Groß-skalige 2D-hydraulische Modellierung: Verbesserung der Analyse der Flutdynamik mit remote sensing und freien geographischen Informationen

This work investigates the integration of hydro-geomorphic models, traditional data (static stage gages) and novel data sources, such as remotely sensed images and Crowdsourced data (Volunteering Geographic Information or VGI), for observation-driven improvements of hydro-modelling tools. The Tiber river basin, was selected as case study with a focus domain on the approximately 120 km channel upstream of Rome for its strategic importance in the protection of the historical city centre and the coastal urbanized zone. A parsimonious hydrological modelling algorithm was implemented, calibrated and validated for calculating the flow hydrographs of the ungauged small basins contributing to the study area. Furthermore, to delineate the boundaries computational domain of the hydraulic model for the Data Assimilation application, a DEM-based hydro-geomorphic floodplain delineation algorithm adapted from literature was tested with different DEMs and considering also its parametrization varying the stream orders. The adopted DA methodology is the Ensemble Kalman Filter (EnKF) that requires multiple simulations for representing the uncertainties related to the model and the observations errors. New approaches were proposed for integrating, as observations in the DA method, traditional static sensors, and simultaneously remotely sensed images and VGI data. Despite the static sensor have already been adopted in literature as observations in a DA framework, some new technical measures were necessary for integrating them in Quasi-2D hydraulic model. The assimilation of satellite images resulted to be effective, since the whole computational domain is interested by the water levels correction, although the improvement of the model performance persisted for only some hours of simulation. The usefulness of VGI have been investigated considering the uncertainties related to their reliability mostly in terms of accuracy and time allocation. Results show the potential of new data for improving the performance of the flood model, partially overcoming the limitations and the potential scarce availability of the traditional sensors. Finally, the simultaneous integration of all the three types of observations gave promising results, improving the performance of the model compared to the ones obtained assimilating only Satellite images or VGI observations.Diese Arbeit untersucht die Integration von hydro-geomorphen Modellen, traditionellen Daten (statische Stufenpegeln) und neuartigen Datenquellen wie Remote-Sensing-Bildern und Crowdsourced-Daten (volunteering Geographic Information oder VGI), um beobachtungsorientierte Verbesserungen von Hydromodellierungswerkzeugen zu erreichen. Das Tiber-Flusseinzugsgebiet wurde als Fallstudie mit einem Schwerpunkt auf dem etwa 120 km stromaufwärts von Rom gelegenen Kanal ausgewählt und zwar wegen seiner strategischen Bedeutung für den Schutz des historischen Stadtzentrums und der urbanisierten Küstenregion. Ein sparsamer hydrologischer Modellierungsalgorithmus wurde implementiert, kalibriert und validiert, um die Fluss-Hydrographen der durch Pegel nicht erfassten kleinen Becken zu berechnen, die zum Untersuchungsgebiet beitragen. Um die Grenzen des rechnerischen Bereichs des Hydraulikmodells für die Data-Assimilation-Anwendung abzugrenzen, wurde außerdem ein DEM-basierter, aus der Literatur angepasster Algorithmus zur Abgrenzung von hydrogeomorphen Flutebenen mit verschiedenen DEMs getestet, wobei auch die Parametrisierung der Stream-Reihenfolge berücksichtigt wurde. Die angenommene DA-Methode ist der Ensemble Kalman Filter (EnKF), der mehrere Simulationen zur Darstellung der mit dem Modell verbundenen Unsicherheiten und Beobachtungsfehler erfordert. Es wurden neue Ansätze für die Integration herkömmlicher statischer Sensoren, von Fernerkundungs-Bildern und von VGI-Daten als Beobachtungen für das DA-Verfahren vorgeschlagen. Obwohl die statischen Sensoren bereits in der Literatur als Beobachtungen in einem DA-Rahmen verwendet wurden, waren einige technische Maßnahmen erforderlich, um sie in das Quasi-2D-Hydraulikmodell zu integrieren. Die Assimilation von Satellitenbildern erwies sich als effektiv, da der gesamte rechnerische Bereich an der Korrektur des Wasserstandes interessiert ist; die Verbesserung der Modellleistung dauerte allerdings nur einige Stunden in der Simulation an. Die Nützlichkeit von VGI wurde unter Berücksichtigung der mit ihrer Zuverlässigkeit verbundenen Unsicherheiten hauptsächlich hinsichtlich Genauigkeit und Zeitzuordnung untersucht. Die Ergebnisse zeigen das Potenzial neuer Daten zur Verbesserung der Leistung des Flutmodells, wobei teilweise die Einschränkungen und die oftmals knappe Verfügbarkeit herkömmlicher Sensoren überwunden werden. Schließlich ergab die gleichzeitige Integration aller drei Arten von Beobachtungen vielversprechende Ergebnisse und verbesserte die Leistung des Modells im Vergleich zur Nutzung nur von Satellitenbilder oder VGI-Beobachtungen

