I modelli numerici surrogati per la gestione delle falde acquifere

SOMMARIO. Nella memoria si tratta dei modelli surrogati applicati in problemi riguardanti le falde acquifere. I modelli surrogati sono metodi di soluzione che, nel tentativo di velocizzare i tempi di calcolo, derogano dalla completa descrizione della fisica e dal dettaglio spazio‐temporale del problema. I modelli surrogati possono essere suddivisi in tre grandi categorie: 1) Modelli surrogati data‐driven che consistono di empiriche approssimazioni dei risultati del modello completo i cui parametri sono calibrati cercando l’accordo con i dati disponibili, siano essi di tipo storico o forniti da un modello completo; 2) Modelli di tipo Projection‐based che, con un processo algebrico, procedono a ridurre l’ordine del sistema risolutivo rendendo quindi più veloce la soluzione numerica; 3) Modelli surrogati detti a multifidelity in cui si deroga dal dettaglio spaziale e si bilancia la ridotta accuratezza con una tecnica multiscala. La memoria presenta infine un esempio applicativo di un modello di tipo multi‐fidelity che analizza le relazioni di correlazione tra i livelli piezometrici in diversi pozzi della regione Emilia‐Romagna (Italia) e gli indici climatici SPI e SPEI. Le relazioni ottenute sono successivamente utilizzate per ricavare una stima degli effetti del cambiamento climatico in più orizzonti temporali a breve (2016‐2035), medio (2046‐2060) e lungo termine (2081‐2100)

Pediatric trauma and emergency surgery: an international cross-sectional survey among WSES members

Background: In contrast to adults, the situation for pediatric trauma care from an international point of view and the global management of severely injured children remain rather unclear. The current study investigates structural management of pediatric trauma in centers of different trauma levels as well as experiences with pediatric trauma management around the world. Methods: A web-survey had been distributed to the global mailing list of the World Society of Emergency Surgery from 10/2021-03/2022, investigating characteristics of respondents and affiliated hospitals, case-load of pediatric trauma patients, capacities and infrastructure for critical care in children, trauma team composition, clinical work-up and individual experiences with pediatric trauma management in response to patients´ age. The collaboration group was subdivided regarding sizes of affiliated hospitals to allow comparisons concerning hospital volumes. Comparable results were conducted to statistical analysis. Results: A total of 133 participants from 34 countries, i.e. 5 continents responded to the survey. They were most commonly affiliated with larger hospitals (> 500 beds in 72.9%) and with level I or II trauma centers (82.0%), respectively. 74.4% of hospitals offer unrestricted pediatric medical care, but only 63.2% and 42.9% of the participants had sufficient experiences with trauma care in children ≤ 10 and ≤ 5 years of age (p = 0.0014). This situation is aggravated in participants from smaller hospitals (p < 0.01). With regard to hospital size (≤ 500 versus > 500 in-hospital beds), larger hospitals were more likely affiliated with advanced trauma centers, more elaborated pediatric intensive care infrastructure (p < 0.0001), treated children at all ages more frequently (p = 0.0938) and have higher case-loads of severely injured children < 12 years of age (p = 0.0009). Therefore, the majority of larger hospitals reserve either pediatric surgery departments or board-certified pediatric surgeons (p < 0.0001) and in-hospital trauma management is conducted more multi-disciplinarily. However, the majority of respondents does not feel prepared for treatment of severe pediatric trauma and call for special educational and practical training courses (overall: 80.2% and 64.3%, respectively). Conclusions: Multi-professional management of pediatric trauma and individual experiences with severely injured children depend on volumes, level of trauma centers and infrastructure of the hospital. However, respondents from hospitals at all levels of trauma care complain about an alarming lack of knowledge on pediatric trauma management

Correction to: Two years later: Is the SARS-CoV-2 pandemic still having an impact on emergency surgery? An international cross-sectional survey among WSES members

