We love our cities and neighborhoods. The crisp, green lawns and bustling streets filled with people going to work, ballgames, festivals and concerts.
But, urbanization has a big impact on our water quality, and engineers, scientists and policy makers work together to try to keep the hustle and bustle from damaging our water. From erosion, to chemical pollution, to flooding, how we live our lives at home and work affects the health of our water and our environment.
Probably the most noticeable thing about cities is all of the concrete, stone and blacktop. These are called non-permeable surfaces and water rushes off of them and cannot drain through them. This is one of the main reasons for several water issues. In undeveloped areas, rain water slowing soaks into soil and is available to plants, fills streams and wetlands, and also recharges the water table (See the green line in Figure 2).
When soil is covered in concrete, all that water rushes off of the pavement instead of seeping into the soil beneath. This reduces the amount of water in the water table, and in some places, the aquifer can disappear. It also means that all the water that would normally remain in the soil now flows into drains that either end up flowing directly into streams (See Figure 3) or heading to waste water treatment plants. This can lead to a couple problems. One is that this water shoots off the pavement quickly and all at once (See the red line in Figure 2), creating a flash flood of sorts in the streams. This causes heavy stream erosion and sedimentation of our waters (See 8/7/2015 post on nutrient pollution and soil erosion).
The other problem is, if a town does not have pipes that separate rain and waste water, then heavy rain events can overwhelm waste water treatment plants. Many towns now are working on plans to remedy this problem by redesigning their waste water infrastructure.
You might be thinking that waste water is our biggest issue. Surprisingly, many waste water treatment plants are fantastic at cleaning our water before it enters the environment again. Now there are differences from facility to facility, and some are better than others, but the few that I have visited are impressive.
These facilities remove carbon waste that can be used in beneficial ways and have tanks filled with bacteria to remove nitrogen. Many also use UV light to kill bacteria now instead of chlorine. I visited one waste water plant whose water was so well processed that they had problems with fresh water sponges growing in their system. They are fascinating places when you stop and think about all they do to make sure the water going back into the environment is as clean as possible.
There are some great strides being taken to reduce the impact of urbanization on our waters. One is the use of green roofs, and green roof infrastructure is growing in popularity. Not only can it help reduce rain water runoff, but it helps maintain a building’s temperature reducing heating and cooling costs. At The National Great Rivers Research and Education Center (NGRREC℠) in Alton, Illinois, the green roof is planted to native plants (See figure 4). NGRREC also has ways of treating the building’s waste water. Small treatment wetlands on the north side of the building use plants to uptake nutrients out of the waste water (See figure 5).
To read more visit www.ngrrec.org/Green_Technology or stop by and see these feature for yourself at 1 Confluence Way, East Alton, Illinois. Lewis and Clark Community College and NGRREC also have areas that have permeable pavement. This is a brick pavement that allows water to soak into the soil instead of flowing off like traditional concrete (See figure 6), and this helps prevent some of the problems described earlier.
Even if you cannot build these types of structures, you can have a big influence on our water. To learn more about indoor water use, check out this great brochure from Lake County, Illinois.
One way to help is to install a rain barrel. This captures rain water that you can save and use later for watering lawns and gardens or washing your car. Planting drought resistant plants in your flowerbed can also reduce your water use and changing lawn watering practices can have a big impact. For more details and water saving tips, check out this nifty guide put together by the City of Decatur, Illinois.
I hope this post and the one before has brought some of our water issues home for you. I know that I will be changing some of my habits at my house to help conserve and protect our water. Be sure to stop in on September 4 for our next guest and first NGRREC scientist blogger, John Sloan, to learn about some of the research he is doing there.