15 September, 2011

A River Runs Through It - Sometimes At Flood Stage

Before Anne Jefferson, floods bored me.

I didn't used to put a lot of thought into how rivers overran. I knew the basics: too much water = overflowing banks. Simple equation, one even an Arizonan can solve. We watched it happen. Rain had a difficult time soaking into hard desert earth. So, every rainstorm, there would be flash floods, and every monsoon season, at least a few people who didn't quite grasp the fact that those floods were, in fact, flash, and furious: they'd get caught by surprise, and stranded, or drown. On one memorable occasion, some New River folk decided it would be a great idea to drive a backhoe into a flooding desert river that was usually a wash so they could see how deep the water was.

It's not a great idea to do that. It's too bad so many of them didn't survive to learn the lesson.

I learned my lessons from other people, and stayed away from flooded things. If the road had water over it (and believe me, Phoenix has lots of roads that seem built specifically so they can flood reliably every summer storm), I'd go another way. I never lived in a place too close to water. I knew vaguely what a floodplain was - it was the place non-natives built houses, and then wondered why they got washed out every few years when the rivers rose. I didn't directly experience a life-impacting flood until I moved to El Norte. Back in November of '07, right after I'd begun working for my present company, North Creek flooded so bad we got evacuated. I had to drive through water that reached the bottom of my car doors - something I'd been told never to do, but the police were there directing traffic, and it was the only way out. I thought I'd come home to find I could float up to my third-floor windows, but Forbes Creek had behaved itself beautifully, and we were as dry as one can get in a Seattle-area winter.

That still didn't make me think much of floods. In some vague way, the waterways in my story worlds would usually behave themselves. I thought of flooding on small scales, sometimes, but never really considered how rivers misbehave and what people who must live beside them do in order to tame them. Floods? Pfft. Boring. We had bigger matters to attend.

Then came Anne.

She's in to something I'd never thought had anything much to do with geology: hydrology. When she wrote a blog post, chances were you'd be getting damp. This is a big world, and more than just strictly local bits of it flood. Some of those floods can impact a region, some an entire country. And, as she said in the title of one memorable blog post, "A flood is a disaster when people are in the way."

Right. So, rivers don't behave themselves all the time. But we like to live by them. So what does a civilization do to deal with it? How do you tame the savage beast?

In order to understand how a river or stream might be at least semi-controlled, you've got to understand how it behaves. What causes it to flood? And what sort of flood does it flood - because I've discovered through her posts that rivers aren't just large generic entities. They have behaviors. A lot of factors influence how they'll flood and what those floods will be like. You get in to geology and geomorphology, even biology. What happens after you've asserted your authority? Because if you change the character of a waterway, you change habitats, and even small changes can lead to drastic impacts. You and I might think nothing of removing a log from a stream so it doesn't get all stagnant and backed up, but the critters who like that large woody debris might have something to say about it. If removing wood from a stream can have such dramatic impact, how much more can a dam, or dredging, or levees cause?

These are things I've never thought about before, not in any but the most fuzzy detail, but my characters have to know it. My civilizations have to deal with it. They have to deal with matters of sediment, how water undercuts banks and digs holes and behaves in different environments. If I want to have a realistic world built, I have to remember that rivers will be rivers, and have a science all their own. And sometimes, quite often in fact, they don't do what you wish them to do.

Because of Anne, I've added a whole new word to my lexicon: hydrogeology. I pay attention to what streams and rivers are up to. I look at watersheds in a completely different way. They fascinate me in ways they never could before. And when I finish this novel and you (hopefully) enjoy it, if there's an authentic ring to the rivers, remember: it began with Anne.


  1. Welcome to the flood-o-philes club! I've written a lot about this, and we do visualizations of what happens at those dangerous low water crossings:

  2. Thank you for the very very very sweet post. You totally made my week. Now will you write a letter to my tenure committee? j/k (but I wish you could)

  3. As I mentioned here, I grew up in an area that floods occasionally, so I try to pay attention to any flood-related subjects. Hadn't realized there was something called "hydrogeology", of course (nor does the Firefox spelling checker), but then there's lots I don't know about geology...

  4. Mmmm. I took undergraduate and graduate hydrogeology in my recent student career, and seriously thought about a career in hydrologic pollution mediation -- where I live, Superfund sites are ubiquitous and new ones are found all the time. (Geographic Information Systems are my true love, however.) Did you know that hydrogeologists have some absolutely BITCHIN' models they use to create computer simulations of pollution situations and mediation strategies??? So, I won't be joining the club, but kudos to the H-G's out there... I thank you all collectively whenever I draw a glass of water from my tap.


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