# Descriptions de la plage de dépôt

**Quelle(s) fonction(s) objective(s) :** la plage de dépôt possède un ouvrage de fermeture muni d'une grille à barres horizontales espacées de 0,5 m. Elle doit réguler le transport solide pour les crues de projet.

**Observations sur le terrain :** Bassin de la plage de dépôt constamment rempli pour toutes crues ; flottants présents.

<table><thead><tr><th colspan="3">Analyses des Modes de Défaillances et de leurs Effets (AMDE) :</th><th colspan="2">Éléments de recommandations proposés</th></tr><tr><th rowspan="2">Modes de défaillance (MD)</th><th colspan="2">Causes potentielles associées</th><th rowspan="2">Effets secondaires néfastes engendrés</th><th rowspan="2">Solutions d'adaptation envisageables</th></tr><tr><th>Premier plan</th><th>Second plan</th></tr></thead><tbody><tr><td colspan="5" style="background-color: #cccccc; font-weight: bold; text-align: left;">OUVRAGE DE FERMETURE</td></tr><tr><td>Colmatage de l'ouvrage par les blocs et les flottants transportés par les écoulements</td><td>- Ouvertures du barrage trop petites ou trop nombreuses</td><td>- Les flottants n'ont pas été considéré lors de la conception de l'ouvrage</td><td>- L'ouvrage de fermeture arrête trop de matériaux, et ce pour toutes les crues<br/>- Le bassin se remplie trop fréquemment</td><td rowspan="2">→ Agrandir les ouvertures de l'ouvrage de fermeture : espacement plus large des barres de la grille ou transformation de l'ouvrage grille en ouvrage fente ou pertuis</td></tr><tr><td colspan="5" style="background-color: #cccccc; font-weight: bold; text-align: left;">BASSIN</td></tr><tr><td>Remplissage très fréquent du bassin pour des crues courantes</td><td>- Curage artificiel peu fréquent ou absent<br/>- Colmatage du barrage par les matériaux (blocs et flottants)</td><td>- Matériaux non valorisables<br/>- Ouvertures de l'ouvrage de sortie trop petites</td><td>- La plage de dépôt est trop souvent remplie et retient trop de matériaux par rapport aux conditions d'écoulement à l'aval<br/>- Déficit sédimentaire à l'aval générant une incision du lit à l'aval</td><td></td></tr></tbody></table>

(Exemple utilisé).
Annexe 14. Guide international "Conception et maintenance des ouvrages filtrants" – Sommaire en v0
# Design guidelines of sediment and large wood traps

Working document V0.1: Layout definition

Released date: July 2017

Coordination: Piton. G., V. D'Agostino, J. Hubl, S.
Carladous

Contribution: Piton G.

## Edition information

<table><caption>Tableau 1 : Versions</caption><thead><tr><td>Version</td><td>Edition date</td><td>Modification</td><td>Written by</td><td>Controlled by</td></tr></thead><tbody><tr><td>0.1</td><td>July 2017</td><td>First edition of the layout and template</td><td>G. PITON</td><td></td></tr><tr><td></td><td></td><td></td><td></td><td></td></tr></tbody></table>

I can give you permission to modify directly this document, please ask me. Object

The present note is the first version of the guidelines' layout. It simply represents IRSTEA's vision and should be improved, eventually on every chapter, by the advices of all contributors.

Lead contributors and contributors of each chapter are identified based on the EGU 2017 meeting and following email discussions. The list is far from being fixed and it will be updated depending on the willingness to participate and investment of each partner.

A template of chapter sections and subsection, table, figures and references is provided at the end of the note. A simple way to manage citations and references using free software (Jabref) is proposed. Another simple way using footnote is proposed for those who would not want to use Jabref.
After finding a consensus on the book layout, IRSTEA will split it in each chapter that will be written by their contributors under the supervision of the coordinator. A review process will be done in a second step as well as a harmonization step.

The setting up of a COST project to fund future meeting and dissemination actions is in progress in parallel.

**Please try to read this short layout and propose improvement by September 15th.**

# Lay out

**Edition information** 1

I can give you permission to modify directly this document, please ask me. Please make sure to comment the note with the "suggesting" mode ON and not in "editing" mode (button at the top right of the screen). **_Errur ! Signet non défini._**

**Object** 1

**Lay out** 2

**Introduction** 4

## 1 Task 1: Scenarios, objectives & design inputs (~45 pages) 5

1.1 Necessity of an integrated view and full catchment study 5

1.2 Estimation of upstream catchment conditions 5

1.2.1 Historical, geomorphological and hydrology/hydraulics approaches 5

1.2.2 Effects of upstream torrent control works 5

1.2.3 Type of phenomena 5

1.2.4 Liquid and solid hydrographs 5

1.2.5 Material size 5

1.2.5.1 Boulders 5

1.2.5.2 Sediment 5

1.2.5.3 Large wood 6

1.3 Assessment of downstream problem(s) 6

1.3.1 Boulder-related problems 6

1.3.2 Large wood-related problem 6

1.3.3 Excess in instantaneous discharge 6

1.3.4 Excess in supplied volume 6

1.3.5 Functions of other torrent control works 6

1.3 Structure objectives 6

1.3.1 Definition of objectives and design input 6

1.3.2 Constraints analysis 7

1.3.3 Secondary effect analysis 7

1.3.4 Overloading and residual risk 7
## 2 Task 2: Procedure to define the structure function and shape (~10 pages) 8

2.1 Main types of traps 8

2.1.1 Location in the catchment 8

2.1.2 Position transversal or parallel 8

2.1.3 Type of barrier 8

2.2 Flow chart for the definition of the protection system 8

## 3 Task 3: Functional design 9

3.1 Dam functional design (~30 pages) 9

3.1.1 Trapping processes 9

3.1.2 Mechanical and hydraulic trapping approaches 9

3.1.3 Hydraulics 9

3.1.3.1 "Pure water" hydraulics 9

3.1.3.2 Debris flow hydraulics 9

3.1.3.3 Additional head losses 9

3.1.4 Low flow outlet 9

3.1.5 Spillway 9

3.1.6 Deposit height near the dam 10

3.1.7 Scouring 10

3.2 Basin functional design (~20 pages) 10

3.2.1 Shape 10

3.2.2 Deposition slope 10

3.2.3 Transversal profile and low flow channel 10

3.2.4 Lateral confinement 10

3.2.5 Inlet structure 10

## 4 Task 4: Architectural and structural design (~50 pages) 11

4.1. Building forms, materials, and landscape preservation 11

4.2. Dam body and wings structural design 11

4.2.1. Geotechnical analysis 11

4.2.2. Design based on limit states 11

4.2.3. Actions, loads, status, stress combinations 16

4.2.4. External stability supporting calculations 16

4.2.5. Internal stability supporting calculations 16

4.3. Structural design of metal parts 12

4.3.1. Products and choice criteria 16

4.3.2. Design of vertical bars 16

4.3.3. Design of horizontal bars 16

4.3.4. Design of inclined grills 16

4.4. Structural design of other components 12

4.4.1. Other components of the main dam 16

4.4.2. Upstream and downstream barriers 16

4.4.3. Lateral embankments protection 16

## 5 Task 5: Comprehensive technical sheets for all structure types' design (~10 pages/structure type) 14
<table><tbody><tr><td>5.1</td><td>Retention dams</td><td>14</td></tr><tr><td>5.1.1</td><td>Classical transversal traps</td><td>14</td></tr><tr><td>5.1.2</td><td>Parallel traps</td><td>14</td></tr><tr><td>5.2</td><td>Boulder traps / debris flow breakers</td><td>14</td></tr><tr><td>5.3</td><td>Woody debris traps</td><td>14</td></tr><tr><td>5.4</td><td>Dosing dams</td><td>14</td></tr><tr><td><b>6</b></td><td><b>Structure management</b></td><td><b>15</b></td></tr><tr><td>6.1</td><td>Monitoring</td><td>15</td></tr><tr><td>6.1.3</td><td>Civil engineering monitoring indicators</td><td>15</td></tr><tr><td>6.1.4</td><td>Geomorphic and filling monitoring indicators</td><td>15</td></tr><tr><td>6.2</td><td>Maintenance</td><td>15</td></tr><tr><td>6.2.1</td><td>Dredging operation triggering</td><td>15</td></tr><tr><td>6.2.2</td><td>Storage and final destination of dredged material</td><td>15</td></tr><tr><td>6.2.3</td><td>Structural maintenance</td><td>15</td></tr><tr><td>6.3</td><td>Life cycle management</td><td>16</td></tr><tr><td>6.3.1</td><td>Access</td><td>16</td></tr><tr><td>6.3.2</td><td>An adaptive design</td><td>16</td></tr><tr><td>6.3.3</td><td>Adaptation of existing traps</td><td>16</td></tr><tr><td>6.3.4</td><td>Global costs</td><td>16</td></tr><tr><td>6.4</td><td>Communicating about sediment and large wood trapping</td><td>16</td></tr><tr><td>6.4.1</td><td>Why trapping is sometimes not a good idea</td><td>16</td></tr><tr><td>6.4.2</td><td>Communication material for stakeholder</td><td>16</td></tr><tr><td><b>7</b></td><td><b>Task 7: Innovation of check dams: New methods, special challenges</b></td><td><b>16</b></td></tr><tr><td><b>References</b></td><td></td><td><b>17</b></td></tr><tr><td><b>8</b></td><td><b>Template of the work</b></td><td><b>18</b></td></tr><tr><td>8.1</td><td>Citation style</td><td>18</td></tr><tr><td>8.2</td><td>Styles list:</td><td>20</td></tr><tr><td><b>9</b></td><td><b>Title 1</b></td><td><b>20</b></td></tr><tr><td>9.1</td><td>Title 2</td><td>20</td></tr><tr><td>9.1.1</td><td>Title 3</td><td>20</td></tr><tr><td>9.1.1.1</td><td>Title 4</td><td>20</td></tr><tr><td>9.1.1.1.1</td><td>Title 5</td><td>20</td></tr><tr><td>A</td><td>Title 6</td><td>20</td></tr></tbody></table>

# Introduction

To do.
# 1 Task 1: Scenarios, objectives & design inputs (~45 pages)

COORDINATOR and contributors :

V. D'AGOSTINO, F. Comiti, J. Hubl, B. Mazzorana, T. Mizuyama, M. Moser, G. Piton, D. Rickenmann, V. Ruiz Villanueva

## 1.1 Necessity of an integrated view and full catchment study

Sediment and large wood trapping should be approached cautiously: excessive trapping may induce strong perturbation of past bio-geomorphological dynamic equilibrium and unexpectedly high maintenance efforts. A full catchment study and an integrated view must prevail before planning an eventual trapping of solid transport (sediment and/or large wood).

The designer first analyzes upstream conditions to propose different scenarios on the top of the alluvial fan (chap. 1.2). Then, he analyses downstream scenarios with related consequences, that we call problems, to identify which scenario(s) have to be treated (chap.1.3). On this basis, he can help to decide objectives given to the structure, taking into account project constraints and downstream potential impacts (chap. 1.4).

## 1.2 Estimation of upstream catchment conditions

Upstream scenario analysis.

### 1.2.1 Historical, geomorphological and hydrology/hydraulics approaches

### 1.2.2 Effects of upstream torrent control works

### 1.2.3 Type of phenomena

Here we analyze scenarios but we do not decide what the design event is. For me, it is decided after downstream problem analysis.
Debris flows, debris floods or bedload-laden floods?
Presence of large woods?

### 1.2.4 Liquid and solid hydrographs

### 1.2.5 Material size

#### 1.2.5.1 Boulders

#### 1.2.5.2 Sediment
1.2.5.3 Large wood

1.3 Assessment of downstream problem(s)

Large wood and sediment transport may aggravate flooding by several processes. A trapping system must be tailored to each site in order to best adjust the trap functions. Thus, a detailed assessment of the geomorphic origin of the flooding aggravation must be done before defining the trap type.

Illustration or short case-study in each case?

1.3.1 Boulder-related problems

Jamming in bridges, channel obstruction

1.3.2 Large wood-related problem

Jamming in bridge, flow section obstruction inducing increase in water stage.

1.3.3 Excess in instantaneous discharge

Transport capacity of the channel is insufficient to transfer the event through the channel, thus triggering deposits, i.e., there is a remaining partial solid transport capacity for debris flows or bedload in the downstream reaches.

1.3.4 Excess in supplied volume

Total trapping necessary due to downstream null transport capacity or partial trapping because of insufficient buffering capacity of downstream bed and confluences. Here the problem comes from the confluence and is backward propagating.

1.3.5 Functions of other torrent control works

Check dams, embankments, bank protection

1.3 Structure objectives

1.3.1 Definition of objectives and design input

Cost-Benefit Analysis (CBA) was proposed in maintenance section (chapter 6), with cost assessment. In ONF-RTM opinion, it is more here because it is a decision-aiding tool to help to define objective given to the protection system. Costs which will be indicated in subsection 6.3.4 are only an input for CBA.

Description of the design event regarding previous elements. It is an important step for transparency in the design process and to define design inputs.
## 1.3.2 Constraints analysis

Before design, designer has to consider all constraints of the project: property, regulation (laws on water), etc.

## 1.3.3 Secondary effect analysis

Objectives consist in having an expected effect on natural phenomena. Nevertheless, designer has to keep in mind that these objective can also have other (unexpected) effects :

- according to downstream conditions, potential progressive incision, potential effect on sedimentary transit at local but also large scale ;

- regressive erosion according to upstream conditions (no check dam or to low one). They must be taken into account to adapt objectives given to the structure.

## 1.3.4 Overloading and residual risk

Here we discuss the issues of residual risk, i.e. the behavior of the dam and the basin in case of overloading, which may be due to a larger run-up height at the dam (e.g. larger/faster flow than assumed for the design) or due to the complete filling of the retention basin.
## 2 Task 2: Procedure to define the structure function and shape (~10 pages)

COORDINATOR and contributors:

J. HUBL, F. Comiti, V. D'Agostino, M. Moser, G. Piton

The definition of the torrential hazard related to the upstream supply and to the downstream problems to sort out enables to clarify how the torrential processes should be modified:

- Removing boulders and diminishing debris flow fronts

- Removing large wood pieces

- Dosing sediment transport by buffering fluxes

- Trapping entirely or partially the solid volumes

Which enable to choose the functions of the trapping system, i.e., one or several structures?

