The main sources of river pollution worldwide are sewage, effluent from livestock farms, manufacturing and industrial discharges, mining wastes, materials from housing and road construction, and the myriad wastes carried in rain runoff, including gasoline and oil. Urbanization adds its own mixture of eroded soil, solid wastes, rubbish, and organic matter. The relative amounts of these pollutants differ between developed and developing countries, but each of these pollutants represents worldwide problems in riparian health.
Four factors cause riparian destruction in addition to pollution: physical alterations; destruction of catchment areas; mismanagement of fish resources; and invasive species. Physical alterations include structures built into or near waterways for the purpose of flood control, landscaping, or power generation. Some urban centers alter waterways simply because the city wants the water to pass through it in a more convenient way. Altering riparian areas is not confined to large cities, as a Glenwood Springs, Colorado, resident pointed out in a 2008 letter to the Glenwood Springs Post Independent: “There are large subdivisions all over the [Roaring Fork] Valley where the prime riparian has been ripped up entirely to support exclusive subdivisions, malls and golf courses. . . . I don’t find golf courses, shopping centers and parking lots a positive addition to the environment. All that manicured green grass, asphalt and chemical warfare has replaced the oak brush, sagebrush and the natural habitat. The irony is the new pavement is named Heron Circle, Eagle Court, Hawk Lane, yet we’ve destroyed the birds’ actual habitat.” Construction that was once well-meaning has turned into a hazard for habitat and biodiversity.
Some of the major restructuring projects that have been completed on rivers and streams that cause major impact on riparian environments are the following:
» dams for flood control, drinking water reservoirs, or power generation
» clearing of riparian vegetation for landscaping
» constructed channelization through urban areas
» river diversion in urban areas
» deepening, straightening, or widening rivers for ship use
» docks and boardwalks for recreation
Physical alterations change waterways’ normal routes, sediment settling, water temperature, and water chemistry. All these factors affect biota from microbes to old-growth trees that live in the catchment area. Catchments consist of mountain lakes, ponds, and streams as well as the moisture stored in trees and soil. New developments on mountaintops that cut down trees and landscape the area for roads and views change the catchment’s capacity to store water for later use downstream. Clear-cutting, mining, and agriculture impose similar effects on catchments.
Mismanagement of fish resources in natural rivers and streams also damages riparian habitat. Illegal fishing, overharvesting, or fishing without regard for the environment affects these habitats as does the use of poisons, nets, and even explosives. Other ills brought by irresponsible fishing are the waste pollution and overuse of the same riparian location. Overuse causes three main damages to the riparian habitat: destroyed terrain; trampled vegetation on the banks; and alteration of wildlife’s normal patterns.
Riparian habitats also receive damage from invasive vines or bushes that people plant along waterways. These plants have the potential to displace native vegetation that serves as food, shelter, and nesting sites for wildlife. Invasive fish species also alter the natural ecosystem in ways that may affect biota far downstream, particularly by interfering with normal food chains.
Source of Information : Green Technology Conservation Protecting Our Plant Resources