Corrado Gisonni

• PhD in Hydraulic Engineering
• Professor (Full) at Università della Campania 'Luigi Vanvitelli'

Vortex drop shafts are used in urban drainage systems to connect two sewers located at considerably different elevations by means of a vertical conduit. The vortex drop shaft was first designed by Drioli (1947). It was then studied by other authors with reference to subcritical approach flow. Vortex shafts specifically conceived for supercritical f...

Vortex drop shafts are used in urban drainage systems to connect two sewers located at considerably different elevations. After their introduction in 1947, these were studied with particular reference to subcritical approach flow. Vortex shafts for supercritical approach flow can also be used, but the intake structure may have relatively high cost...

Spurs are river engineering elements used to protect river banks from erosion and to concentrate flow to the river axis. Today, spurs are also employed for promoting environmental conditions along a river bank. These elements are characterized by a large variety of geometrical parameters, of which none is definitely fixed. Based on a preliminary st...

Manholes often contain small drops for various reasons, the most important being submergence. While this may be appropriate for subcritical flow, its effect was considered doubtful for supercritical flow. This note aims at investigating the effect of a manhole drop on the hydraulics of sewer flow. Based on systematic experimental observations, the...

The breakdown of supercritical flow in sewer manholes may be dangerous when designed according to current practice. This issue is particularly relevant for drainage systems conveying discharge in both stormwater and combined sewers. Based on detailed hydraulic experimentation, the main features of three manhole types were observed, including the th...

In this paper, the capability of selected sustainable drainage systems (SuDS) to accomplish hydraulic hydrological invariance (HHI) was analyzed. The HHI principle is achieved if both the peak flow and the volume runoff of the urbanized catchment remain equal after any increase of impervious surfaces. In particular, the hydraulic performance of gre...

The replacement of deteriorated pipe segments in aging water distribution networks often results in hybrid pipelines, consisting of segments of different materials of comparable length. The fact that short segments of polymeric material have a strong effect on the transient response of metallic pipelines authorizes to consider it important to exami...

The OBREC (Overtopping Breakwater for wave Energy Conversion) is based on the overtopping phenomenon [1] where incoming waves run over an overtopping ramp and fall into a reservoir located above the sea level inside a conventional rubble mound breakwater, or into a vertical caisson breakwater. The wave energy is transformed into potential energy, w...

A massive use of nitrogen based fertilizers in agriculture is worldwide one of the main causes for nitrate contamination of groundwater. Methods for removing nitrate from aquatic environment through physical and/or chemical processes often turn out to be not applicable because of unaffordable financial resource as well as essential infrastructure l...

Sewer bend manholes are frequent elements of urban drainage systems. Any deviation of straight-lined supercritical flow, as within the manhole, generates shock waves, possibly impinging at the manhole end or imposing a hydraulic jump. Then the free-surface flow regime abruptly breaks down and backwater effects occur. Thus it is important to know th...

If the operation of existing vortex drop shafts should be verified, then it is essential to know the hydraulic performance of these special structures under both subcritical and supercritical flow regimes. The purpose of the present research consisted, then, in providing practical guidelines and recommendations for managing the hydraulic design and...

Currently, the dye industry is increasing its production as a consequence of the growing need for their products in different manufacturing sectors, such as textiles, plastics, food, paper, etc... Thereafter, these industries generate very large volumes of effluents contaminated by these dyes, which require proper removal treatment before final dis...

In the last years green roofs are being used as a control measure for urban stormwater management as they retain, detain and slowly release rainwater. Green roofs present many economic, social and environmental benefits. After a general overview of the main features of green roofs, the paper focuses on the main outcomes highlighted by selected lite...

In the present literature review paper several experimental investigations on physical and numerical models of drop manholes and vortex drop shafts were considered. The examination of the experimental data led to the definition of a simple empirical equation, initially suggested for one type of drop manhole, to estimate the total head loss coeffici...

Overtopping-type wave power conversion devices represent one of the most promising technology to combine reliability and competitively priced electricity supplies from waves. While satisfactory hydraulic and structural performance have been achieved, the selection of the hydraulic turbines and their regulation is a complex process due to the very l...

