scholarly journals Flooding of Piazza San Marco (Venice): Physical Model Tests to Evaluate the Overtopping Discharge

Water ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 427 ◽  
Author(s):  
Piero Ruol ◽  
Chiara Favaretto ◽  
Matteo Volpato ◽  
Luca Martinelli
Keyword(s):  
Water Level ◽  
Cross Sections ◽  
Vertical Wall ◽  
Drainage System ◽  
Water Levels ◽  
Irregular Wave ◽  
Wave Flume ◽  
Physical Model Tests ◽  
Floating Breakwaters ◽  
The Waves

This paper aims at evaluating the wave overtopping discharge over the pavement of “Piazza S. Marco” (Venice) in order to select the best option to mitigate the risk of flooding of the Piazza and to protect the monuments and historic buildings, e.g., the “Basilica S. Marco”. In fact, the MO.S.E. (MOdulo Sperimentale Elettromeccanico) system is designed to keep the water level below a certain value, for the safety of the lagoon, but it does not guarantee the defence of the Piazza, where flooding is still possible, being its pavement locally much lower than the maximum expected water level. To completely defend the Piazza, specific additional works are planned to prevent the back-flow through the natural drainage system (now the primary pathway) or by filtration or by overtopping. This paper investigates on the overtopping mechanism, under conditions compatible with a fully operational MO.S.E. system, through 2-D experiments. The pavement of the Piazza is gently sloping towards the masonry quay which, in some parts is formed by 5 descending steps, and in some other parts, is just a vertical wall. Close to the “Marciana” Library, a critical part is present, with a slightly lower crest freeboard. In total, three cross-sections were examined in the 36 m long wave flume of the Padova University. The test programme includes 10 irregular wave attacks and three different water levels. The test results differ considerably from the results of the available formulas, since the investigated cross-sections by far exceed their range of applicability. The presence of the steps affects only the reflection coefficient rather than the overtopping discharges. In general, if the waves incident to the Piazza are higher than 40 cm, which is a possible scenario, some other adaptation works must be considered, such as the pavement rise, temporary barriers or the reduction of the waves impacting the quay through, for instance, floating breakwaters.

Interaction between water pressure in the basal drainage system and discharge from an Alpine glacier before and during a rainfall-induced subglacial hydrological event

1997 ◽  
Vol 24 ◽  
pp. 288-292 ◽  
Author(s):  
Andrew P. Barrett ◽  
David N. Collins
Keyword(s):  
Water Level ◽  
Water Pressure ◽  
Drainage System ◽  
Water Levels ◽  
Drainage Network ◽  
Alpine Glacier ◽  
Hydraulic Conditions ◽  
Borehole Water ◽  
Progressive Growth ◽  
Resultant Increase

Combined measurements of meltwater discharge from the portal and of water level in a borehole drilled to the bed of Findelengletscher, Switzerland, were obtained during the later part of the 1993 ablation season. A severe storm, lasting from 22 through 24 September, produced at least 130 mm of precipitation over the glacier, largely as rain. The combined hydrological records indicate periods during which the basal drainage system became constricted and water storage in the glacier increased, as well as phases of channel growth. During the storm, water pressure generally increased as water backed up in the drainage network. Abrupt, temporary falls in borehole water level were accompanied by pulses in portal discharge. On 24 September, whilst borehole water level continued to rise, water started to escape under pressure with a resultant increase in discharge. As the drainage network expanded, a large amount of debris was flushed from a wide area of the bed. Progressive growth in channel capacity as discharge increased enabled stored water to drain and borehole water level to fall rapidly. Possible relationships between observed borehole water levels and water pressures in subglacial channels are influenced by hydraulic conditions at the base of the hole, distance between the hole and a channel, and the nature of the substrate.

Interaction between water pressure in the basal drainage system and discharge from an Alpine glacier before and during a rainfall-induced subglacial hydrological event

1997 ◽  
Vol 24 ◽  
pp. 288-292 ◽  
Author(s):  
Andrew P. Barrett ◽  
David N. Collins
Keyword(s):  
Water Level ◽  
Water Pressure ◽  
Drainage System ◽  
Water Levels ◽  
Drainage Network ◽  
Alpine Glacier ◽  
Hydraulic Conditions ◽  
Borehole Water ◽  
Progressive Growth ◽  
Resultant Increase

