Thalweg Surveys

Nerd Terrarium warning: Some terminology and concepts may be considered nerdy.

My first thalweg survey was in a Forest and Range Hydrology class at Cal Poly San Luis Obispo. We were surveying San Luis Creek downstream of downtown San Luis Obispo. I remember we reached a big, deep pool, and as a taller person, I got to go into it with the survey rod because I could reach the deeper parts while still standing. I remember climbing onto a big log and reaching out into the pool to place the rod in what I thought was the deepest point.

And that is what a thalweg survey is. The thalweg is the deepest part of a channel. If you are in a boat and not wanting to run aground, you would typically follow the thalweg. If you were walking up or down a stream, unless you wanted to get really wet, you would typically avoid the thalweg. A survey of the thalweg is done in order to produce a profile view of the creek--from which you can see the slope and pools and riffles.

On Sunday I walked downstream. It was a hot day, but I wasn't prepared to go in too deeply or do too much climbing over debris because I was carrying my sleeping son in a carrier on my chest. Nevertheless, I got farther than the debris-jam and pool that stopped me last year. Peak flows during the winter cleared the jam and deposited sediment in the pool.

The Last Bedload-mobilizing Peak Flow of the Season

Okay, you read the title and wonder, "why wasn't this in the Nerd Terrarium category?" Because that is a pretty nerdy title. I almost created that category when I wrote the title. I still may.

So the weather is warmer, the sun is stronger, and San Geronimo Creek is low. This gets me thinking about walking up the creek again on a warm day. Last year I walked from our house up to the next bridge upstream. The first attempt ended at a neck-deep pool on a not-warm-enough day when I wasn't appropriately attired. Turning around and walking downstream ended at a debris-jam with a similarly-intimidating pool.

Now I look downstream and see that the debris jam appears to be gone. The set of storms and resulting peak flows this winter were not big enough to jam more debris, but big enough to clear out the debris already there. I want to go downstream to investigate.

I am not an Environmentalist

A friend of mine shared this article with me recently, prompting me to think of this "Best of" from my former Website, republished below, which touches on many of the ideas mentioned in the article.

I am not an Environmentalist

circa 2001

I don't like stereotypes and labels, and this is no exception. It is too easy for someone to say, "Oh, he thinks that because he's an environmentalist." This devalues the worth of your ideas and allows someone with different ideas to brush them off without even considering them because of who you are.

It Matters What Kind of Bullets You Use

"The Iraqi city of Fallujah has seen a dramatic rise in birth defects and childhood cancer since 2004, when U.S. forces used depleted-uranium shells and white phosphorous against militants. Doctors say the city's birth-defect rate is 14.7 percent--much higher than in Hiroshima after World War II." --The Week, January 20, 2012

After reading this in The Week a couple of months ago, I couldn't help but think this is an "I told you so" moment (and what took the mainstream media so long to notice this story?!!!). This seems like a good time to post another "Best of Beyond the Batholith--Essays from the Eastern Sierra" that I wrote around 2007:

Control

I was walking into an office building and noticed the landscaping: concrete, ivy, wood chips, and tidy, evenly-spaced.... hold on a second. I want to say "evenly-spaced flowers" but I'm the kind of guy that would want to drive over there and double-check before writing that they were evenly-spaced. They sure felt like they were evenly-spaced.

So, where was I... Oh yeah, so the landscaping in this interior-building alcove was all about control. The concrete controls the buried earth and prevents anything from growing there and allows dirt and foot traffic to be easily controlled. The ivy is a weedy and invasive plant that controls everything else--nothing else will be able to grow where the ivy is, and the gardener

Getting to Know the Local Environmentalists Part 2: Saving the Coast

Subdivisions Averted 1: on display at the San Geronimo
Valley Community Center.

What would West Marin be like if there had not been heroic efforts to save it? It would probably be like the rest of the Bay Area. As you come over White's Hill from Fairfax, instead of traveling on two-lane Sir Francis Drake Blvd, you would be driving on a four-lane superhighway all the way to Limantour Beach. You'd want that superhighway to deal with the congested traffic, since there would be a lot more development and a quarter million people living in West Marin--as many as live in the entire county now. San Geronimo Valley would be built up to the ridges on both sides. The Coho Salmon

And the Rains Finally Came

I walked outside on Thursday morning and it hit me. The air smelled so so good! The high humidity just before it started raining was making the trees exhale the most delicious flavor.

We hadn't smelled moist air like that in weeks. Since around Thanksgiving, aside from a quarter of an inch of rain in December, it had been cold and dry. On Tuesday morning I ran up the hill on the north side of the valley and looked down from a grassy slope thawing in the morning sun--down into the frosty foggy white valley bottom, as if looking into a pool of iced-over water. The golf course was as white as if a dusting of snow had fallen. The air in the valley bottom was thick with white fog and wispy smoke and when combined with the white ground, was a view unlike any I had ever seen. It contrasted sharply with the green trees and sunny thawed slopes above the inversion layer.

The morning that the rain finally came,