0000000000139019
AUTHOR
G. Corato
Continuous Discharge Monitoring Using Non-contact Methods for Velocity Measurements: Uncertainty Analysis
At gauged site, water stage and discharge hydrographs can be related also during unsteady flow conditions, using the one-dimensional diffusive hydraulic model, DORA, and exploiting sporadic surface velocity measurements carried out with a radar sensor, during the rising limb of the flood. Indeed, starting from the measured surface velocity, the application of a simplified entropic velocity distribution model allows obtaining the benchmark discharge for the Manning’s roughness calibration. The aim of this work is twofold. First, to address the uncertainty of the approach. Second, to detect the minimum water level along the rising limb in which the occasional surface velocity measurement shou…
ASSESSMENT OF RIVER FLOW WITH SIGNIFICANT LATERAL INFLOW THROUGH REVERSE ROUTING MODELING
The discharge hydrograph estimation in rivers based on reverse routing modeling and using only water level data at two gauged sections is here extended to the most general case of significant lateral flow contribution, without needing to deploy rainfall-runoff procedures. The proposed methodology solves the Saint-Venant equations in diffusive form also involving the lateral contribution using an ‘head driven’ modeling approach where lateral inflow is assumed to be function of the water level at the tributary junction. The procedure allows to assess the discharge hydrograph at ends of a selected river reach with significant lateral inflow, starting from the stage recorded there and without n…
Computation of vertically averaged velocities in irregular sections of straight channels
Abstract. Two new methods for vertically averaged velocity computation are presented, validated and compared with other available formulas. The first method derives from the well-known Huthoff algorithm, which is first shown to be dependent on the way the river cross section is discretized into several subsections. The second method assumes the vertically averaged longitudinal velocity to be a function only of the friction factor and of the so-called "local hydraulic radius", computed as the ratio between the integral of the elementary areas around a given vertical and the integral of the elementary solid boundaries around the same vertical. Both integrals are weighted with a linear shape f…
Discharge estimation combining flow routing and occasional measurements of velocity
A new procedure is proposed for estimating river discharge hydrographs during flood events, using only water level data at a single gauged site, as well as 1-D shallow water modelling and occasional maximum surface flow velocity measurements. One-dimensional diffusive hydraulic model is used for routing the recorded stage hydrograph in the channel reach considering zero-diffusion downstream boundary condition. Based on synthetic tests concerning a broad prismatic channel, the “suitable” reach length is chosen in order to minimize the effect of the approximated downstream boundary condition on the estimation of the upstream discharge hydrograph. The Manning’s roughness coefficient is calibra…
Combining flow routing modelling and direct velocity measurement for optimal discharge estimation
Abstract. A new procedure is proposed for estimating river discharge hydrographs during flood events, using only water level data measured at a gauged site, as well as 1-D shallow water modelling and sporadic maximum surface flow velocity measurements. During flood, the piezometric level is surmised constant in the vertical plane of the river section, where the top of the banks is always above the river level, and is well represented by the recorded stage hydrograph. The river is modelled along the reach directly located downstream the upstream gauged section, where discharge hydrograph is sought after. For the stability with respect to the topographic error, as well as for the simplicity o…
Discharge estimation in open channels by means of water level hydrograph analysis
A new methodology, based on the synchronous measurement of stage hydrographs in two river sections located some kilometers from each other, was developed to estimate the discharge hydrograph in the upstream section. The methodology is based on the one-parameter calibration of a numerical flow routing algorithm, solving the Saint-Venant equations in diffusive or complete form. The methodology was validated using results of laboratory experiments carried out at the Polytechnic of Bari University. A known discharge hydrograph was generated in the upstream tank of a rectangular flume, where two water level sensors were located. Two different bed materials have been used, to account for differen…
Uniform flow formulas for irregular sections
Abstract. Two new methods for uniform flow discharge computation are presented, validated and compared with other available formulas. The first method derives from the well-known Huthoff algorithm, which is first shown to be dependent on the way the river cross-section is discretized into several sub-sections. The second method assumes the vertically averaged longitudinal velocity to be a function only of the friction factor and of the so-called "local hydraulic radius", computed as the ratio between the integral of the elementary areas around a given vertical and the integral of the elementary solid boundaries around the same vertical. Both integrals are weighted with a linear shape functi…