Effects of climate change on the Nossana karst spring (northern Italy): future discharge projections and water distribution system sustainability

Nossana represents an important pre-Alpine karst spring located in Lombardy Region (Northern Italy). It is used for drinking supply and it sustains a water distribution system serving 300,000 people, including the city of Bergamo. The objective of this study was to project Nossana discharges, to evaluate potential supply limits for four future periods (2021-2040, 2041-2060, 2061-2080, 2081-2100). The study was carried out following a four-step approach. First, the EURO-CORDEX bias-corrected Regional Climate Models (RCMs) available for all the emission scenarios (RCP2.6, RCP4.5, RCP8.5) were evaluated in terms of precipitation and temperature monthly climatology. Second, they were statistically downscaled by means of change factors and a stochastic weather generator. Third, a rainfall-runoff model ensemble accounting also for snow dynamics (GR4J with CemaNeige module) was calibrated and validated on historical time series (1998-2017). Finally, the future downscaled time series were used as input in the calibrated model and the projected discharges evaluated in terms of low flow. In detail, two warning discharge thresholds - one for high water demand periods and one for ordinary water demand periods - were recognized with the service company managing the spring (Uniacque S.p.A.). Then, the number of (consecutive) days below them were calculated for each future period and compared to the historical time series. For each emission scenario, the calibrated model ensemble counted three RCMs and ten rainfall-runoff parameterizations. Projected ensemble mean discharges are lower than observations for all future periods and RCPs (from -3% for 2021-2040 and RCP4.5 to -23% for 2081-2100 and RCP8.5), although they do not show a clear trend between the four time periods. Days characterized by discharges lower than the warning thresholds are projected to decrease except for the RCP8.5 emission scenarios and the period 2081-2100 (14% increase for the ordinary-demand threshold, 10% increase for the high-demand threshold). Conversely, consecutive days are expected to increase between 2061 and 2100 for all emission scenarios and the two thresholds (by 0% and 26% for RCP 2.6, by 8% and 15% for RCP 4.5, by 28% and 48% for RCP 8.5). These results reflect the projected precipitation trend, characterized by longer, drier summer periods and wetter autumns in comparison to today\u2019s climate. Also, they indicate the need to develop a plan for the research and use of alternative drinking water resources for the long-term period. Therefore, the proposed methodology demonstrated to deliver useful information for water management planning. Future studies are intended to focus on chemistry and isotopic composition of water

Risorse idriche e cambiamenti Climatici: la sorgente Nossana

Le sorgenti carsiche svolgono un ruolo fondamentale per l\u2019approvvigionamento idrico umano a larga scala, sia dal punto di vista strategico sia dal punto di vista delle relazioni socio \u2013 economiche (Bakalowicz, 2005). Quantificare e prevedere le portate delle sorgenti \ue8 necessario per gestire l\u2019approvvigionamento idrico nelle aree carsiche, specialmente a fronte degli effetti relativi al cambiamento climatico. Infatti, secondo l\u2019Intergovernmental Panel on Climate Change (IPCC, 2014), la temperatura media \ue8 destinata a crescere a livello globale lungo tutto il XXI secolo con conseguente aumento delle ondate di calore, dei periodi siccitosi e degli eventi di precipitazione intensa in molte regioni del mondo. La previsione della risposta a questi cambiamenti dei sistemi idrogeologici, soprattutto se sfruttati per approvvigionamento potabile, diventa di vitale importanza

Giochi d'acqua

Si descrivono alcune esperienze didattiche sugli inviluppi realizzate mediante getti d'acqua o gocce cadent

Da Pitagora a Borges. Discussioni in rete sull’infinito

Un inatteso contatto permette all'autore di dialogare, o meglio, di “chattare” con numerosi personaggi, vissuti in diverse epoche, dall'antichità al secolo scorso, e collocati nel mondo dantesco. Eminenti letterati, matematici e filosofi (da Omero a Borges, da Pitagora a Poincaré, da Aristotele a Pascal, passando per Euclide e Archimede, Dante, Galileo, Newton e Leibniz e numerosi altri) parlano tra loro e con l'autore usando sovente le loro stesse parole, in un dialogo a più voci surreale e ucronico che Maria Gaetana Agnesi tenta inutilmente di moderare. Il gusto della citazione dotta ma anche impertinente, sovente riportata anche nella lingua originale, si accompagna a quello della curiosità su tutto, importante o futile che sia, al gioco di parole e al piacere del divulgare in allegria. Il libro è una carrellata sul mondo dell'infinito, avente la matematica come filo conduttore ma senza tecnicismi né pretese di completezza, pieno di digressioni, variazioni sul tema, spunti di riflessione inaspettati

The role of geometry in reasoning and teaching

Ever since the very beginning of ancient philosophy, from Pythagoras to Plato, we know that the world is made up of numbers and figures. Greek mathematicians used drawings as a natural tool for proofing their theories, as the works of Archimedes and Euclid clearly show. Actually, the ruler-and-compass constructions are the most ancient examples of a perfectly well designed formal language, whose power is equivalent to up to second-degree equations. Drawings often provide wordless proofs that everybody can easily see: for instance, Pythagoras’ theorem and the statement that the sum of odd numbers in increasing order is a perfect square can be proved through a self-explaining drawing. The invention of symbolic algebra in the early seventeenth century, led mathematicians to a more abstract approach to mathematics. These tools are indeed very powerful, and they often need only a calculating capability instead of a deep understanding of the problems. However, especially in the nineteenth century, an analytical approach seemed to be safer than a geometrical one, and the drawing as a means was excluded from most books of mathematics, which had a negative impact on learning. On the other hand, functional analysis introduced a geometrical language in order to be able to describe many abstract concepts. Nowadays students have a very poor geometrical insight, the main fault for which lies in the scholastic institutions. Most of them cannot comprehend the large amount of information that a drawing contains, in spite of the existence of numerous geometrical softwares designed to construct and dynamically modify figures in order to verify guesses about their properties (to be eventually proved by a formal demonstration, of course). This naturally affects all branches of knowledge, as mathematics is ubiquitous. What can we do in order to improve their skills

La regola di Ruffini: pro o contro?

Discussione sulla complessità computazionale della regola di Ruffin

Matematica e vita civile nel Politecnico di cento anni fa: la vicenda di Max Abraham

The main events in the life of Max Abraham are described, with particular reference to his activity at the Politecnico di Milano during the period from 1909 to 1915. Documents are provided relating to his confirmation as full professor, including two letters by Levi-Civita and Maggi, and some news and discussion about the training of engineers. Thorough treatment is given to a problem of mechanics (the falling cat), which was then taken up by C. E. Gadda, one of Abraham’s pupils. Finally, the events of April 1915 are described, culminating in Abraham’s decision to leave Italy

IPERBOLE: UN PONTE MATEMATICO TRA FINITO E INFINITO

Si passano in rassegna alcuni punti significativi della storia e delle proprieta' dell'iperbole, uniti dal filo conduttore del concetto di infinito