Development and Evaluation of a Prototype Turbidity Sensor for In Situ, Long-Term Measurements.

Abstract : State and federal regulations require the U.S. Army Corps of Engineers (USACE) to mitigate adverse environmental impacts resulting from increased turbidity levels which occur during coastal operations. Quantifying turbidity levels prior to, during, and after coastal operations is difficult due to existing turbidity measurement technology and water quality standards. Existing methods for turbidity measurement are limited to short term deployment, which does not include the impacts of seasonal variations, meteorological effects, and storm conditions. A turbidity monitoring system for collecting long term in situ measurements is currently in the conceptual design phase. A transmissometer, which is the sensing device for turbidity measurement, fabricated, and tested, and is the focus of this report. The design of the transmissometer considers the requirements for successful long-term in situ deployments. The laboratory calibrated prototype sensor provides the basis for the design and development of a long term operation USACE turbidity monitoring system. The design of the prototype transmissometer and the laboratory tests, calibration, and results are presented.