paving paradise: the peril of impervious surfaces.
In the United States alone, sidewalks and other permeable surfaces cover more than 43,000 square miles. -
Close to Ohio. -
According to a study published in the June 15, 2004 issue of the American Geophysical Union Newsletter Eos.
Bruce Ferguson, director of the School of Environmental Design at the University of Georgia and author of 2005 book, porous pavement, said the United StatesS.
Acres are laid or re-laid every year.
The permeable surface can be concrete or asphalt or a roof or a parking lot, but they all have at least one thing in common ---
Water flows from them, not from them.
A series of problems followed.
From a global perspective, it is a bit difficult to judge the square mileage of the water surface.
Ferguson said: \"We can infer the United States to some extent, but there are too many variables to be accurately judged.
\"The United States has a lot of cars, and Americans tend to make more cars than many other countries (and wider)roads, more (and bigger)
Parking lot, more (
Shopping malls and larger houses (
With a bigger roof).
He said, \"the United States may be on par with Europe, but we are very different from India or any country with a large population, scattered villages, most of them do not have paved roads, parking lots, etc.
\"According to non
The basin protects profit centers, where up to 65% of the non-permeable covering in the landscape of the United States consists of streets, parking lots and lanes ---
The center staff called it \"the habitat of the car \".
\"You see something really crazy in this country,\" said Roger Bannaman, a researcher at the Natural Resources Department of Wisconsin . \".
I have seen a community of Thirty to 40 feet wide streets.
As wide as two. lane highway.
Most developers are going back to 20. five-to twenty-eight-
But you can still see these huge streets.
\"In these car habitats, a variety of substances fall and hang the rest of the story.
The permeable surface collects particles in the atmosphere, nitrogen oxides in the exhaust gas of the car, rubber particles in the tires, debris in the braking system, phosphate in residential and agricultural fertilizers, and dozens of other pollutants.
\"In the parking lot, for example, we show the accumulation of hydrocarbons, bacterial contamination, the metal of the worn brake lining and the spilled antifreeze,\" Ferguson said . \".
On an open road
Graded aggregate (stone)
This substance will penetrate into the pavement and soil, and the microbial community living there will begin a rapid decomposition process.
But contaminants cannot penetrate through the permeable surface, and the rapid flow of rainwater on the permeable surface means that these contaminants will eventually enter the water.
\"So,\" said Ferguson, \"Not only do you have too much water, but you move too fast, you pollute the water, kill the fish, and make the water unsuitable for drinking or entertaining.
\"When there is nowhere to go for water across the country, the growth in the area covered by the permeable surface is being affected.
In Maryland, for example, when the basin is polluted by more than 25%, only stronger reptiles and amphibians can thrive, and more pollution
According to a 1999 report by the Department of Natural Resources in Maryland called \"from mountains to oceans\", sensitive species have been eliminated.
In streams that cannot be evaluated as \"good\", more than 15% of the basin\'s uncivilized nature can lead to pollution, the report said --
Sensitive stream troutThe 1. 1-million-
The acre Chesapeake Bay basin is one of the most diverse and subtle ecosystems in the world and is currently being affected by the 400,000-acre water surface in Maryland.
The Great Lakes, the streams and rivers of the Pacific Northwest, the Everglades of Florida ---
The run-off of streets, parking lots and roofs affects everyone in one or more ways.
Bannerman has been studying the effects of water flow and urbanization on the basin for the past 30 years, including the depletion of groundwater reserves.
\"It is a very serious problem not to allow rainfall to penetrate back into the aquifer,\" he said . \".
\"If this happens, you will lose the basic traffic [
That part of the water from the underground water source]
For streams, you will lose the wetland fed by spring water.
This is a complete destruction of the hydrological cycle.
\"Feng Chen Wingra, Lake, for a month. 3-square-
Kilometers of Lake Madison
\"Hundreds of years ago,\" he said, \"The lake is about thirty.
Five independent springs.