Typical structures are: boulder traps / debris flow breakers, large wood traps, dosing dams and retention dams.

### 2.1 Main types of traps

#### 2.1.1 Location in the catchment

To recall the best position of structures, taking into account constraints [CS1] :

- as close as possible to elements-at-risk : to avoid structures far from elements-at-risk with a difficult access and potential downstream recovering of materials before them ;

- for a system, setting up of several structures in series or in parallel ?

#### 2.1.2 Position transversal or parallel

#### 2.1.3 Type of barrier

Wehrmann et al. (2006) classification?

### 2.2 Flow chart for the definition of the protection system
# 3 Task 3: Functional design

Once a trap function is defined, the design must address several steps: first, design of the barrier and of the basin based on hydraulics and sediment transport consideration, and secondly architectural and structural design of the civil engineering structures.

## 3.1 Dam functional design (~30 pages)

COORDINATOR and contributors :

G. PITON, S. Schwindt, A. Armanini, V. D'Agostino, J. Hubl, M. Larcher, T. Mizuyama, G.

Rossi, L. Schmocker

### 3.1.1 Trapping processes

Origin, initiation and development of the trapping

### 3.1.2 Mechanical and hydraulic trapping approaches

Water stage – discharge equations

Opening sizes and jamming probability

### 3.1.3 Hydraulics

#### 3.1.3.1 “Pure water” hydraulics

- Slit capacity

- Slot capacity

- Grill and fins capacity

- SABO frame structure capacity

#### 3.1.3.2 Debris flow hydraulics

Differences with pure water

#### 3.1.3.3 Additional head losses

- Sediment transport

- Woody debris on rakes

### 3.1.4 Low flow outlet

On the necessity to maintain a partial sediment transport continuity

- Interest

Applicability of Eq proposed in §3.1.3.1 and combination approach

Effect on deposition initiation and threshold effects

### 3.1.5 Spillway

- Design approach (event scenario)

- Hydraulic capacity

- Freeboard
Run-up height

The estimation of the (maximum) run-up height (on the dam), depending on approach flow conditions of debris-flow surges, on the geometry of the basing and the retention dam (or outlet structure), and on possible changes in geometry due to prior deposition of sediments.

3.1.6 Deposit height near the dam

3.1.7 Scouring

Estimation of scouring

Mitigation measures

## 3.2 Basin functional design (~20 pages)

COORDINATOR and contributors:
G. PITON, S. Schwindt, D. Rickenmann, R. Canelas, F. Comiti

3.2.1 Shape

Aspect ratio influences

3.2.2 Deposition slope

Estimation for volume capacity assessment

Estimation for dyke crest design and by-pass prevention

3.2.3 Transversal profile and low flow channel

Deposition related to simple flow spreading

Interest and design of low flow channel

3.2.4 Lateral confinement

Dykes and riprap protection

3.2.5 Inlet structure

Necessity, security, influence on the trapping initiation and development
# 4 Task 4: Architectural and structural design
(~50 pages)

COORDINATOR and contributors :

J. HUBL, V. D'Agostino, JM Tacnet, R. Canelas, S. Carladous

As an introduction for this chapter, we could talk about current standards, guidelines available in each country. For instance:

- France, we mainly use a design guideline (Deymier, 1995) which has to be uptaded: objective of the present guideline

- Austria : ONR 24800, 24801, 24802

## 4.1. Building forms, materials, and landscape preservation

Recall of different components that need to be structurally designed (structure of dam, opening dam, dikes, upstream check dam, downstream dam protection)

Design characteristics of different barriers: check dam, large slot barrier, debris flows breaker, etc.

For each component, description of :

- different existing types of structures (weight, self-supporting, etc.);

- different materials used (reinforced concrete, metal, ripraps, etc.);

- landscape preservation technics

## 4.2. Dam body and wings structural design

### 4.2.1. Geotechnical analysis

- Needed geotechnical data

- Some estimations

- Means to specify data

- Main elements designer must be careful about

### 4.2.2. Design based on limit states

Supporting calculations principle

Ultimate limite state (ULS)

Serviceability limit state (SLS)

### 4.2.3. Actions, loads, status, stress combinations

Design criteria: Debris flows and bedload

Persistent, transient and accidental actions

Impact forces to take into account to proof the stability (ULS) and the serviceability (SLS)
Relevant stress combinations

Extreme event scenario

### 4.2.4. External stability supporting calculations

Failure types

Partial safety factors for actions

Stability supporting calculations principle for each limit state and each status

### 4.2.5. Internal stability supporting calculations

Material characteristics

Partial safety factors for resistance of materials

Stability supporting calculations principle for each limit state and each status

## 4.3. Structural design of metal parts

### 4.3.1. Products and choice criteria

### 4.3.2. Design of vertical bars

### 4.3.3. Design of horizontal bars

### 4.3.4. Design of inclined grills

## 4.4. Structural design of other components

### 4.4.1. Other components of the main dam

Spillway

Protection against abrasion

Scour protection area

Downstream flow chenalization
4.4.2. Upstream and downstream barriers

4.4.3. Lateral embankments protection
# 5 Task 5: Comprehensive technical sheets for all structure types' design (~10 pages/structure type)

COORDINATOR and contributors :

G. PITON, A. Schleiss, V. D'Agostino, J. Hubl

Each of these sheets would be a synthesis recalling the object of the structure type, their main features in term of basin and dam designs and a full design procedure with each step. It should be nearly self-standing but only roughly detailed concerning the equations and approaches, the details would be found in the previous chapters.

## 5.1 Retention dams

### 5.1.1 Classical transversal traps

### 5.1.2 Parallel traps

## 5.2 Boulder traps / debris flow breakers

## 5.3 Woody debris traps

## 5.4 Dosing dams
In ONF-RTM opinion, two main aspects should be evoked in this chapter 6 introduction:

- monitoring and maintenance conditions must be taken into account since the design process:

access, monitoring and maintenance cost, an adaptive design during life cycle of the system

- how to make monitoring and maintenance in practice.

Likewise in chapter 4, we could talk about current standards, guidelines, and tools available in each country for structure monitoring and maintenance of structures. For instance:

- in France, we presently use a database (DTRTM, 2007) with some indicators to describe structural and functional state of the system. Nevertheless, there is no national guideline

- Austria: ONR 24803 and corresponding maintenance guidelines (Suda, 2013)

# 6 Structure management

## 6.1 Monitoring

### 6.1.3 Civil engineering monitoring indicators

Descriptors / indicators to take into account for each civil engineering structure, components

### 6.1.4 Geomorphic and filling monitoring indicators

Descriptors / indicators to take into account for functional analysis of the system

## 6.2 Maintenance

### 6.2.1 Dredging operation triggering

When and why
Self-cleaning operations

### 6.2.2 Storage and final destination of dredged material

Having enough room to buffer supplies
Legal and technical issues in using trapped material

### 6.2.3 Structural maintenance
## 6.3 Life cycle management

### 6.3.1 Access

To the basin and to the dam: to be taken into account since the design process

### 6.3.2 An adaptive design

It is extracted from recent visits in Trento. For a same given function, design takes into account feasibility of changes in functional design (more holes for vertical bars, vertical ones, etc.) taking into account field feedback on events. It is a way to consider uncertainty in the design process.

### 6.3.3 Adaptation of existing traps

Feedback from the fields, experience of tests and trials

It corresponds to change main function(s) of the system. Thus, this steps correspond to a new design process, taking into account existing structure and new objective function.

### 6.3.4 Global costs

Elements from feedbacks: these elements can be taken into account as an input in cost-benefit analysis (CBA) and other decision-aiding tools which are used to help to define system objectives during the design process (cf subsection 1.3.1)

- Investment Monitoring

- Dam maintenance

- Dredging

## 6.4 Communicating about sediment and large wood trapping

### 6.4.1 Why trapping is sometimes not a good idea

### 6.4.2 Communication material for stakeholder

# 7 Task 7: Innovation of check dams: New methods, special challenges

(to see later)
References

Breton, P. 1867. « Mémoire sur les barrages de retenue de graviers dans les gorges des torrents. » [Essay on gravel trapping dam within the gorges of the torrents] (Dunod, Ed.), Paris, France.

Deymier, C., J.-M.Tacnet, and N. Mathys. 1995. « Conception et calcul de barrages de correction torrentielle. » [Design of torrential dams] (Cemagref Ed.), Grenoble, France.

DTRTM. 2007. « Observatoire des Risques Naturels en Montagne, Notice Générale, Tome 1, Définition et descripteurs, Base de données RTM » [Observatory of natural hazards, General framework, Vol. 1, Definitions and descriptors, RTM database], Grenoble, France

ONR 24800. 2009. « Schutzbauwerke der Wildbachverbauung - Begriffe und ihre. Definitionen sowie Klassifizierung » [Protection works for torrent control - Terms and their definitions as well as classification], Vienne, Austria.

ONR 24801. 2013. « Schutzbauwerke der Wildbachverbauung - Statische und dynamische Einwwirkungen » [Protection works for torrent control - Static and dynamic actions on structures], Vienne, Austria.

ONR 24802. 2013. « Schutzbauwerke der Wildbachverbauung - Projektierung, Bemessung und konstruktive Durchbildung » [Protection works for torrent control - Design of structures], Vienne, Austria.

ONR 24803. 2008. « Schutzbauwerke der Wildbachverbauung - Betrieb, {"U}berwachung und Instandhaltung » [Protection works for torrent control - Operation, monitoring, maintenance], Vienne, Austria.

Piton, G., and A. Recking. 2016. Design of sediment traps with open check dams. I: hydraulic and deposition processes. Journal of Hydraulic Engineering 142:1–23.

Suda, J. 2013. « Schutzbauwerke der Wildbachverbauung - Handbuch zur Durchf{"u}hrung einer Bauwerkskontrolle » [Protection works for torrent control – Guideline for structure monitoring], Vienne, Austria.

Wehrmann, H., J. Hübl, and G. Holzinger. 2006. Classification of Dams in Torrential Watersheds. Pages 829–838 INTERPRAEVENT Conference Proceedings. Universal Academy Press, Inc. Tokyo, Japan.

Zollinger, F. 1983. «Die Vorgänge in einem Geschiebeablagerungsplatz (ihre Morphologie und die Möglichkeiten einer Steuerung) [Processes in debris detention basins for torrent control (A morphology and the possibilities of control)]». Ph.D. thesis, ETH Zürich, Zurich, Switzerland.
# 8 Template of the work

## 8.1 Citation style

A rigorous and consistent way of citing bibliography should be used in the book. We will use the author – year format. E.g.: (Piton and Recking 2016) or Piton and Recking (2016).

The faster way is to use a reference data base. We propose to use a bibtex ".bib" format. This format is consistent with both MS Word and Latex. Each time you download or search for the citation of a paper, e.g., on Google Scholar, it is directly possible to download the .bib reference.

<figure><img src="image_244.png" /></figure>

You can copy and paste it in Jabref[1], a free software that, between other strengths, make easier your .bib database management.

The link between this database and the MS Word document is very easily done with Docear4word[2], an add-on to MS Word that enables to cite and update the reference list in a fast and rigorous way. It is included directly in your MS Word interface:

<figure><img src="image_245.png" /></figure>

By clicking on "Add Reference", a window opens and enables to search for one or several references based on author name or title words:
<figure><img src="image_246.png" /></figure>

In case you do not want to use it, please provide your database in another format or each time you first cite a document, add the reference in footnote, e.g., Piton (2016)[3]
## 8.2 Styles list:

# 9 Title 1

## 9.1 Title 2

### 9.1.1 Title 3

#### 9.1.1.1 Title 4

##### 9.1.1.1.1 Title 5

A Title 6
Normal

<caption>Figure 1: Figure caption: BELOW the Figure</caption>

<table><caption>Table 2: Table caption: ABOVE the Table</caption><thead><tr><th>Column title</th><th>Column title</th><th>Column title</th></tr></thead><tbody><tr><td>Data</td><td></td><td></td></tr><tr><td></td><td></td><td></td></tr><tr><td></td><td></td><td></td></tr><tr><td></td><td></td><td></td></tr><tr><td></td><td></td><td></td></tr><tr><td></td><td></td><td></td></tr></tbody></table>

<footnote>[1] https://www.fosshub.com/JabRef.html</footnote>

<footnote>[2] http://www.docear.org/software/add-ons/docear4word/download/</footnote>

<footnote>[3] Piton, G., & Recking, A. (2015). Design of sediment traps with open check dams. I: Hydraulic and deposition processes. Journal of Hydraulic Engineering, 142(2), 04015045.</footnote>
Annexe 15. COST Action – Fiche projet déposée le 15/11/2018
# Open Call Collection OC-2018-2

## Proposal Reference OC-2018-2-23569

## Title: Solid Material Regulation and Trapping in mountain rivers

## Acronym: SMARTrapping in rivers

## Summary

This Action will gather scientific experts and practitioners in sediment and large wood transport in piedmont and mountain rivers working on open structures aiming at regulating, filtrating and trapping this solid transport. Sediment and/or large wood transport strongly aggravate flood hazards and risks. This solid transport could be regulated or trapped in suitable locations with open structures called open check dams, SABO dams in Japan, torrential barriers or flexible barriers. They may be very effective structures, yet used in some pioneer countries. Two obstacles prevent their mainstreaming worldwide to effectively prevent hazards in thousands of catchments: ill-design structures are costly to maintain and trigger environmental degradation and practitioners lack understanding of their functioning to trust them. There is thus a clear need for accurate descriptions of processes at work in debris trapping structures and clear recommendations on their design to fit their purposes. In addition, end-users as civil engineers and river managers need training for their design and management.

This Action will enable to clearly and fully define innovating structures able to filtrate, dose or trap gravel and/or large wood, write design and maintenance guidelines in a general consensual way by a group gathering most of the best experts on the topic in the world and Europe. It will additionally enable to train the next generation of European torrent control managers and researchers that are part of the Action and end-users who will participate in training schools organized to disseminate the Action results and enabling capacity building in all countries.

