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- a porous device for removing impurities or solid particles from a liquid or gas passed through it.
Impervious surfaces disrupt natural hydrology from occurring
Impervious surfaces are any surface that prevents water from being absorbed into the ground. These areas include pavements, rooftops, decks, and compacted soils. As natural areas are replaced with these hardened surfaces, water runoff volumes are increased. Soil, forests, and wetlands (pervious surfaces) act as sponges and soak up the rain. Through this natural system, the water is infiltrated into the soil and then released slowly into the streams, rivers, and bays through groundwater.
What do you think is the consequence of replacing pervious surfaces with impervious surfaces?
Impervious Surfaces in the Chesapeake Bay Watershed
The map shows the impervious versus pervious surfaces found in Chesapeake Bay Watershed.
Impervious surfaces and flooding
Why is this house wearing stilts?
This picture shows a house across the street from Peachtree Creek, near downtown Atlanta, Georgia, USA.
Question: "Why is the front door 10 feet off the ground?"
Answer: "Because the first floor of the house is 10 feet up."
Question: "Why would someone build a house with the first floor so high?"
Answer: "They didn't. In 1977 the house was raised 10 feet because Peachtree Creek flooded the first floor in 1975 and 1976."
Question: "Why would someone build a house where it floods?"
Answer: Well, this is harder to answer. One possibility is that when these houses were built in the late 1940's and early 1950's that Peachtree Creek did not flood as often and as severely as it does now. Studies have shown that as development and the amount of impervious surfaces increases in a watershed, severe flood events happen more often.
If you are not familiar with the term "impervious surface," this picture will help explain it. As cities grow and more development occurs, the natural landscape is replaced by roads, buildings, housing developments, and parking lots. The metro Atlanta region has experienced explosive growth over the last 50 years, and, along with it, large amounts of impervious surfaces have replaced the natural landscape.
Impervious surfaces can have an effect on local streams, both in water quality and streamflow and flooding characteristics. Many water-quality problems can occur from development.
Effects of impervious surfaces on streamflow
A significant portion of rainfall in forested watersheds is absorbed into soils (infiltration), is stored as groundwater, and is slowly discharged to streams through seeps and springs. Flooding is less significant in these conditions because some of the runoff during a storm is absorbed into the ground, thus lessening the amount of runoff into a stream during the storm.
As watersheds are urbanized, much of the vegetation is replaced by impervious surfaces, thus reducing the area where infiltration to groundwater can occur. Thus, more stormwater runoff occurs - runoff that must be collected by extensive drainage systems that combine curbs, storm sewers, and ditches to carry stormwater runoff directly to streams. More simply, in a developed watershed, much more water arrives into a stream much more quickly, resulting in an increased likelihood of more frequent and more severe flooding.
One Solution to the Water Runoff Problem...
A special road and walking surface has been developed to allow water to easily pass through it. There are many brands to choose from...
What Does Colonel Do With its Waste Water?
There are close to 400 students that attend CRMS each school day. Most of them use the bathroom or get a drink throughout the day. Did you ever wonder what happened to the water when it goes down the drain?
When you wash your hands or flush the toilet, the water runs down the drain and moves through underground pipes to the back of the property. This is where we have our own water treatment plant.
The water runs through several stages. At each stage the water becomes a little bit cleaner as larger pieces of waste sink to the bottom.
At the end, the water is treated with a special ultraviolet light that kills any remaining bacteria before it is pumped into the ditch at the back of the property.
Questions to Ponder
How could we find out if the water is actually clean when it reaches the ditch?
What might happen if we did not have a method for cleaning up the waste that we produce each day?
