Organisms in these waters have adapted to higher turbidity levels. In other environments turbidity is naturally high. In these environments dredging is often limited or avoided entirely during spawning season to protect marine life. Some water habitats have very clear (less turbid) water and any change to light penetration will adversely affect the underwater species. The nephelometer measures the clarity of the water and NTU represent the average volume of particles scattered over a defined angular range.įor instance, a satellite image of on-site data indicating the NTU of various dredging vessel plumes can be compared with the baseline measurements previously taken to determine if these values exceed the turbidity threshold values.ĭredging contractors and environmental scientists spend a great deal of attention to when, where and how dredging takes place so as to minimise disturbances. Turbidity is commonly measured by a nephelometer in Nephelometric Turbidity Units (NTU). Then using periodic monitoring during dredging with various instrumentation, the level of turbidity can be evaluated. But turbidity during a dredging operation can be measured, monitored and controlled.īefore the start of a dredging project, a baseline study is usually done which establishes the norm for turbidity in a given area. Although storms, waves and heavy currents can cause increased turbidity, which can impact water quality with subsequent health and hygiene repercussions, there is little one can do about natural causes. Turbidity is a natural phenomenon that occurs in all bodies of water – oceans, lakes or rivers and is in itself not a pollutant. If it is too cloudy or opaque it can result in the disturbance or blockage of sunlight, which can impact marine flora and fauna. Water that contains particles which cause cloudiness or muddiness is called turbid. Turbidity is an optical quality of water and describes how clear or transparent water is. “Facts About Turbidity & Dredging” describes the characteristics of turbidity and the importance of measuring and monitoring turbidity during dredging.
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