Designing the Sustainable Site, Enhanced Edition by Heather L. Venhaus

Author:Heather L. Venhaus
Language: eng
Format: epub
Publisher: Wiley
Published: 2012-02-23T05:00:00+00:00

Figure 5-1: Flooding in North Yorkshire, UK.

Ronald Hudson/Bigstock.com

Chapter 5

Sustainable Solutions: Urban Flooding and Water Pollution

Humanity has a long, complex—and interdependent—relationship with water. Human civilization itself was born in a place we now call the Fertile Crescent, an area swaddled by the Tigris, the Euphrates, and the Nile rivers. As civilized society spread throughout the globe, cities sprouted along the banks of waterways: Shanghai at the mouth of the Yangtze, Paris on the river Seine, Kanpur on the Ganges, Rome on the Tiber, and New Orleans at the mouth of the mighty Mississippi. Water bodies attract development because of the many advantages they offer in transportation, commerce, energy production, food, and recreation. With these benefits, however, come disadvantages—primarily flooding and water pollution.

Flooding is a natural process. It is necessary for maintaining the function and biodiversity of many aquatic and terrestrial ecosystems. Floodwaters create critically important habitat, return nutrients to the land, recharge groundwater supplies, and replenish topsoil. Flooding becomes problematic, however, when property damage occurs and people’s homes and businesses are affected.

Land-use changes associated with urban development often exacerbate flood conditions and are a major source of water pollution. Impervious surfaces, which cover significant portions of our built environment, increase both stormwater volume and runoff rate, which adds to the pollution of the vital waterways on which we depend.

Clean water legislation has been effective at slowing the degradation of, and in some cases even improving, water quality; however, there is still much work to be done. In the United States, half of the rivers and streams—roughly 463,000 river and stream miles (745,126 km); 66 percent of the lakes, reservoirs, and ponds—equaling approximately 11 million acres (4.5 hec); and 100 percent of the Great Lakes open waters—an area of 56,709 square miles (146, 875 km2)—have been classified as “impaired” (U.S. EPA 2011), meaning they have been polluted to the point that they no longer meet water quality standards for their designated use. And most state agencies are able to sample or monitor only a small percentage of their waters. A more comprehensive look at all aquatic ecosystems in the United States would likely uncover higher percentages of impairment.

The good news is that sustainable site development can reduce urban flooding and improve water quality by restoring the ecosystem processes that capture and cleanse water. In this chapter, the relationship between urban flooding, water pollution, and site development is explored. Pollutant sources and their impacts on human health and the environment are discussed, along with strategies to restore floodplain function, reduce stormwater runoff, and improve water quality.

Point Source and Nonpoint Source Water Pollution

Water pollution can be classified as either point source or nonpoint source. Pollution discharged into a body of water from a discernible, confined, and specific location, such as a pipe, ditch, or sewer, is defined as point source water pollution. Because it originates from a discrete location, it is typically easier to trace, monitor, and control. Point source pollution is typically associated with industrial water discharges and sewage treatment plants.

Nonpoint source water pollution is dispersed and is not attributable to a single point of discharge.

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