HTML } sub printInfoLogging{ print <<"HTML";
Pristine Forest
The pristine forest in our model is untouched, old growth woodlands. The forest has not been impacted by human use, and therefore remains unhindered in its growth and its functions. This station can be used as a comparison to the other stations because it represents an idealized subwatershed.
Non Point Source Pollution in Logging Forests
HTML } sub printInfoAgricultural{ print <<"HTML";Nearly 500 million acres of forested lands are managed for the production of timber in the United States. Although only a very small percentage of this land is harvested each year, forestry activities can cause significant water quality problems if improperly managed. The latest National Water Quality Inventory reports that forestry activities contribute to approximately 9 percent of the water quality problems in surveyed rivers and streams.
Sources of NPS pollution associated with forestry activities include removal of streamside vegetation, road construction and use, timber harvesting, and mechanical preparation for the planting of trees. Road construction and road use are the primary sources of NPS pollution on forested lands, contributing up to 90 percent of the total sediment from forestry operations. Harvesting trees in the area beside a stream can affect water quality by reducing the streambank shading that regulates water temperature and by removing vegetation that stabilizes the streambanks. These changes can harm aquatic life by limiting sources of food, shade, and shelter.
Non Point Source Pollution in a Mixed Agricultural Area
Our agricultural land usage is 80,000 acres of mixed agriculture. This means that we model not only land that is used by farmers growing crops, but also land that is used to raise livestock. These two usages produce different effects on the indicators, but our simulator combines the result into a single station. Agricultural activities can result in increases in sediment, increased nutrients, and increased toxins. The growing of crops with relatively shallow roots leads to a decrease in the ability of the vegetation to "hold onto the soil", thus increasing sediments as well does the constant grazing of livestock. Livestock increase nutrients in the watershed by deposition of fecal matter. Nutrients are also increased by fertilizers added to crops and pesticides, which increase the amount of toxins.
From
EPA
Pointer
No. 6
EPA841-F-96-004F
HTML
}
sub printInfoResidential{
print <<"HTML";
The many causes to non point source pollution in the suburban area include:
HTML } sub printInfoIndustrial{ print <<"HTML";
- Suburban landscapes are covered by paved surfaces like sidewalks, parking lots, roads, and driveways. They prevent water from percolating down into the ground, cause runoff to accumulate, and funnel into storm drains at high speeds. When quickly flowing runoff empties into receiving waters, it can severely erode stream banks.
- Paved surfaces also transfer heat to runoff, thereby increasing the temperature of receiving waters. Native species of fish and other aquatic life cannot survive in these warmer waters.
- Altering the natural contours of yards during landscaping and planting with non-native plants that need fertilizer and extra water can increase the potential for higher runoff volumes, increase erosion, and introduce chemicals into the path of runoff.
- Malfunctioning or overflowing septic systems release bacteria and nutrients into the water cycle, contaminating nearby lakes, streams, and estuaries, and ground water.
- Household cleaners, grease, oil, plastics, and some food or paper products should not be flushed down drains or washed down the street. Over time chemicals can corrode septic system pipes and might not be completely removed during the filtration process. Chemicals poured down the drain can also interfere with the chemical and biological breakdown of the wastes in the septic tank.
The many causes to non point source pollution in a shopping area include:
HTML } sub printInfoMarsh{ print <<"HTML";
- Shopping malls typically have large parking lots. Precipitation that falls on the lot runs off and carries along oil and rust from the cars, as well as salt used for melting ice. Without a well maintained stormwater drainage system all of this finds its way into the watershed.
- Parking lots generate almost 16 times as much runoff as an undeveloped meadow.
- Herbicides are often used to control plant growth around parking lots.
HTML } sub printInfoUrban{ print <<"HTML";Wetlands Area
Healthy wetlands benefit fish, wildlife, and humans because they protect many natural resources, only one of which is clean water. Unfortunately, over half of the wetlands in the lower-48 states were lost between the late 1700s and the mid-1980s, and undisturbed wetlands still face threats from development. Improper development or excessive pollutant loads can damage wetlands. The degraded wetlands can no longer provide water quality benefits and become significant sources of NPS pollution. Excessive amounts of decaying wetlands vegetation, for example, can increase biochemical oxygen demand, making habitat unsuitable for fish and other aquatic life. Degraded wetlands also release stored nutrients and other chemicals into surface water and ground water.
The wetlands area that is dealt with in the RiverWeb model is one that has been overdeveloped, and is far from pristine. There are several paved roads running through the habitat, and the area is heavily used by humans. Activities include hiking, driving, biking, swimming, and fishing. Powerboats and personal watercraft are common, and contribute to noise as well as water pollution.
HTML }Non Point Source Pollution in an Urban Area
Increased Runoff. The porous and varied terrain of natural landscapes like forests, wetlands, and grasslands trap rainwater and snowmelt and allow it to slowly filter into the ground. Runoff tends to reach receiving waters gradually. In contrast, nonporous urban landscapes like roads, bridges, parking lots, and buildings don't let runoff slowly percolate into the ground. Water remains above the surface, accumulates, and runs off in large amounts.
Cities install storm sewer systems that quickly channel this runoff from roads and other impervious surfaces. Runoff gathers speed once it enters the storm sewer system. When it leaves the system and empties into a stream, large volumes of quickly flowing runoff erode stream banks, damage streamside vegetation, and widen stream channels. In turn, this will result in lower water depths during non-storm periods, higher than normal water levels during wet weather periods, increased sediment loads, and higher water temperatures. Native fish and other aquatic life cannot survive in urban streams severely impacted by urban runoff.
Increased Pollutant Loads. Urbanization also increases the variety and amount of pollutants transported to receiving waters. Sediment from development and new construction; oil, grease, and toxic chemicals from automobiles; nutrients and pesticides from turf management and gardening; viruses and bacteria from failing septic systems; road salts; and heavy metals are examples of pollutants generated in urban areas. Sediments and solids constitute the largest volume of pollutant loads to receiving waters in urban areas.
When runoff enters storm drains, it carries many of these pollutants with it. In older cities, this polluted runoff is often released directly into the water without any treatment. Increased pollutant loads can harm fish and wildlife populations, kill native vegetation, foul drinking water supplies, and make recreational areas unsafe.