1,721,177 research outputs found
Estimation of flood warning runoff thresholds in ungauged basins with asymmetric error functions
No full textIn many real-world flood forecasting systems, the runoff thresholds for
activating warnings or mitigation measures correspond to the flow peaks with
a given return period (often 2 years, which may be associated with the
bankfull discharge). At locations where the historical streamflow records
are absent or very limited, the threshold can be estimated with
regionally derived empirical relationships between catchment descriptors and
the desired flood quantile. Whatever the function form, such models are
generally parameterised by minimising the mean square error, which assigns
equal importance to overprediction or underprediction errors.
Considering that the consequences of an overestimated warning threshold
(leading to the risk of missing alarms) generally have a much lower level of
acceptance than those of an underestimated threshold (leading to the
issuance of false alarms), the present work proposes to parameterise the
regression model through an asymmetric error function, which penalises the overpredictions more.
The estimates by models (feedforward neural networks) with increasing degree
of asymmetry are compared with those of a traditional, symmetrically trained
network, in a rigorous cross-validation experiment referred to a database of
catchments covering the country of Italy. The analysis shows that the use of
the asymmetric error function can substantially reduce the number and extent
of overestimation errors, if compared to the use of the traditional square
errors. Of course such reduction is at the expense of increasing
underestimation errors, but the overall accurateness is still acceptable and
the results illustrate the potential value of choosing an asymmetric error
function when the consequences of missed alarms are more severe than those
of false alarms
ALCUNE CONSIDERAZIONI DELLA SOCIETÀ IDROLOGICA ITALIANA SULLA GRAVE SICCITÀ DELL’ESTATE 2022
No full textLa siccità che ha colpito il nostro Paese fin dall’inizio del 2022, ha posto all’attenzione della popolazione, at- traverso i media, un tema che i gestori delle risorse idriche, i tecnici e i ricercatori hanno ben presente, ma che non aveva ancora suscitato adeguato interesse nel dibattito politico. L’articolo del Ministro della Transizione Ecologica, Roberto Cingolani, pubblicato sul Corriere della Sera lo scorso 11 luglio, è un utile stimolo, per amministratori e politici, ad affrontare il tema della scarsità di risorse idriche e delle misure necessarie per mi- tigare l’impatto dei fenomeni siccitosi
Effectiveness of smart meter-based urban water loss assessment in a real network with synchronous and incomplete readings
No full textThe availability of smart metered high-resolution water consumption data introduces, through the synchronous readings of the smart meters, new perspectives in the proactive approach to the monitoring of water losses. Measuring or transmission systems problems are unavoidable in real-world networks and, if not appropriately addressed, may compromise the ability to use smart meters to estimate water losses. The proposed Synchronous Water Balance methodology allows the near-real time assessment of water losses taking into account incomplete readings through a water consumption data validation and reconstruction model. The impact on water loss monitoring due to the lack of an increasing number of smart meters is investigated applying a random sampling and evaluating the corresponding error. The results, tested on a district of the city of Fano (Italy), suggest that the availability of near real-time synchronous water consumption measures can substantially improve the assessment of water losses in comparison to traditional approaches
Monitoring soil retention properties in a riverbank susceptible to fluvial erosion
No full textOne of the principal source of vulnerability for riverbanks is given by slopes instabilities, which is triggered on the riverside by fluvial erosion. In order to mitigate such erosion, the establishment of a dense herbaceous cover aims at promoting the slope protection and reducing the likelihood of embankment failure. In fact, the aerial parts of vegetation reduce the mechanical impact of river level fluctuations and rainfall on the embankment and retain sediment transported, while the belowground parts reinforce mechanically the materials forming the top of the embankment, facilitating drainage in the topmost layers and promoting plant water uptake, thus contributing to the regulation of the drying/wetting cycle.
Plating deep-rooting perennial, herbaceous species on earth embankments therefore represent a sustainable, green intervention for the protection of a riverbank susceptible to fluvial erosion, contributing to the preservation of the fluvial ecosystem environment and avoiding a wide use of grey solutions. The European research project OPERANDUM is testing also this typology of NBS, with an experimental site selected on the river Panaro, one of the main tributary of the main Po River, Italy. To investigate the effect of vegetation on the riverbank soil, a monitoring system has been installed at shallow depths. The system estimates soil water content, matric suction and pore water pressure, in order to quantify the effects of the growth of different vegetation species, which have been recently seeded on site, for analyzing the plant-soil-atmosphere interaction. The work will present the site preparation and the system implementation. The analysis of the first collected data and the outcomes of the preliminary investigations, including site and laboratory experiments, will then be discussed. Monitoring data collected along the entire vegetation growth cycle, that is expected to take around two years, will allow to quantify the influence of vegetation in the soil-atmosphere interaction processes and, on the long-term, verify its effective contribution in riverbank protection
Hybridization of an alpine pumped-storage hydropower plant with floating solar photovoltaics: a study from the water resource perspective
No full textVariable renewable energy sources, like wind and solar power, are crucial for decarbonizing electricity systems, but pose challenges due to their intermittency. Hybridization (i.e., joint operation) with reservoir-based hydropower, which is a programmable resource, can address this issue. However, an open question is still how hybridization of existing hydropower plants could affect the water resources management. We propose a modelling framework for an existing pumped-storage hydropower plant located in the Swiss pre-alpine region, complemented by a fictional floating solar photovoltaic plant with a nominal capacity equal to about 50 % of the hydropower plant. The modelling framework considers reservoir management constraints and environmental flow requirements. The hourly simulations over 38 years show: (i) a 20 % increase in overall annual energy production, (ii) an improvement in the system reliability through mutual complementarity, and (iii) a potential for enhancing downstream environmental flow up to 50 % during the hot summer season, thereby enabling more streamflow for ecological purposes
Assessing the significance of tourism and climate on residential water demand: Panel-data analysis and non-linear modelling of monthly water consumptions
No full textThe concentration in time and space of tourists and of specific water-demanding touristic activities can add considerable pressure on available water supplies in coastal regions. The impact of tourism has not been adequately addressed in the water demand literature, especially at sub-annual scale: the present study includes the role of tourism on the monthly water demand in a set of Mediterranean coastal municipalities in a panel data framework. The influence of both climatic and touristic drivers on the water demand is investigated through a correlation analysis, thus deconstructing the seasonal variability of the consumption, and the development of both linear and non-linear models. The results demonstrate the improvement allowed by non-linear over linear modelling and the value of the information embedded in both climatic (in particular temperature daily maxima and minima and number of rainy days) and touristic determinants as drivers for the water demand at sub-annual scale
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
No full text“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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