The changing face of floodplains in the Mississippi River Basin detected by a 60-year land use change dataset

Floodplains provide essential ecosystem functions, yet \u3e80% of European and North American floodplains are substantially modified. Despite floodplain changes over the past century, comprehensive, long-term land use change data within large river basin floodplains are limited. Long-term land use data can be used to quantify floodplain functions and provide spatially explicit information for management, restoration, and flood-risk mitigation. We present a comprehensive dataset quantifying floodplain land use change along the 3.3 million km2 Mississippi River Basin (MRB) covering 60 years (1941–2000) at 250-m resolution. We developed four unique products as part of this work, a(n): (i) Google Earth Engine interactive map visualization interface, (ii) Python code that runs in any internet browser, (iii) online tutorial with visualizations facilitating classroom code application, and (iv) instructional video demonstrating code application and database reproduction. Our data show that MRB’s natural floodplain ecosystems have been substantially altered to agricultural and developed land uses. These products will support MRB resilience and sustainability goals by advancing data-driven decision making on floodplain restoration, buyout, and conservation scenarios

Citizens AND HYdrology (CANDHY): conceptualizing a transdisciplinary framework for citizen science addressing hydrological challenges

Widely available digital technologies are empowering citizens who are increasingly well informed and involved in numerous water, climate, and environmental challenges. Citizen science can serve many different purposes, from the "pleasure of doing science" to complementing observations, increasing scientific literacy, and supporting collaborative behaviour to solve specific water management problems. Still, procedures on how to incorporate citizens' knowledge effectively to inform policy and decision-making are lagging behind. Moreover, general conceptual frameworks are unavailable, preventing the widespread uptake of citizen science approaches for more participatory cross-sectorial water governance. In this work, we identify the shared constituents, interfaces, and interlinkages between hydrological sciences and other academic and non-academic disciplines in addressing water issues. Our goal is to conceptualize a transdisciplinary framework for valuing citizen science and advancing the hydrological sciences. Joint efforts between hydrological, computer, and social sciences are envisaged for integrating human sensing and behavioural mechanisms into the framework. Expanding opportunities of online communities complement the fundamental value of on-site surveying and indigenous knowledge. This work is promoted by the Citizens AND HYdrology (CANDHY) Working Group established by the International Association of Hydrological Sciences (IAHS)

Tetti verdi multistrato per lo sviluppo sostenibile di città resilienti: quattro casi studio italiani