## Key Expertise needed for evaluation

### Earth and related Environmental sciences

Hydrology, water resources

### Environmental engineering

Risk assessment, prevention and mitigation

### Civil engineering

Civil engineering

### Environmental engineering

Water management and technology

### Civil engineering

Fluid mechanics, hydraulic-, turbo-, and piston engines

## Keywords

sediment and large wood transport

Flood hazard mitigation

mountain and piedmont rivers

<figure><img src="image_247.png" /></figure>
Protection measures

Debris flows and debris floods
# TECHNICAL ANNEX

## 1 S&T EXCELLENCE

### 1.1 SOUNDNESS OF THE CHALLENGE

#### 1.1.1 DESCRIPTION OF THE STATE-OF-THE-ART

Flood hazards in mountain and piedmont regions **involve more than just water**: rivers and torrents **carry sediment and large woods** during extreme events. Flood risk mitigation involves a panel of measures both non-structural (land-use regulations, risk maps, alert systems, local people education) and structural (civil- and bio-engineering protection works). **No one-type-fit-all protection system exists** in mountains because **each catchment has peculiarities**, e.g., landslides, lakes, glacier, narrow bridges and channels, changing slopes, which require a fair appraisal and a consistent **protection system tailoring**. Sediment and large wood trapping facilities are promising candidates for best-adjusted mitigation because they may achieve precise purposes, e.g., trapping only boulders or large woods. These structures are likely to be effective, efficient and increasingly used in protection schemes but are still very complicated to design and maintain due to a lack of knowledge on what exactly control their selectivity, and thus of design guidelines. The scientific and technical knowledge on these structures, currently spread between laboratories, institutes and agency, has recently reached a cumulated critical mass enabling to fully define innovating structures with clear purposes **and** the related comprehensive design guidelines, to finally disseminate them to engineers and other end-users. This Action seeks to gather and improve this knowledge to use and transfer it. Designing effective protection works and keeping them reliable, cost-effective and Environnement-friendly is an essential issue. **The main objective** of this COST action is **to improve** the **technical and economic effectiveness** of sediment and large wood **selective trapping facilities** through the **full definition of structure types** able to cope with small to extreme events **with clearly assigned purposes** and a **framework enabling to choose the relevant protection measures to implement in each catchment**. Clear, comprehensive and smart design and maintenance procedures transferable to various geomorphology and climatic conditions will be proposed, published in journals and finally gathered in an open-access book. It is based on a unique gathering of pan-European experts in mountain hydraulics, solid transport-related hazards and torrent control works who will share their know-hows, best-practices, lessons from the past and recent research results, **in essence, to define the next generation of torrent control structures** as described hereafter.

**Flood hazards are key threats for most of societies.** We define hereafter a flood as a 'transient submersion of usually dry areas resulting from excess of water discharge compared to the conveyance capacity of the river channel'. Areas at risk from floods host peoples: 1.2 billion today and up to around 1.6 billion in 2050, i.e., nearly 20% of the world's population in 2015 from projections, but also assets evaluating to worth around US$ 45 trillion by 2050, a growth of over 340% from 2010 (OECD 2012 p. 221). As a consequence, floods hazards affect or kill about 60-120 million people per year worldwide, with peaks of 200 million or more.

Part of these people and assets are located in mountains and piedmont regions. In mountainous and hilly contexts, rivers and streams are steeper, more energetic and thus regularly damage assets, transportation, energy and communication networks and economy or threaten peoples. Flood events in steep environments generally extend on smaller and more numerous areas but with more intense damages (Fig. 1a). Roads and fields are eroded or buried under thick layers of sediment (Fig. 1b). Bridges and houses are destroyed by debris flows. Debris floods and bedload transport events entrain

<figure><img src="image_248.png" /></figure>
and transport huge quantities of gravels, as well as large wood and boulders. Indirect impacts related to road and railway cutting are stronger because villages and cities have less connections in mountains than in plains. In addition traffic disruptions last much longer than in lowlands due to the higher damages: removing large wood accumulations, debris flow deposits or reconstructing bridges and roads take times. Areas at risk thus need to be protected from solid transport and flood events.

<figure><img src="image_249.png" /><figcaption>Figure 1: (a) Debris-flow deposits on a torrential fan (Glyssibach at Brienz, canton of Berne, © Swiss Air Force, 24 August 2005, taken in Rickenmann and Koschni, 2010), (b) massive deposit of gravel in the Chantelouve municipality in France Aug. 2014 (© RTM38), (c) a huge wood jam created by a bridge during a flood event in Italy, © Province of La Spezia, taken in Comiti et al. (2016)</figcaption></figure>

These flood events have specific features in mountainous environment. In steeper beds, floods are flashier, thus harder to predict, which jeopardize alert and evacuation possibilities. In addition, their higher energy enables flows to scour, erode, transport and later deposit solid material: small sediment and coarse sediment such as gravels, cobbles, and sometimes boulders and large wood pieces. Solid transport is a natural process occurring systematically during flood events but this coarse fraction usually aggravates flood hazards by depositing in channels reducing their conveyance capacity and obstructing bottle-neck sections of the rivers (Fig. 1).

After a disaster, it is complicated to unravel the roles of the water flood on the one hand, and the hazard related to solid transport on the other hand. The second is however known to be a key process. An interesting back analysis of an insurance-claim database showed that solid transport was directly responsible of - or at least aggravated - the flooding and damages for at least 36%-40% of the 212M€ of mean annual damages observed in Switzerland between 1972 and 2007 (Hilker et al. 2009, Badoux et al. 2014). This, despite the numerous existing protection structures in the country. We assume that it is worse or much worse in countries less advanced in torrential protection implementation. In other words, **solid transport plays a key role in flood and debris flow hazards in mountain and piedmont areas** (Ruiz-Villanueva et al. 2014, Rickenmann et al. 2016).

When stakeholders clearly understood during the 19th century that chronic excesses in sediment transport were responsible for widespread flood and torrential hazards, they rapidly paid attention to land conservation and erosion control technics. Series of disastrous events finally triggered country-scale political responses to launch mountain land restoration policies (Piton et al. 2017). Large scale plans were launched to reforest, implement soil conservation operations and build large numbers of structures to curtail erosion in the highlands. Check dams, i.e., transversal structures built across torrents and gullies, were the most widespread type of structure. They aimed at stabilizing the bed, also consolidating the adjacent hillslopes, reducing flow energy and trapping and buffering sediment transport. These " torrential control" operations initially sought to definitively stop sediment production and transport. They were complementary to embankments of torrents and rivers on alluvial fans and land use planning to prevent vulnerability increase in areas at risk. Old retention ‘closed face’ check dams trap both coarse and fine sediment and require regular crest rising or an addition of new trapping structures. They had thus a strong impact on the sediment cascade while being expensive to use. Nonetheless, the affordable workforce available at that time built from cut or raw stones, or masonry with local boulders and rocks, thousands of closed check dams since the late 19th century.

Reinforced concrete appeared and enabled to test new kinds of structures with openings (Piton and Recking 2016). They could be dredged using the increasingly-used earth moving machineries. They are called open check dams, debris flow barriers, slit dams, or SABO dams in Japan. Pioneer works with open structures date back to the 1950s. The actual testing phase with increasing number of structures dates from the 1970s to the 1990s. They were designed on a trial and error basis and adapted by local empirical approaches, scientific works focusing on this topic at that time were extremely rare and no design criteria existed. In this situation of fuzziness and heavy doubts, design
engineers were naturally very often conservative in their choices: they created open dams with small openings, thus trapping gravel and large wood during all events: for extreme events obviously but also all 'routine events', i.e., small events not threatening assets even though transporting solid material. We continue to heavily suffer two consequences of this latter point: (i) empirically- and conservatively-designed structures generate very high maintenance costs to dredge yearly thousands of cubic meters of armless sediment, typically at 2-10€/m³ (Bergmeister et al. 2009, Papež et al. 2015); (ii) these sediment not reaching the downstream reaches trigger sediment starving problems, e.g., bridges and bank protection collapses due to river bed degradation, new stabilization structures must be built and fish and aquatics species lack gravel to spawn, live and feed (Wohl 2006).

The importance of the sediment cascade in the good environmental status of rivers is now widely acknowledged and stressed (Rinaldi et al. 2011) and is included in some regulations as the European Water Framework Directive (EU 2000). **Mountain streams and rivers are consequently managed under a permanent trade-off** between, on the one hand, building and maintaining torrent control structures that trap sediment and large woods for protection purposes and, on the other hand, facilitating sediment cascade continuity, keeping river beds and deltas natural and minimizing dredging and other maintenance costs. **Open check dams are acknowledged to have a key role to play in this trade-off** (Armanini et al. 1991, Armanini and Larcher 2001, Rinaldi et al. 2011, Comiti et al. 2016), **obviously if correctly designed;** which is sadly not the case at the moment because of a spreading in scientific and technical knowledge between too many researchers and practitioners.

More precisely, the following points remain unclear:

* Which peculiarities of the catchment (upstream) and the channel crossing the area at risk (downstream) must be taken into account to choose, define and tailor a protection system in a given site and how to take into account these peculiarities?

* Practitioners know how to design a very large structure that fully protect elements at risk but is very expensive to build and to maintain while having dramatic side effects. Which structure types and how to design them precisely would minimize maintenance costs and side effects while having high protection effectiveness?

The Action work aims at providing responses to these questions based on top level scientific knowledge to these very practical and relevant questions.

### 1.1.2 DESCRIPTION OF THE CHALLENGE (MAIN AIM)

The challenge that this COST action will be to go beyond the current know-how and to build upon the recent advances in scientific knowledge and field empirical evidences to define the future ways torrential hazards will be approached and mitigated, notably using promising and innovative open structures.

The practical question of 'how to choose and design open check dams in a particular catchment?' could appear a purely technical question, no longer deserving scientific attention since closed for a long time. The Action Members gather a great experience on the topic and know that this question appear simple but hide several particularly complicated and unresolved challenges in mountain geomorphology, hydraulics, ecology and civil engineering, notably:

* Torrent control structures are designed to withstand extreme, rare and violent events that are poorly known and difficult to anticipate. Indeed the physics of debris flows and extreme sediment- and wood-laden flows are still only partially understood (Ruiz-Villanueva et al. 2016; Ravazzolo et al. 2017). These events are too unpredictable and context specific to be already comprehensively observed, monitored and measured. They are additionally naturally variable in time and space. As a consequence, **how to approach hazard scenarios and to describe the processes likely to reach an area at risks deserve a clear scientific update coming from a relevant high level group** as is the Action consortium. It will be based on both the cumulated experience of the Members shared during the Action Workshops and explorations of promising approaches during Short Term Scientific Missions granted by the Action.

* Once debris flows, debris floods or large wood-laden floods reach a deposition area, what exactly occur? How deposition and eventual transfer or self-cleaning occur? This functioning is complex because at least four effects may lead to sediment/wood deposition (Zollinger 1985): (1) lower energy due to milder slope in the basin, (2) lower transport capacity due to flow spreading in a basin wider than the upstream channel, (3) lower velocity in the backwater area upstream of the structure and (4) mechanical blockage of coarse material unable to pass
by small openings. **These effects may overlap, self-reinforce or on the contrary counter-act each other's.** Defining structure shapes enabling to change torrential processes in a certain way while not disrupting another component is the corner stone of open check dam design and remains an open scientific and technical challenge. Several detail points and processes were subjected to research programs in the last decades and **knowledge on torrential processes reached a critical mass enabling to provide a comprehensive description** of coarse sediment and large wood deposition and erosion, and how it should influence design decisions.

* This advanced knowledge in torrential processes' interaction with structures **are also required to tailor a torrential hazard protection scheme** to a catchment and channel peculiarities because they also concern the **prevention of channel malfunctions**, e.g., bridge clogging, chronic deposition triggering bank overtopping or channel backfilling from the confluence (Mazzorana and Fuchs 2010, Rickenmann et al. 2016, Mazzorana et al. 2017).

These hidden questions and challenges naturally lead to the three research questions the Action will address:

**Research question #1: Why does sediment and large wood deposition occur and aggravate flooding?** What chains of events and process interactions may lead to solid transport deposition and hazard increases in river channels? How indicators related to supplies from the upstream and hydro-geomorphological features of the downstream river channel system may help to understand them?

**Research question #2: How sediment, water and wood interact in the particular and artificial areas that are detention basins to finally deposit, erode or pass the structures?** How torrential processes in all their complex fluid mechanics and granular behaviors dynamically interact to trigger deposition or erosion? How this knowledge can help us to design innovative structures with relevant selectivity?

**Research question #3: How solid-fluid mixtures can hit, scour and damage structures?**
What do we know about forces and energy interactions between torrential processes and structures?
How high can be impacts forces, loading and how to survive them to prevent failures? What do we know about failure modes and their prevention?

**The knowledge gained on torrential processes** through the Action will thus **serve** both new structure **design**, existing structure **adaptation** and **appraisal** and **anticipation** of potential malfunctions triggering an **adaptive management and helping to tailor much more relevant protection schemes. **

Countries as Austria yet published standards in torrent control work classification, structural design and maintenance (ONR24803 2008, ONR24800 2009, ONR24802 2010, ONR24801 2013). *They are however planned to be revised and updated in the next years.* Japan also published design standards (Moase 2017) and *an updating is also in progress*. The Action Members will engage exchanges with both initiatives so that national guidelines are written in accordance with the most up-to-date international knowledge. Such local initiatives and the recent knowledge gained in research institutes and management administrations should be shared and discussed. It is time to do a comprehensive appraisal to clarify:

* Which parts of old and updated Japanese and Austrian methods can be transferred worldwide and which parts should be adapted and enhanced by local complementary knowledge?

* What are the remaining knowledge gaps? They should be highlighted and explained to help decision making in an imperfect knowledge context.

## 1.2 PROGRESS BEYOND THE STATE-OF-THE-ART

### 1.2.1 APPROACH TO THE CHALLENGE AND PROGRESS BEYOND THE STATE-OF-THE-ART

The networking activities and workshops will thus focus on clarifying our understanding and providing recommendations on several aspects to help the community to shift from current paradigms in hazard mitigation to new paradigms more in line with Nature variability, efficient and enlighten river management and preventing regrets due to unexpected although predictable structure side-effects. The Action will notably help:
* To shift from the current paradigm of having mostly a 'one design event' approach, usually based on the last experienced extreme event, to comprehensive definitions of scenarios for all events used in design: from routine ones to most extreme events;

* To shift the paradigm of 'trapping all material for all events' to catchment- and channel-tailored selective trapping, smartly chosen for sufficient ranges of event magnitudes.

On the contrary to old “closed” structures, open structures aim at being selective in their trapping. At least four objectives can theoretically be achieved using them (Rudolf-Miklau and Suda 2013): (i) breaking debris flow granular fronts and trapping mainly their boulders while letting pass the debris flow body carrying smaller grains; (ii) filtrating large wood pieces while letting most of the gravel passing; (iii) dosing sediment transport by trapping sediment during high transport stages and later self-cleaning the basin to simply buffer sediment transport peak discharges; (iv) definitively trap coarse solid transport in retention structures that are not supposed to self-clean, to later mechanically dredge them. This could sometimes be achieved with heavy, light (racks) or flexible structures (net dams). Although these main functions had been theoretically described, defining structures and basins able to achieve them for any event is far from being clear. The Action will enable to bring and share scientific knowledge required to propose new structure types or improve the most promising ones with the relevant details on bottom outlet, main openings, crest spillway and basin geometry.

Workshops, collaborations through Short Term Scientific Missions between the relevant Members and co-writing and designing of frameworks, research reports and scientific papers will enable to:

* Clarify *why, where and when trapping / regulating solid fluxes is the good option and where it is not*, other options will be described and exemplified with the relevant references;

* Set fair and up-to-date scientific descriptions of functional and structural interactions between torrential processes and structures.

* Deduce from these descriptions innovative designs of selective open check dams, several on-going patents and ideas that emerged in the last years will be deepened during exchanges, reviewed and discussed in the light of the Members' cumulated experience;

* Provide guidance, good practice examples and helpful hints to ensure that the structures achieve their protection objectives while having the lightest possible footprint on solid fluxes. This second feature is the most complicated to achieve: retention, oversized structures are relatively easy to design but they have dramatically high construction and maintenance costs and maximum secondary effects. Better options should be defined;

* Propose, review, organize and criticize design criteria and monitoring methods in a comprehensive way, for both the functional and structural design of these structures;

* Provide a fair and consensual vision of the remaining gaps in the understanding of processes origin and interactions with structures.

* Sediment and large wood transport models are currently available and under development but data to benchmark, test and calibrate them are scarcely available, the Action will make available data for model validation and calibration in a new database.

The approach to tackle the Action main challenge is to gather experts in mountain hydraulics, solid transport-related hazards and torrent control works to define a **new framework helping the tailoring of protection strategies to catchments' peculiarities, full description of innovative open structures having clear functions** and a common publication of up-to-date, comprehensive and consensual **guidelines for the design and maintenance** of open structures intending to regulate, filtrate and trap solid fluxes in mountain rivers and torrents.

### 1.2.2 OBJECTIVES

#### 1.2.2.1 Research Coordination Objectives

The Action four main research coordination objectives are:

1. To define a new way to understand torrential hazard origin, cascading processes and chain of events triggering flooding. It will be inspired by recent research results on fluid mechanics and granular matter bring together with actual field observations and lessons from the past, as
e.g., feedback of structure failures or unexpected and surprising consequences of ill-design or
good designs of protection structures.

2. To cross-compare the more recent patents and research works dedicated to process-structures interactions in order to comprehensively define innovative open structures for solid transport trapping and regulation, from their concept to their full functional and structural design criteria. The existing tried and tested solutions that proved to be effective will at least be improved on detail points to limit side-effects and identified failure modes.

3. To gather and make widely accessible relevant existing data. Good research build upon good and available data: a specific Working Group will be in charge to gather, create and make openly accessible online a new database on observations of open check dam interactions with torrential flows. These data will mostly come from hydraulic laboratories but also from fields measurements and will form the basis of future model development, benchmarking or calibration by academics and engineers.

4. To improve and develop the new hazard analysis framework as well as the innovative and improved structures with new data and collaborations between Action Members through Short Term Scientific Missions. Some Members have more experience and data from field monitoring or laboratory experiments, while other develop innovative numerical and theoretical approaches. These missions and exchanges will enable to set new collaborations, to benchmark existing tools and to demonstrate the relevance of more innovative methods or structures, thus cross-feeding Action purposes.

1.2.2.2 Capacity-building Objectives

The capacity-building objectives of the Action cover two scales: within the action consortium and beyond with a wider range of stakeholders:

1. The Action will greatly increase capacities and train the current and next generations of torrent control researchers, managers and decision makers participating in the Action.

a. Existing results and empirical knowledge will be shared enhancing future works and preventing repetitions of mistakes or overlapping researches, also generating synergies at the European scale through both several Short Term Scientific Missions and a 'white paper' that will review the remaining challenges the community must address.

b. Two training schools will be organized within the consortium to train all participants. They will focus on 'innovative and tried-and-tested open check dam design across the world' and 'application of a new step-by-step definition and design procedure of open structures'. The new generation of Early Career Investigators (ECIs) on torrential hazard mitigation will thus benefit from comprehensive presentations of recent research works, innovation in hazard mitigation, a deep appraisal work and debate between experts, a better network and strong scientific and technical capacities.

2. Once the paper describing the new structures and their design and maintenance guidelines written and available, the Action members will disseminate them and train stakeholders as design and construction engineers from private and public bodies, risk and structure managers, administration officers and graduate students during training schools and courses.

a. Ten training schools at least will be organized to explain the guidelines' use and exemplify it on case studies for advanced users; one day being rather dedicated to advertise to officers from ministries, basin agencies and other state services who will spread the news about it existence and potential.

b. An open access, ready to use course will be prepared and disseminated to be taught at a Master level worldwide. It will synthesize the essence of the guidelines focusing on concepts and key messages. References to the guidelines documents will enable to go more in depth and address quantitative analyses.

c. To prepare communication and informative material carrying the key take-home messages of the action to non-expert and end-users. In addition to the scientific
papers, technical guidelines, we feel that some educational material as a few flyers
must be prepared to better inform stakeholders and non-experts about the
possibilities, limits and relevance of trapping - or not - solid transport.

2 NETWORKING EXCELLENCE

2.1 ADDED VALUE OF NETWORKING IN S&T EXCELLENCE

2.1.1 ADDED VALUE IN RELATION TO EXISTING EFFORTS AT EUROPEAN AND/OR INTERNATIONAL LEVEL

In addition to numerous national projects, connections will be created with peoples involved in past and current research projects or working groups on torrential hazards, mitigation measures and solid transport management, notably (non-exhaustive list):

* EU AlpineSpace [SedAlp project](https://sedalp.eu/) on integrated management of sediment transport in Alpine basins. A work package was dedicated to structure design and management.

* EU [StartItUp project](https://startitup.eu/) that created a state-of-the-art database document in Risk Management Technology for engineering practice and policy.

* Water JPI [STEEP STREAMS project](https://www.steepstreams.eu/) aiming at researching structural innovative solutions and design criteria reliable to mitigate the impacts of wood-laden flash floods and debris flows.

* EU EFRE [SEDIPLAN-r project](https://sediplan-r.eu/) that investigates and quantifies the sediment transport and morphological changes of river channels at different spatial and temporal scales with the final goal of identifying priorities for sediment management.

* Bilateral *Austria-Italy project* on field measurements of impacts forces in the Gadria torrent.

• UNDP support to Macedonia for torrential hazard mitigation in the region of Polog.

* EU Erasmus+ SETOF project on soil erosion and torrential flood prevention in the Balkans.

* Ongoing revision of the mentioned Austrian Standards with the Austrian Standards institute.

* Ongoing research projects of the Japanese Members on design of open structures.

2.2 ADDED VALUE OF NETWORKING IN IMPACT

2.2.1 SECURING THE CRITICAL MASS AND EXPERTISE

The consortium has been selected and tailored to be critically relevant for addressing the objectives and challenges of the Action. First, many of the most knowledgeable researchers on torrent control, debris flow hazard assessment and mitigation or mountain sediment and large wood transport in Europe leading these researches in their respective countries are part of the consortium. The main domains of the Members' expertise are nonetheless well balanced between earth and related environmental sciences, civil engineering and environmental engineering ensuring a broad and comprehensive perspective. Second, the Action has clearly a twofold component, scientific and technical: the Action will clarify the scientific consensus to define the state-of-the-art techniques and build new structure types or improve the most promising existing ones. Such an approach could have been a challenge for researchers not used to direct field application and transfer to end-users. However, a large part of the participants are indeed also working closely and regularly on case-studies and consulting, i.e., directly with stakeholders and risk managers. Several Members are even actually managers of torrent control structures; they will obviously make sure that the Action deliverables can be directly transferred and used in the fields on real case-studies.

The scientific production of the consortium on the topics addressed by the Action has been regular in the last decade and very active recently, both in local non-English journals for end-users as well as in high-profile journals. The Action will benefit from several past and on-going productive and successful collaborations among the Members, which led to European and nationally funded projects.

The geographic coverage of the Member extends on most of mountain massifs subjected to active erosion and regular torrential disasters in Europe, Japan and America spanning notably oceanic, temperate, continental, Mediterranean, tropical and arid climate zones, contrasted land used and risk management practices and policies, hereby covering a wide range of situations and issues.
## 2.2.2 INVOLVEMENT OF STAKEHOLDERS

Representatives of most relevant stakeholders are already within the consortium: private and public design engineers, construction engineers, maintenance engineers, management administrations and scientists. In addition, the Action Members will perform:

* High networking with existing associations and working groups dealing with and interested in open check dams and solid transport management. Connections will be created with e.g.:

* Debris Flow and Steep Creek Hazards Mitigation Committee of the Association of GeoHazards Professional;

* INTERPRAEVENT association, the international research society on mountain disaster risk reduction;

* FAO Mountain Partnership group, and subgroup working on mountain hazards;

* International Commission on Large Dams (ICOLD);

* Swiss Commission on Flood Protection (KOHS), the Natural Hazard Experts (FAN);

* National torrent control services, e.g., BMNT die-wildbach in Austria, Servicio Bacini Montani in Italia, ONF-RTM in France as well as ministries' services in charge of risks.

* Advertising and publication of synthesis papers presenting the Action work in local technical and scientific journals having a mostly end-user audience, e.g.: Wasser Energie Luft (SWI.), La Houille Blanche (FRA.), Journal of Erosion Control Engineering (JAP.), Journal of Mountain Science (CHI.), Bulletin of the Faculty of Forestry (SER.), Wildbach- und Lawinenverbau (AUT), L'Acqua (IT), Journal of Agricultural Engineering (IT.), etc.

* Training school for end users and ministry officers as presented §1.2.2.2 and in §3.2.2.

## 2.2.3 MUTUAL BENEFITS OF THE INVOLVEMENT OF SECONDARY PROPOSERS FROM NEAR NEIGHBOUR OR INTERNATIONAL PARTNER COUNTRIES OR INTERNATIONAL ORGANISATIONS

Torrent control activities and more specifically the use of open check dams are much older and advanced in some countries as Austria, yet equipped with more than 2,500 structures, or Japan where part of the 50,000 trained torrents are equipped with such structures, proving their relevance and probable heavy need in optimization. Conversely in other countries, only a few structures only yet exist but thousands will be planned in the future. The **interest in these structures is indeed shared** in all countries (Lopez 2010, Moase 2017) and the lack of open check dams in some of them is generally related to the **absence of any experts from academic or engineering on this topic able to design local structure or train engineers** to do so. The inclusion of several countries from the Balkans and Mediterranean coast (Spain, Greece, Turkey) or Portugal in the Action will **set seeds of technics and capacities** in locations where there are expectations and needs.

In addition to the more than 30 European Members coming from 14 COST member countries, highly relevant experts from International Partner Countries (IPC) are included in the action and will participate in the training of the Members and possibly of end-users:

* Prof. Takahisa MIZUYAMA is a leading figure in torrent control work research and technology from the National Graduate Institute for Policy Studies of Tokyo, Japan, where he held the chair in Erosion Control Engineering (SABO in Japanese). He has the support from the Japanese Ministry of Land and Transport (MLIT) of the Government and Sabo Technical Center (STC) to join the Action and attend meetings and training schools. He will be supported by Dr. Akihiko IKEDA of STC who is expert in debris flows rheology, master plan and countermeasures for debris flows, design of SABO facilities and disaster investigation and Prof. Toshiyuki HORIGUCHI from the National Defence Academy, also expert in SABO dams.

* Prof. Bruno MAZZORANA from Univ. Austral de Chile has a long experience in design of more reliable and more functional structural protection measures and their management.

* Prof. José Luis LOPEZ from Univ. Central de Venezuela was in charge of the design of open structures and mitigation measures after a huge debris-flow disaster in Vargas in 1999.

* Dr. Matthias JAKOB and MSc. Emily MOASE from BGC engineering in Vancouver, Canada, are North American experts in torrential hazards, mitigation measure design.
# 3 IMPACT

## 3.1 IMPACT TO SCIENCE, SOCIETY AND COMPETITIVENESS, AND POTENTIAL FOR INNOVATION/BREAK-THROUGHS

### 3.1.1 SCIENTIFIC, TECHNOLOGICAL, AND/OR SOCIOECONOMIC IMPACTS (INCLUDING POTENTIAL INNOVATIONS AND/OR BREAKTHROUGHS)

The scientific, technical and socioeconomic perspectives of this Action are notably related to:

* The definition of the next generation of solid transport regulation and trapping structures, through cross-comparison, cross-feeding and improvement of the recent researches, patents and feedback from the field gathered by the Action Members who are highly willing to lead breakthroughs in the current paradigms in risk assessment and mitigation approaches.

* Countries with existing open structures will need guidance to optimize a large number of them for better selectivity and safety, consistently with new protection standards or old- and ill-design generating un-adapted trapping, probable failure mode and unreliable structures.

* Countries with less structures plan to build a large number of them. Regarding their density and effectiveness in countries as Austria and Japan, it seems reasonable to consider that thousands of open structures will be built in mountainous inhabited regions globally in the next twenty to thirty years, each of them worth typically 200-2,000 k€ and their ill-design usually rapidly weight several thousands of euros yearly or more for dredging costs and downstream channel stabilization. Currently, the lack of guidance and local expertise is the main obstacle to the mainstreaming of these effective and efficient technologies. If innovating structures are not defined and guidelines are not published, more people will suffer from hazards, the same mistakes, trial and errors will be performed in all mountain regions worldwide, millions of euros will be spent in dredging gravel, with additional ecological impacts complicated to valuate.

* Provide data for model calibration and validation: at least one data paper will be published to provide a clear view of the existing data concerning interactions between open structures and torrential flows, enabling people to practice and benchmark their approaches.

