إطماء
الإطماء Siltation أوsiltification هي تلوث الماء بمواد by particulate terrestrial clastic material, with a particle size dominated by silt or clay. It refers both to the increased concentration of suspended sediments, and to the increased accumulation (temporary or permanent) of fine sediments on bottoms where they are undesirable. Siltation is most often caused by soil erosion or sediment spill.
Sometimes siltation is called sediment pollution, although that is an undesirable term since it is ambiguous, and can also be used to refer to a chemical contamination of sediments accumulated on the bottom, or pollutants bound to sediment particles. Siltation is the preferred term for being unambigiuous, even if not entirely stringent since it also includes other particle sizes than silt.
المسببات
The origin of the increased sediment transport into an area may be erosion on land, or activities in the water.
Climate change also affect siltation rates.
Another important cause of siltation is the septage and other sewage sludges that are discharged from households or business establishments with no septic tanks or wastewater treatment facilities to bodies of water.
Vulnerabilities
Siltation can also affect navigation channels, or irrigation channels. It refers to the undesired accumulation of sediments in channels intended for vessels, or for distributing water.
القياس والمراقبة
Siltation of the magnitude that it affects shipping can also be monitored by repeated bathymetric surveys.
تفادي الإطماء
== المراجع ==
- ^ U.D. Kulkarni; et al. "The International Journal of Climate Change: Impacts and Responses » Rate of Siltation in Wular Lake, (Jammu and Kashmir, India) with Special Emphasis on its Climate & Tectonics". The International Journal of Climate Change: Impacts and Responses. Retrieved 2009-11-16.
