Evidences of relationships between statistics of rainfall extremes and mean annual precipitation: an application for design-storm estimation in northern central Italy

International audienceSeveral hydrological analyses need to be founded on a reliable estimate of the design storm, which is the expected rainfall depth corresponding to a given duration and probability of occurrence, usually expressed in terms of return period. The annual series of precipitation maxima for storm duration ranging from 15 min to 1 day are observed at a dense network of raingauges sited in northern central Italy are statistically analyzed using an approach based on L-moments. The study investigates the statistical properties of rainfall extremes and identifies important relationships between these properties and the mean annual precipitation (MAP). On the basis of these relationships, we develop a regional model for estimating the rainfall depth for a given storm duration and recurrence interval in any location of the study region. The reliability of the regional model is assessed through Monte Carlo simulations. The results are relevant given that the proposed model is able to reproduce the statistical properties of rainfall extremes observed for the study region

Relationships between statistics of rainfall extremes and mean annual precipitation: an application for design-storm estimation in northern central Italy

Several hydrological analyses need to be founded on a reliable estimate of the design storm, which is the expected rainfall depth corresponding to a given duration and probability of occurrence, usually expressed in terms of return period. The annual series of precipitation maxima for storm duration ranging from 15 min to 1 day, observed at a dense network of raingauges sited in northern central Italy, are analyzed using an approach based on L-moments. The analysis investigates the statistical properties of rainfall extremes and detects significant relationships between these properties and the mean annual precipitation (MAP). On the basis of these relationships, we developed a regional model for estimating the rainfall depth for a given storm duration and recurrence interval in any location of the study region. The applicability of the regional model was assessed through Monte Carlo simulations. The uncertainty of the model for ungauged sites was quantified through an extensive cross-validation

Smooth regional estimation of low-flow indices: physiographical space based interpolation and top-kriging

Recent studies highlight that spatial interpolation techniques of point data can be effectively applied to the problem of regionalization of hydrometric information. This study compares two innovative interpolation techniques for the prediction of low-flows in ungauged basins. The first one, named Physiographical-Space Based Interpolation (PSBI), performs the spatial interpolation of the desired streamflow index (e.g., annual streamflow, low-flow index, flood quantile, etc.) in the space of catchment descriptors. The second technique, named Topological kriging or Top-kriging, predicts the variable of interest along river networks taking both the area and nested nature of catchments into account. PSBI and Top-kriging are applied for the regionalization of <i>Q</i><sub>355</sub> (i.e., a low-flow index that indicates the streamflow that is equalled or exceeded 355 days in a year, on average) over a broad geographical region in central Italy, which contains 51 gauged catchments. The two techniques are cross-validated through a leave-one-out procedure at all available gauges and applied to a subregion to produce a continuous estimation of <i>Q</i><sub>355</sub> along the river network extracted from a 90m elevation model. The results of the study show that Top-kriging and PSBI present complementary features. Top-kriging outperforms PSBI at larger river branches while PSBI outperforms Top-kriging for headwater catchments. Overall, they have comparable performances (Nash-Sutcliffe efficiencies in cross-validation of 0.89 and 0.83, respectively). Both techniques provide plausible and accurate predictions of <i>Q</i><sub>355</sub> in ungauged basins and represent promising opportunities for regionalization of low-flows

Safer_RAIN: A DEM-based hierarchical filling-&-spilling algorithm for pluvial flood hazard assessment and mapping across large urban areas