Combined measurements of meltwater discharge from the portal and of water level in a borehole drilled to the bed of Findelengletscher, Switzerland, were obtained during the later part of the 1993 ablation season. A severe storm, lasting from 22 through 24 September, produced at least 130 mm of precipitation over the glacier, largely as rain. The combined hydrological records indicate periods during which the basal drainage system became constricted and water storage in the glacier increased, as well as phases of channel growth. During the storm, water pressure generally increased as water backed up in the drainage network. Abrupt, temporary falls in borehole water level were accompanied by pulses in portal discharge. On 24 September, whilst borehole water level continued to rise, water started to escape under pressure with a resultant increase in discharge. As the drainage network expanded, a large amount of debris was flushed from a wide area of the bed. Progressive growth in channel capacity as discharge increased enabled stored water to drain and borehole water level to fall rapidly. Possible relationships between observed borehole water levels and water pressures in subglacial channels are influenced by hydraulic conditions at the base of the hole, distance between the hole and a channel, and the nature of the substrate.

scholarly journals Statistical Analysis of the Stability of Rock Slopes

2019 ◽  
Vol 7 (3) ◽  
pp. 60 ◽  
Author(s):  
Marcel van Gent ◽  
Ermano de Almeida ◽  
Bas Hofland
Keyword(s):  
Statistical Analysis ◽  
Physical Model ◽  
Model Tests ◽  
Water Levels ◽  
Test Series ◽  
Length Effect ◽  
Wave Flume ◽  
Physical Model Tests ◽  
Erosion Area ◽  
The Stability

Physical model tests were performed in a wave flume at Deltares with rock armoured slopes. A shallow foreshore was present. At deep water, the same wave conditions were used, but by applying different water levels, the wave loading on the rock armoured slopes increased considerably with increasing water levels. This allowed an assessment of the effects of sea level rise. Damage was measured by using digital stereo photography (DSP), which provides information on each individual stone that is displaced. Two test series were performed five times. This allowed for a statistical analysis of the damage to rock armoured slopes, which is uncommon due to the absence of statistical information based on a systematic repetition of test series. The statistical analysis demonstrates the need for taking the mean damage into account in the design of rock armoured slopes. This is important in addition to characterising the damage itself by erosion areas and erosion depths. The relation between damage parameters, such as the erosion area and erosion depth, was obtained from the tests. Besides tests with a straight slope, tests with a berm in the seaward slopes were also performed. A new method to take the so-called length effect into account is proposed to extrapolate results from physical model tests to real structures. This length effect is important, but is normally overlooked in the design of rubble mound structures. Standard deviations based on the presented model tests were used.

scholarly journals INTEGRASI SIG-INFOWORKS RIVER SIMULATION UNTUK PEMODELAN HIDRODINAMIK SUNGAI SADDANG DAN SUNGAI MATA ALLO

2020 ◽  
Vol 2 (2) ◽  
pp. 178
Author(s):  
Srie Wulandarie
Keyword(s):  
Water Level ◽  
Water Flow ◽  
Cross Section ◽  
Cross Sections ◽  
Hydrodynamic Model ◽  
Simulation Models ◽  
Water Levels ◽  
Average Increase ◽  
Hydrodynamic Models ◽  
Gis Data

AbstractThe purpose of this study was to determine the hydrodynamic model of the river so that can know the capacity of the river to accommodate the incoming water flow. The simulation models can be used in structural mitigation plan as an attempt to prevent flooding in the future. The application program used to create hydrodynamic models that Infoworks River Simulation integrated with GIS. Data cross-section of the river as much as 39 points inputted into Infoworks River Simulation program. Furthermore, the discharge input the Saddang River and the Mata Allo River to determine variations in water level at each cross-section. The results of this study showed an average increase in water level of the Saddang  and Mata Allo River in the event of the maximum discharge of 2.59 meters. Sectional increased water levels are all cross sections along the Saddang and Mata Allo River Saddang used in modeling the variation of the rise in water level of 0.8 to 5.39 meters.

scholarly journals EFFECTS OF WATER LEVEL VARIATIONS ON THE STABILITY OF ROCK ARMOURED SLOPES

2018 ◽  
pp. 44 ◽  
Author(s):  
Marcel R.A. Van Gent ◽  
Suzanna A.A. Zwanenburg ◽  
Jan Kramer
Keyword(s):  
Water Level ◽  
Physical Model ◽  
Model Tests ◽  
Water Levels ◽  
Level Variation ◽  
Water Level Variation ◽  
Stepwise Approach ◽  
Physical Model Tests ◽  
Water Level Variations ◽  
The Stability