Negli ultimi anni le inondazioni in ambito urbano sono state sempre più frequenti, provocando notevoli danni sia livello sociale che a livello economico. Questo fenomeno è in parte determinato da un aumento di urbanizzazione causato dalla crescita della popolazione, che tende sempre più a spostarsi dalle zone rurali alle aree urbane, che si espandono molto velocemente, spesso con infrastrutture idrauliche inadeguate. Inoltre, a causa di cambiamenti climatici, soprattutto nelle aree mediterranee, si può osservare un aumento di lunghi periodi di siccità, intervallati da piogge di breve durata, ma di sempre più forte intensità e frequenza. La presenza di questi fenomeni di pioggia intensa, in un ambiente altamente urbanizzato, determina un forte rischio di inondazione urbana. I tetti verdi, detti anche tetti giardino, sono stati ampiamente studiati come possibile soluzione di ingegneria naturalistica per ridurre il deflusso superficiale generato dalla presenza di tetti, trattenendo una frazione della precipitazione nello strato di terreno. Oltre alla significativa capacità di mitigazione del deflusso urbano, i tetti verdi presentano molteplici vantaggi in diversi ambiti: per esempio la presenza di queste strutture garantisce una riduzione della temperatura media dell’ambiente circostante, riducendo così l’effetto di isola di calore, che caratterizza le grandi città moderne. I tetti verdi, inoltre, garantiscono un isolamento termico per gli edifici sottostanti, favorendo il risparmio di energia per il funzionamento di impianti di climatizzazione e riscaldamento. Da un punto di vista ecologico, i tetti verdi riproducono parzialmente un ambiente naturale: assorbono CO2 e attraggono diverse specie di insetti e piccoli animali, facilitando così l’aumento della biodiversità. Infine, aumentano il valore estetico della città e possono essere utilizzate per attività ricreative, migliorando il benessere della comunità. Tra le varie tipologie di tetti verdi, quelli multistrato presentano uno strato aggiuntivo che permette di raccogliere l’acqua che percola dallo strato di terreno, stoccarla e utilizzarla in un secondo momento per diversi usi in cui non viene richiesta acqua potabile (come ad esempio l’irrigazione di giardini domestici o il lavaggio delle strade). Il presente lavoro illustra i risultati preliminari del progetto “the Polder Roof field lab”, nell’ambito del quale alcuni prototipi di tetti verdi multistrato proposti dalla compagnia olandese MetroPolder Company sono stati installati in 4 città italiane (Fig.1, Cagliari, Palermo, Perugia e Viterbo) al fine di valutare le potenzialità di questa “nature-based solution” in un clima Mediterraneo, soprattutto in termini di riduzione del deflusso superficiale durante eventi intensi di pioggia e di isolamento termico per l’edificio sottostante.Nello specifico, questo contributo ha, dunque, l’obiettivo di presentare le caratteristiche dei quattro casi studio, discutendo, sulla base dei risultati preliminari, le possibili linee di ricerca future. Le analisi preliminari, condotte studiando le misure di deflusso e di temperatura durante il periodo invernale da dicembre 2020 a marzo 2021, sottolineano l’elevata capacità di ritenzione durante eventi di pioggia intensi e la capacità di mitigazione dell’escursione termica giornaliera ottenibili con l’utilizzo di queste tecnologie

The Baryon Oscillation Spectroscopic Survey of SDSS-III

The Baryon Oscillation Spectroscopic Survey (BOSS) is designed to measure the scale of baryon acoustic oscillations (BAO) in the clustering of matter over a larger volume than the combined efforts of all previous spectroscopic surveys of large scale structure. BOSS uses 1.5 million luminous galaxies as faint as i=19.9 over 10,000 square degrees to measure BAO to redshifts z<0.7. Observations of neutral hydrogen in the Lyman alpha forest in more than 150,000 quasar spectra (g<22) will constrain BAO over the redshift range 2.15<z<3.5. Early results from BOSS include the first detection of the large-scale three-dimensional clustering of the Lyman alpha forest and a strong detection from the Data Release 9 data set of the BAO in the clustering of massive galaxies at an effective redshift z = 0.57. We project that BOSS will yield measurements of the angular diameter distance D_A to an accuracy of 1.0% at redshifts z=0.3 and z=0.57 and measurements of H(z) to 1.8% and 1.7% at the same redshifts. Forecasts for Lyman alpha forest constraints predict a measurement of an overall dilation factor that scales the highly degenerate D_A(z) and H^{-1}(z) parameters to an accuracy of 1.9% at z~2.5 when the survey is complete. Here, we provide an overview of the selection of spectroscopic targets, planning of observations, and analysis of data and data quality of BOSS.Comment: 49 pages, 16 figures, accepted by A

A catalogue of structural and morphological measurements for DES Y1

We present a structural and morphological catalogue for 45 million objects selected from the first year data of the Dark Energy Survey (DES). Single Sersic fits and non-parametric ´ measurements are produced for g, r, and i filters. The parameters from the best-fitting Sersic ´ model (total magnitude, half-light radius, Sersic index, axis ratio, and position angle) are mea- ´ sured with GALFIT; the non-parametric coefficients (concentration, asymmetry, clumpiness, Gini, M20) are provided using the Zurich Estimator of Structural Types (ZEST+). To study the statistical uncertainties, we consider a sample of state-of-the-art image simulations with a realistic distribution in the input parameter space and then process and analyse them as we do with real data: this enables us to quantify the observational biases due to PSF blurring and magnitude effects and correct the measurements as a function of magnitude, galaxy size, Sersic ´ index (concentration for the analysis of the non-parametric measurements) and ellipticity. We present the largest structural catalogue to date: we find that accurate and complete measurements for all the structural parameters are typically obtained for galaxies with SEXTRACTOR MAG AUTO I ≤ 21. Indeed, the parameters in the filters i and r can be overall well recovered up to MAG AUTO ≤ 21.5, corresponding to a fitting completeness of ∼90 per cent below this threshold, for a total of 25 million galaxies. The combination of parametric and non-parametric structural measurements makes this catalogue an important instrument to explore and understand how galaxies form and evolve. The catalogue described in this paper will be publicly released alongside the DES collaboration Y1 cosmology data products at the following URL: https://des.ncsa.illinois.edu/releases