The increase in frequency and intensity of extreme precipitation events caused by the changing climate (e.g., cloudbursts, rainstorms, heavy rainfall, hail, heavy snow), combined with the high population density and concentration of assets, makes urban areas particularly vulnerable to pluvial flooding. Hence, assessing their vulnerability under current and future climate scenarios is of paramount importance. Detailed hydrologic-hydraulic numerical modeling is resource intensive and therefore scarcely suitable for performing consistent hazard assessments across large urban settlements. Given the steadily increasing availability of LiDAR (Light Detection And Ranging) high-resolution DEMs (Digital Elevation Models), several studies highlighted the potential of fast-processing DEM-based methods, such as the Hierarchical Filling-&-Spilling or Puddle-to-Puddle Dynamic Filling-&-Spilling Algorithms (abbreviated herein as HFSAs). We develop a fast-processing HFSA, named Safer_RAIN, that enables mapping of pluvial flooding in large urban areas by accounting for spatially distributed rainfall input and infiltration processes through a pixel-based Green-Ampt model. We present the first applications of the algorithm to two case studies in Northern Italy. Safer_RAIN output is compared against ground evidence and detailed output from a two-dimensional (2D) hydrologic and hydraulic numerical model (overall index of agreement between Safer_RAIN and 2D benchmark model: sensitivity and specificity up to 71% and 99%, respectively), highlighting potential and limitations of the proposed algorithm for identifying pluvial flood-hazard hotspots across large urban environments

Electro-chemical deposition of zinc oxide nanostructures by using two electrodes

One of the most viable ways to grow nanostructures is electro deposition. However, most electrodeposited samples are obtained by three-electrode electrochemical cell. We successfully use a much simpler two-electrode cell to grow different ZnO nanostructures from common chemical reagents. Concentration, pH of the electrolytes and growth parameters like potentials at the electrodes, are tailored to allow fast growth without complexity. Morphology and surface roughness are investigated by Scanning Electron and Air Force Microscopy (SEM and AFM) respectively, crystal structure by X-Ray Diffraction measurements (XRD) and ZnO stoichiometry by core level photoemission spectroscopy (XPS)

Fruit ripening in Vitis vinifera: spatiotemporal relationships among turgor, sugar accumulation, and anthocyanin biosynthesis

This study reports the first observations indicating the spatiotemporal relationships among genetic and physiological aspects of ripening in the berry of Vitis vinifera. At the onset of ripening in the red flesh variety Alicante Bouschet, colour development began in the flesh at the stylar end of the fruit and progressed toward the pedicel end flesh and into the skin. Tissue solute potential and cell turgor also decreased first in the flesh. The decrease in flesh solute potential was due to accumulation of sugars, glucose and fructose, an accumulation that is integral to ripening. Expression of the anthocyanin biosynthesis-related genes VvMybA and VvUFGT was linearly related to the decrease in solute potential. Expression of VvMybA, and to a lesser extent VvUFGT, was correspondingly low in green tissue, higher in the red, stylar end flesh of berries beginning to ripen, and greatest in red berries. In contrast, expression of the abscisic acid biosynthesis-related genes VvNCED1 and VvNCED2 was not correlated with the other spatiotemporal aspects of the onset of ripening. These results, together with earlier work showing that sugar accumulation and acid loss also begin in the stylar flesh in other varieties, indicate that ripening in the grape berry originates in the stylar end flesh

Identification of coherent flood regions across Europe by using the longest streamflow records

This study compiles a new dataset, consisting of the longest available flow series from across Europe, and uses it to study the spatial and temporal clustering of flood events across the continent. Hydrological series at 102 gauging stations were collected from 25 European countries. Five geographically distinct large-scale homogeneous regions are identified: (i) an Atlantic region, (ii) a Continental region, (iii) a Scandinavian region, (iv) an Alpine region, and (v) a Mediterranean region. The months with a higher likelihood of flooding were identified in each region. The analysis of the clustering of annual counts of floods revealed an over-dispersion in the Atlantic and Continental regions, forming flood-rich and flood-poor periods, as well as an under-dispersion in the Scandinavian region that points to a regular pattern of flood occurrences at the inter-annual scale. The detection of trends in flood series is attempted by basing it on the identified regions, interpreting the results at a regional scale and for various time periods: 1900-1999; 1920-1999; 1939-1998 and 1956-1995. The results indicate that a decreasing trend in the magnitude of floods was observed mainly in the Continental region in the period 1920-1999 with 22% of the catchments revealing such a trend, as well as a decreasing trend in the timing of floods in the Alpine region in the period 1900-1999 with 75% of the catchments revealing this trend. A mixed pattern of changes in the frequency of floods over a threshold and few significant changes in the timing of floods were detected

Expansion and subfunctionalisation of flavonoid 3',5'-hydroxylases in the grapevine lineage