The coagulation-flocculation-sedimentation process is widely used for removal of suspended solids and water turbidity reduction. The most common coagulants used to conduct this process are aluminum sulfate and ferric sulfate. In this paper, the use of Aloe vera as a natural-based coagulant for drinking water treatment was tested. The bio-coagulant...

Sediment trapping by reservoir is a problem of global severity with associated environmental, social and economic repercussions. Reservoirs trap 100% of river bedload and a not negligible percentage of suspended load. The water storage is destinated for decreasing over the time, the aquatic habitat in the downstream channel is increasingly deprived...

Vortex drop shafts are special manholes designed to link sewer channels at different elevations. Significant energy head dissipation occurs across these structures, mainly due to vertical shaft wall friction and turbulence in the dissipation chamber at the toe of the shaft. In the present study two aspects, sometimes neglected in the standard hydra...

The vortex drop shaft is a benchmark structure in hydraulic engineering. It is often used in sewers and hydropower systems, given that a significant energy dissipation combined with a reduced space occupation is achieved. Conversely, the flow pattern establishing along the structure may lead to the occurrence of unstable phenomena as vibrations, ab...

The vortex drop shaft is a reference structure in hydraulic engineering. It is often used in sewers and hydropower, systems, given that a significant energy dissipation combined with a reduced space occupation is achieved. Conversely, the flow pattern establishing along the structure may lead to the occurrence of unstable phenomena as vibrations, a...

The overtopping phenomenon at the rear side of breakwaters has particular importance in harbor protection. Undoubtedly, this topic needs to be taken even more seriously, considering the sea level rise. The present study focuses on the effectiveness in the reduction of the wave overtopping of a triangular parapet placed on the top of an innovative c...

The present Discussion aims to evaluate the applicability of the empirical criteria defined for symmetric four-branched junction manholes in the Technical Note. These recommendations are herein used to estimate the maximum shock wave heights and the discharge capacity of 45° and 90° three-branched supercritical junction manholes with variable inlet...

Vortex drop shafts are special drop structures typically installed in urban drainage systems or rarely as spillways for hydropower plants. The knowledge about the hydraulic behavior of vortex drop shafts was improved over the years but some gaps still have to be filled, with particular concern to the hydraulic aspects of the intake structure and of...

Vortex drop shafts, as special sewer manholes, operate optimally if an adequate energy dissipation is guaranteed and the integrity of the structural components is safeguarded. The results of an experimental study on a vortex drop shaft with supercritical inflow are discussed herein. The hydraulic behaviour of the spiral inlet, the vertical shaft an...

Vortex drop shafts, as special sewer manholes, operate optimally if an adequate energy dissipation is guaranteed and the integrity of the structural components is safeguarded. The results of an experimental study on a vortex drop shaft with supercritical inflow are discussed herein. The hydraulic behaviour of the spiral inlet, the vertical shaft an...

In a time span of over 3,000 years, the function of harbor breakwaters has remained the same (i.e., the energy dissipation), with differences depending on the general breakwater configurations: rubble mound breakwaters or caisson breakwaters. The recent demands of the sea level rise and the intensification of extreme events related to climate chang...

Junction manholes are a part of urban drainage infrastructures. They merge inlet branches into an outlet branch. Former studies focused on junction flow by considering a specific manhole layout: identical diameters were assigned to the branches and the invert was flush. Nevertheless, engineers are often involved in designing junctions under general...

Vortex drop shafts serve to overcome important elevation differences in drainage systems. If well designed, they are performant in terms of energy dissipation and safety. However, the standard design requires well-defined approach flow conditions to ensure the reliability of the structure. In practice, these conditions are frequently ignored due to...

Hydropeaking flow alterations in the Volturno River (Campania, Italy) were analyzed with reference to the river reach downstream of the hydropower plant of Mignano Montelungo. The performance of a retention basin to mitigate the hydropeaking effect is also discussed.

The safe operation of urban drainage systems may be limited by the failure of sewer manholes. For super-critical flows, the design of such structures has to be focused on the estimation of flow choking features.

