Massimo Guerrero

Flow Field and Morphology Mapping Using ADCP and Multibeam Techniques: Survey in the Po River

An 8-km-long and 250-m-wide reach of the Po River (Italy) was surveyed with two vessels, aiming to investigate the channel morphology and flow field characterizing this major Italian river and to provide data for the calibration of a numerical model. The first vessel was equipped with a multibeam ecosounder (MBES), whereas an acoustic doppler current profiler (ADCP) was located on the second one. Fixed-vessel ADCP measurements were used to preliminarily investigate the turbulence variability affecting the reliability of moving-vessel measurements. To evaluate the friction velocity by using moving-vessel measurements, the vertical variance of velocity profiles as an alternative to logarithmic fitting of ADCP profiles was estimated. An average of 30-m cells of depth-averaged velocity, friction velocity, and surface-bottom velocity angle are presented in maps as the most relevant flow field features. The flow field and channel morphology at bed-form or channel scales showed noticeable correlations (0.9). In ...

Multi-frequency acoustics for suspended sediment studies: an application in the Parana River

A method of using two acoustic Doppler current profilers operating at different frequencies and employed at the same measuring vertical to sample a profile of suspended sediment concentration has been previously applied in the Parana River (Argentina) but has not been validated by direct sediment samples. The present work fills this gap by reporting new field data and comparing them with acoustically inferred sediment concentrations. The agreement between directly measured sediment concentrations and grain sizes with corresponding estimates from an employed backscatter model was found to be good (squared correlation coefficients are 0.9 and 0.8, and mean deviations are 14 and 6%, respectively). The interrelations between flow velocity and suspended sediment concentration at fixed locations and in a moving mode along a river cross-section have been also investigated. Observed events of bed sediment re-suspension were found to be highly correlated with fluctuations of the vertical flow velocity, with a 100–150s quasi-periodicity. The size of re-suspension plumes was increasing from the channel thalweg to the low-submerged bar areas.

Estimation of Concentration and Load of Suspended Bed Sediment in a Large River by Means of Acoustic Doppler Technology

Fil: Latosinski, Francisco Guillermo. Universidad Nacional del Litoral. Facultad de Ingenieria y Ciencias Hidricas. Departamento de Hidraulica; Argentina. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Santa Fe; Argentina

Bed-roughness investigation for a 2-D model calibration: the San Martín case study at Lower Paranà

Abstract This paper illustrates how the acoustic Doppler current profiler (ADCP) and single-beam echo-sounder (SBES) recordings can be used for the calibration of existing software to assist in generalizing the morphodynamic processes in large rivers at key sites such as bifurcations and confluences. Calibration of the MIKE21C numerical model by the Danish Hydraulic Institute at the 25-km-long reach of Lower Parana near Rosario (Argentina) is presented. This reach includes two downstream confluences and two bifurcations. The model simulates a 2-D depth-averaged flow velocity and the related sediment fluxes to predict the bifurcation morphodynamics that affects the Parana waterway. To investigate the river channel bathymetry, roughness, flow discharge allocation at bifurcations, suspended sediment concentration and grain size distributions, several instruments were used. These instruments included two ADCPs by Teledyne RDI working at frequencies of 600 and 1,200 kHz, a Sontek ADCP working at a frequency of 1,000 kHz and a SBES. The method to assess suspended sediment concentration and grain size distributions has been previously described. This paper focuses primarily on investigating dune morphology (by means of SBES depth measurements) and friction velocity (by means of ADCP profiling) to determine the river channel bed-roughness. The 2-D model results agree with observed values of bed-roughness, flow velocity and suspended sediment concentration distributions at the investigated sections, known data of water slope and total load of bed sediment are in good agreement with model results.

Parana River morphodynamics in the context of climate change

ABSTRACT This paper presents an analysis of the sediment dynamics that takes place at different scales within the Middle and the Lower Parana River in the La Plata Basin. The aim of this study is to provide a multi-disciplinary and multi-scale approach for the prediction of river future morphology in the context of climate change, the intended use of which is the prognosis of river morphodynamics’ long-term impact on manmade structures and activities over or near the river. The study is based on three levels of mathematical modelling, with the output of wider-scale models providing the input conditions for more specific ones. Climate models give the input ensemble, i.e. future precipitation and temperature over La Plata Basin. The semi-distributed macroscale variable infiltration capacity hydrological model simulates the flow discharge time series that are applied to an own-developed 1D morphodynamic model. The 1D model simulates future rate of sediment transport and corresponding bed-level changes at watershed scale and provides the boundary conditions for a 2D model. Therefore, streamflow divagations at channel scale are simulated by means of the MIKE21C code developed by the Danish Hydraulic Institute. The analysis indicates a rather low sensitivity of the Parana River bed profile, i.e. 1D morphology, to the increase predicted in flow discharge, whereas the streamflow appreciably divagates. In particular, surpassing an upper bound in the most frequent discharge appears effective in driving the actual bifurcated morphology into a meandering-multithread configuration.

Effect of climate change on navigation channel dredging of the Parana River

This paper presents an analysis of the effect of climate change on modifying the dredging cost to maintain the navigation channel at the actual capacity of the Parana waterway (Argentina). The Parana−Paraguay Rivers system is one of the most important inner navigation waterways in the world, where approximately 100 million tons of cargo are transported per year. Maintenance of the navigation channel requires continuous dredging by Hidrovía SA (limited liability company), which is responsible for ensuring the minimum water depth for navigation. A failure event occurred during January 2012 when a bulk cargo carrier ran aground, interrupting fluvial trading for 10 days. Numerical models were applied to simulate hydro-sedimentation processes at the Lower Parana River to estimate dredging costs for a given flow discharge. The resulting function relates the sedimentation rate (i.e. the dredging effort required to keep the present depth for vessel draft) to forcing hydrology conditions. This function and the statistical evaluation of climate scenarios were used to calculate the probability of failure for navigation and the associated cost of channel maintenance. The most appropriate dredging effort was estimated by detecting the minimum total cost (i.e. dredging plus failure) to varying the yearly average discharge and by analysing the sensitivity of the total cost to different degrees of economic impact.

Po River Morphodynamics Modelled with the Open-source Code iRIC

The paper presents the numerical modelling of the hydro-morphological evolution of a 10 km reach of the Po River in Italy. The simulation is performed with the freeware code iRIC, recently developed by an international community of scientists and practitioners. Starting from a non-detailed description of the studied area and using synthetic data, the reach has been modelled adopting a 2-D solver. Based on a Digital Elevation Model of the area, the domain is discretized by an unstructured grid with triangular meshes. First results show a promising capability of the model in reproducing the behaviour of the reach, both in terms of liquid flow and morphodynamics, if compared with historical data measured along the watercourse and reported in literature. In the future, additional simulations will be performed, enlarging the studied area and using detailed input data measured with traditional and innovative techniques.