* Provide a fair appraisal of the current state of knowledge limits through a perspective paper reviewing where do we stand after a comprehensive appraisal and what are the remaining knowledge gaps and research needs.

* Consolidate research networks, particularly through Short Term Scientific Missions (STSM).

* Consolidate and train the next generation of scientists and high level engineers in sediment transport management and modelling, and protection structures' design and management.

* Make available comprehensive and up-to-date guidelines to help the design of profoundly complex structures having long term impacts on hazards, environment and local economy;

* Immediately train practitioners through ten training schools for the design of future structures enabling safer risk mitigation, reduce number of failures and ill-designs and optimized solid transport management in a more efficient and sustainable way worldwide.

* Communicate with decision makers and citizens on hazards and mitigation measures.

## 3.2 MEASURES TO MAXIMISE IMPACT

### 3.2.1 KNOWLEDGE CREATION, TRANSFER OF KNOWLEDGE AND CAREER DEVELOPMENT

* Working Groups have been defined to address the four steps of best-adjusted protection measure design, namely (i) definition of the protection requirement and objectives, (ii) definition of the protection structure type and geometry, (iii) selection and design of structural components and (iv) life-cycle assessment including monitoring and maintenance. Action Members come from broad horizons and types of affiliations to bring together all the required backgrounds, know-hows, research and practical knowledges to set a comprehensive trans-disciplinary approach of each challenge and transfer knowledge on these four domains.
* Actions Participants were selected with wide ranges of experiences and career stages: from PhD students to emeritus professors. ECIs will take great advantage of the workshops, at least two per Action year, and STSMs (see below) to find mentors, launch by-lateral discussions and learn from the exchanges with and between more senior experts.

* The Action will organize 12-20 STSMs between Members (number to define depending on the budget and duration). Promising methods and approaches identified along the Action will be explored with the help of the newly gathered data and / or using newly or recent tools and models. It will start, strengthen and facilitate exchanges, more relevant researches in future projects and better collaborations in and beyond Europe, e.g., with Japan, Chile, Venezuela and Canada, also preventing overlapping or repetition with existing works.

* Action years #3 and #4 will be devoted to the writing of papers on remaining research challenges and review of failure cases and failure modes, to the finalization of design and maintenance guidelines in the form of a book and to external training schools to teach and train end-users.

* The Members will learn a lot through these papers' writing on future research needs and analysis of errors and ill-designs: such lessons from the past are meaningful.

* Writing a book is a different exercise than scientific papers, giving room to more in-depth analysis and illustrative applications from which ECIs will also learn a lot.

### 3.2.2 PLAN FOR DISSEMINATION AND/OR EXPLOITATION AND DIALOGUE WITH THE GENERAL PUBLIC OR POLICY

The first half part of the Action work is centred on innovation, knowledge sharing and capacity building between Members, enabling to prepare the second half part which is essentially dedicated to dissemination, training and spreading of the Action fruits in at least five different public domains:

1. **Decision makers** in risk management and **citizens** living in risk areas whose participation in decision making is increasing requiring tools to stress *pro and cons* of open structures and other topics deserving communication material (see deliverable #15).

2. **River managers and administration officers** must be aware of the guidance documents, communication tools and activities and expertise of the local Members:

a. Ministries in charge of risks or other national agencies will be approached in each country to find money for the translation in local languages of the guidelines and communication tools and to raise their awareness of Members' involvement.

b. During the external training schools (see below), one day will be dedicated to an audience of ministries officers and stream managers to raise their awareness on the Action results, content of guidelines and potential of open structures. One to two hundreds of public officers at least will thus spread the word to stakeholders and ask private companies to refer to the Action outcomes, encouraging direct use of them.

3. Training and technical support of **senior engineers** in charge of the actual implementation through the edition of guidance document and training to use them:

a. At least ten 'External' training schools will be organized in European countries during year #3 for English spoken and year #4 after the translation (see above) for non-English spoken audiences. Couples will be created with one mentor Member helping one less-experienced Member, each couple teaching in the training school of the both Members' countries. Overall, a cumulated number of 80 to 150 public and private engineers will be trained to the application of guidelines on prepared case studies.

b. The guidelines will be a key Action output for the Action results' dissemination. It will enable a direct transfer to practitioners of the innovations emerging from the networking, collaborations and synthesis shared and performed by the Members.

4. Students will be trained by Members with teaching activities and by others using the lecture material (see deliverable #16). The Members will advertise, in universities teaching mountain hazards, the relevance and availability of this open source material easing medium to long term impacts by the **education** of hundreds of **future practioners**, yearly.

5. **Research funding and management** on the remaining challenges as already stressed.

## 4 IMPLEMENTATION
# 4.1 COHERENCE AND EFFECTIVENESS OF THE WORK PLAN

## 4.1.1 DESCRIPTION OF WORKING GROUPS, TASKS AND ACTIVITIES

The action is organized in 5 working groups (WGs): one dedicated to the database creation, which is transdisciplinary and four that address the main steps of torrent control work design: hazard assessment, functional and structural designs and lifecycle management. All Members are interested in the activities of more than one WG, thus even though the activities of WGs are not perfectly evenly organized along the Action's four years; everybody can always participate and follow at least one WG.

**Notation:** Milestones and their number are represented as numbers in open circles, e.g., Milestone #1 is noted ①; deliverable are similarly noted in colored circles; colored in dark grey for reports e.g., Deliverable #8 is noted ⑧, and in red for scientific journal papers e.g., Deliverable #3 (journal paper) is noted ③; '#1' denotes for instance Action year number one; Task 2 of WG 1 is noted 'WG1-T2'.

**WG1:** Scenarios, objectives, design inputs

**Objectives:** Working group 1 (WG1) will focus on why, which, how much and where trapping and regulating solid transport may be relevant.

**Tasks:** WG1-T1: As mentioned above, a torrential disaster is characterized by massive entrainment, transport and deposition of sediment and large woods, and by flooding of assets following a river channel malfunction. A challenge in determining the suitable protection system is to understand the possible chains of events that may lead to the disaster. In other words, the symptoms of fan/valley flooding may have several causes as boulders and/or large wood obstructing bottleneck sections, insufficient transport capacity of the channel or cumulated volume in excess compared to the system buffering capacity. WG1-T1 will provide a **new framework to unravel the origin of torrential hazards.** It will naturally help clarifying the objectives a tailored protection system should achieve, e.g., removing material coarser than a certain size from the flow, break debris flow fronts, reduce instantaneous discharge below a certain value, trap all volume above a given value; while – here is the challenge – minimizing impact on stream morphology and routine events and biota migration.

**WG1-T2:** Existing methods for hazard characterization will be reviewed, stressing their pro and cons, as well as the required data. A focus will be done on methods providing input parameters required for the design, e.g., solid volume supplied, hydrograph, size of boulders and large woods, debris flow velocities and heights, this for **several scenarios** if required and for all range of events from routine ones up to extremes. The possible influence of climate change on the processes will be reviewed. Criteria to determine the best location for the structure(s) will also be addressed.

**Activities:** WG1 will mostly focus on WG1-T1 during Y#1 and organize the 1st internal training school; on WG1-T2 beginning of Y#2 and writing of the guidelines' Chapter 1 on Y#2; general papers and full guidelines, training and lecture material and external training schools during Y#3-4.

**Milestones:** ① First draft of the framework to appraise channel potential malfunction. ④ First internal training school program, content and material. ⑥ Lay-out and content of the guidelines (chapter 1).

**Deliverables:** ① Paper on a conceptual framework for the characterization of possible channel malfunctions. ③ Paper on decision aids in the selections of the events and scenarios used in the design. ⑧ Chapter one of the guidelines.

**WG2:** Structure type and functional design

**Objectives:** WG2 will improve the design of existing open structures, describe new structures types and provide a step-by-step framework for their functional design: dams and basins shape definition.

**Tasks:** WG2-T1: There is a great diversity of open check dam shapes and choosing which one is suitable for a given site is very complicated. The first task of WG2 will be to design a flow chart for the selection of the relevant protection measures to implement in order to prevent the identified-channel malfunctions, eventually with open check dam(s) but other measures will also be identified. Not only the type of open check dams is important, but the number of dams, required to trap or regulate the solid volumes estimated in the previous step, has to be determined. If new functions or objectives emerge late in the Action, this flow chart will be updated and adapted.
**WG2-T2:** WG2 will then clarify in detail how to design the shape, geometries of the structures and their upstream deposition basins to achieve the desired functions. The key roles of large woods and low and extreme magnitude events will be specially emphasized. Finally an iterative step-by-step procedure will enable the full functional design of structures including bottom outlets, main openings, spillways for extreme events, scouring protections and lateral embankment design. A free computational tool is likely to be produced to merge the panel of design criteria reviewed in the Action.

**Activities:** WG2 will mostly focus on WG2-T1 during Y#1, on WG1-T2 in parallel with the 2^nd^ internal training school organization and writing of guidelines' Chap. 2 on Y#2; general papers and full guidelines, training and lecture material and external training schools during Y#3-4.

**Milestones:**
② Draft of the protection scheme selection flow chart;
⑥ Lay out and content of the guidelines (chapter 2);
⑦ Second internal training school program, content and material with WG3.

**Deliverables:**
② Protection scheme selection flow chart;
⑥ Synthesis paper(s) on concept and functional design of selective open and flexible barriers;
⑨ Guidelines' chapter 2.

## WG3: Architectural and structural design

**Objectives:** WG3 will harmonize the knowledge on impact load and civil engineering design of open structures and provide a step-by-step framework to define the actions, loads and stress combinations.

**Tasks:** WG3-T1: Current, recent and old data on impact forces of torrential flows against solid and flexible barriers will be compared, analyzed and an harmonized approach acknowledging peculiarities and particular effects of geology, rainfall regimes and geomorphic processes at work will be proposed.

**WG3-T2:** Using inputs from WG1 (e.g., type of events, flow velocity and heights) and the general shape, dam height, size of the openings and basin geometry drawn from WG2, WG3 will define ways to perform the structural design of open structures in the framework of Eurocodes. Internal and external stability calculations will be reviewed for the check dam itself, its eventual metallic parts (grills, piles) and the embankments or upstream and downstream barriers. The actions, loads and stress combinations depending on the scenario will be proposed, including the prevention of long-term decay of the structure. Relevant architectural features for landscape integration and suitable construction materials will also be defined.

**Activities:** WG3 will mostly focus on WG3-T1 during Y#1 and beginning of Y#2; and on WG3-T2 and writing of the guidelines' Chap. 3 on end of Y#2; general papers and full guidelines, training and lecture material and external training schools during Y#3-4.

**Milestones:**
⑤ List of existing papers and datasets on impact forces against solid and flexible structures;
⑥ Lay-out and content of the guidelines (chapter 3).
⑦ Second internal training school program, content and material with WG2.

**Deliverables:**
④ Synthesis paper on impact forces, design load and structural design of solid and flexible barriers;
⑩ Guidelines' chapter 3.

## WG4: Monitoring, maintenance and life cycle management

**Objectives:** WG4 will provide best practices in the management of open check dams.

**Tasks:** WG4-T1: Open check dam monitoring and maintenance best practices will be reviewed and synthetized using both civil engineering and geomorphic indicators. Partial or full dredging policies will be discussed to explain when and how to perform it?; where to store the dredged sediment?; and what to do with boulders, large woods, and gravels. If specific regulations are applied in some countries they will be synthesized.

**WG4-T2:** A review of direct and indirect costs related to open check dams will be given to enable global costs analysis. From our experience, the temporal variability of torrents' activity and our imperfect knowledge of the processes require an adaptive management of some structures. Good practices of trap adaptation will be reviewed and exemplified with emblematic case studies. WG4 will report key questions managers should answer to determine if adaptation is required or not. Finally, life cycle management of open check dam will be presented.
**Activities:** WG4 will mostly focus on WG4-T1 during Y#1 and on WG4-T2 and writing of the guidelines' Chap. 4 on Y#2; general papers and full guidelines, training and lecture material and external training schools during Y#3-4.

**Milestones:** ③ Draft template of monitoring and maintenance forms. ⑥ Lay-out and content of the guidelines (chapter 4).

**Deliverables:** ⑤ Template of comprehensive forms for open structures structural and functional monitoring and maintenance. ⑪ Guidelines' chapter 4.

## WG5: A new database for model benchmarking

**Objectives:** Creating a database of observations on open check dam functioning (laboratory and field)

**Tasks:** WG5-T1: Design and maintenance engineers use numerical and small scale models to study structures shapes and loads. Small scale models are still regularly required because full comprehension of the physics of debris flows and solid transport are still lacking, this jeopardizing the accuracy of numerical models. The number of small scale and field observations has been increasing for two decades, and numerous results remain un- or partially-published and generally difficult to access. Model developments or improvements suffer this lack of data availability. WG5 will organize a survey to list, describe and whenever possible make openly available existing observations of sediment and large wood trapping in structures. This new database will enable faster and more comprehensive model benchmarking in the future.

WG5-T2: WG5 will facilitate the use of the database in the exploration works performed through Short Term Scientific Missions. At least one data paper will publicly present the content, structure and potential of this database, notably thank to these exploration.

**Activities:** WG5 will mostly focus on WG5-T1 during Y#1 and on WG5-T2 on Y#2-3.

**Milestones:** ⑦ Database structure description and first list of available dataset; ⑨ Pilot version of the database.

**Deliverables:** ⑦ Database online. ⑫ Data paper presenting the database.

## 4.1.2 DESCRIPTION OF DELIVERABLES AND TIMEFRAME

Hereafter are listed the Action deliverables. Their submission date is noted in year and trimester, e.g., Deliverable ① (Y#1-T3; WG1) means that deliverable 1 is due on 3rd trimester of year 1 by WG1.

**Deliverable** ① (Y#1-T3; WG1): creation of a new framework to apply to river channels in order to disentangle the cascading processes leading to solid material deposition and flooding; i.e., a channel malfunction identification framework. This framework will enable to clarify how the torrential processes should be changed to reduce efficiently hazards: e.g., filtration of coarse materials, dozing of high peak discharges, trapping of a given volume. It will be based on a flow chart and several hydraulics- and topographical-based indicators and criteria. Its journal submission will likely wait for its full maturation at the time scale of the Action.

