Assessment of the susceptibility of roads to flooding based on geographical information – test in a flash flood prone area (the Gard region, France)

International audienceIn flash flood prone areas, roads are often the first assets affected by inundations which make rescue operations difficult and represent a major threat to lives: almost half of the victims are car passengers trapped by floods. In the past years, the Gard region (France) road management services have realized an extensive inventory of the known road sub- mersions that occurred during the last 40 years. This inven- tory provided an unique opportunity to analyse the causes of road flooding in an area frequently affected by severe flash floods. It will be used to develop a road submersion suscep- tibility rating method, representing the first element of a road warning system.This paper presents the results of the analysis of this data set. A companion paper will show how the proposed road susceptibility rating method can be combined with dis- tributed rainfall-runoff simulations to provide accurate road submersion risk maps.The very low correlation between the various possible ex- planatory factors and the susceptibility to flooding measured by the number of past observed submersions implied the use of particular statistical analysis methods based on the general principals of the discriminant analysis.The analysis led to the definition of four susceptibility classes for river crossing road sections. Validation tests con- firmed that this classification is robust, at least in the con- sidered area. One major outcome of the analysis is that the susceptibility to flooding is rather linked to the location of the road sections than to the size of the river crossing structure (bridge or culvert)

Flavour compounds of clones from different grape varieties

The selection of highly productive and characteristic clones is essential for the maintenance and improvement of the viticultural and commercially valuable qualities of certain grape varieties. In the future, this very difficult and time consuming selection of adapted clones will be supplemented with more precise analytical techniques. In this regard, GC analysis will be most valuable. Analytically, German white wines can be divided into three groups by the content of only a few monoterpene compounds ('terpene profiles'): 'Riesling', 'Muscat' and 'Sylvaner' or 'Weissburgunder' types. Furthermore, the use of linear discriminant analysis on some components allows the differentiation within types (e. g. for 'Riesling'-tpye: Riesling, Müller-Thurgau, Bacchus, Kerner, Ehrenfelser, Scheurebe). Till now no significant differentiation could be made from flavour compounds of Riesling clones, although clear differences can be perceived between wines from Traminer clones. Wines with a low sensory appraisal typically have a low content of monoterpene compounds. Differences can also be recognized in the aroma profiles of Chardonnay clones, allowing an analytical differentiation between aromatic and non-aromatic types. Certain clones, however, show differing compositions of flavour compounds when grown in different areas (clones with an 'unstable' aromatic character). Also during ripening of the berries, differences occur within individual Chardonnay clones, resulting in a few clones having recognizable ripening curves for monoterpene compounds

Aroma components of Galician Albariño, Loureira and Godello wines

Wines of the three most interesting Galician white grape varieties have been deeply analyzed for three aroma categories: the volatile compounds, except for monoterpenols, the monoterpenols and the bound forms. Many compounds showed significant differences between the wine groups, as proved by Tukey's test, e.g. for methanol, trans and cis 3-hexen-1-ols and relevant ratio, benzaldehyde and 4-vinylguaiacol in the first category, and for the most part of compounds of the other two categories. Loureira and most Albariño wines contain linalool and ho-trienol at a level of sensorial contribution. The relevant average terpene profiles show many similarities, especially for Albariño and particularly if considering the contents and relevant ratios of furan and pyran linalool oxide isomers, of ho-diendiols I and II and of geraniol. On the other hand differences could be stated for some compounds, mostly under the bound forms. Godello wines, with the poorest content of monoterpenols under both forms, are principally characterized by a marked level of bound benzaldehyde, with contemporary presence of a considerable average level of the free form. PCA data treatments on both monoterpenols and aglycons from the bound forms, showed a good separation among the groups as well a good homogeneity and varietal correspondence of the wines

Structural identification and presence of some p-menth-1-enediols in grape products

The present work aims at clearing the structure of some p-menthenediols, which are already known to be present in musts and wines as glycosides, referred to as isomers 1, 2 and 3. Isomers 2 and 3 correspond to cis-p-menth-1-ene-6,8-diol and p-menth-1-ene-7,8-diol; isomer 1, which is only found in traces, is probably identical with trans- p-menth-1-ene-6,8-diol. Their concentration is reported for both free and bound forms in musts from some varieties and compared with the alpha-terpineol and 2-exo-hydroxy-1,8-cineole concentrations. In general, the free forms were scarcely present; among the bound forms p-menth-1-ene-7,8-diol first and then cis-p-menth-1-ene-6,8-diol prevailed. Besides improvement of varietal classification, the compounds identified give evidence of allylic hydroxylase activity in grape berries

Methyl trans geranate and farnesoate as markers for Gewürztraminer grape skins and related distillates

