Thanos Papanicolaou
IIHR - Hydroscience & Engineering, The University of Iowa

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Application Note: Sediment Transport
 
Noncohesive Sediment: Understanding the mechanisms involved in the transport and fate of noncohesive soils in natural channel systems remains an open case in water-related engineering disciplines.  The main challenge in studying noncohesive sediments is the complex character of the bed geometry which governs the velocity, as well as the turbulence structure of the flow which in turn, control the sediment-carrying capacity of the flow.  Bed geometry is controlled by stochastic processes and subject to drastic changes due to changes in the flow condition.  Bedforms, clusters, step and pools are few examples of such complicated bed geometry.  In addition, sediment may consist of a wide range of grain sizes.
   
Suspended load: Flume experiments were conducted to measure the suspended load of sand. The suspended sediment concentration profile was measured using a Sedimeter, an instrument composed of a vertical array of optical backscatter sensors and an internal data logger.  The instrument was designed for long-term deployments to track bed levels. The use of the Sedimeter for measuring suspended sediment concentration is relatively new.  The Sedimeter reads the amount of material in concentration through its array of optical backscatter sensors. A total of 16 co-linear sensors are spaced 9 mm apart on a 3/8” shaft. The lowest sensor was 1.5 inches from the end of the shaft. Each sensor emits an infrared beam and subsequently reads the light reflected from the suspended particles. The vertical distribution of water velocity was simultaneously measured using an Acoustic Doppler Velocimeter (ADV). The data obtained by the Sedimeter is coupled with that from the ADV to produce suspended sediment transport rates.