Rainwater Harvesting

Last week I had the pleasure of attending a talk by Brad Lancaster, a rainwater harvesting expert. Brad has a background in permaculture, which is the practice of designing human systems to mimic natural systems with the goal of increasing efficiency, with the ultimate goal of making our practices fully sustainable. Brad, who also has a blog, makes the point that we, as a society, are pretty thoroughly water-phobic and do our best to shed water away from our structures and properties as quickly as possible. He encourages us to treat water as a precious resource and harvest it with our landscapes. By doing this himself, he was able to transform his own lot in Tucson, Arizona, USA from a dry, dead landscape with a few of the toughest desert plants to an urban oasis with lush vegetation and abundant fruit, all with little or no additional water. He did this by collecting as much water as he could, mostly by grading the dirt to retain water and by covering the dirt with organic material, which helps the dirt act like a sponge, soaking up rainwater. He also collected rainwater from his roof and the street* in front of his house. All of this means that the runoff from his property is very minimal, as is the water he uses from his tap to water his plants.

As a civil engineer, I think his observation that we are water-phobic is a little extreme, but not too far off base. As engineers, we sometimes get sued over our designs. 90% of the lawsuits against civil engineers are because of drainage or traffic. Water can be very damaging and must be handled carefully. However, our caution of the damage it can do locally has created other, wider problems, opening the door to more damage by water. In a natural system, dirt absorbs water and ground cover, like plants, slow down the flow of water. During rainstorms in natural environment, the water levels in creeks and streams rise slowly to a peak flow and then subside back to normal flow. In urbanized areas, surfaces don’t absorb and are designed to get water out of the way as quickly as possible. That means that for the same amount of rainfall, more water runs off and it runs off more quickly. So the flood stage in the local streams occurs quicker than with a natural system and the water level is higher. Municipalities have begun trying to alleviate this problem with detention and retention basins (detention basins detain water while retention basins retain water). By collecting and slowing the water, we can help to restore the water to a more natural runoff rate. However, I believe that Brad’s way is better yet. By treating water as a resource, he takes extra steps to allow the water to seep into the ground, replenishing aquifers and decreasing our reliance on irrigation. It also increases plant cover, especially for arid climates, which improves our air quality.

So I really agree with Brad, and as an engineer, I think we can do better. But a lot of times we have to convince others. I can help a little with that. When faced with an intractable city engineer, put it in terms they can understand. Tell them that you are exceeding the requirements for retention on your site.

For more information, I highly recommend Brad’s two books: Rainwater Harvesting for Drylands (Vol. 1): Guiding Principles to Welcome Rain into Your Life And Landscape and Rainwater Harvesting for Drylands and Beyond (Vol. 2): Water-Harvesting Earthworks

* As a civil engineer, collecting water from the street makes me a bit nervous, for two reasons. The first is that the curbs and ditches in front of your house usually belong to the city and modifying them can get you in trouble. Secondly, a street is an engineered system. Just cutting holes in the curbs modifies the engineering. It would be like cracking open your computer and soldering on a few more wires. 90% of the time it would be fine, but the other 10% of the time you are potentially opening yourself up for flooding or other problems. Talk to your local city or county engineer before attempting this. Again, use arguments that explain how you will be increasing retention.

Earth Day

Today is Earth Day! As people all over the country (and world, so I hear) attend rallies and listen to music, how can we, the garden geeks, the biology geeks, the bioneers, help. First, remember what Earth Day is all about. It isn’t a day to worry about this great big ball of rock and iron orbiting the sun. We needn’t worry about the core or the mantle (unless, perhaps you live in Iceland). It IS a day to worry about Earth’s surface infection we call life and the interwoven relationships that they create, collectively called the ecosystem. The ecosystem, combined with physical factors such as weather, tides, soil chemistry, seawater chemistry, and much, much more make up the environment. Earth Day is a day to remember how important the environment is to all of us. It is a day to reflect on what has gotten us where we are and, more importantly, where we need to go from here and how can we get there. So what can we do to make a difference? I have taken the liberty of making a list.

1) Recognize the importance of science. The first thing to remember is what science is. It is not a belief system, a dogma. It is, quite simply, a method, a tool. As a great man said, “You don't use science to show that you're right, you use science to become right.” The entire purpose of science is to study and discover the truth, the actual, unbiased, complete truth. There are those out there who say that it is science that got us into this mess in the first place. Well, yes and no. True, without science we wouldn’t have nearly the problems with pollution and global warming and all the other stuff. But we would also still be riding horses and watching our children die of horrible diseases for lack of medicine and starving to death because we can’t grow enough food to feed everyone. Science has improved every quality of life. Yes, we have problems, but the problems weren’t caused by science, they were caused by INCOMPLETE science. We didn’t do enough science early along to realize what effect our technologies have on the world around us. Science helped not only discover that we have new problems, but also helped identify the sources of the problems. And it is science that will get us out of this mess. So, please, do what you can for science. Teach it. Encourage it. Fund it. We need science.

2) Did I mention that we should recognize the importance of science?

3) Seek to understand the various roles of organisms in our environment. Generally speaking (REALLY generally), animals consume oxygen and plant or animal material and secrete carbon dioxide and waste material that is high in nutrients. Plants consume carbon dioxide and nutrients from the soil to produce oxygen and their own body mass, which either sequesters carbon or is consumed by animals. Fungi and bacteria consume oxygen and secrete carbon dioxide (mostly) and feed by cleaning up waste material, including dead organisms, and turning it into soil. With this in mind, think about what you want to accomplish. If you want to remove carbon dioxide and other pollutants from the air, plants are your best bet. The faster a plant grows, the faster it will pull carbon from the air. The longer the plant lives, the longer it will hold on to that carbon. Trees are always a good bet for this. If you want to clean up pollutants in the soil or the water, fungus and bacteria do a good job for this. Give them the conditions they need to grow, especially oxygen and do your best to pick the right organism for the job.

4) Think globally, act locally. Do something. Here are a few ideas:

Plant a Garden

A garden is actually a huge help. By growing plants, you are removing carbon dioxide from the air. By producing food a few feet from where you eat it, you are reducing the fuel it takes to get it to you plate, thus reducing carbon used. Also consider that burning that carbon costs money and you, the end user, get to pay for it. If you don’t have lots of time to take care of a garden, go for perennials. Fruit trees especially do a good job of sequestering carbon while continuing to produce low-maintenance food every year. Blackberries, strawberries, raspberries, blueberries, asparagus and rhubarb, among many, many others, are also lower maintenance than annuals and will continue to grow for years.

Compost

If everyone composted their organic waste, it would remove a really significant portion of the trash stream. In addition, compost builds the soil, increases moisture retention of the soil, and increases the health of plants, allowing them to do their job better.

Harvest Rainwater

Taking advantage of all the free water falling from the sky is really beneficial to your pocketbook as well as our aquifers.

There is plenty more you can do, but these are really easy ones. They are also beneficial to you as well as the planet.