Tuesday, October 10, 2006

It's Raining

When most people think of Texas, they think hot and humid. What they often fail to consider is that Texas is huge and has several different climates. All of Texas is hot, but the humidity is mostly confined to the Gulf coast and the east. West Texas is actually the eastern-most part of the Chihuahuan desert which stretches from Mexico to the Pecos river in Texas and then transitions to the Texas hill country that spreads east until it abruptly stops at interstate 35 which splits Texas roughly in half. Austin and San Antonio are right on the edge of the hill country and most of time their climate is dominated by the arid desert to the west. Austin is green, but that is an illusion for the tourists and visitors. All the greenery is provided by live oaks and scrub junipers which are evergreen trees that are well adapted to arid climates. If you go hiking in the woods you will realize that very little grows in the rocky "soil" under the trees except patchy grass and prickly pear cactus. So while Austin is definitely hot, it's usually not very humid.

People talk about droughts as if they are noteworthy. But when you are on the edge of a desert, a drought is the status quo and wet weather is the exception. Austin is currently a couple of years into the current drought cycle. Lake Travis is as low as I ever remember and over the summer sand bars first became small islands, then large islands, then islands connected by spits, and finally virtual peninsulas running from the shore out to the middle of the lake. I stopped by the county park on Saturday to see how low the water was and was surprised to find no water at all. The entire boat ramp ends at dry land and the whole branch of the lake is dry as far as I could see. The lake is currently 25 feet below its average level for October and falling. The lake is several hundred feet deep in the main channel so we're not in danger of running out of water soon even if it has become nearly impossible for boaters to get to the lake.

Anyway, I woke this morning to the sound of thunder and rain. The irony of living on the edge of the desert is that even though it doesn't rain often, when it does it really pours. That's why we have Lake Travis. Or rather, that's why they have a series of dams along the Colorado river. When it rains here, it comes down hard and since it is very hilly and the hills have almost no topsoil the water runs to the lowest spot and very quickly turns gullies and streams into rushing rivers, rivers into raging torrents, and anything in their path into flotsam. Some of the dams, like Longhorn dam which forms Town Lake in Austin, are required by law to maintain the water level within a couple of feet no matter what the weather. Others like Lake Travis are there to hold back the storm surge and prevent flooding. What inevitably happens is that over the course of several years the water level in Lake Travis will drop and drop and drop. Then a series of storms will fill the lake in a matter of days with enough water to supply the area with water for the next several years of drought. It is truly amazing to see the lake level rise 50+ feet in a few short days and then see all of the flood gates open as the flood waters can no longer be contained. At that point Lake Austin and Town Lake go from being lazy lakes with little current to strongly flowing rivers as all of the dams start releasing water down stream to prevent flooding.

Unfortunately, the days rains only added up to a little over an inch so very little water reached the lakes and the level will keep on dropping until the winter monsoons hit. The Pacific ocean has an El Nino which usually means a warm, wet winter for Texas, so I'm expecting the drought to end soon and the next drought to start around Memorial Day of next year.

1 comment:

Sister Mary Lisa said...

Interesting about the weather. We have had drought in MT for many years but no desert conditions like you have. And definitely no torrential downpours like that, either.