Why Rainfall Doesn’t Always Help Us
September 17, 2012
Why rainfall doesn't help us. The geological structure of the greater Austin area is composed of a base of limestone, because most of Texas was the bottom of an ancient lake. Most of the greater Austin area has a very thin layer of topsoil, averaging as little as 4 to 6 inches; and underneath that, solid limestone. This is especially true of the Hill country, which makes up the majority of the watersheds for our 2 main reservoirs, lakes Austin and Buchanan. Because of this geological structure, rainfall general measurements are a poor indicator of the amount of water that ends up in our reservoirs. Our predominant rainfall comes in the form of thunderstorms, which produce brief but torrential rains. The initial 20 min. or so of what is called a gully washer, is quickly absorbed by the dry and parched topsoil. The water fall after that rapidly runs off and ends up in the Gulf of Mexico. So, unless the generalized pattern of scattered thunderstorms produces a storm directly over the relatively small watershed areas of the 2 reservoirs, it adds nothing to our water reserves. Since we live in a County with a high population density, approximately 1.7 million people in the greater Austin area, we are totally dependent on these reservoirs for a constant steady and reliable source of water. To make matters worse, the growth of this area has been in the high tech sector which has attracted people from all over the United States and abroad for these jobs in cutting edge high tech industries. Included, in the high-tech sector are many semi-conductor fabrication plants (approximately 14 in number). These “chip fabs”, as they are called in the industry, use phenomenal amounts of water in their manufacturing process. For example, it takes over 800 gallons of highly purified water to rinse a single 8 inch silicone wafer. Each of these factories produce thousands of wafers every day. An article on the subject, estimated that an average chip fab used an amount of water that would support a city of over 50,000 people. Therefore, these drought conditions with ever declining water levels in our reservoirs puts these chip fab factories in jeopardy. Since they represent enormous capital investment to build and maintain, and require a very highly educated and sophisticated workforce, they have tremendous leverage on the local economy, and thus the politicians who stake their careers on Austin's reputation on a national level as a high tech center which produces a constant stream of highly placed well-paying jobs.
It has become increasingly evident that this conflict of interest between the high-tech industries that attract people to this area, and the normal and unavoidable need for water to sustain life and maintain other facilities that make Austin such a wonderful place to live within its beautiful lakes and parks and other amenities. This conflict produced a dramatic example last year, 2011, the hottest and driest year in the state of Texas ever recorded. In spite of the miserable relentless heat, Travis County saw 26,000 people move into the area from all over the country. Then last winter, nature gave us an unexpected break from the relentless heat and lack of rainfall, and we were blessed with 7 straight months of average rainfall. And the result, which is counter intuitive, we saw our reservoirs levels went down. There can be no mistake about the data, for the lake levels are measured several times a day by state of the art techniques using feet above sea level as the standard. This data is published daily on the LCRA (Lower Colorado River Authority) web sight.
The meaning of this is clear, we have simply outgrown what nature will give us in terms of replacing the water that we use from our reservoirs. And I repeat, these 2 reservoirs are our only source of water. The problem is of course not purely a growth issue, but partially due to the fact that only a very specific pattern of rainfall adds a significant amount of water to our reservoirs. Generally speaking, the predominant rainfall pattern comes in the form of scattered thunderstorms, is almost useless. The only rainfall pattern that can be counted on to enter the reservoirs is a slow gentle constant rainfall over a large part of the greater Austin area, which we just experienced over this past weekend, September 15-17.
This is exactly the common rainfall pattern in Seattle Washington. I know this well because I lived there for 20 years. Seattle only receives about 42 inches of rain per year, which is about the same as Houston Texas, and only slightly more than the Dallas Fort Worth area. Yet, the average tree, which is a Douglas fir, is 150 feet tall with trunks 3 feet in diameter. And these are 2nd growth trees. The trees that were present when the loading industry arrived averaged between 250 and 300 feet in height. An average tall tree in any Texas urban area averages about 50 feet, and these trees have the benefit of irrigation. The point of all this is that the slow heavy drizzle type rainfall is so much more effective for plant life, that when compared to a radically different pattern of rainfall such as our scattered thunderstorm, it renders evaluating drought in terms of average rainfall almost completely useless. When assessing drought conditions, and the chances of recovery or worsening of those conditions, rainfall patterns and population density must be weighted at least as much as measurements of total rainfall. None of the standard rainfall maps that are thrown in our faces by the Austin-American newspaper consider anything but soil moisture. The originals of this type of map made sense when the population was spread out into small town's and the dominant industry was agriculture. Our local newspaper ran a front-page story about a month ago stating the case that the drought was getting better. They published a map from an institution that I was not familiar with. I looked it up, and the source was a research organization in Omaha, Nebraska, whose main concern is the soil moisture as it affects their main agricultural products: hogs, corn & soybeans. Their database covered the entire country and our newspaper selected a portion that included Central Texas which do make it appear that drought conditions were improved. But this is intentional deception, clearly meant to soften local concerns about our drought. We grow computer chips here, not hogs or soybeans and maybe a tiny bit of corn. As far as I know, and though I readily admit I am not an expert on the history of Travis County. But I do have a good working knowledge of horticulture, and I know that you can not grow vigorous crops of corn or soy beans on 6 inches of top soil. The situation a few miles to the northeast of Round Rock (home of Dell Computer), in the area around Hutto and Taylor, the soil is rich and deep and is some of the most productive in the state. However, that area shares our water shortage and an 8 foot pipeline to supply Hutto with water has just been completed.
As far as I know, there has never been an agricultural basis for the economy here in Travis County. Austin has always been an intellectual and political power center, propelled by the large state government and the huge and highly ranked University of Texas. Since I attended there in the 1960s, this prestigious university have and still has 55,000 students, including over 20,000 graduate students whose research before and after graduation brings in countless dollars and corporate investment and facilities. The highly trained and sophisticated PhD's produce a virtual endless stream of talent for any company doing any type of research and development. Therefore, comparing the rainfall and it's affect on the economy of the agricultural based small town of Omaha Nebraska, to the intellectual research and development mecca with a population of over 30 times the size of Omaha is laughable, as well as being deceptive. It is disturbing that Perry and his allies stoop to cheap tricks to deceive the public about the level of danger that brewing and getting worse by the day.
I we the people of Travis County do not wake up and see clearly that we are rapidly running out of water, in as soon a six months; AND absolutely nothing is being done to mitigate the situation. There are not even in plans in the making as to what emergency measures need to be taken IF we run out of water (which is a as close to a scientific certainty as is possible). We are in a long term drought pattern with no end in sight, and we use much more on a daily basis the the reservoirs can supply, even given an occasional break from nature.
Climactic change which produces less resources in the form of rain and food production, in a culture whose economic system based on a need for constant growth, and the need for essentially endless recourses, is a conflict so basic it is bound to be profoundly disruptive. But WE humans must adapt to these changes or we will perish. No better argument for conservation and “living within your means” has ever been made that the current situation in Central Texas where I live. It is a heart wrenching process to watch. We are being tested by nature, and at this point it appears to me that we are going to fail. But Texans and all of humanity have risen to the demands of worse situations that this, so I remain hopeful.