But today, since the lake is now almost completely surrounded by the city, there are only four streams that provide food for the lake.
Local organizations have become active in efforts to restore the water quality of the lake, but it is not the same as it was a hundred years ago.
\"Lake Wingra now has algae breeding due to over-fertilization, beach closures caused by bacterial contamination, turbidity and drying of surrounding wetlands.
Bruce Wilson, a research scientist at the Minnesota Pollution Control Department, is conducting a satellite survey of the state\'s non-permeable surface area.
So far, what Wilson has seen is enough to raise serious concerns about the growth and development of the country and the impact of the water system on the surface of the water.
\"The surface that does not penetrate is affecting lakes and streams on multiple fronts,\" he said . \".
The speed of runoff is very large.
The water flows so fast from these surfaces that it produces mini
The tsunami can cause serious or even irreparable damage to the river ecosystem. . . .
Of course, the recharge capacity of the groundwater system has also been affected.
If you enter a 20to thirty-
Percentage of penetration decline [
Enter the reservoir
This means that the loss of base flow, the impact on the stream supplied by surface water will be further amplified.
\"Another big problem in urban areas is that when heavy rain falls over the city, flash floods may occur;
According to water writer Matt Kelsch, he is the authority of urban flash floods, an atmospheric research company at Boulder University.
Because the runoff on an acre of pavement is about 10-
Kelsch said that the surface of the water will lead to devastating floods quickly, which may cause a series of environmental health hazards.
\"In urban areas, rainfall from 30 to 40% flows directly into any river in the area, and in highly urbanised areas, rainfall may exceed 50%,\" he explained . \" (
He said that by contrast, the amount of runoff in undersaturated woodlands is usually less than 5%).
\"If the water flows over the river bank, it will seek the path with the least resistance.
This will be the road in most cases.
Kelsch said: \"In many desert areas, engineers use natural terrain to build houses at higher altitudes and install roads to residential areas.
This makes the road more dangerous.
According to Kelsch, more than 50% of the deaths in the floods occurred on the road.
Floods are usually given digital names such as \"hundred-year floods\", which means that such floods occur every 100 (
Or a 1% chance of happening in any year).
The federal emergency response authority has kept a national flood zone list and a map of the affected areas.
\'The problem is we changed the venue, \'says Kelsch.
\"There are several factors at work,\" he said . \"
\"First of all, it\'s still a fairly new country, so most places haven\'t developed long enough to understand the historical risks of devastating floods.
Secondly, when we urbanize a region, we change the historical frequency of these events.
The more areas we develop, the more rain we put directly into streams that have evolved into only dealing with a portion of the runoff, and the more this happens, the more likely catastrophic flooding is.
\"In the 1980 s, there were several floods like this in New Orleans, and three attacks on St. Paul-
Between 1990 and 2001, Minni apores.
Heat waves and the Wilson River are also looking at the effects of the \"heat wave\" on the Minnesota trout stream, he said, and that evidence and experience suggest that the effect is significant.
Surfaces that do not penetrate, especially roads and parking lots, are usually dark and therefore hot
Absorb, so they heat the rain when it hits.
A sudden thunderstorm struck the parking lot that had been sitting under the scorching sun (
The surface temperature is 120 [degrees]
F is not unheard)
10 can be easily released 【degrees]
The temperature of rainfall rises.
The heated water is not just a parking lot or a street, it is more likely to be a few, all of which add heated water to streams or rivers.
Many aquatic organisms at different stages of life are vulnerable even if the water temperature rises slightly.
\"I saw Trout churn all over the population elsewhere in Wisconsin and in the Middle West, at least in part because ---
\"The run-off on the surface of the water meter causes the temperature to rise,\" Wilson said . \".
\"An increase in temperature also reduces the ability of water to maintain oxygen, which has a further adverse effect on aquatic organisms.
\"Warm temperatures can cause a variety of problems for fish, including decreased egg survival, delayed growth of Fry and smolt, increased susceptibility to disease, and the ability of small fish to compete for food and avoid predators.