Vortex drop shafts (VDSs) are special drop structures typically adopted for elevation differences larger than about 5 m (Gisonni and Hager 2012). In few cases (Volkart 1984; Bruschin and Mouchet 1985) they were utilized also to combine various sewer collectors. This uncommon concept was adopted to realize the new VDS operating in Cossonay, Switzerl...

An adequate operation of combined sewer systems is related to the efficiency of sewer manholes. Sometimes, sewer manholes are designed to convey safely storm water discharges with a return period shorter than the infrastructure life time. In other cases, the manhole discharge capacity is sufficient but the flow structure established in the manhole...

Il pozzo a vortice nella fognatura di Cossonay (Svizzera) è stato progettato adottando una soluzione diversa dagli standard, con una camera che raccoglie le portate in arrivo da quattro collettori. La sperimentazione su modello fisico ha evidenziato un comportamento idraulico globale più che soddisfacente, con una capacità idrovettrice maggiore di...

The drainage network of the city of Cossonay (Switzerland) is currently being adapted for future needs. In particular, it is required to drain increased storm discharges due to a population augmentation and to provide an adequate concept to overcome unfavorable geotechnical conditions. Vortex drop shafts are sewer manholes commonly applied in steep...

Although many studies have investigated flow hydraulics in compound channels, Divided Channel Method (DCM) remains as one of the most used approach for computing stage-discharge rating curves in practical applications. Indeed, it ensures calculation simplicity but, on the other hand, its concept neglects the momentum exchange at the interface betwe...

Sideweirs are hydraulic structures commonly used in combined sewer systems for separating excess storm water from urban sewage. In the case of low-crested sideweirs, the design is difficult because supercritical flows may establish along the overflow reach. This can lead to transcritical conditions not easily modelled in many cases. The present pap...

The functionality of sewer networks is strongly affected by the correct operation of their appurtenances; the dendritic structure of urban drainage systems implies that junction manholes represent a crucial hydraulic structure, allowing two conduits merging into one. Hydraulic features of combining flows become quite complex when supercritical flow...

The ‘Floods Directive’ 2007/60/CE by the European Parliament requires the characterization of flood hazard by multi-scenario hydraulic analyses, based on the estimation of flow velocity and water depth or free-surface level over flooded areas. In principle, this evaluation demands a complete analysis of the watershed hydraulics, based on two- or ev...

Former studies on combining flows resulted in an efficient layout of sewer junctions operated under supercritical approach flow conditions. Straight extensions allowed a reduction in the shock wave heights generated by the merging flows, so that the global discharge capacity was significantly increased. Herein, an extensive experimental campaign is...

Il territorio italiano è caratterizzato dalla presenza di estese aree densamente antropizzate, notoriamente afflitte da fenomeni di inquinamento dei corpi idrici superficiali, oltre che di dissesto idrogeologico. In tale contesto, gli aspetti “quantitativi” e “qualitativi” dei deflussi urbani richiedono notevole attenzione da parte di studiosi e te...

The study of unsteady shallow-layer flows, as those occurring during floods, may be performed through either fully dynamic models or using simplified momentum equations (e.g. kinematic, diffusion and quasi-steady approximations). Among the latter, kinematic approximation may provide a significant reduction of the computational effort, which represe...

The sustainable management of water supply networks requires the control of physical pipe leakages, as those due to junction obsolescence or pipe creeping. These leakages usually increase with the operating pressure, and their discharge is commonly assumed to scale with a power of the pressure. The same functional form is also employed to evaluate...

On October 23, 2007, the European Parliament approved the ‘Floods Directive’ 2007/60/CE (FD), aimed to regulate the procedures for hydraulic risk assessment. One of its most innovative aspects consists in the characterization of flood hazard by multi-scenario hydraulic analyses, based on the estimation of flow velocities and water depths all over t...

La combinaison d’écoulements représente un des phénomènes hydrauliques des plus fascinants, en particulier pour les écoulements torrentiels. L’efficacité des réseaux d’écoulement à surface libre, comme les systèmes d’évacuation des eaux en milieu urbain, dépend fortement du bon fonctionnement des regards de jonctions. Récemment, des études poussées...

In una corrente idrica, le perdite di energia (o di carico) possono essere distinte in due tipologie fondamentali: perdite distribuite e perdite localizzate. Le prime sono essenzialmente originate dalle resistenze al moto indotte dagli attriti in corrispondenza della parete del canale e dalla viscosità del fluido; le seconde dipendono principalment...

Vengono illustrati i tre principi fondamentali che governano lo studio dell’Idraulica: l’equazione di continuità che assicura la conservazione della massa, il principio di conservazione della quantità di moto ed il principio di conservazione dell’energia. Il capitolo illustra le suddette leggi fondamentali, anche con l’ausilio di alcuni riferimenti...

La condizione di stato critico si instaura allorché si verifica un insieme di condizioni, che vengono dettagliatamente esaminate. La condizione di stato critico viene quindi analizzata con specifico riferimento alle tre sezioni standard: circolare, ovoidale ed a ferro di cavallo. Tra i parametri fondamentali del moto critico, particolare attenzione...

In corrispondenza della sezione terminale di un collettore, ovvero nel caso in cui si presenti un salto, è possibile effettuare una misura della portata defluente, disponendo così di un mezzo alternativo a quello dei dispositivi illustrati nel capitolo precedente. Verranno passate in rassegna le caratteristiche di funzionamento idraulico dello sboc...

Gli stramazzi sono prevalentemente utilizzati come dispositivo di misura della portata, ma possono anche essere impiegati per realizzare una sezione di controllo nella estremità di valle di un canale. L’obiettivo è quello di illustrare le varie tipologie di stramazzo, con i rispettivi vantaggi che ne hanno consentito un diffuso impiego nella pratic...

In via generale è possibile considerare due tipi di manufatti di salto: i pozzetti di salto e i pozzi a vortice. Verranno descritte entrambe le tipologie, delineandone gli ambiti di applicazione, i principi di funzionamento idraulico, nonché i fondamentali criteri di progettazione, anche alla luce di recenti risultati ottenuti da ricercatori italia...

I canali di gronda rappresentano un’ulteriore applicazione della teoria sui canali a portata variabile in cui, a differenza degli sfioratori laterali, la portata aumenta nella direzione del moto. Si tratta, generalmente, di manufatti di breve lunghezza in cui è possibile trascurare gli effetti delle resistenze al moto. La differenza di comportament...

La gestione di un sistema fognario può richiedere che si debba procedere alla misura estemporanea della portata defluente in un collettore, anche accontentandosi di una stima approssimata del suo valore. Sono illustrati alcuni dispositivi mobili, di notevole utilità per la misura in campo della portata defluente in canali a sezione rettangolare, tr...

Il moto uniforme ha origine dalla condizione di equilibrio tra le forze motrici e le forze resistenti al moto. Viene anzitutto descritta in maniera dettagliata la condizione di moto uniforme, con indicazione delle formule di moto uniforme da applicare nel caso di correnti a pelo libero in canali a sezione circolare, ovoidale ed a ferro di cavallo....

Il profilo di corrente rappresenta l’andamento della superficie libera di una corrente in un canale a pelo libero. In condizioni di moto permanente, il profilo di corrente dipende dal valore della portata defluente e dalle condizioni al contorno. Nella maggior parte dei casi, il tracciamento di un profilo di corrente può risultare piuttosto laborio...

Nell’ambito della attività di progettazione di un sistema di drenaggio urbano, il dimensionamento idraulico dei manufatti rappresenta una fase cruciale di estrema importanza. Di norma, la progettazione viene effettuata sulla base di due particolari valori della portata di progetto: la portata minima e la portata massima. Il valore della portata min...

In alcuni casi di pratico interesse, quale ad esempio un impianto di depurazione di acque reflue, può essere necessario progettare un canale che distribuisca la portata lungo il proprio percorso. Una particolare tipologia di tale manufatto è rappresentata dagli sfioratori laterali che vengono spesso impiegati come scaricatori di piena nei sistemi f...

Nei punti del sistema fognario in cui interviene la variazione di anche un solo parametro idraulico o geometrico è opportuno prevedere la realizzazione di un apposito manufatto. Peraltro, anche in assenza di qualsivoglia variazione, è comunque buona norma prevedere la realizzazione di un manufatto di accesso; infatti, la normativa italiana vigente...

La transizione da corrente veloce a corrente lenta induce la insorgenza di un risalto idraulico; tale fenomeno viene qui illustrato a partire dai concetti fondamentali e dalla applicazione del principio di conservazione della quantità di moto. In particolare, oltre al classico caso riferito alla sezione rettangolare, vengono illustrati anche i casi...

Il venturimetro per canali, anche detto canale Venturi, è diffusamente utilizzato per la misura di portata in sistemi fognari, in quanto il suo funzionamento è compatibile con la presenza di materiali grossolani trasportati dalla corrente. Tale dispositivo è costituito da un restringimento della sezione del canale, quasi sempre senza innalzamento d...

Sebbene le pompe e le stazioni di pompaggio appartengano ad un settore altamente tecnologico, verranno trattati alcuni argomenti essenziali per le stazioni di sollevamento fognarie, comprendendo anche importanti nozioni relative alle coclee (o viti di Archimede). Saranno altresì descritte le principali caratteristiche di alcuni dispositivi limitato...

L’efficienza di un sistema fognario di tipo misto dipende fortemente dal corretto funzionamento dei manufatti per lo scarico delle portate di piena e, in particolare, degli sfioratori laterali. Il regolare funzionamento idraulico di tali manufatti è di primaria importanza, poiché le eventuali disfunzioni possono compromettere lo stato ambientale de...

I manufatti fognari possono indurre notevoli perdite di carico in presenza di particolari condizioni di funzionamento. Viene illustrato come, in corrispondenza di pozzetti per fognature, le perdite di carico per correnti subcritiche sono assimilabili al caso di correnti in pressione. In tal modo, la conoscenza delle condizioni di valle e dei coeffi...

Il capitolo è dedicato alla caratterizzazione idraulica del processo di efflusso che ha luogo negli scaricatori a salto di fondo, prevalentemente utilizzati in presenza di orrenti veloci; il loro principio di funzionamento è stato formalizzato per la prima volta circa 50 anni fa. In particolare, per questo manufatto vengono illustrati i criteri di...

Si illustra il comportamento idraulico di tre particolari manufatti, per i quali possono presentarsi sia condizioni di deflusso a superficie libera che in pressione. I tombini sono opere idrauliche tipicamente utilizzate per la realizzazione di intersezioni tra canali ed infrastrutture di trasporto realizzate in rilevato; vengono illustrate le dive...

This work describes the main hydraulic features of vortex dropshafts along with some examples of their mis-designs and consequent malfunction. Laboratory experiments were conducted to test the hydraulic performance of subcritical vortex intakes using supercritical approach flow design basis. The purposes of these drop structures are to: (i) convey...

P. Novak, A.I.B. Moffat, C. Nalluri and R. Narayanan, Taylor and Francis, ISBN 978-0-415-38626-5, 4th edition, 736 pp, 61.99 US dollar/35.00 pound, 2007

Vortex drop shafts are widely used in practice to connect sewer mains characterized by large elevation difference. These structures conventionally include three key elements: intake structure, vertical shaft and outlet structure, also named dissipation chamber. The latter has not received much attention as compared to the first two parts, and only...

River training techniques are often based on spurs whose main purposes are to prevent bank erosion, besides an enhancement of ecological conditions in the proximity of river shores. Actually, no general design criteria are available, given the large variety of geometrical parameters which characterize a spur set. In addition, the duration and relia...

The recognition of Henry Bazin (1829–1917) as being one of the outstanding experimenters in hydraulics of the 19th century was founded by his 1865 report Recherches Hydrauliques. This paper presents the main findings of that historically important work including the fundamental results on uniform flow, open channel velocity distributions, gradually...