**Deliverable** ② (Y#1-T4; WG2): creation of a flowchart chart for the selection of the open check dam(s) or other protection options able to fulfill the process change objectives selected thanks to the initial hazard appraisal, notably using methods developed in WG1 (① and draft of ③). This flow chart will clarify where open check dams are relevant and where they are not. It will also make clear not only the type of open check dams to implement, but the number of dams, required for trapping or regulating the solid volumes estimated in the previous steps.

**Deliverable** ③ (Y#2-T2; WG1): scientific paper on decision aids in the selections of the events and scenarios use in the design. It will provide clear recommendations and guidelines on how to define (i) routine events that should be transferred through the protection system with marginal changes; (ii) design events for which protection effectiveness should be maximum; (iii) inflow design events to design the safety spillway; and (iv) safety check events above which structure failure become probable; which are used to check that failure modes should occur for sufficiently rare events.
**Deliverable** ④ (Y#2-T2; WG3): Paper describing a harmonized approach of old and recent results in impact forces, design load and structural design of solid and flexible barriers submitted to debris flows and debris flood processes, notably with a comparison between on-going field measurements in several countries. This should allow a European consensus description of impact loads preventing the emergence of country-specific rules related to smaller observation samples.

**Deliverable** ⑤ (Y#2-T2; WG4): Proposition and providing of comprehensive forms for the structural and functional monitoring and maintenance of open structures.

**Deliverable** ⑥ (Y#2-T3; WG2): Scientific paper(s) and technical design notes with supplementary examples of application describing how work and how to functionally design innovative open check dams with clear objectives regarding events from the frequent routine ones to extreme safety check ones. We suspect that at least 6 structure types will be described: (i) retention dams enabling routine event to pass, (ii) boulder traps, large wood traps both (iii) heavy, (iv) light and (v) flexible, and (vi) dozing dams.

**Deliverable** ⑦ (Y#2-T3; WG5): New open database of open structures functioning from laboratory and field observations enabling new model development and existing model calibration.

**Deliverable** ⑧ (Y#2-T4; WG1): Chapter 1 of the guidelines summarizing methods and approaches to use in the definition of supply conditions from upstream, likely channel malfunction downstream and fuelling the protection strategy definition flowchart.

**Deliverable** ⑨ (Y#2-T4; WG2): Chapter 2 of the guidelines describing the protection strategy definition flowchart and the functional design of open check dams.

**Deliverable** ⑩ (Y#2-T4; WG3): Chapter 3 of the guidelines describing the structural design of open check dams: impact forces, design load, internal and external equilibrium. WG3 will make sure to provide recommendations on the safety factors to use in the Eurocode design standard and the assumptions related to the recommended values. No project had enabled to date the relevant scientists and practitioners to discuss and agree on this key question of civil engineering design.

**Deliverable** ⑪ (Y#2-T4; WG4): Chapter 4 of the guidelines describing open structure life cycle management: cost-benefit analysis methods and data on investment and maintenance costs to use at the design stage; monitoring and maintenance good practices; best-practices and relevant example in adaptive management.

**Deliverable** ⑫ (Y#3-T3; WG5): Data paper presenting the database and its potential use exemplified by several benchmarking approaches implemented during STSMs related to the Action.

**Deliverable** ⑬ (Y#3-T4; all Members): Review paper on failure modes and adaptive maintenance of open structures used for solid transport management.

**Deliverable** ⑭ (Y#4-T1; all Members): Review paper on research needs and remaining challenges in research on interactions between torrential processes and torrent control works.

**Deliverable** ⑮ (Y#4-T2; all Members): Communication flyers for stakeholders illustrating take-home messages on solid transport management good practices, e.g., "How solid transport aggravates floods?", "Why and why not regulating or trapping part of the solid transport?", "Direct and side effects of irrelevant solid transport management" or "Potential and limits of open protection structures".

**Deliverable** ⑯ (Y#4-T3; all Members): Lecture material for a 6*2h course dedicated to Master students explaining: (1) Good and wrong reasons for trapping solid transport (coarse sediment and large woods), (2) Ways to do that: open check dams and other options, (3) Data and studies required: upstream catchment and downstream channel, (4) Functional design, (5) Structural design and (6) Life cycle analysis. Its draft version is Milestone ⑩ due beginning of Y#4.

**Deliverable** ⑰ (Y#4-T4; all Members): Full design and maintenance guidelines of open structure dedicated to regulate and trap solid material in mountain rivers and torrents. The draft version for external review is Milestone ⑧ due beginning of Y#3.

### 4.1.3 RISK ANALYSIS AND CONTINGENCY PLANS
**Risks** on the Action level will be overseen by the Chair who will use dedicated methods for project planning and control. A good and regular communication between subgroups of the consortium, i.e., according to COST guidelines, Management Committee (MC), Steering Committee (SC), WGs and Action Members, will ensure to prevent and anticipate risks before they arose. Risks and related contingency plans were identified with respect to (i) project management, e.g., Chair or WG leader failing to manage his task or Grant Holder failing to address his responsibilities. → Each leading position will be assigned a vice- or co-leader that will bring support as soon as necessary. The SC will be informed and nomination of a new leader or support in the task management will be found among the Members. (ii) Excess in workload, e.g., too high work load for individual Members or (iii) the time plan, e.g., delay in producing deliverables. → WG leaders will organize the work effort and deliverable production according to Members' capacities and availability. Regular progress check will be held, notably Milestones were created ahead of critical contributions to the Action result. Their submission dates were chosen early enough to reorganize the WG to ensure the deliverable production in due time if issues are appearing. Draft version progresses will be tracked to meet the submission deadline with all necessary Members' contributions. (iv) Partnerships, e.g., partner or Member fails or refuses to provide data, to assist workshop or to organize training schools. → The dispute management plan will be implemented in such case (see below). The consortium has additionally been tailored large enough to benefit from several Members with skills and data covering all Action domains to secure the work. (iv) Complexity, e.g., difficulties to define a framework or innovative new structures, or misalignments between stakeholder needs and structures / methods developed. → If the new innovative structures developed by recent researches or new framework finally prove not to satisfy the practitioners needs, the Action will rather focus on improving the most satisfying existing solutions for instance with recent works on fish-friendly outlet, routine event transfers and reliability to extreme events. In essence, risk management will be a continuous process led by the Chair and a Steering Committee (SC). Risks will systematically be identified at each workshop and mitigation measures will be initiated accordingly.

**Disputes** will be resolved in accordance with a clearly defined process: (i) A solution in agreement with the objectives of all parties is aimed for; (ii) The dispute should be resolved at the appropriate level, with all discussions conducted in an open and honest manner. In case of a dispute the Chair shall be immediately informed and will assess the potential effect of the dispute on the entire Action, and following consultation with experts of the Chair's institute and the SC, will decide on the appropriate approach for resolving the dispute. This may be achieved by local intervention or, in extreme cases, calling an emergency meeting where possible courses of action can be discussed and voted upon. The WG leaders will compile and regularly update a Risk Statement Form, which describes each risk and its threat to the Action. The Chair will then assign the issue to a Member or a group of Members who will then actively work on a resolution. The status of the resolution will be tracked by the Chair. After resolving an issue, the process will be documented and shared among the consortium. In case of major problems or delays the Chair will immediately communicate with the consortium to ensure that corrective actions are agreed upon and implemented at an early stage.

### 4.1.4 GANTT DIAGRAM

<table><thead><tr><th>Year</th><th colspan="4">Y#1</th><th colspan="4">Y#2</th><th colspan="4">Y#3</th><th colspan="4">Y#4</th></tr><tr><th>Trimestre</th><th>1</th><th>2</th><th>3</th><th>4</th><th>1</th><th>2</th><th>3</th><th>4</th><th>1</th><th>2</th><th>3</th><th>4</th><th>1</th><th>2</th><th>3</th><th>4</th></tr></thead><tbody><tr><th>MC Meeting</th><td>X</td><td>X</td><td></td><td>X</td><td></td><td>X</td><td></td><td>X</td><td></td><td>X</td><td></td><td></td><td>X</td><td></td><td>X</td><td></td></tr><tr><th>WG Meeting</th><td></td><td>X</td><td></td><td>X</td><td></td><td>X</td><td></td><td>X</td><td></td><td>X</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><th>SG Meeting</th><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td></tr><tr><th>STMSs</th><td></td><td></td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td></tr><tr><th>Internal Training School</th><td></td><td></td><td></td><td>X</td><td></td><td></td><td>X</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><th>External Training School</th><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td>X</td><td>X</td><td>X</td><td></td><td>X</td><td>X</td><td></td></tr><tr><th>Translation (externally funded)</th><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td>X</td><td>X</td><td></td><td>X</td><td></td><td></td></tr><tr><th>Open final conference</th><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td>X</td></tr><tr><th>Milestones</th><td>①</td><td>②</td><td>③</td><td>④</td><td>⑤</td><td>⑥</td><td>⑦</td><td>⑧</td><td>⑨</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><th>Deliverable involving - all Members</th><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td>13</td><td>14</td><td>15</td><td>16</td><td>17</td></tr><tr><th>-WG1</th><td></td><td></td><td></td><td></td><td></td><td></td><td>③</td><td></td><td>⑧</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><th>-WG2</th><td></td><td></td><td></td><td></td><td>②</td><td></td><td></td><td>⑥</td><td>⑨</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><th>-WG3</th><td></td><td></td><td></td><td></td><td></td><td></td><td>④</td><td></td><td>⑩</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><th>-WG4</th><td></td><td></td><td></td><td></td><td></td><td></td><td>⑤</td><td></td><td>⑪</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><th>-WG5</th><td></td><td></td><td></td><td></td><td></td><td></td><td>⑦</td><td></td><td></td><td>⑫</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr></tbody></table>

Notation: Milestones: ①-⑩, Deliverables, grey=reports ②-⑯, red=papers ①-⑭
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Wohl (2006) *Geomorphology* 79:217–248.

Zollinger (1985) *Proc. of Inter. Symp. on Erosion, Debris Flow and Disaster Prevention*. Tokyo. p. 433–438, In German
## COST Mission and Policies

Flood hazards in mountain and piedmont regions involve more than just water: rivers and torrents carrying sediment and large woods during extreme events. Sediment and large wood regulating and trapping facilities (SLWRTFs) can be effective and efficient structures that are increasingly used in protection schemes but still very complicated to design due to a lack of knowledge on the processes at work in their functioning. The main objective of the COST Action is to improve the technical and economic effectiveness of SLWRTFs through the creation of innovative selective structures and writing of full guidelines for their design and maintenance. The Action is specifically designed to gather and improve the best level of knowledge in the pan-European community to spread and mainstream effective protection solutions globally. The Action is in line with the COST association mission and policy, particularly:

* The development of European-based scientific and technological networks and encouraging and enabling researchers from less research-intensive countries across Europe to set up or join COST Actions

The Action will create new and consolidate existing collaborations between European scholars and engineers studying mountain hazard mitigation. Several Short Term Scientific Missions will be organized each year between Action Members. At least two meetings per working group will also enable an effective transfer of knowledge and skills between research-intensive countries toward Inclusiveness Target Countries (ITC). The consortium comprises partners from seven ITC with skills in hazard assessment; forestry management and erosion control, but usually less knowledge in SLWRTFs which have been poorly used in their countries. This high number of ITC partners is specifically intended to maximize the Action impact on the entire European research network.

* The provision for collaboration opportunities to all researchers in order to employ all talented and creative human resources, providing networking opportunities for early career investigators and counterbalancing research communities' unequal access to knowledge, infrastructures, funding and resources

More than twenty Early Carrier Investigators (ECIs) participate in the Action. They will particularly benefit from training of skilled International experts from Japan, Canada, Venezuela and Chile in addition to their top level European colleagues. Innovative new structures and existing best-practices improved by recent results of all the community will thereby be rapidly assimilated in all Europe. At a broader scale, the European community will benefit from the advanced skills of Japanese experts. The Action will thus form and train a leading group of experts in hazard mitigation knowing about European and pan-European best practices, adapted to any climate and context worldwide. They will be able to improve each national best-practices but also to intervene anywhere in the world to disseminate the European know-how on SLWRTFs. By defining new solutions and coordinating guideline edition for SLWRTFs, a European group takes the leading position on the topic and consolidates the European key position in technology and science for a safer and environment-friendly world.

* The exploitation of the research outcomes by integrating all stakeholders

Structure managers, design engineers and administrators are involved in the Action. They will actively coordinate Working Groups and participate in the writing process. The Action organization thereby ensures the involvement of these key stakeholders as well as an internal control for the immediate applicability of the Action outcomes. The numerous training schools organized within the Action are a significant effort by the Members to ensure the immediate additional dissemination, transfer and application of the guidelines to end-users.

* The dissemination of results of research activities in order to improve their scientific, social and economic impact;

Partners of the Action already participated in research projects on mountain rivers, mitigation measures and solid transport management for instance through national and European projects (e.g., Intereg, H2020). They have skills and experience in field, numerical and laboratory observations of SLWRTFs. They are thus used to write recommendations, technical notes, papers and books on the Action topics. However their past works are often only partially published, sometimes accessible only to a national audience because not
available in English and globally spread in numerous existing reports, thesis and papers difficult to access for end-users. Nonetheless, the knowledge gained in the two past decades is significant and worthwhile to be more disseminated. It is thus relevant to take the time to perform a comprehensive appraisal, to organize debates between experts on points to clarify and to define the next generation of protection structures along with comprehensive design and maintenance procedures. This is the main objective of the Action. The scientific, technologic and societal impacts of all the past researches will immediately strongly gain in impact, being the pillars and foundations of the proposed innovating selective structures.

The Action is also a good opportunity to list the existing dataset currently stored in archives and to gather them in a new open database on observation of SLWRTF functioning. This database is an Action deliverable and will be useful for end-users and researchers to calibrate their models and better understand how sediment and large woods are trapped in SLWRTFs enabling optimization.

* Promoting geographical, age and gender balance throughout its activities and operations.

The action consortium is composed of about forty proposers coming from 18 countries: 14 COST countries institutions, half of them being ITC and 4 international partners. More than half of the consortium partners are Early Carrier Investigators which is very consistent with the Action objective to train the next generation of world experts in mountain stream hazard mitigation. The main domains of the members' expertise are well balanced between earth and related environmental sciences, civil engineering and environmental engineering ensuring a broad and comprehensive perspective.

* Increasing the impact of research on policy makers, regulatory bodies and national decision makers as well as the private sector.