Background: The SARS-CoV-2 pandemic is still ongoing and a major challenge for health care services worldwide. In the first WSES COVID-19 emergency surgery survey, a strong negative impact on emergency surgery (ES) had been described already early in the pandemic situation. However, the knowledge is limited about current effects of the pandemic on patient flow through emergency rooms, daily routine and decision making in ES as well as their changes over time during the last two pandemic years. This second WSES COVID-19 emergency surgery survey investigates the impact of the SARS-CoV-2 pandemic on ES during the course of the pandemic. Methods: A web survey had been distributed to medical specialists in ES during a four-week period from January 2022, investigating the impact of the pandemic on patients and septic diseases both requiring ES, structural problems due to the pandemic and time-to-intervention in ES routine. Results: 367 collaborators from 59 countries responded to the survey. The majority indicated that the pandemic still significantly impacts on treatment and outcome of surgical emergency patients (83.1% and 78.5%, respectively). As reasons, the collaborators reported decreased case load in ES (44.7%), but patients presenting with more prolonged and severe diseases, especially concerning perforated appendicitis (62.1%) and diverticulitis (57.5%). Otherwise, approximately 50% of the participants still observe a delay in time-to-intervention in ES compared with the situation before the pandemic. Relevant causes leading to enlarged time-to-intervention in ES during the pandemic are persistent problems with in-hospital logistics, lacks in medical staff as well as operating room and intensive care capacities during the pandemic. This leads not only to the need for triage or transferring of ES patients to other hospitals, reported by 64.0% and 48.8% of the collaborators, respectively, but also to paradigm shifts in treatment modalities to non-operative approaches reported by 67.3% of the participants, especially in uncomplicated appendicitis, cholecystitis and multiple-recurrent diverticulitis. Conclusions: The SARS-CoV-2 pandemic still significantly impacts on care and outcome of patients in ES. Well-known problems with in-hospital logistics are not sufficiently resolved by now; however, medical staff shortages and reduced capacities have been dramatically aggravated over last two pandemic years

Diversity and ethics in trauma and acute care surgery teams: results from an international survey

Background Investigating the context of trauma and acute care surgery, the article aims at understanding the factors that can enhance some ethical aspects, namely the importance of patient consent, the perceptiveness of the ethical role of the trauma leader, and the perceived importance of ethics as an educational subject. Methods The article employs an international questionnaire promoted by the World Society of Emergency Surgery. Results Through the analysis of 402 fully filled questionnaires by surgeons from 72 different countries, the three main ethical topics are investigated through the lens of gender, membership of an academic or non-academic institution, an official trauma team, and a diverse group. In general terms, results highlight greater attention paid by surgeons belonging to academic institutions, official trauma teams, and diverse groups. Conclusions Our results underline that some organizational factors (e.g., the fact that the team belongs to a university context or is more diverse) might lead to the development of a higher sensibility on ethical matters. Embracing cultural diversity forces trauma teams to deal with different mindsets. Organizations should, therefore, consider those elements in defining their organizational procedures. Level of evidence Trauma and acute care teams work under tremendous pressure and complex circumstances, with their members needing to make ethical decisions quickly. The international survey allowed to shed light on how team assembly decisions might represent an opportunity to coordinate team member actions and increase performance

Geostatistical estimation of the hydraulic conductivity field under the Parma Dam

The city of Parma (Italy) located on the large alluvial fan of the Parma River, is preserved upstream by a flood control dam. The structure has the purpose of damping the Parma River floods storing a portion of the flood volume and releasing it, downstream, at a controlled rate. A concrete stilling basin is located downstream the dam in order to dissipate the energy of the discharged flow. The underneath deposits are surrounded by a grout wall that reaches an impervious clayey layer with the aim of realizing a confined "box". Groundwater levels inside the box are controlled by a 110 m long drainage trench located upstream the stilling basin (under the dam) and 3 m below its floor. Unfortunately, according to field data (boreholes and head observations) the box is not completely sealed both upstream and downstream. The aquifer beneath and surrounding the structure has been investigated by means of stratigraphical, lithological and hydrogeological characterization and in situ permeability tests. The groundwater monitoring network consists of 14 piezometers with dataloggers. The aquifer below the structure is multilayered, with prevailing silty gravels and relatively thin silty and clayey strata, and it can be simplified in three layers: a phreatic aquifer (0 to 20 m depth), a thin clayey layer (20 to 25 m) and a regional confined aquifer (beneath 25 m). In this work, the hydraulic conductivity field and a single value of the storage coefficient of the phreatic aquifer beneath the dam and the stilling basin has been investigated by means of a Bayesian Geostatistical Approach (BGA). The BGA method allows to estimate the hydraulic conductivity field (unknowns) constrained by prior information on its structure and, in the same time, to counteract uncertainties in the predictions and errors in the observations. The prior soft knowledge about the structure of the unknowns is related with the degree of smoothness and/or continuity of the parameters and serves also the role of regularization. The geostatistical inversion was performed by means of a computer code, bgaPEST, developed according to the free PEST software concept. The methodology needs a numerical model of the study area able to reproduce the boundary conditions, the geometry of the aquifer and the hydraulic heads in the observation points. In this work the groundwater flow process and the sensitivities of observations to parameters (required by the inverse procedure) has been simulated by means of an adjoint state formulation of MODFLOW_2005. The numerical model consists of a finite difference grid of 22 rows, 51 columns and 13 layers. Each cell is 4 m x 4 m x 2 m except the deeper ones that are truncated to the clayey layer. The upstream boundary conditions are the reservoir water level and a barrier simulating the grout wall that delimits the box below the dam. The downstream boundary condition is no flow except where the grout wall does not reach the clayey layer. This region has been described by means of a general head boundary condition; a drain condition was instead considered below the dam. In 2008, during a test period (5 months) of the hydraulic structure, the reservoir was filled capturing the tails of the spring flood events. The resulting head levels in the aquifer monitoring points and the reservoir water level were recorded. The hydraulic conductivity field and the storage coefficient of the numerical model were estimated considering an observation period of 15 days (one observation per day for each monitoring point). The entire model was then validated considering all the observations collected during the 5 months test period. The BGA methodology was able to estimate the hydraulic parameters and the storage coefficient of the aquifer, identifying the local heterogeneities. The calibrated numerical model allows to understand the interactions between the reservoir and the aquifer in different scenarios and to forecast head levels due to strong flood events