The Baryon Oscillation Spectroscopic Survey of SDSS-III

The Baryon Oscillation Spectroscopic Survey (BOSS) is designed to measure the scale of baryon acoustic oscillations (BAO) in the clustering of matter over a larger volume than the combined efforts of all previous spectroscopic surveys of large-scale structure. BOSS uses 1.5 million luminous galaxies as faint as i = 19.9 over 10,000 deg(2) to measure BAO to redshifts z < 0.7. Observations of neutral hydrogen in the Ly alpha forest in more than 150,000 quasar spectra (g < 22) will constrain BAO over the redshift range 2.15 < z < 3.5. Early results from BOSS include the first detection of the large-scale three-dimensional clustering of the Ly alpha forest and a strong detection from the Data Release 9 data set of the BAO in the clustering of massive galaxies at an effective redshift z = 0.57. We project that BOSS will yield measurements of the angular diameter distance d(A) to an accuracy of 1.0% at redshifts z = 0.3 and z = 0.57 and measurements of H(z) to 1.8% and 1.7% at the same redshifts. Forecasts for Ly alpha forest constraints predict a measurement of an overall dilation factor that scales the highly degenerate D-A(z) and H-1(z) parameters to an accuracy of 1.9% at z similar to 2.5 when the survey is complete. Here, we provide an overview of the selection of spectroscopic targets, planning of observations, and analysis of data and data quality of BOSS

The Eleventh and Twelfth Data Releases of the Sloan Digital Sky Survey: Final Data from SDSS-III

The third generation of the Sloan Digital Sky Survey (SDSS-III) took data from 2008 to 2014 using the original SDSS wide-field imager, the original and an upgraded multi-object fiber-fed optical spectrograph, a new near-infrared high-resolution spectrograph, and a novel optical interferometer. All of the data from SDSS-III are now made public. In particular, this paper describes Data Release 11 (DR11) including all data acquired through 2013 July, and Data Release 12 (DR12) adding data acquired through 2014 July (including all data included in previous data releases), marking the end of SDSS-III observing. Relative to our previous public release (DR10), DR12 adds one million new spectra of galaxies and quasars from the Baryon Oscillation Spectroscopic Survey (BOSS) over an additional 3000 deg2 of sky, more than triples the number of H-band spectra of stars as part of the Apache Point Observatory (APO) Galactic Evolution Experiment (APOGEE), and includes repeated accurate radial velocity measurements of 5500 stars from the Multi-object APO Radial Velocity Exoplanet Large-area Survey (MARVELS). The APOGEE outputs now include the measured abundances of 15 different elements for each star. In total, SDSS-III added 5200 deg2 of ugriz imaging; 155,520 spectra of 138,099 stars as part of the Sloan Exploration of Galactic Understanding and Evolution 2 (SEGUE-2) survey; 2,497,484 BOSS spectra of 1,372,737 galaxies, 294,512 quasars, and 247,216 stars over 9376 deg2; 618,080 APOGEE spectra of 156,593 stars; and 197,040 MARVELS spectra of 5513 stars. Since its first light in 1998, SDSS has imaged over 1/3 of the Celestial sphere in five bands and obtained over five million astronomical spectra. \ua9 2015. The American Astronomical Society

Supplement: "Localization and broadband follow-up of the gravitational-wave transient GW150914" (2016, ApJL, 826, L13)

This Supplement provides supporting material for Abbott et al. (2016a). We briefly summarize past electromagnetic (EM) follow-up efforts as well as the organization and policy of the current EM follow-up program. We compare the four probability sky maps produced for the gravitational-wave transient GW150914, and provide additional details of the EM follow-up observations that were performed in the different bands