.

I've got a camera up at Fox Point watching the river mouth, and its been a fun ride this winter will all of this water pushing through. The mouth has been making a lot of changes...check it out below. What you see here are the average of individual photos taken every 30 minutes during daylight hours. This helps to adjust for variations in lighting and water level associated with tides, and better visualize the actual morphology change at the river mouth:

The timeline of this video aligns with the plot above - 90 days. I've also added notations to the slides on days when flow falls into one of three bins: >10K cfs (but less than 20K), >20K cfs (but less than 30K), and >30K cfs.

In particular what I think is cool is that the video suggests that the river is building new bars (visible by the end of the video emerging above the waterline) at locations seaward of the mouth position in early November...probably due to the at the mouth building on top of sediment that was pushed off of the delta during the large floods of mid-November. To better control for water level here is a photo taken at the the lowest part of the daylight tide on 6 November 2015..the water level was about 0.8 m MLLW according to the P.A. gauge:

and here is a photo taken at the same water level (+/- 10cm according to the P.A. gauge) on 1 February 2016: