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Freshwater mussels (FM) are suitable biological indicators to assess environmental stressors. Behaviour is a good parameter to measure rapid mussel’s responses. In this sense, valvometric method, that exploits the Hall sensor (real-time remote monitoring tool), has been used to measure the behavioural responses of mussels (valve opening amplitude and valve opening-closure frequency). During the last two decades, these methodologies have been used to measure the presence of the pollutants in the waterbodies. However, studies that focus on physical disturbances in the environment related to climate changes are lacking. Since future climatic scenarios in Europe predict an increase in temperature and change in the hydrological conditions, the main objective of this study was to evaluate the influence of water temperature increase and water discharge rates (without and with sediment transport) in four endpoints of mussel's behaviour: normal activity, resting, transition and avoidance. Our results suggest, that on experiments with increasing temperatures and high variation in water discharge rates with sediment transport, mussels presented high valve opening-closure frequencies and amplitudes. In this sense, mussels could be used as biological sensors to monitor changes in thermal and hydrological conditions which are increasing with climate changes.

Freshwater mussels are considered suitable bioindicators and used in real-time remote monitoring systems to detecting disturbances on ecosystems. One of the most successful methods is the valvometric technique that exploits the Hall sensor to measure the valve gaping behavior of mussels. The duration and frequency of valve opening amplitude and closure can therefore be recorded. These technologies have been used in the past to detect pollutants in the water, whereas studies that address the impact of hydromorphological pressures are still lacking. The main aim of the present study is to assess the influence of flow with sediment transport as well, both in steady and in unsteady (transient) conditions, in four endpoints of mussel's behavior: normal activity, resting, transition and avoidance. To this aim, experiments in laboratory flumes with mussels on a bed made of sands, for varying flow discharges, have been conducted. Results suggest that during transients and in the presence of sediment transport, mussels change their behavior, showing an increase of their valve opening-closure frequencies and amplitudes. These results are encouraging to support the use of mussels as biosensor also in their natural habitat (rivers or lakes) to monitor the occurrences of natural events involving hydro-morphological variations, as floods.

Il modello di entropia sviluppato da Chiu (1988) consente di correlare la velocità media, um, e umax mediante una relazione lineare, um,=Φ(M) umax, che dipende dal parametro entropico, M, caratteristico della sezione fluviale. Tale formulazione è stata verificata su diversi corsi d’acqua naturali con differenti caratteristiche idrauliche e geometriche (Ammari et al. 2010, Xia, 1997; Moramarco et al. , 2004). Nel presente lavoro, l’attenzione è rivolta alla verifica della relazione entropica tra la velocità media e la velocità massima al variare delle configurazioni planimetriche del canale (andamento rettilineo e andamento curvilineo) e in presenza di elementi forzanti come la curvatura del canale e la deformazione del fondo. L’analisi è condotta con l’ausilio di dati sperimentali raccolti in canali di laboratorio realizzati presso il Dipartimento DICAM dell’Università di Palermo.

Limitations of satellite radar altimetry for operational hydrology include its spatial and temporal sampling as well as measurement problems caused by local topography and heterogeneity of the reflecting surface. In this study, we develop an approach that eliminates most of these limitations to produce an approximately 3 day temporal resolution water level time series from the original typically (sub)monthly data sets for the Po River in detail, and for Congo, Mississippi, and Danube Rivers. We follow a geodetic approach by which, after estimating and removing intersatellite biases, all virtual stations of several satellite altimeters are connected hydraulically and statistically to produce water level time series at any location along the river. We test different data-selection strategies and validate our method against the extensive available in situ data over the Po River, resulting in an average correlation of 0.7, Root-Mean-Square Error of 0.8 m, bias of -0.4 m, and Nash-Sutcliffe Efficiency coefficient of 0.5. We validate the transferability of our method by applying it to the Congo, Mississippi, and Danube Rivers, which have very different geomorphological and climatic conditions. The methodology yields correlations above 0.75 and Nash-Sutcliffe coefficients of 0.84 (Congo), 0.34 (Mississippi), and 0.35 (Danube).

