Présentation au sujet: "The evaluation of attitudes towards alluvial deposits and floods"— Transcription de la présentation:
1 The evaluation of attitudes towards alluvial deposits and floods Evaluer les attitudesà l'égard des dépôts alluviaux et des inondationsThe evaluation of attitudestowards alluvial deposits and floodsHugard de la Tour, Inondation à Chamouny (1855)
2 L’Isère (Cliché : Philippe Belleudy) « (…) des plages de sable, des archipels de galets bordent son lit principal, pareil à quelque grand miroir qui magnifie ce qui vient s’y refléter ».Bergounioux« Flot, requiers pour ta marche un galet au sol terneQu’à vernir en ta source au premier pas tu perdes ».F. Ponge, Le parti-pris des choses.
3 Content 1. The attitudes towards riverscapes 2. Perception of braided river landscapes3. Floods in local newspapers
7 Plan 1. The attitudes towards riverscapes 2. Perception of braided river landscapes3. Floods in local newspapers
8 Due to the present degree of environmental alteration along the Magra River, the need for sustainable sediment management is urgent. It is therefore important:to understand how local stakeholdersperceive a river channel that is richin gravels,to better evaluate whether or not theywill support proposed braided channelrestoration projects .
10 Postulat: The visual features of riverscapes have an influence on the evaluation and behaviour of observors.Ten photographs of the river were shown to each participant depicting:different proportions of water, vegetation, and mineral bar,and different sizes of gravels.
11 Five distinct groups of participants (total n=127) Students attending college near the Magra River,Students attending college far-away from the river,People with a scientific understanding of river ecosystem function,Local river managers working for the government watershed authority,- and other Magra River users.
12 The evaluation of riverscape characteristics Three quantitative variables: Aesthetic quality Beneficial uses of the river Need for active river managementUnpleasant PleasantVisual analogic scale (VAS)
13 The evaluation of riverscape characteristics Two categorical variables:the categories of uses to which the riverscape shown would be most suited1 – no activity;2 – fishing;3 – swimming;4 – navigation,5 – relaxation,6 – gravel mining,7 – hydroelectric generation,8 – domestic/agricultural water withdrawal,9 – nature conservation) la caractérisation de l’intervention envisagée
14 The evaluation of riverscape characteristics Two categorical variables:the categories of uses to which the riverscape shown would be most suited;the appropriate types of management activities for each riverscape:1 – no management,2 – improved landscaping,3 – wildlife protection,4 – bank stabilization,5 – channel cleaning,6 – engineered structures
15 Surface area of each photograph (A through J) occupied by water, vegetation, and sediments, and the visually-assessed grain size classes of the sediment shown (0 - no sediment, 1 - gravel, 2 - pebbles, and 3 - large boulders)PhotographWater(%)VegetationSedimentGrain sizeclassesA42.2545.990.53B8.0252.411C21.935.3534.22D26.2040.9123.802E1.0737.1761.503F24.3310.7033.96G60.1615.512.14H24.6039.57I12.0328.6132.62J59.369.8911.76
16 Correlation Matrix (calculated with average Bravais-Pearson coefficients) for the survey response variables (aesthetic value, beneficial uses, and needs for management action) and the landscape components (area occupied by water, vegetation, and mineral bar). Significant values with p < 0.05 are in bold typeAestheticsUsesManagementWaterVegetationMineral Bar0.964-0.9040.7590.155-0.702-0.9440.8680.022-0.805-0.8990.0690.827-0.101-0.916-0.121
23 Introduce infrastructures List of infrastructures Flooding / variable Type of damages expectedNormal / flooded flowsHistorical photos, substantial gravel or notChosing photos / drive perceptionShow real risky versus no risk situationsVery nice picturesSmall numbers of photos contrasted level of gravels in natural riverscapesand then photos with impliedgravel associated risk and then a second set of photos like the first (hyp. effect of phot order)Very much related to the time since flow events (memory effect).Two different places one with a recent big flood, one without.Use expert jugement as a ref.Risk? Riverscape with eroding banks (natural, with a house), vulnerable infrastrcuture (culver), bridge (public interest), house (private interest). Identification / risksTriplate photos / braided rivers with fine sediment implicting aggradation, gravel bar (implication of potential instability), cobble / paved channels.How people perceive risk through sediment process (torrential fans – may think house at risk far from the site)QuestionsDistance to the closest riverIf this house is sell, will you buy it? Will you be safe in this house?Would you like to live there?Divergence of the managers? Do you simply survey citizens? Other groups?Natural or man-influenced?More information that you want and real questions.3 questions? Safe/dangerous,Aerial photos. Where would you built your house. Where would it be risky to live? Oblique photos + gravel bars / far