Particularly affected are species that require cold water at most stages of their lives, such as trout and salmon.
In the end, if there is no additional change, the temperature will drop, but the impact on wildlife may be serious during this period.
Oregon is a state of science that is studying the effects of water temperature on stream life.
Oregon\'s best standard for raising and migrating salmon and trout requires a water temperature of 64. 4[degrees]F.
According to the 2004 report of the Oregon independent multi-disciplinary science group, the report advises the state government on scientific issues related to salmon and watershed management in Oregon, and studies show that at a temperature of 69 °c, adult salmon began to die. 8-71. 6[degrees]
F, and some trout varieties with slightly higher temperatures.
While young salmon can survive at a slightly higher temperature, the effects on their growth and survival are well documented.
The impact of building materials that have not been recorded in detail is the impact of pollutants released into rainwater runoff by the building and paving materials themselves.
Asphalt is a concern because it contains recognized human carcinogens-coal tar and multi-ring aromatic hydrocarbons (PAHs)
Including benzene [a]
Pyrene, another carcinogenic substance.
Another potential source of pollution is wood used for Poles, rides and other structures treated with chromium-treated arsenic copper (CCA;
A substance is now being eliminated due to health problems)
PCP or chowder.
According to a paper published by Melinda Lal, professor of environmental engineering at the University of Alabama, Birmingham, at 2004 annual water resources conference, in 1987 alone, the United States produced about 11 copies.
CCA-900 million cubic metersTreated Wood, 1.
PCP 4 million cubic meters-
Treated wood, and 2.
8 million cubic meters of miscellaneous oiltreated wood.
Once constructed with this material, it is intended to last for a long time.
The health risks of arsenic and chromium are well known, and while copper is generally not a human health risk, the low concentration of certain ion forms of this metal is toxic to marine flora and fauna.
\"In general, pollutant levels tend to vary depending on the age of the material and the severity of the exposed environment,\" Lalor said.
As the material ages, it is exposed to high levels of sunlight, extreme temperatures, chemicals in the environment (such as salt on the road, etc. ), and the shower will increase.
\"If the pollution source is a coating, then the level of pollution will decrease as you age, but it will still have a significant impact,\" she said.
\"If you look at the asphalt used in the parking lot, the coating on it is quite toxic.
So if you have a heavy rain [soon]
It\'s not uncommon to see fish kill dowstream after parking goes in.
Lalor cited a study published in Volume 35 of Issue 9 (1997)
Water Science and Technology shows that the rain on roofs and streets contributes 50-
80% flow of cadmium, copper, lead and zinc measured by Switzerland\'s combined sewer system.
The metal concentration of the polyester roof material is the highest, followed by the tile roof and then the flat gravel roof.
Swiss researchers also found multi-ring and organic halogen hydrocarbons in roof runoff.
Released chemicals can have a significant impact on the environment and potential human health.
Lalor said: \"Some materials, such as metals, are particularly toxic to animals at different stages of the life cycle, while some organic matter, especially oil --
Based on organic matter, it can be used as a fake estrogen.
Thus, while they may not lead to death, they may cause significant disruption to the physiology of organisms exposed to these contaminants.
\"According to Lalor, despite the prescribed urban rainwater emission tests, there is no current provision for testing of building materials to determine their potential to release toxic substances.
\"If a community wants to develop around their sources of drinking water, they should know the potential for the release of building materials so that they can carefully choose the building materials they use,\" she said . \".
\"We don\'t have the science to support it yet, but being able to go to the builder and say \'Look, here\'s a list of twelve alternatives to building materials, these alternatives are the best for the environment for this site and these conditions.
New Zealand has been a leader in such research and the country is preparing to develop regulations on building materials and environmental impacts, Lalor said.
But in the United States, this kind of research has not yet been raised to a high enough priority to build the science we need to make new policies.