Methyl ester of trans geranic and farnesoic acids, farnesol and two alpha-farnesene isomers are remarkable compounds in skins of mature grapes as well as in marc distillates of Traminer variety. Considerations about their level in both products of other floral varieties, like Yellow and Rose Muscats and Müller-Thurgau, as well as about their relationships with the main skin monoterpenols and other compounds, including two unidentified stereoisomeric sesquiterpenes present only in distillates, were discussed. Finally, results of PCA data treatments as for the distillates are show

A new 1,1,6-trimethyl-1,2-dihydronaphthalene (TDN) precursor isolated from Riesling grape products: Partial structure elucidation and possible reaction mechanism

A heteroside, which produces 1,1,6-trimethyl-1,2-dihydronaphthalene (TDN) by acid hydrolysis, was isolated from Riesling grapes by retention on Amberlite XAD-2 resin, followed by preparative TLC and HPLC techniques. It was partially identified by NMR spectroscopic procedures. The presence of a megastigm-4-en-9-one structure with an enol-ether function in the C4 position and a OH/OR function in the C6 position was ascertained. The sugar part should be constituted of two or three glucose moieties with the same NMR characteristics. The linkage of these moieties to the megastigmane structure in the C4 position and possibly also in the C6 position remains to be determined. The isolated conjugated form produced only a TDN-d4 isomer when reacted at 50 degrees C in D2O at different acid pH values. A possible reaction mechanism was proposed, considering the kinetics of TDN-d(4) formation during the hydrolysis of the raw glycosidic fraction from two differently aged Riesling wines at pH 2, and comparing it with the kinetics of TDN formation as well. The latter may correspond to the mechanism proposed by WINTERHALTER (1991). Thus, the presence of at least two different TDN precursors in grape products at different concentrations was proved

Bartlett pear unsaturated ethyl deconoates and C9 compounds among components characterizing cv. Catalan roxo grape marc distillates

Catalan roxo marc distillates contain compounds at an unusual level in a grape derivate. The most peculiar are several unsaturated ethyl decanoates typical of Bartlett pear distillates and derived from ethyl esters found in the grape skins, some of which partially modified in the stereoisomery probably by the fermentation process. Remarkable compounds are unbranched aliphatic C-9 compounds at different oxidation state as well as ethyl nonanoate. At sensorially interesting levels methyl and ethyl salicylate and ethyl cinnamate, monoterpenols typical of floral-like varieties, vitispiranes and 4-ethylguaiacol are detected. Methyl salicylate is found in the berry as free and bound compound as several monoterpenols

Methylanthranilate (''foxy taint'') concentrations of hybrid and Vitis vinifera wines

Research NoteMethylanthranilate, contributing to the typical hybrid/foxy taint of wines from American hybrids and wild vines, was also detected in white wines from Vitis vinifera varieties in concentrations up to 0.3 µg/l. In wines from newly bred fungus resistant cultivars methylanthranilate contents were found to be at the same low level, not exceeding the perception threshold of ca. 300 µg/l and therefore not negatively affecting the wine quality

2-Aminoacetophenon: Verursachende Komponente der ,untypischen Alterungsnote" (,Naphthalinton", ,Hybridton") bei Wein

Research Note2-aminoacetophenone: Causal component of 'untypical aging flavour' ('naphthalene note', 'hybrid note') of wineFrom wines (Vitis vinifera cvs Müller-Thurgau, Riesling, Silvaner) with an untypical aging note (also called 'naphthalene note' or 'hybrid note') 2-aminoacetophenone could be identified as the causal compound by GC-MS technique, after enrichment of the aroma constituents and fractionated separation of the extracts. This aroma compound known as 'foxy' smelling component of Labruscana grapes has not been found in V. vinifera evs up to now.

Nachweis und Bestimmung von 2-Aminoacetophenon in vergorenen Modelllösungen

Research NoteDurch zweidimensionale Gaschromatographie und unter Verwendung eines spezifischen Stickstoffdetektors (NPD) kann 2-Aminoacetophenon noch bis zu Gehalten von 20 ng/1 quantitativ bestimmt werden. In Weinen wurden bisher Gehalte von 20 ng/1 bis 2500 ng/1 nachgewiesen. In Gärversuchen mit synthetischen Nährlösungen wurde eine von der N-Quelle und der Zusammensetzung des Gärsubstrates abhängige Bildung von 2-Aminoacetophenon festgestellt; mit Tryptophan als einziger N-Quelle wurden die größten Mengen 2-Aminoacetophenon gebildet.  Determination of 2-aminoacetophenone in fermented model wine solutionsUsing twodimensional GC in combination with a nitrogen-specific detection, 2-aminoaceto-phenone can be determined quantitatively up to 20 ng/l. In wines concentrations between 20 and 2,500 ng/l could be found. In fermentation experiments with synthetic media a significant influence of the medium composition, especially the nitrogen source, is ascertained. In the case of tryptophane as N source the highest amount of 2-aminoacetophenone is synthesized