Baldassare Bacchi - Academia.edu (original) (raw)

Papers by Baldassare Bacchi

As well know in many geographical areas some of the annual rainfall and flood max- ima exhibit on... more As well know in many geographical areas some of the annual rainfall and flood max- ima exhibit one or more values ranking much higher than the bulk of the remaining data. These data are reported as outliers and can be modelled by the Two Component Extreme Value distribution. In addition orographic effects due to forced convection in- duced by topography generally produce an increase of precipitation as directly corre- lated to the elevation, but also rain-shadowing effects are induced by mountain ridges. The TCEV distribution was applied to about 220 maxima daily-hourly rainfall series and 35 annual peak-flow series coming from rain and stream gauges located in the North-Eastern Italian Alps (a region of about 25,000 km2). Regional dimensionless frequency curves are realised, able to perform estimates of rainfall and peak-flow in- dexes also in non-monitored sites. The determination of the local rainfall mean values of assigned duration can be realised using "isohyetal lines&qu...

In the Italian Alps most of the settlements have been historically founded on alluvial fans as a ... more In the Italian Alps most of the settlements have been historically founded on alluvial fans as a consequence of their higher position with respect to the surrounding floodplains, which often used to be unhealthy and unsafe. On the other hand, alluvial fans usually originate from highly impulsive and destructive mass movements, and clearly may be, by definition, highly unsafe areas. As a matter of fact, the strong time intermittence of these genetic processes with respect to the average human life, made the perception of the debris flow and landslide related risks rather blurred. Nowadays, the growing antropic pressure and the increased value of properties exposed to this risk call for a reliable evaluation of the hydraulic risk induced by debris flow on alluvial fans. During some recent surveys on this matter we have observed that in Italy no clear quantitative criteria is available to classify hydraulic risk. To our knowledge, in other countries, at best, a classification on the ba...

In the last decades hydrological models have been extensively used in research fields in order to... more In the last decades hydrological models have been extensively used in research fields in order to improve water bal-ance assessment and to support integrated water resources management by quantifying the soil–plant–atmosphere interface. Due to complexity of the physical system, the mathematical models can generally represent and simulate only the basic components of the system. On the other hand, calibration and validation processes of the hydro-logical models in ungauged basins are still complex tasks, due to the lack of reliable methods and the uncertainty in representing the hydrological processes and the physical features of a basin. Therefore, in order to practically apply model's results, there is a continuous needing to assess their accuracy through the calibration and validation processes at gauged sites. In this context, an integrated approach is presented that couples a semi–distributed hydrological model called Distributed model for Runoff, Evapotranspiration, and Ant...

Water Resources Research, 1992

A stochastic approach is developed for the determination of the reduction ratio between the annua... more A stochastic approach is developed for the determination of the reduction ratio between the annual maximum flow averaged over a consecutive D hour period and the annual maximum of peak instantaneous flow with the same frequency of occurrence. Initially, crossing properties of the integrated flow process are related to those of the instantaneous flows, using a Gaussian hypothesis. The scale of fluctuation of the river flow process is the key parameter which governs the theoretical reduction function. Application is made to numerous historical series from Italy. To facilitate the applicability of the model, a method of calibration based on currently available hydrometric information is proposed. Quantiles of flood volumes are obtained from the theoretical reduction function. it is verified that the reduction ratio is independent of the return period and appears to be insensitive to the underlying distributions of the component processes. The non-Gaussian case and scaling properties are discussed.

Journal of Hydrology, 1994

... estimate its parameters. Its principal aim is to reproduce extremes. The proposed method will... more ... estimate its parameters. Its principal aim is to reproduce extremes. The proposed method will provide estimates of mean intensity and mean duration of the process which generates extreme rainfall events. These can then be ...

Earth Surface Processes and Landforms, 1997

ABSTRACT The genetic layering of the soil hydrological properties can significanly affect a numbe... more ABSTRACT The genetic layering of the soil hydrological properties can significanly affect a number of processes as the onset of soil-slips, the runoff production and those related to the interaction between soil, water, plants and atmosphere. Therefore, with the aim of better understanding some aspects of these processes, we focused on the effect, during an imbibition process, of the decrease of the soil hydraulic conductivity at saturation Ks. A laboratory experiment was setup in order to observe the conditions and dynamics of the onset of a perched water in a gradually layered soil. A prismatic column was realised and filled with 9 different soil strata, each 0.1 m deep, whose grain-size distribution curve and porosity were such as to reproduce an exponential decay of Ks, on the basis of the application of a modified Kozeny-Carman relatioship. The so-rebuilt soil was artificially wetted by means of a rainfall simulator at a rate previously determined in order to maintain a constant water content on the surface for 9 hours. Istantaneous volumetric water content profiles were measured along the soil profile by means of 9 TDR probes and a multiplexer device. As a result of the experiment we observed and documented the formation of a water content peak at about 0.15 m depth, about 1.5 h after the beginning of the imbibition process. Then the peak emphasised and moved downward and a perched water formed at an intermediate height in the column, about 6 h after the beginning of the experiment. By this experiment we could then verify the formation of a water content peak, as predicted by a previously developed theoretical model and by a finite volume numerical simulation. The peak is then enveloped reaching the saturation as the wetting front moves downward. The perched water depth then rapidly increased upward while the wetting front slowly travelled downward. Before the transition toward saturation, the experiment supported the phoenomenological aspects enlightened by the analytical solution, although the adopted Gardner's constitutive laws tend to overestimate the unsaturated conductivity for most of the soils. A quantitative good agreement was observed between the experimental data and the numerical simulations.

