Calibration of an aDp to estimate suspended sand concentrations in a large river

SZUPIANY, RICARDO; AMSLER, MARIO; GARCÍA, CARLOS MARCELO

Lake Placid - Nueva York - USA

Conferencia; Hydraulic Measurements & Experimental Methods 2007 Conference; 2007

Environmental and Water Resources Institute (EWRI) od the American Society of Civil Engineers (ASCE)

ABSTRACT. The standard procedures used for sampling suspended sands in large streams require the vessel to be anchored at a proper number of several verticals during a certain period of time. These methods are usually time-consuming, rather expensive, and have a limited spatial resolution. Additionally, a potential risk for the vessel safety exists in navigable rivers. The acoustic Doppler technology has been recognized as a tool that may give quantitative information on suspended sediment concentrations through the acoustic backscattering strength avoiding several drawbacks implicit in the traditional methods. In this paper a relation between the backscatter acoustic intensity recorded by an Acoustic Doppler Profiler (ADP) and suspended sand concentrations obtained from classic depth-integrated samplings, is presented and discussed. The resulting relation compared fairly well with the theoretical straight line slope suggested by the ADP manufacturer. It is concluded that the similarity between the suspended sand sizes and the type of particles which present maximum sensitivity to the backscatter acoustic intensity according to the inherent characteristics of the ADP instrument used in this case, is a crucial issue to explain the results consistency. The standard procedures used for sampling suspended sands in large streams require the vessel to be anchored at a proper number of several verticals during a certain period of time. These methods are usually time-consuming, rather expensive, and have a limited spatial resolution. Additionally, a potential risk for the vessel safety exists in navigable rivers. The acoustic Doppler technology has been recognized as a tool that may give quantitative information on suspended sediment concentrations through the acoustic backscattering strength avoiding several drawbacks implicit in the traditional methods. In this paper a relation between the backscatter acoustic intensity recorded by an Acoustic Doppler Profiler (ADP) and suspended sand concentrations obtained from classic depth-integrated samplings, is presented and discussed. The resulting relation compared fairly well with the theoretical straight line slope suggested by the ADP manufacturer. It is concluded that the similarity between the suspended sand sizes and the type of particles which present maximum sensitivity to the backscatter acoustic intensity according to the inherent characteristics of the ADP instrument used in this case, is a crucial issue to explain the results consistency.