The evaluation of attitudes towards alluvial deposits and floods

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 attitudes à l'égard des dépôts alluviaux et des inondations The evaluation of attitudes towards alluvial deposits and floods Hugard 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 terne Qu’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 landscapes 3. Floods in local newspapers

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7 Plan 1. The attitudes towards riverscapes
2. Perception of braided river landscapes 3. 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 stakeholders perceive a river channel that is rich in gravels, to better evaluate whether or not they will support proposed braided channel restoration projects .

9 Expert Psychophysical Cognitive Experiential
Subject type Trained observer Respondent respondent Participant observer Ignitiating Landscape features Artistic, ecological and development principes Perceived physical features (feature, clarity, depth…) Quality and preference (beauty, danger…) Everyday experience (familiarity, sociability…) Data collect Structural analysis Questionnaire Field Photo., diapo. Video Interviews Auto. Photo. Literature and art. References Griselin, 2004 Huang, 2000 Cossin, 1999 Mosley, 1989 Daniel, 1983 Campbell, 2002 Lekagul, 2002 Faulkner, 2001 Smith, 1995 Asakawa, 2004 Eisler, 2003 Ryan, 1998 Gregory, 1992 Brown, 1991 Nunneri, 2004 Dakin, 2003 Yamashita, 2002 Chételat, 2001 Michelin, 1998

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 management Unpleasant Pleasant Visual analogic scale (VAS)

13 The evaluation of riverscape characteristics
Two categorical variables: the categories of uses to which the riverscape shown would be most suited 1 – 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) Photograph Water (%) Vegetation Sediment Grain size classes A 42.25 45.99 0.53 B 8.02 52.41 1 C 21.93 5.35 34.22 D 26.20 40.91 23.80 2 E 1.07 37.17 61.50 3 F 24.33 10.70 33.96 G 60.16 15.51 2.14 H 24.60 39.57 I 12.03 28.61 32.62 J 59.36 9.89 11.76

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 type Aesthetics Uses Management Water Vegetation Mineral Bar 0.964 -0.904 0.759 0.155 -0.702 -0.944 0.868 0.022 -0.805 -0.899 0.069 0.827 -0.101 -0.916 -0.121

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23 Introduce infrastructures List of infrastructures Flooding / variable
Type of damages expected Normal / flooded flows Historical photos, substantial gravel or not Chosing photos / drive perception Show real risky versus no risk situations Very nice pictures Small 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 / risks Triplate 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) Questions Distance to the closest river If 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 evaluation What is natural is not always aesthetics The preference for maintained nature (rather than wild and regulated nature) The role of familiarity A difference between local/expert knowledges In terms of restoration project: Consider the archetypes that influence public as well as decision makers Promote campaigns of environmental education to explain the objectives

28 Content 1. The attitudes towards riverscapes
2. Perception of braided river landscapes 3. Floods in local newspapers

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31 140 articles : 68 in Le Crestois 72 in Le JDD Le Crestois Le JDD 1981
CP 168/19 CP 176D/8 2008 CP 168/51 CP 168/52 CP 176D/26 140 articles : 68 in Le Crestois 72 in Le JDD

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33 Presentation of each article
Statistics with R Textual data analysis : ALCESTE and TXM GIS : places quoted (communes, rivers, catchment) Article Newspaper Year Season Nature Writer Evocated stakeholders Uses Places 1 …

34 Stakeholders form a system characterized by different uses
stakeholders quoted 40% users 31% politicians 21% riverside people uses of the river 51% production 42% protection

35 Stakeholders form a system characterized by different uses
production quoted : farmers and riverside people natural condition brutality and damages protection quoted : quarrymen prevention acts leisure activities anglers

36 Crisis and memory Hydrological extremes and article distribution 4 years without articles A mean of 5 articles per year the role of floods and the maximum of articles What is the influence of the season? autumn and spring winter and summer crisis and management 1994, 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 maintenance A spatial variability A temporal variability

39 Two different communities in a same basin
A spatial variability Each subcatchement focuses on its subcatchment Two different communities in a same basin Which integrated management is then possible ?

40 The water territory (Ghiotti) and the risk territory
Identify the risk places An archipelagic geography Some 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 of different playors different uses of the river a political choice but some local adaptations… Different places the alea is not the same everywhere the urban communes are more quoted but … a specific place the Ramières…

42 A diachronic approach The repetition of alea and the more quoted places An environmental disruption the difficulty of fixing the flood causes some stakeholders with different aims a 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 des événements (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 (Torre et 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 et politiques 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-makers C) The perception of gravel bars by public and expert Which variables in the set of photographs? Which evaluative features? Which questions about floods to better understand the spatial and temporal framework of riverine landowners? Le Crestois, 1984

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