Veza između granulometrijske krive i hidrauličkih karakteristika nezasićenog zemljišta zasnovana na teoriji (multi)fraktala

APSTRAKT: Za simulaciju tečenja kroz nezasićenu poroznu sredinu neophodno je poznavanje osnovnih hidrauličkih karakteristika tla poput krive vlažnosti i krive vodoprovodljivosti. Veza između vlažnosti / vodoprovodljivosti i kapilarnog potencijala u nezasićenoj poroznoj sredini najčešće se opisuje analitičkim funkcijama sa nekoliko empirijskih parametara čije se vrednosti određuju kalibracijom modela infiltracije. Kako bi model davao pouzdane rezultate za različite tipove zemljišta, umesto empirijskih potrebno je koristiti funkcije sa fizički zasnovanim parametrima, što je predmet istraživanja u ovom radu. Polazeći od pretpostavke da način pakovanja zrna u zemljištu određuje zastupljenost različitih veličina pora što direktno utiče na vlažnost i vodoprovodljivost tla, izvesno je da postoji veza između granulometrijske krive zemljišta i njegovih hidrauličlih karakteristika u nezasićenim uslovima. Koristeći teoriju multifraktala, koja predstavlja statistički alat za opisivanje heterogenosti, razvijen je analitički, fizički zasnovan model granulometrijske krive. U slučaju krive raspodele veličina pora, pomenuti multifraktalni model se svodi na jednostavniji fraktalni koji se dalje koristi za izvođenje novih fizički zasnovanih funkcija vlažnosti i vodoprovodljivosti. Razvijene (multi)fraktalne funkcije granulometrijske krive i nezasićenih hidrauličkih karakteristika poređeni su sa eksperimentalnim podacima različitih tipova zemljišta, pri čemu su dobijena veoma dobra slaganja. Time je potvrđena jasna fizička veza između prethodno navedenih karakteristika tla, što se na dalje može koristiti za bolju procenu hidrauličkih svojstava zemljišta i pouzdaniju simulaciju tečenja kroz nezasićenu poroznu sredinu

High resolution radar rainfall for urban pluvial flood management: Lessons learnt from 10 pilots in North-West Europe within the RainGain project

ABSTRACT Precipitation and catchment information needs to be available at high resolution to reliably predict hydrological response and potential flooding in urban catchments. While recent advances have been made in weather radar technology and availability of DTM for urban flood modelling, the question is whether these are sufficient to provide reliable predictions for urban pluvial flood control. The RainGain project (EU-Interreg IVB NWE) brings together radar technologists and hydrologists to explore a variety of rainfall sensors, rainfall data processing techniques and hydrodynamic models for the purpose of fine-scale representation of urban hydrodynamic response. High resolution rainfall and hydrodynamic modelling techniques are implemented at 10 different pilot locations under real-life conditions. In this paper, the pilot locations, configurations of rainfall sensors (including X-Band and C-Band radars, rain gauges and disdrometers) and modelling approaches adopted within the RainGain project are introduced. Initial results are presented of hydrodynamic modelling using high resolution precipitation inputs from dual-polarisation X-band radar, followed by a discussion of differences in hydrodynamic response behaviour between the pilots

French Roadmap for complex Systems 2008-2009

This second issue of the French Complex Systems Roadmap is the outcome of the Entretiens de Cargese 2008, an interdisciplinary brainstorming session organized over one week in 2008, jointly by RNSC, ISC-PIF and IXXI. It capitalizes on the first roadmap and gathers contributions of more than 70 scientists from major French institutions. The aim of this roadmap is to foster the coordination of the complex systems community on focused topics and questions, as well as to present contributions and challenges in the complex systems sciences and complexity science to the public, political and industrial spheres

Assessing communication as one of the drivers of urban resilience to weather extremes

International audienceThe quality of science and technology communication has become more challenging due to the fact that access to information has hugely increased in terms of variety and quantity. This is a consequence of different factors, among others the development of public relations by research institutes and the pervasive role of digital media (Bucchi 2013; Trench 2008). A key question is how can we objectively assess science and technology communication? Relatively few studies have been dedicated to the definition of pertinent indicators and standards (Neresini and Bucchi 2011). This research aims to understand how communication strategies, addressed to the general public, can opti-mise the impact of research findings in hydrology for resilient cities and how this can be assessed. Indeed urban resilience to extreme weather events relies both on engineering solutions and increased awareness of urban communities as it was highlighted by the FP7 SMARTesT project and the experiences carried out in the framework of TOMACS (Tokyo Metropolitan Area Convective Studies for Resilient Cities) and CASA (Engineering Research Center for Collaborative Adaptative Sensing of the Atmosphere, supported by the U.S. National Science Foundation). Communication assessment should be included in an alternative approach to evaluate urban resilience to weather extremes. Various qualitative and quantitative methods to monitor communication exist. According to this study, resilience indicators shouldn't only consider communication infrastructures but should also assess communication processes and their interactions with other resilience drivers; furthermore quantitative variables are considered as particularly relevant. Last, but not least, interesting inputs are provided by those case studies that exploit resilience assessment campaigns as an opportunity to practice participatory communication. This research is being led in the framework of the Chair Hydrology for Resilient Cities, co-founded by Veolia, Fondation des Ponts, and École des Ponts ParisTech

Développement de techniques de prévision de pluies basées sur les propriétés multi-échelles des données radar et satellites

MARNE-LA-VALLEE-ENPC-BIBL. (774682303) / SudocSudocFranceF

Joint multifractal analysis : further developments and implementation on rainfall data

International audienc

Generating a missing half of multifractal fields with a blunt extension of discrete cascades

International audienceGenerating a missing half of multifractal fields with a blunt extension of discrete cascades Despite strong limitations, discrete random multiplicative cascades are often used to address scale issues which are ubiquitous in geosciences. A blunt extension based on the parsimonious framework of Universal Multifractals has recently been suggested. It preserves its simplicity and intuitiveness while overcoming its non-stationarity features. It relies on smoothing through a geometrical moving average the increments at each cascade step. Here a space-time extension is suggested. Theoretically expected multifractal behaviour is retrieved on numerical simulations for typical rainfall parameters. A new algorithm to generate the missing half of multifractal fields in 1D, 2D or 3D is developed and tested on rainfall fields and numerical simulations. It basically consists in stochastically generating half of the increments and deterministically iteratively reconstructing the others to retrieve the available data and ensure a smooth transition with the unknown portion while preserving the multifractal behaviour. Potential applications to nowcasting of hydro-meteorological extremes are discussed