Response to Comment on ‘‘Reverse level pool routing: Comparison between a deterministic and a stochastic approach’’ by H. Md. Azamathulla, J. Hydrol. (2012), http://dx.doi.org/10.1016/j.jhydrol.2012.09.005

This discussion is in reply to the comments made by Dr. Azamathulla (in press) on the results presented in D’Oria et al., 2012 concerning a comparison between a deterministic and a stochastic approach for reverse level pool routing. In this article we summarize and answer all the comments and we try to clarify all the highlighted reservations concerning the applicability of the inverse procedures even if they are not strictly relevant to the focus of our paper. We believe that Dr. Azamathulla has overlooked some important points already reported in the discussed paper that are crucial to explain the obtained results and we reassert here their correctness

Probabilistic Flood Hazard Mapping Considering Multiple Levee Breaches

Probabilistic methods are widely adopted for residual flood hazard assessment in flood-prone areas protected by levees. Such methods can consider various sources of uncertainty, including breach location and flood event characteristics, and allow for the quantification of the result confidence. However, the possible occurrence of multiple levee breaches during the same flood event is usually disregarded. This paper presents a probabilistic method based on levee fragility functions and basic probability rules to estimate the probability of selected breach scenarios, including multiple breaching events. The flood hazard classification is based on inundation variables calculated for flood events of different return periods. A combined 1D-2D hydrodynamic model is used for flood simulations. Probabilistic inundation extent maps and probabilistic flood hazard level maps are then created. Finally, probabilistic flood hazard estimates are summarized in a map of a suitable central tendency of the hazard level, coupled with a map of the Shannon entropy as uncertainty indicator. This pair of statistical maps provides concise and effective information on design flood hazard along with the associated uncertainty. The method was applied to a region located along the middle reach of the Po River (northern Italy). Similar central flood hazard estimates are obtained for the two sets of breaching events including or not multiple breaches. Considering multiple breaches led to higher uncertainty in central hazard level assessment. This result highlights the importance of considering multiple breaching events in flood risk management

Bayesian Estimation of a Highly Parameterized Hydraulic Conductivity Field: A Study Case

AbstractComprehensive characterization of the spatial variability of aquifer hydraulic parameters is fundamental to correctly design a structure that interacts with the groundwater system, e.g. a detention reservoir. A flood control structure has been planned to dampen the Baganza River floods, upstream the city of Parma (Northern Italy), storing a portion of the flood volume then released at a controlled rate. The location and the geometry of the planned reservoir are already set and the aquifer system beneath the structure is under investigation and monitoring. A large numbers of boreholes identified a sequence of gravel-sand and clayey layers that gives rise to two distinct aquifers (one unconfined and one confined). A numerical model has been developed by means of MODFLOW_2005 in order to simulate the unconfined aquifer under current conditions. The numerical model has been calibrated in steady-state conditions by means of 11 observations of water levels (collected during spring 2013). About 18000 hydraulic conductivity values have been defined and estimated by means of a Bayesian Geostatistical Approach. The inverse methodology estimates the hydraulic conductivity field using both field observations (head data) and prior information on the structure of the unknown parameters. The inverse procedure requires the calculation of the sensitivity of each observation to each of the estimated parameters that has been efficiently evaluated making use of an adjoint state formulation of the forward model MODFLOW_2005-Adjoint. The inverse code is the freeware bgaPEST, a highly parameterized inversion software package developed according to the PEST software concept. The Bayesian Geostatistical Approach is shown to be able to constrain the hydraulic conductivity field with a large number of parameters and just few observations. The results of the inversion are consistent with the alluvial nature of the investigated aquifer and the information content of the data. The calibrated model can then be used as a support tool for the design and the management of the new flood control structure