The Importance of Automated Data Collection:

The ability to collect useful information about suspended sediment transport, pollutants and water discharge is dependent on the timing and frequency of data collection during run-off events. All channel and pipe flow that exhibits a rapid response to rainfall or releases benefit from automated data collection. Small watersheds and urban sites with large impervious areas transport 90% or more of the suspended sediment and pollutants loads during infrequent large run-off events.

Objectives of Turbidity Threshold Sampling:

• Reliably define the turbidity-suspended sediment relationship for each event
• Accurately estimate event or annual loads from the nearly-continuous turbidity record.
• Automate data collection and sampling to ensure important events are measured
• Limit the number of suspended sediment samples for each event thereby reducing costs

Turbidity is an optical measure of the number, size, shape, and color of particles in suspension. A number of manufacturers offer turbidity probes that can be deployed on a continuous basis in streams. The optical properties of sediment, mainly size and shape, have a large influence on the magnitude of the turbidity signal.

Turbidity Threshold Sampling Instrumentation:

• Programmable data logger executing the sampling code
• Turbidity sensor
• Automatic pumping sampler
• Stage/discharge measurements

BMP Flow-based Composite Sampling:

• A programmable data logger triggers sample collection based on flow and/or rainfall
• User can easily adjust accumulated discharge or rainfall volumes to achieve desired sampling requirements
• Number of samples per bottle is under program control and easily modified by the user
• Stage/discharge is recorded for each measurement interval

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