She added, \"We need to address the entire life cycle of building materials, from their creation to the impact of the building on the environment, on anything they may lose in their lifetime, to the end --of-
Disposal of life
\"Although there is a lot of evidence to support the negative relationship between the non-penetration surface and the environment, the promise of the porous road surface, no one would seriously suggest that we stop laying streets or building parking lots.
So, what are the options?
According to Ferguson, there are 9 different kinds of porous pavement materials.
Some of these materials are well known in the United States;
Seam paving that can be filled with turf or aggregate, \"soft\" paving materials such as wood coverings and crushed shells, and traditional paving.
Other families include the porous concrete and asphalt being developed by engineers and landscape architects.
Ferguson said the materials use the same components and manufacturing processes as traditional non-permeable materials, \"In general, health and environmental issues are the same. . . .
The same chemicals, the same energy costs, but the benefits in use are very different.
\"These new recipes still provide a solid, safe surface for walking and vehicle traffic, but also allow rain to penetrate into the underground soil.
The porosity of porous asphalt is achieved only by using a fine aggregate concentration lower than that of conventional asphalt;
It can be mixed in traditional asphalt plants.
Under the porous asphalt coating is a bed consisting of clean aggregates.
It is important that the size of this aggregate is the same, which maximizes the gap space between the rocks, allowing for water filtration.
A layer of geotextile under this bed allows the flow of water into the soil and prevents the soil particles from moving up into the stone.
According to Ferguson, porous asphalt was actually developed more than 30 years ago, but it was not successful at the time.
Part of the problem, he believes, is ---
Low levels of federal-funded research
\"Back in the early 80 s, the Environmental Protection Agency [EPA] when the porous pavement is new [EPA]
\"I am very interested, especially in porous asphalt,\" he said . \"
\"But one problem with porous asphalt at the time was that on a hot day, the adhesive softened and migrated down to a colder layer.
Release surface aggregates and plug the lower layer.
\"According to Ferguson, the EPA has become frustrated and stopped studying.
However, Ferguson said researchers in France, Belgium and Ireland have improved porous asphalt technology since then.
In the late 1980 s and early 1990 s, they found that adding polymer fibers and liquid polymers to the asphalt could prevent the adhesive from being discharged through the aggregate.
Today, though [porous asphalt]
\"From here on, we are using imports from Europe,\" he said . \".
Ferguson said vulnerable roads account for only a small percentage of the annual roads in the United States.
\"However,\" he continued, \"The growth rate of the porous pavement is very high in percentage terms, mainly because of public concern and legal requirements for urban rainwater management.
This growth has occurred both in the Dali Green and concrete industry and in smaller industries that supply competitive materials such as concrete blocks and plastic basement.
An argument against the surface of high permeability
Traffic areas are not as long-lasting as the ancestors they did not penetrate.
Ferguson said it was not true at all.
\"I have seen good permeable roads in places like Minnesota and Alaska, where there is a huge extreme climate,\" he said . \".
\"In Georgia and Oregon, it has become routine to re-lay highways by laying a layer of permeable asphalt on the permeable surface below.
In this way, water is drained horizontally below the surface, giving you better traction and visibility.
\"While the main benefit of this approach is road safety, not re-
Water penetrates into the groundwater, and it still allows more water to return to the groundwater level, not to the surface that does not penetrate, where it simply evaporates back into the atmosphere.
Another benefit of some permeable surfaces is to allow contaminants to come into contact with microorganisms under the surface.
According to Ferguson, these naturally occurring microbial communities thrive on the large surface area of pores inside the permeable plate and break down contaminants (
Oil in particularproducts)
Before they enter the water supply system.
\"Scientists at Coventry University recently did a study where they simulated a porous road surface with oil in the lab,\" he said . \".
\"They dumped a lot more waste oil on the surface than you found in the parking lot, and none of the oil reached the soil layer below \"--
On the contrary, microorganisms digest all this.
Coventry team led by Christopher J.