Physical model tests on the stability of rock armoured slopes have been performed to demonstrate the importance of water level variations during a storm, due to a tide or a storm surge. For the stability of rock armoured slopes also the importance of the sequence of storms at various water levels has been studied. The test results indicate that a smooth sinusoidal water level variation leads to an increase in damage compared to the same wave conditions at a constant water level. Furthermore, a stepwise approach of the sinusoidal water level elevation leads to other results than the approach with a continuous water level variation, whereas the continuous water level variation resembles the peak of a storm or the tidal water level variation better than a stepwise approach. If storms with different water levels attack the armour layer, the damage is generally smaller than if all storms attack the armour layer at the same water level. Furthermore, the results have been discussed based on earlier analyses where the statistics of rock armoured slopes have been addressed and the importance of the length effect has been illustrated using a method to apply results from physical model tests to real structures.

scholarly journals Water storage and subglacial drainage conditions inferred from borehole measurements on Gornergletscher, Valais, Switzerland

1996 ◽  
Vol 42 (141) ◽  
pp. 233-248 ◽  
Author(s):  
Almut Iken ◽  
Kristian Fabri ◽  
Martin Funk
Keyword(s):  
Cross Sections ◽  
Water Pressure ◽  
Water Storage ◽  
Drainage System ◽  
Water Levels ◽  
Sediment Layer ◽  
Northern Margin ◽  
Upstream Side ◽  
Different Depths ◽  
Subglacial Drainage

AbstractMeasurements of change in length of a borehole, or displacements of poles and of subglacial Water pressure were combined with drainage tests and electrode tests in boreholes, in experiments near the northern margin of Gornergletscher, Valais, Switzerland, at the upstream side of an overdeepening. The measurements suggest that the subglacial drainage system consisted of discrete conduits at that location, presumably linked cavities on “clean” bedrock. Changes in subglacial water pressure were followed by variations in subglacial water storage, together with similar variations in elevation of a pole. The variations in subglacial water storage caused changes in cross-sections of subglacial passageways and thereby changed the frequencies of slug-test oscillations. Similar experiments conducted near the center line of the glacier revealed different subglacial conditions: impeded drainage through a sediment layer, and different depths of water levels in different boreholes. These results are discussed in relation to previous studies.

scholarly journals Assimilating SAR-derived water level data into a hydraulic model: a case study

2011 ◽  
Vol 8 (1) ◽  
pp. 2103-2144 ◽  
Author(s):  
L. Giustarini ◽  
P. Matgen ◽  
R. Hostache ◽  
M. Montanari ◽  
D. Plaza ◽  
...  
Keyword(s):  
Particle Filter ◽  
Water Level ◽  
Cross Sections ◽  
Hydraulic Model ◽  
Water Levels ◽  
Hydraulic Models ◽  
Level Data ◽  
Water Level Data ◽  
Assimilation Scheme

Abstract. Satellite-based active microwave sensors not only provide synoptic overviews of flooded areas, but also offer an effective way to estimate spatially distributed river water levels. If rapidly produced and processed, these data can be used for updating hydraulic models in near real-time. The usefulness of such approaches with real event data sets provided by currently existing sensors has yet to be demonstrated. In this case study, a Particle Filter-based assimilation scheme is used to integrate ERS-2 SAR and ENVISAT ASAR-derived water level data into a one-dimensional (1-D) hydraulic model of the Alzette River. Two variants of the Particle Filter assimilation scheme are proposed with a global and local particle weighting procedure. The first option finds the best water stage line across all cross sections, while the second option finds the best solution at individual cross sections. The variant that is to be preferred depends on the level of confidence that is attributed to the observations or to the model. The results show that the Particle Filter-based assimilation of remote sensing-derived water elevation data provides a significant reduction to the model forecast uncertainty. Moreover, it is shown that the periodical updating of hydraulic models through the proposed assimilation scheme leads to an improvement of model predictions over several time steps. However, the performance of the assimilation depends on the skill of the hydraulic model and the quality of the observation data.

scholarly journals Comparison the monitoring data of an on-site stormwater detention (OSD) and the results in the use of theoretical methods for its design

RBRH ◽  
2018 ◽  
Vol 23 (0) ◽  
Author(s):  
Pedro de Paula Drumond ◽  
Priscilla Macedo Moura ◽  
Márcia Maria Lara Pinto Coelho
Keyword(s):  
Water Level ◽  
Drainage System ◽  
Water Levels ◽  
Rational Method ◽  
Monitoring Data ◽  
Data Logger ◽  
Theoretical Methods ◽  
Level Sensor ◽  
Belo Horizonte ◽  
The Impact