Once the guidelines available, at least ten training schools will be organized for stakeholders as design and construction engineers from the public and private sectors, risk and structure managers and administration officers. Additionally open access, ready to use lecture notes will be prepared and disseminated to be taught in universities worldwide. It will synthesize the essence of the guidelines focusing on concepts and key messages.
## Network of Proposers - Features

### COST Inclusiveness target countries

50.00 %

### Number of Proposers

38

### Geographic Distribution of Proposers

<table><thead><tr><td>Country</td><td>ITC/ non ITC/ other</td><td>Number of institutions from that country</td><td>Number of researchers from that country</td><td>Percentage of the proposing network</td></tr></thead><tbody><tr><td>Austria</td><td>non ITC</td><td>3</td><td>3</td><td>7.89 %</td></tr><tr><td>Bulgaria</td><td>ITC</td><td>1</td><td>1</td><td>2.63 %</td></tr><tr><td>Canada</td><td>other</td><td>1</td><td>1</td><td>2.63 %</td></tr><tr><td>Chile</td><td>other</td><td>1</td><td>1</td><td>2.63 %</td></tr><tr><td>Czech Republic</td><td>ITC</td><td>1</td><td>1</td><td>2.63 %</td></tr><tr><td>France</td><td>non ITC</td><td>3</td><td>3</td><td>7.89 %</td></tr><tr><td>Germany</td><td>non ITC</td><td>1</td><td>1</td><td>2.63 %</td></tr><tr><td>Greece</td><td>non ITC</td><td>2</td><td>2</td><td>5.26 %</td></tr><tr><td>Italy</td><td>non ITC</td><td>4</td><td>5</td><td>13.16 %</td></tr><tr><td>Japan</td><td>other</td><td>3</td><td>3</td><td>7.89 %</td></tr><tr><td>Portugal</td><td>ITC</td><td>3</td><td>3</td><td>7.89 %</td></tr><tr><td>Serbia</td><td>ITC</td><td>2</td><td>2</td><td>5.26 %</td></tr><tr><td>Slovenia</td><td>ITC</td><td>1</td><td>1</td><td>2.63 %</td></tr><tr><td>Spain</td><td>non ITC</td><td>2</td><td>2</td><td>5.26 %</td></tr><tr><td>Switzerland</td><td>non ITC</td><td>4</td><td>5</td><td>13.16 %</td></tr><tr><td>Turkey</td><td>ITC</td><td>2</td><td>2</td><td>5.26 %</td></tr><tr><td>Venezuela</td><td>other</td><td>1</td><td>1</td><td>2.63 %</td></tr><tr><td>fYR Macedonia</td><td>ITC</td><td>1</td><td>1</td><td>2.63 %</td></tr></tbody></table>

### Gender Distribution of Proposers

84.2% Males

15.8% Females

### Average Number of years elapsed since PhD graduation of Proposers with a doctoral degree

14.6

### Number of Early Career Investigators

22

### Core Expertise of Proposers: Distribution by Sub-Field of Science

34.2% Civil engineering

31.6% Earth and related Environmental sciences

26.3% Environmental engineering

2.6% Agriculture, Forestry, and Fisheries

2.6% Other engineering and technologies

2.6% Unspecified
## Institutional distribution of Network of Proposers

84.2% Higher Education & Associated Organisations

10.5% Government/Intergovernmental Organisations except Higher Education

5.3% Business enterprise

Higher Education & Associated Organisations:32

* **Number by Field of Science of Department/Faculty of Affiliation**
  Earth and related Environmental sciences:10
  Civil engineering:13
  Agriculture, Forestry, and Fisheries:4
  Environmental engineering:4
  Other engineering and technologies:1

* **Number by Type**
  Research Oriented:13
  Education Oriented:19

* **Number by Ownership**
  Fully or mostly public:31
  50-50 Public and Private:1

Government/Intergovernmental Organisations except Higher Education:4

* **Number by Level**
  Central and Federal Government:3
  Local government:1

* **Number by Type**
  Government department or government-run general public services:3
  Non-R&D executive agencies, including sector specific regulatory bodies:1

Business enterprise:2

* **Number by Market sector of unit of affiliation**
  Professional, Scientific And Technical Activities:1
  Construction:1

* **Number by Type**
  Private enterprises:2

* **Number by Ownership and International Status**
  Independent Enterprise:2

* **Number by Size**
  SME (EU Definition provided underneath after selection):1
  Large company:1

**COST Country Institutions(14)**: Austria, Bulgaria, Czech Republic, France, Germany, Greece, Italy, Portugal, Serbia, Slovenia, Spain, Switzerland, Turkey, fYR Macedonia

**Near-Neighbour Country Institutions(0)**

**COST International Partners(4)**: Canada, Chile, Japan, Venezuela

**European Commission and EU Agencies(0)**

**European RTD Organisations(0)**

**International Organisations(0)**
## Network of Proposers - Details

### Main Proposer's Details

<table><tr><td>Title:</td><td>Dr</td><td>Gender:</td><td>M</td></tr><tr><td>First Name:</td><td>Guillaume</td><td>Years from PhD:</td><td>2</td></tr><tr><td>Last Name:</td><td>PITON</td><td>Telephone Number:</td><td>+33476762825</td></tr><tr><td>Email:</td><td>guillaume.piton@irstea.fr</td><td>Type of Institution:</td><td>Higher Education & Associated Organisations</td></tr><tr><td>Institution:</td><td>irstea</td><td></td><td></td></tr><tr><td>Address of the Institution:</td><td colspan="3">2 rue papeterie, BP76, 38402 Gières, France</td></tr><tr><td>Sub-field of Science of Department:</td><td>Earth and related Environmental sciences</td><td>Core Area of Expertise:</td><td>Earth and related Environmental sciences (Hydrology, water resources)</td></tr></table>
## Secondary Proposers' Details

<figure><img src="image_251.png" /></figure>

### Austria

**Prof Johannes Huebl (Universität für Bodenkultur Wien - Institute of Mountain Risk Engineering)**

Participating as Secondary Proposer

E-mail: ian@boku.ac.at

Telephone: +4314765487100

Core Expertise: Environmental engineering: Risk assessment, prevention and mitigation

Gender: M

Years from PhD: 23

**Mr Georg Nagl (University of Natural Resources and Life Sciences, Vienna - Institute of Mountain Risk Engineering [Department of Civil Engineering and Natural Hazards])**

Participating as Secondary Proposer

E-mail: georg.nagl@boku.ac.at

Telephone: +43 1 47654-87123

Core Expertise: Environmental engineering: Risk assessment, prevention and mitigation

Gender: M

Years from PhD: 0

**Ms Monika Stanzer (University of Natural Resources and Life Sciences Vienna - Institute of Mountain Risk Engineering [Department of Civil Engineering and Natural Hazards])**

Participating as Secondary Proposer

E-mail: monika.stanzer@boku.ac.at

Telephone: +43 1 47654 87100

Core Expertise:

Gender: F

Years from PhD: 0

<figure><img src="image_252.png" /></figure>

### Bulgaria

**Ms Eli Pavlova-Traykova (Bulgarian Academy of Science - Forest Research Institute [Forest ecology])**

Participating as Secondary Proposer

E-mail: pavlova.eli77@gmail.com

Telephone: +359 2 962-04-47

Core Expertise: Earth and related Environmental sciences: Soil erosion

Gender: F

Years from PhD: 0

<figure><img src="image_253.png" /></figure>

### Canada

**Ms Emily Moase (BGC Engineering Inc.)**

Participating as Secondary Proposer

E-mail: emoase@bgcengineering.ca

Telephone: (604)684-5900

Core Expertise: Environmental engineering: Geotechnics

Gender: F

Years from PhD: 0

<figure><img src="image_254.png" /></figure>

### Chile

**Prof Bruno Mazzorana (Universidad Austral de Chile - Universidad Austral de Chile - Chile [Facultad de Ciencias, Instituto de Ciencias de la Tierra])**

Participating as Secondary Proposer

E-mail: bruno.mazzorana@uach.cl

Telephone: 005696515334

Core Expertise: Environmental engineering: Risk assessment, prevention and mitigation
Gender: M

Years from PhD: 9

<figure><img src="image_255.png" /></figure>

## Czech Republic

Dr Tomáš Galia (University of Ostrava [Department of physical geography and geocology])

Participating as Secondary Proposer

E-mail: tomas.galia@osu.cz

Telephone: +420 597 092 2360

Core Expertise: Earth and related Environmental sciences: Physical geography

Gender: M

Years from PhD: 6

<figure><img src="image_256.png" /></figure>

## France

Dr Simon Carladous (Office National des Forêts - Office National des Forêts [Natural Hazards Department])

Participating as Secondary Proposer

E-mail: simon.carladous@onf.fr

Telephone: 04 76 86 39 82

Core Expertise: Environmental engineering: Risk assessment, prevention and mitigation

Gender: M

Years from PhD: 1

Dr Stéphane LAMBERT (IRSTEA [ETNA])

Participating as Secondary Proposer

E-mail: stephane.lambert@irstea.fr

Telephone: +33476762794

Core Expertise: Civil engineering: Civil engineering

Gender: M

Years from PhD: 11

<figure><img src="image_257.png" /></figure>

## Germany

Mr Jan Schäble (Bavarian Environment Agency [Flood Protection and Alpine Natural Disasters])

Participating as Secondary Proposer

E-mail: Jan.Schaeble@lfu.bayern.de

Telephone: 49 (0)821 / 9071 - 5949

Core Expertise: Environmental engineering: Alpine Natural Hazards

Gender: M

Years from PhD: 0

<figure><img src="image_258.png" /></figure>

## Greece

Prof Panagiotis Stefanidis (Aristotle University of Thessaloniki - Aristotle University of Thessaloniki [School of Forestry and Natural Environment])

Participating as Secondary Proposer

E-mail: stefanid@for.auth.gr

Telephone: 00302310992712

Core Expertise: Earth and related Environmental sciences: Hydrology, water resources

Gender: M

Years from PhD: 0

Dr Dimitris Myronidis (Aristotle University of Thessaloniki - School of Forestry and Natural Environment [DEPARTMENT OF FOREST AND WATER ENGINEERING])

Participating as Secondary Proposer

E-mail: Myronid@gmail.com

Telephone: +00302310992736

Core Expertise: Earth and related Environmental sciences: Hydrology, water resources

Gender: M
<figure><img src="image_259.png" /></figure>

## Italy

### Prof Vincenzo D'Agostino (Università degli Studi di Padova [TESAF Department])

Participating as Secondary Proposer

E-mail: vincenzo.dagostino@unipd.it

Telephone: 0039 8272682

Core Expertise: Civil engineering: Fluid mechanics, hydraulic-, turbo-, and piston engines

Gender: M

Years from PhD: 0

### Mr Loris Torresani (University of Padova [TESAF department])

Participating as Secondary Proposer

E-mail: loris.torresani@phd.unipd.it

Telephone: +39 3481204134

Core Expertise: Earth and related Environmental sciences: Hydrology, water resources

Gender: M

Years from PhD: 0

### Dr Lorenzo Picco (University of Padova [TESAF Dept.])

Participating as Secondary Proposer

E-mail: lorenzo.picco@unipd.it

Telephone: 3407840268

Core Expertise: Earth and related Environmental sciences: Hydrology, water resources

Gender: M

Years from PhD: 8

### Prof Francesco Comiti (Free University of Bozen-Bolzano [Faculty of Science and Technology])

Participating as Secondary Proposer

E-mail: francesco.comiti@unibz.it

Telephone: +393287299963

Core Expertise: Earth and related Environmental sciences: Hydrology, water resources

Gender: M

Years from PhD: 14

### Prof Michele Larcher (Free University of Bozen-Bolzano [Faculty of Science and Technology])

Participating as Secondary Proposer

E-mail: michele.larcher@unibz.it

Telephone: +39 0471 017694

Core Expertise: Environmental engineering: Maritime and hydraulic engineering

Gender: M

Years from PhD: 15

<figure><img src="image_260.png" /></figure>

## Japan

### Prof Takahisa Mizuyama (National Graduate Institute for Policy Studies [Policy Studies])

Participating as Secondary Proposer

E-mail: byk01260@nifty.com

Telephone: +81-72-622-0247

Core Expertise: Earth and related Environmental sciences: Hydrology, water resources

Gender: M

Years from PhD: 46

### Dr AKIHIKO IKEDA (Sabo and Landslide Technical Center)

Participating as Secondary Proposer

E-mail: ikeda@stc.or.jp

Telephone: +81-3-5276-3275

Core Expertise: Civil engineering: Civil engineering
Gender: M

Years from PhD: 7

## Dr Toshiyuki Horiguchi (National Defense Academy [Civil Engineering/Structure mechanics laboratory])

Participating as Secondary Proposer

E-mail: [debrissegmentation@gmail.com](mailto:debrissegmentation@gmail.com)

Telephone: +81468413810

Core Expertise: Civil engineering: Civil engineering

Gender: M

Years from PhD: 4

<figure><img src="image_261.png" /></figure>

## Portugal

### Dr Ricardo Birjukovs Canelas (Instituto Superior Técnico)

Participating as Secondary Proposer

E-mail: [ricardo.canelas@ist.utl.pt](mailto:ricardo.canelas@ist.utl.pt)

Telephone: +351968922054

Core Expertise: Environmental engineering: Maritime and hydraulic engineering

Gender: M

Years from PhD: 3

### Prof Rui Ferreira (Instituto Superior Técnico Universidade de Lisboa)

Participating as Secondary Proposer

E-mail: [ruif@civil.ist.utl.pt](mailto:ruif@civil.ist.utl.pt)

Telephone: +351218418148

Core Expertise: Civil engineering: Fluid mechanics, hydraulic-, turbo-, and piston engines

Gender: M

Years from PhD: 13

### Prof Rodrigo Proença de Oliveira (Instituto Superior Técnico - Universidade de Lisboa [Departamento de Engenharia Civil, Arquitectura e Georecursos])

Participating as Secondary Proposer

E-mail: [rodrigopoliveira@tecnico.ulisboa.pt](mailto:rodrigopoliveira@tecnico.ulisboa.pt)

Telephone: +351218418140

Core Expertise: Civil engineering: Sustainable engineering, adaptation to long-term environmental changes