Pratt published an overview of their work in the Journal of Engineering geology and hydrology, published in November 2004.
Other methods of controlling runoff, in addition to changing the building materials themselves, can also deal with the diffusion of non-permeable surfaces.
Returning to a more reasonable street width is a measure, says Kelsch, and many communities are increasing the number of green spaces to allow rainfall to penetrate underground.
For urban areas with nearby lakes, the construction of a \"rain garden\" is becoming a popular way for homeowners and businesses to help control rainwater runoff, banaman said.
The design of this garden is to plummet in the center to catch the water, then the water can slowly filter to the ground rather than running into the rain drain.
Ideally, these gardens are located next to hard surfaces such as sidewalks or lanes, planting hard-working native species that can thrive without the need for fertilizers or pesticides.
Another option is to use a basin like in Fresno.
The city in the San Joaquin Valley of Southern California has less than 12 inch annual rainfall, and most of its water comes from underground reservoirs and nearby Kings and the San Joaquin River.
Since the end of 1960, the city began to build several water basins. -
Large basins where rain can precipitate, then drain through the soil.
Lon Martin, water system manager, said that the city has two goals in establishing these water basins: \"The first is to prevent rainwater runoff from flooding the city and flowing into the river, which may cause water quality problems.
Second, the city has begun plans for an intentional supply of water reservoirs.
\"So far, he said, the city has connected nearly 80 of the 150 possible water-accumulation basins to groundwater recharge systems.
Rain replenishment is part of the equation, but it is also possible for cities --
In October, the amount of water in the two rivers was distributed, flowing water to these basins, and then allowed gravity to pull water down into the aquifer through the sandy fertile soil.
Another way to control rainwater runoff-a green roof, as the name implies, is to plant a roof of all types of vegetation.
Also known as \"ecology
The roof, \"these surfaces can be extensive (
Lighter weight, relying on a few inches of soil, using plants such as herbs, grass and wildflowers)or intensive (
Inches of soil depth for trees and shrubs).
According to the Earth Commitment Foundation, a non-profit organization, green roofs can absorb nearly 75% of rain and reduce the island effect of cities.
The green roof plays several roles, one of which is collecting water, or basically collecting rain water for use elsewhere.
\"The water is cleaner than the water on the sidewalk,\" Ferguson said . \". \"[
Now, this practice is being carried out in areas with insufficient water supply, such as the Southwest or the Pacific Northwest, which is dry in summer. . . . [It]
This may be a valuable tool in areas where water is scarce.
\"In Germany, about 10% of the buildings have green roofs, and Tokyo recently stipulated that more than 1,000 of the available roof space on the top of the new building must be 20% green.
Green roofs are also available in North American cities such as Chicago, Toronto and Portland, Oregon.
In addition to recognizing the environmental health threats of permeable surfaces and other sources of pollution, EPA has also established a rain permit program under the national pollutant emission elimination system.
The first phase of the rain water plan promulgated in 1990 requires separate rain water system permits for communities of more than 100,000 people, as well as rain water emissions related to at least five acres of industrial and construction activities.
The second phase, promulgated in 1999, involved the remaining issues and urban areas with less than 100,000 people, as well as smaller construction sites and retail, commercial and residential activities.
However, further changes require us to change our perception of runoff.
\"What we have started and have to continue to do is get rid of the idea that rain is waste water ---
Something to throw away and pass on to the neighbors downstream.
We need to put it where it falls, and the way to keep it is to put it back on the ground.
Kelsch said there is no solution for flash floods.
The flood will happen even though we can do everything.
What we need to do is do what we can to reduce the inevitable impact.
This means building on the flood plain, increasing the amount of rain we send back to the reservoir, while reducing the amount we discharge into the stream.
\"Building Design and the use of permeable paving materials will help, but we need to be aware that these are not solutions,\" he said.
Also, he added, \"If we get stuck in the mindset that we have to have a solution, we may not do anything.
This will make the problem even more serious.