ABSTRACT On-site stormwater detention – OSD has been constructed in big Brazilian cities, as a way to reduce the impact of urbanization on the drainage system. However, there are a few studies about its efficiency in real scale. This article aims to compare the monitoring data of an OSD built in a hospital in Belo Horizonte and the results determined by theoretical methods, commonly used in the design of this structure. Inside the OSD was installed a level sensor to monitor water level during rain events. The data was recorded on a data logger every 30 seconds during the period April 2015 to March 2017. It was analyzed the OSD filling during the occurrence of 48 precipitation events. In the maximum heights of water level comparison, it was found that the monitored values were higher than theoretical values and the results using Rational Method were closer to monitoring data than the results with SCS-HU Method. It was also found that the peak and recession time calculated with Rational Method represented better the water levels monitored.

scholarly journals Assimilating SAR-derived water level data into a hydraulic model: a case study

2011 ◽  
Vol 15 (7) ◽  
pp. 2349-2365 ◽  
Author(s):  
L. Giustarini ◽  
P. Matgen ◽  
R. Hostache ◽  
M. Montanari ◽  
D. Plaza ◽  
...  
Keyword(s):  
Particle Filter ◽  
Water Level ◽  
Cross Sections ◽  
Hydraulic Model ◽  
Water Levels ◽  
Hydraulic Models ◽  
Level Data ◽  
Water Level Data ◽  
Assimilation Scheme

Abstract. Satellite-based active microwave sensors not only provide synoptic overviews of flooded areas, but also offer an effective way to estimate spatially distributed river water levels. If rapidly produced and processed, these data can be used for updating hydraulic models in near real-time. The usefulness of such approaches with real event data sets provided by currently existing sensors has yet to be demonstrated. In this case study, a Particle Filter-based assimilation scheme is used to integrate ERS-2 SAR and ENVISAT ASAR-derived water level data into a one-dimensional (1-D) hydraulic model of the Alzette River. Two variants of the Particle Filter assimilation scheme are proposed with a global and local particle weighting procedure. The first option finds the best water stage line across all cross sections, while the second option finds the best solution at individual cross sections. The variant that is to be preferred depends on the level of confidence that is attributed to the observations or to the model. The results show that the Particle Filter-based assimilation of remote sensing-derived water elevation data provides a significant reduction in the uncertainty at the analysis step. Moreover, it is shown that the periodical updating of hydraulic models through the proposed assimilation scheme leads to an improvement of model predictions over several time steps. However, the performance of the assimilation depends on the skill of the hydraulic model and the quality of the observation data.

scholarly journals Diurnal fluctuations in borehole water levels: configuration of the drainage system beneath Bench Glacier, Alaska, USA

2008 ◽  
Vol 54 (185) ◽  
pp. 297-306 ◽  
Author(s):  
T.J. Fudge ◽  
Neil F. Humphrey ◽  
Joel T. Harper ◽  
W. Tad Pfeffer
Keyword(s):  
Water Level ◽  
Numerical Test ◽  
Drainage System ◽  
Water Levels ◽  
Water Level Fluctuations ◽  
Diurnal Changes ◽  
Ablation Area ◽  
Orthogonal Grid ◽  
Borehole Water ◽  
Diurnal Fluctuations

AbstractWater levels were measured in boreholes spaced along the entire length of Bench Glacier, Alaska, USA, for a period in excess of 2 years. Instrumented boreholes were arranged as nine pairs along the center line of the glacier and an orthogonal grid of 16 boreholes in a 3600 m2 region at the center of the ablation area. Diurnal fluctuations of the water levels were found to be restricted to the late melt season. Pairs of boreholes spaced along the length of the ablation area often exhibited similar fluctuations and diurnal changes in water levels. Three distinct and independent types of diurnal fluctuations in water level were observed in clusters of boreholes within the grid of boreholes. Head gradients suggest water did not flow between clusters, and a single tunnel connecting the boreholes could not explain the observed pattern of diurnal water-level fluctuations. Inter-borehole and borehole-cluster connectivity suggests the cross-glacier width of influence of a segment of the drainage system connected to a borehole was limited to tens of meters. A drainage configuration whereby boreholes are connected to a somewhat distant tunnel by drainage pipes of differing lengths, often hundreds of meters, is shown with a numerical test to be a plausible explanation for the observed borehole behavior.

Sign in / Sign up

Export Citation Format

Share Document