The aim of this study is to implement a conceptual framework to consider, in a statistical sense,... more The aim of this study is to implement a conceptual framework to consider, in a statistical sense, the residual risk related to possible levee failures in flood hazard mapping. Extending previous analyses on statistics of levee failure type and breach size on a 98 km-reach of the Po River, here we analyze flood events occurred in the Piave, Tagliamento and Adige rivers, in Northern Italy, providing statistics of some hundreds of historical breaches occurred in the last two centuries. Levee failure spatial density, temporal frequency and, partially, size are presented as a function of the geomorphology of the river (i.e. braided, sinuous and meandering) of levees geometry and of flood intensity. A levee fragility function is introduced to take into account the influence of hydraulic and geotechnical factors on the probability of failure. On average a spatial density and temporal intensity of 0.8 levee's failure km -1 100 years -1 was observed on the four rivers, in a range between 0.5 and 1.1 for levees designed with a return period ranging from 100 to 200 years and a freeboard between 0.5 and 1 m, on average. This means that the residual risk for the flooding areas is locally higher than the design one. A stochastic framework for probabilistic flood mapping is then discussed, taking into account in a Monte Carlo approach the effect of position, size, density of levees failures on the statistics of depth and velocity of inundated areas. An example is shown of the resulting residual hazard map for the 100-years return period flooding map for a 23km-reach in the middle-lower portion of the Po River catchment between the gauging station of Cremona (upstream) and Borgoforte (downstream), in a floodprone area of 100 km 2 in size.

This paper presents a simplified procedure for the characterization of the wave following the par... more This paper presents a simplified procedure for the characterization of the wave following the partial collapse of concrete gravity dams. The proposed approach uses a simplified representation of the reservoir geometry and is based on the numerical solution of shallow water equations to study the two-dimensional evolution of the water surface within the reservoir. The numerical results are made dimensionless and reorganized so that it is straightforward to compute the peak discharge, the duration and the recession limb of the dam break wave. The proposed practical approach provides a quite satisfactory reproduction of the computed wave for a wide set of real situations that have been simulated in detail.

DESCRIPTION The copula approach is exploited to derive a peak discharge distribution from a joint... more DESCRIPTION The copula approach is exploited to derive a peak discharge distribution from a joint distribution of the rainfall depth and the wet weather duration

Flooding hazard mapping in floodplain areas affected by piping breaches in the PoRiver, Italy, J.... more Flooding hazard mapping in floodplain areas affected by piping breaches in the PoRiver, Italy, J. Hydrol. Eng., ASCE, published in preview at http://dx.ABSTRACT 5 In the recent years the flood-related risk is increasing worldwide being inundations among 6 the natural disaster which induces the maximum damage in terms of economic losses. In 7 this study a methodology to map the flooding residual hazard due to levees failure events 8 induced by piping in embankments protecting flood-prone areas is proposed. Ensemble 9 simulations are used to account for uncertainties in location, geometry, and time evolution of 10 the levee breaches. Probabilistic flooding hazard maps are generated combining the results 11 of 192 inundation scenarios, simulated by using 1D and 2D hydrodynamic models. The 12 methodology is applied considering 96 different locations and sizes of breaches occurred 13 along a 23-km reach protected by the right levee of the Po river, the right levee of the Taro 14 river and the left levee of the Parma river, which limit a 100 km 2 study area. The influence of 15 obstacles to the flood propagation and consequent hazard mapping was investigated, taking 16 into account several standard criteria to map flooding hazard in different European countries. 17 The results obtained from this study provide an example of a rational method to map the 18 residual hazard in areas protected against flooding due to embankment overtopping taking 19 into account uncertainties due to breach location, levees fragility and to the presence of 20 topographic obstacles. All these details should be taken into account in land planning and 21 flood risk management. 22 23 analysis; Residual risk. 24 30 the levees, in order to let the design flood being conveyed with a given safety freeboard, 31 reduce the flooding hazard and, theoretically, the risk. At a practical level, these structural 32 measures can induce the well known "levee paradox" on the floodprone area (Vis et al. 2003; 33 Burton and Cutter 2008; Castellarin et al. 2011; Ludy and Kondolf 2011), that is related 34 to the change in the hazard perception related to the levee strengthening. The lower the 35 hazard perception, the higher the urbanization in the floodprone areas and the exposure 36