Nell’articolo si studia l’effetto di una cassa d’espansione posta a monte di un’area fluviale soggetta a rischio idraulico. Lo strumento utilizzato è un software bidimensionale sviluppato per simulare la propagazione delle piene fluviali. Il dominio di calcolo è rappresentato da una mesh triangolare non strutturata con una maggiore densità di elementi all’interno dell’alveo e nelle zone immediatamente limitrofe. Per facilitare gli accumuli temporanei di parte dei volumi di piena, si ipotizza la costruzione di un restringimento dell’alveo per mezzo di due pareti verticali che avvicinano le sponde fluviali. Durante la piena, il passaggio per lo stato critico nel restringimento provoca un rigurgito a monte, e quindi un agevole riempimento della cassa d’espansione. La perimetrazione di tale cassa è definita con la costruzione di un rilevato arginale di adeguata altezza. Per meglio simulare il rigurgito a monte della strozzatura, si introduce una scabrezza equivalente negli elementi della strozzatura, per riprodurre le perdite di carico nel restringimento e nel successivo risalto idraulico, malgrado l’ipotesi diffusiva utilizzata nel software di calcolo. La conoscenza delle aree allagate in due eventi di piena storici e dei due relativi idrogrammi di piena, ha consentito la determinazione del coefficiente di Manning quale misura della scabrezza in alveo e fuori alveo. Mediante l’applicazione del modello proposto è possibile validare sia il posizionamento degli argini a monte del restringimento per il contenimento della piena, sia la riduzione delle aree di valle soggette a rischio idraulico.

Le metodologie attualmente disponibili per la misura di pieno campo delle portate possono essere classificate in base al tipo di sensore utilizzato ed al numero delle stazioni idrometriche. Per ognuna delle possibili tipologie vengono presentate le tecniche di analisi più recenti e delineati possibili sviluppi futuri. Viene quindi introdotta una nuova metodologia, basata sull’integrazione di misure dirette ed indirette. Nell’approccio proposto la portata viene calcolata come valore al contorno di monte di un modello di propagazione 1D a cui vengono assegnati i tiranti di monte quale condizione misurata. Il modello viene calibrato attraverso sporadiche misure istantanee di velocità, consentendo di pervenire ad una registrazione continua delle portate mediante l’ausilio delle sole osservazioni dei tiranti in una sola stazione di misura. L’approccio è validato attraverso serie storiche di tiranti e di portate misurate in una stazione idrometrica del Fiume Tevere.

A methodology for determining the bathymetry of river cross-sections during floods by the sampling of surface flow velocity and existing low flow hydraulic data is developed . Similar to Chiu (1988) who proposed an entropy-based velocity distribution, the flow depth distribution in a cross-section of a natural channel is derived by entropy maximization. The depth distribution depends on one parameter, whose estimate is straightforward, and on the maximum flow depth. Applying to a velocity data set of five river gage sites, the method modeled the flow area observed during flow measurements and accurately assessed the corresponding discharge by coupling the flow depth distribution and the entropic relation between mean velocity and maximum velocity. The methodology unfolds a new perspective for flow monitoring by remote sensing, considering that the two main quantities on which the methodology is based, i.e., surface flow velocity and flow depth, might be potentially sensed by new sensors operating aboard an aircraft or satellite.

Soil Moisture (SM), being one of the main variables within the system that controls the hydrological interactions among soil, vegetation and atmosphere, plays a key role in the water cycle. Satellite systems, both active and passive, have already demonstrated their capability to provide reliable SM measurements. The European Space Agency (ESA) Soil Moisture and Ocean Salinity (SMOS) mission, launched in November 2009, was the first specific SM satellite mission. In this work we assessed the capability of SMOS data to accurately capture SM dynamics over a long time period by comparing them with in situ observations. To better assess the performance of such results, they were also compared with those obtained with alternative satellite-based SM products, considering in particular those generated by Advanced Microwave Sounding Radiometer (AMSR-E) and Advanced SCATterometer (ASCAT) data.