24 Intra-group variability of the scores attributed to each of the survey response variables
25 Categorization of beneficial uses recommended by survey respondents for each photograph
26 Categorization of management actions recommended for each riverscape photograph
27 Elements of discussion In terms of riverscape perception:The influence of water on landscape evaluationWhat is natural is not always aestheticsThe preference for maintained nature (rather than wild and regulated nature)The role of familiarityA difference between local/expert knowledgesIn terms of restoration project:Consider the archetypes that influence public as well as decision makersPromote campaigns of environmental education to explain the objectives
28 Content 1. The attitudes towards riverscapes 2. Perception of braided river landscapes3. Floods in local newspapers
33 Presentation of each article Statistics with RTextual data analysis : ALCESTE and TXMGIS : places quoted (communes, rivers, catchment)ArticleNewspaperYearSeasonNatureWriterEvocated stakeholdersUsesPlaces1…
34 Stakeholders form a system characterized by different uses stakeholders quoted40% users31% politicians21% riverside peopleuses of the river51% production42% protection
35 Stakeholders form a system characterized by different uses productionquoted : farmers and riverside peoplenatural condition brutality and damagesprotectionquoted : quarrymenprevention actsleisure activitiesanglers
36 Crisis and memoryHydrological extremes and article distribution4 years without articlesA mean of 5 articles per yearthe role of floods and the maximum of articlesWhat is the influence of the season?autumn and springwinter and summercrisis and management1994, 2003 et 2005
37 The crisis and its temporal management 2 groups : the crisis and its immediate management (physical and temporal management) / the resilience of the system (to prevent a new crisis from happening)
38 The most quoted- dams, dikes … and others works of civil engineering- restoration and maintenanceA spatial variabilityA temporal variability
39 Two different communities in a same basin A spatial variabilityEach subcatchement focuses on its subcatchmentTwo different communities in a same basinWhich integrated management is then possible ?
40 The water territory (Ghiotti) and the risk territory Identify the risk placesAn archipelagic geographySome discontinuities
41 The Drôme as a management model Versus the floods as a crisis… The time of management and political decisions (PPRi)Two subcatchment (upstream and downstream) because ofdifferent playorsdifferent uses of the rivera political choice but some local adaptations…Different placesthe alea is not the same everywherethe urban communes are more quoted but …a specific place the Ramières…
42 A diachronic approachThe repetition of alea and the more quoted placesAn environmental disruptionthe difficulty of fixing the flood causessome stakeholders with different aimsa system resilience : which management of the crisis?memory : exemplary floods, memory lapses, places which are forgotten
43 La presse locale, une bonne source d'information ? A) Des biais importants : une échelle territoriale restreinte et parfois peu significative (Caron et Torre, 2005) la diversité du métier de journalistes (Bucher et Strauss, 1961 ; Neveu, 2004 ; Ruellan,2005) l'incomplétude de l'information (Vicard et al., 2005) et la partialité du choix desévénements (Caron et Torre, 2005) les filtres culturel et idéologique, ainsi que la ligne éditoriale (Grawitz, 2001; Allard,B) Les atouts : une diffusion considérable et la quasi-exclusivité de l'information locale (Torreet al., 2005) le reflet des attentes du public (Bourdieu, 1966 ; Grawitz, 2001) un support pour les débats et une source pour l'étude des conflits (Caron et Torre,2005 ; Torre et al., 2005) des archives propices à l'analyse d'événements (Sautter, 1994 ; SPOTTER, 2005),mais aussi à l'étude diachronique des inondations et des représentations etpolitiques publiques associées (Allard, 2005)
44 Perspectives A) Floods in newspapers (Isère basin) Drome catchment: 100 articles in local newspapers (Emeline Comby)Isere catchment through Le Petit Dauphinois and Le Dauphiné Libéré from 1880 to 2010 (Silvia Flaminio, Master 1)B) 20/30 entretiens semi-directifs sur l’Isère (risque inondation)experts, managers, practitioners, local decision-makersC) The perception of gravel bars by public and expertWhich variables in the set of photographs?Which evaluative features?Which questions about floods to better understandthe spatial and temporal framework of riverinelandowners?Le Crestois, 1984