In recent years, flood-related risk has been increasing worldwide, being inundations among the na... more In recent years, flood-related risk has been increasing worldwide, being inundations among the natural disasters which induce the maximum damage in terms of economic losses. In the research reported in this paper, a methodology to map the flooding residual hazard due to levee failure events induced by piping in embankments protecting flood-prone areas is proposed. Ensemble simulations are used to account for uncertainties in location, geometry, and time-evolution of the levee breaches. Probabilistic flooding-hazard maps are generated combining the results of 192 inundation scenarios, simulated by using one-dimensional (1D) and two-dimensional (2D) hydrodynamic models. The methodology is applied considering 96 different locations and sizes of breaches occurred along a 23-km reach protected by the right levee of the Po River, the right levee of the Taro River, and the left levee of the Parma River, which delimit a 100-km 2 study area. The influence of obstacles to the flood propagation and consequent hazard-mapping was investigated, taking into account several standard criteria to map the flooding hazard in different European countries. The results obtained from the research reported in this paper provide an example of a rational method to map the residual hazard in areas protected against flooding due to embankment-overtopping, taking into account uncertainties due to breach location, levee fragility, and the presence of topographic obstacles. All these details should be taken into account in land-planning and flood-risk management.

An experimental field was installed in Summer 2012 in a mountain environment (Cividate Camuno, Og... more An experimental field was installed in Summer 2012 in a mountain environment (Cividate Camuno, Oglio river basin, Central Italian Alps, 274 m a.s.l.) in order to investigate the soil–water balance and the effectiveness of the eddy correlation technique to measure the evapotranspirative fluxes in a complex topography. The soil is young, shallow and anthropized, grown on the debris of a power plant workings. The genetic sequence is given by A, C and D horizons, as it is common in many Alpine sites. USDA textural classes are silty loam (A, up to 9 cm depth), loam (upper C, 9 to 22 cm), silty clay loam (lower C, 22 to 28 cm) and silty loam (D, deeper than 38 cm), with increasing gravel fraction (pebbles) with depth. Due to the meaningful pebbles presence, the sampled soil cores were disturbed and considered reliable only for porosity, grains size distribution, water content and soil– water retention relationships. In the field a single ring infiltrometer was used to estimate the soil co...

Unsaturated Soils: Research and Applications, 2012

Procedia Environmental Sciences, 2013

An experimental field campaign was performed during summer 2012 in an Alpine environment (Cividat... more An experimental field campaign was performed during summer 2012 in an Alpine environment (Cividate Camuno, Oglio river basin, 274 m a.s.l.) in order to assess the water balance of an anthropized soil at the local scale. A micrometeorological station equipped with traditional sensors coupled with eddy covariance apparatus and TDR was installed in order to measure precipitation, evapotranspiration and soil-water content at different depths. The soil water properties were determined after field and laboratory investigations. Here the preliminary results of the campaign are presented and discussed, focusing on the assessment of the evapotranspiration and of the water exchanges in the vadose zone as ones of the major problems of water imbalance. mountain areas . Anyway the application of the eddy covariance technique, particularly in areas with complex orography, is still affected by uncertainties which are evident in the energy imbalance problem , so that a comparison of the results with traditional methods, such as the FAO Penman-Monteith model of evapotranspiration , is still required in order to assess the underestimation of the eddy covariance fluxes . Also the groundwater exchange can be hardly measured, by means of lysimeters or coupling tensiometer measurement with the knowledge of the soil-water constitutive laws [10], but in most of the cases it is indirectly estimated. In mountain environments, furthermore, soils are typically non-mature and both the soil and the ground-water table are shallow, so that the hydrologically active soil layer is often not evident and an important role in the water balance is played by the groundwater exchange.

Carmen de Jong/Climate and Hydrology in Mountain Areas, 2005

Saturated Hydraulic Conductivity and Water Retention Relationships for Alpine Mountain Soils STEF... more Saturated Hydraulic Conductivity and Water Retention Relationships for Alpine Mountain Soils STEFANO BARONTINI, ALBERTO CLERICI, ROBERTO RANZI AND BALDASSARE BACCHI Department of Civil Engineering, University of Brescia, Brescia, Via Branze 38, 1-25123, ...