<p>Abstract</p> <p>Background</p> <p>Flavonoid 3',5'-hydroxylases (F3'5'Hs) and flavonoid 3'-hydroxylases (F3'Hs) competitively control the synthesis of delphinidin and cyanidin, the precursors of blue and red anthocyanins. In most plants, <it>F3'5'H </it>genes are present in low-copy number, but in grapevine they are highly redundant.</p> <p>Results</p> <p>The first increase in <it>F3'5'H </it>copy number occurred in the progenitor of the eudicot clade at the time of the γ triplication. Further proliferation of <it>F3'5'H</it>s has occurred in one of the paleologous loci after the separation of Vitaceae from other eurosids, giving rise to 15 paralogues within 650 kb. Twelve reside in 9 tandem blocks of ~35-55 kb that share 91-99% identity. The second paleologous <it>F3'5'H </it>has been maintained as an orphan gene in grapevines, and lacks orthologues in other plants. Duplicate <it>F3'5'H</it>s have spatially and temporally partitioned expression profiles in grapevine. The orphan <it>F3'5'H </it>copy is highly expressed in vegetative organs. More recent duplicate <it>F3'5'H</it>s are predominately expressed in berry skins. They differ only slightly in the coding region, but are distinguished in the structure of the promoter. Differences in <it>cis</it>-regulatory sequences of promoter regions are paralleled by temporal specialisation of gene transcription during fruit ripening. Variation in anthocyanin profiles consistently reflects changes in the <it>F3'5'H </it>mRNA pool across different cultivars. More <it>F3'5'H </it>copies are expressed at high levels in grapevine varieties with 93-94% of 3'5'-OH anthocyanins. In grapevines depleted in 3'5'-OH anthocyanins (15-45%), fewer <it>F3'5'H </it>copies are transcribed, and at lower levels. Conversely, only two copies of the gene encoding the competing F3'H enzyme are present in the grape genome; one copy is expressed in both vegetative and reproductive organs at comparable levels among cultivars, while the other is transcriptionally silent.</p> <p>Conclusions</p> <p>These results suggest that expansion and subfunctionalisation of <it>F3'5'H</it>s have increased the complexity and diversification of the fruit colour phenotype among red grape varieties.</p

Invigorating hydrological research through journal publications

Over the past five years, the editors of a number of journals in the discipline of hydrology have met informally to discuss challenges and concerns in relation to the rapidly changing publishing landscape. Two of the previous meetings, in Götenborg in July 2013 and in Prague in June 2015, were followed by joint editorials (Blöschl et al. 2014; Koutsoyiannis et al. 2016) published in all participating journals. A meeting was convened in Vienna in April 2017 [during the General Assembly of the European Geosciences Union (EGU)] that was attended by 21 editors representing 14 journals. Even though the journals are published in very different settings, the editors found common cause in a vision of the editor’s role beyond just that of gatekeeper ensuring high-quality publications, to also being critical facilitators of scientific advances. In that enabling spirit, we as editors acknowledge the need to anticipate and adapt to the changing publishing landscape. This editorial communicates our views on the implications for authors, readers, reviewers, institutional assessors, and the community of editors, as discussed during the meeting and subsequently

Evolutionary leap in large-scale flood risk assessment needed

Current approaches for assessing large-scale flood risks contravene the fundamental principles of the flood risk system functioning because they largely ignore basic interactions and feedbacks between atmosphere, catchments, river-floodplain systems and socio-economic processes. As a consequence, risk analyses are uncertain and might be biased. However, reliable risk estimates are required for prioritizing national investments in flood risk mitigation or for appraisal and management of insurance portfolios. We review several examples of process interactions and highlight their importance in shaping spatio-temporal risk patterns. We call for a fundamental redesign of the approaches used for large-scale flood risk assessment. They need to be capable to form a basis for large-scale flood risk management and insurance policies worldwide facing the challenge of increasing risks due to climate and global change. In particular, implementation of the European Flood Directive needs to be adjusted for the next round of flood risk mapping and development of flood risk management plans focussing on methods accounting for more process interactions in flood risk systems