Gender: M

Years from PhD: 24

<figure><img src="image_262.png" /></figure>

## Serbia

### Dr STANIMIR KOSTADINOV (Institute of Forestry, Belgrade)

Participating as Secondary Proposer

E-mail: [stanimir.kostadinov@sfb.bg.ac.rs](mailto:stanimir.kostadinov@sfb.bg.ac.rs)

Telephone: +381113053851

Core Expertise: Agriculture, Forestry, and Fisheries: Soil erosion, Torrential floods, Erosion and torrent control

Gender: M

Years from PhD: 33

### Dr Tijana Vulevic (University of Belgrade, Faculty of Forestry)

Participating as Secondary Proposer

E-mail: [tijana.andrijanic@sfb.bg.ac.rs](mailto:tijana.andrijanic@sfb.bg.ac.rs)

Telephone: +38113053901

Core Expertise: Environmental engineering: erosion and torrent control, multi-criteria decision analysis

Gender: F

Years from PhD: 1
<figure><img src="image_263.png" /></figure>

## Slovenia

### Dr Jošt Sodnik (University of Ljubljana [Faculty of Civil and Geodetic Engineering])

Participating as Secondary Proposer

E-mail: jost.sodnik@gmail.com

Telephone: +386 1 476 85 00

Core Expertise: Civil engineering: Torrent control, erosion, slope stability, river training

Gender: M

Years from PhD: 1

<figure><img src="image_264.png" /></figure>

## Spain

### Dr Marcel Hurlimann (UPC BarcelonaTECH)

Participating as Secondary Proposer

E-mail: marcel.hurlimann@upc.edu

Telephone: +34934017377

Core Expertise: Earth and related Environmental sciences: Geology, tectonics, volcanology

Gender: M

Years from PhD: 19

### Dr Ernest Bladé (Universitat Politècnica de Catalunya [Flumen Institute])

Participating as Secondary Proposer

E-mail: ernest.blade@upc.edu

Telephone: 934017070

Core Expertise: Civil engineering: Civil engineering

Gender: M

Years from PhD: 13

<figure><img src="image_265.png" /></figure>

## Switzerland

### Dr Virginia Ruiz-Villanueva (University of Geneva [Institute for Environmental Sciences (ISE)])

Participating as Secondary Proposer

E-mail: virginia.ruiz@unige.ch

Telephone: 0041798575861

Core Expertise: Earth and related Environmental sciences: Physical geography

Gender: F

Years from PhD: 5

### Dr Dieter Rickenmann (Swiss Federal Research Institute WSL [Mountain Hydrology and Mass Movements])

Participating as Secondary Proposer

E-mail: dieter.rickenmann@wsl.ch

Telephone: +41 44 739 24 29

Core Expertise: Earth and related Environmental sciences: Hydrology, water resources

Gender: M

Years from PhD: 28

### Dr Lukas Schmocker (ETH Zürich [VAW])

Participating as Secondary Proposer

E-mail: schmocker@vaw.baug.ethz.ch

Telephone: +41446325278

Core Expertise: Civil engineering: Civil engineering

Gender: M

Years from PhD: 0

### Dr Volker Weitbrecht (ETH Zürich [VAW])

Participating as Secondary Proposer

E-mail: wv@ethz.ch

Telephone: +41446326823

Core Expertise: Civil engineering: Sustainable engineering, adaptation to long-term
environmental changes

Gender: M

Years from PhD: 0

### Dr Isabella Schalko (ETH Zurich [D-BAUG])

Participating as Secondary Proposer

E-mail: schalko@vaw.baug.ethz.ch

Telephone: +41 44 632 41 19

Core Expertise: Environmental engineering: Maritime and hydraulic engineering

Gender: F

Years from PhD: 1

<figure><img src="image_266.png" /></figure>

## Turkey

### Dr Emre AKÇALI (General Directorate of State Hyradulic Works [22th Regional Directorate])

Participating as Secondary Proposer

E-mail: emreakcali@dsi.gov.tr

Telephone: 00905336436505

Core Expertise: Civil engineering: Civil engineering

Gender: M

Years from PhD: 7

### Prof Ibrahim Gurer (Gazi University, Engineering Faculty, [Civil Eng, Hydraulics])

Participating as Secondary Proposer

E-mail: i.gurers@gmail.com

Telephone: +90 312 2351107

Core Expertise: Civil engineering: Water Resources Engineering, Gravity Flows (Floods, Avalanches)

Gender: M

Years from PhD: 43

<figure><img src="image_267.png" /></figure>

## Venezuela

### Dr Jose Luis Lopez (Universidad Central de Venezuela [Facultad de Ingeniería, Instituto de Mecánica de Fluidos])

Participating as Secondary Proposer

E-mail: lopezjoseluis7@gmail.com

Telephone: 58-212-6053131

Core Expertise: Civil engineering: Civil engineering

Gender: M

Years from PhD: 40

<figure><img src="image_268.png" /></figure>

## FYR Macedonia

### Prof Ivan Blinkov (Ss. Cyril and Methodius University in Skopje, [Faculty of Forestry Skopje, Unit of Land and Water])

Participating as Secondary Proposer

E-mail: ivanblinkov12@yahoo.com

Telephone: +3893072068

Core Expertise: Other engineering and technologies: watershed management - erosion and torrent control

Gender: M

Years from PhD: 20
Annexe 16. European Geosciences Union (EGU) – Résumé et présentation du 19 avril 2019
# Open check dams: field inventory overview and feedback from the French experience

Simon Carladous (1), Guillaume Piton (2), Mélanie Brachet (3), and Yann Quefféléan (1)

(1) ONF, Natural Hazards Department, Grenoble, France (simon.carladous@onf.fr), (2) Univ. Grenoble Alpes, IRSTEA, ETNA Research Unit, Grenoble, France (guillaume.piton@irstea.fr), (3) Univ. Savoie Mont-Blanc, Bourget-du-Lac, France (melanie.brachet@etu.univ-savoie.fr)

Within a torrential watershed, several complementary facilities can protect people, housing, networks and facilities generally located on alluvial fans. Amongst them, open check dams have an effect on solid transport, i.e. boulders, gravel and wood, before it reaches elements-at-risk. They are generally associated with complementary components: deposit area for the dredged material, access path, and downstream scouring protection.

Almost 320 open check dams were inventoried in 2017. About one-quarter are located in French public forests and are managed by the department of Restoration of Mountainous Areas of the National Forestry Office (ONF-RTM). Although the three other quarters are managed by municipalities, the ONF-RTM officers were involved in the design of the majority of them.

In France, pioneer structures were implemented just after World War II. However, most of open check dams were built between 1980 and 2000. We aimed at understanding why their implementation has decreased in France since 2000? First hypothesis is that maintenance experience puts on light several problems such as downstream incision, excessive dredging costs, etc. Second hypothesis is that design is not so easy in practice. A field inventory and feedback was thus undertaken to cluster and formalize main problems. This contribution to EGU aims at presenting its method and main results.

The used methodology involved four main steps. (1) A bibliography analysis specified potential functions of open check dams, physical mechanisms involved and existing design processes. (2) A GIS general inventory of French open check dams sorted them according to their storage capacity but also achieved functions. (3) A more detailed inventory was implemented by field ONF-RTM officers for ‘large’ open check dams, i.e. with more than 1000 m3 retention capacity. They described design context, involved solid transport processes, elements-at-risk, structural components, history of maintenance interventions, and malfunctions. (4) In-depth feedbacks on a dozen of specific facilities involved a watershed analysis, description of local peculiarities, definition of structure objectives, and functional and structural analysis. It was performed by gathering several specialists on site.

As a result of step 3, no malfunctions were reported for 60 % of registered large open check dams. For the other 40%, main identified functional malfunctions were (i) deposit areas too frequently filled (46 %), (ii) lateral bypasses of the structure (27 %), (iii) structures located too upstream along the channel (21 %), and (iv) a lack of regular dredging. For step 4, a feedback methodology with standardized forms was developed and tested allowing clustering and disentangling several failure modes of open check dams. Thanks to this feedback, the global design process has been improved on three main points: (i) analysis for a minimum of three scenarios (frequent, project, danger), (ii) clarification of potential functions of open check dams, (iii) design of their opening sizes.

Finally, this feedback approach helps to exchange between specialists and field practitioners, to cluster information according to a similar knowledge, and to improve design and maintenance processes. As it is based on a formalized methodology and reporting tools, it can be easily implemented in other sites and countries.
EGU 2019, Vienna

<figure><img src="image_269.png" /></figure>

<figure><img src="image_270.png" /></figure>

## Open check dams: field inventory overview and feedback from the French experience

S. Carladous, G. Piton, M. Brachet, Y. Quefféléan

<figure><img src="image_271.png" /></figure>

### SEDIMENT TRAPS: PROTECTIVE FACILITIES

<figure><img src="image_272.png" /></figure>

<figure><img src="image_273.png" /></figure>

EGU 2019, Vienna

<figure><img src="image_274.png" /></figure>

The torrent of Manival, © Sébastien Gomimet, 2010

© Piton et al., 2016

<figure><img src="image_275.png" /></figure>

1

### SEDIMENT TRAPS: PROTECTIVE FACILITIES

<figure><img src="image_276.png" /></figure>

<figure><img src="image_277.png" /></figure>

EGU 2019, Vienna

<figure><img src="image_278.png" /></figure>

The torrent of Manival, © Sébastien Gomimet, 2010

© Piton et al., 2016

### OUTPUTS AND FEEDBACK METHODOLOGY

<figure><img src="image_279.png" /></figure>

<figure><img src="image_280.png" /></figure>

EGU 2019, Vienna

* in France, first sediment traps after WWII and last inventory in 1997
  → **inventory updating**

* implementation has decreased since the 2000s
  maintenance experience puts on light technical problems? design difficulties? too expensive?
  → **field feedback**

1

<figure><img src="image_281.png" /></figure>

2

<figure><img src="image_282.png" /></figure>
## OUTPUTS AND FEEDBACK METHODOLOGY

<figure><img src="image_283.png" /></figure>

<figure><img src="image_284.png" /></figure>

EGU 2019.
Vienna

<figure><img src="image_285.png" /></figure>

* in France, first sediment traps after WWII and last inventory in 1997
  → **inventory updating**

* implementation has decreased since the 2000s
  maintenance experience puts on light technical problems? design difficulties? too expensive?
  → **field feedback**

1. Bibliography: several potential functions

2. GIS general inventory

3. More detailed inventory and general feedback

4. In-depth feedback on specific facilities

<figure><img src="image_286.png" /></figure>

2

## OUTPUTS AND FEEDBACK METHODOLOGY

<figure><img src="image_287.png" /></figure>

<figure><img src="image_288.png" /></figure>

EGU 2019.
Vienna

<figure><img src="image_289.png" /></figure>

* in France, first sediment traps after WWII and last inventory in 1997
  → **inventory updating**

* implementation has decreased since the 2000s
  maintenance experience puts on light technical problems? design difficulties? too expensive?
  → **field feedback**

1. Bibliography: several potential functions

2. GIS general inventory

3. A more detailed inventory and general feedback

4. In-depth feedback on specific facilities

<figure><img src="image_290.png" /></figure>

2

## SEDIMENT TRAPS COMPONENTS

<figure><img src="image_291.png" /></figure>

<figure><img src="image_292.png" /></figure>

EGU 2019.
Vienna

<figure><img src="image_293.png" /></figure>

1. inlet structure; solid body dam

2. scour protection

3. **basin**

4. lateral dikes

5. **maintenance access**

6. **open check dam**

7. counter dam

<figure><img src="image_294.png" /></figure>

Piton et Recking 2016a,
adapted from Zallinger 1983

<figure><img src="image_295.png" /></figure>

The torrent of Saint-Bernard. © A. Pernet,
23/05/2018

<figure><img src="image_296.png" /></figure>

3

## SEDIMENT TRAPPING MECHANISMS

<figure><img src="image_297.png" /></figure>

<figure><img src="image_298.png" /></figure>

EGU 2019.
Vienna

<figure><img src="image_299.png" /></figure>

* **Mechanisms depending on basin shape (a & b)**

<figure><img src="image_300.png" /></figure>

* slope breaking

<figure><img src="image_301.png" /></figure>

* stream widening

* **Mechanisms depending on open check dam (c & d)**

<figure><img src="image_302.png" /></figure>

* hydraulic control of the deposits

<figure><img src="image_303.png" /></figure>

* mechanic controlled deposits

<figure><img src="image_304.png" /></figure>

* mixed controlled deposits

<figure><img src="image_305.png" /></figure>

4
SEDIMENT TRAPS FUNCTIONS, GIVEN SCENARIOS

<figure><img src="image_306.png" /></figure>

<figure><img src="image_307.png" /></figure>

EGU 2019.
Vienna

<figure><img src="image_308.png" /></figure>

<figure><img src="image_309.png" /></figure>

The torrent of Manival, © Sébastien Gorninet, 2010

■ « frequent » event:

is not damageable for downstream elements-at-risk

⇒ function: to transfer flow with solid materials

⇒ opening in check dams

■ « project » event:

is damageable for downstream elements-at-risk

⇒ function: to act on solid transport

⇒ limitation of opening

■ « hazardous» event:

⇒ function: to transfer flow without increasing downstream potential damage

⇒ spillway

SEDIMENT TRAPS FUNCTIONS, GIVEN SCENARIOS

<figure><img src="image_310.png" /></figure>

<figure><img src="image_311.png" /></figure>

EGU 2019.
Vienna

<figure><img src="image_312.png" /></figure>

<figure><img src="image_313.png" /></figure>

The torrent of Manival, © Sébastien Gorninet, 2010

■ « frequent » event:

is not damageable for downstream elements-at-risk

⇒ function: to transfer flow with solid materials

⇒ opening in check dams

■ « project » event:

is damageable for downstream elements-at-risk

⇒ function: to act on solid transport

⇒ limitation of opening

■ « hazardous» event:

⇒ function: to transfer flow without increasing downstream potential damage

⇒ spillway

« PROJECT » EVENT FUNCTIONS

<figure><img src="image_314.png" /></figure>

<figure><img src="image_315.png" /></figure>

EGU 2019.
Vienna

<figure><img src="image_316.png" /></figure>

■ solid material **temporary retention with dredging** ⇒ **included**

<figure><img src="image_317.png" /></figure>

open check dam, with slits (could be grills)

<figure><img src="image_318.png" /></figure>

The torrent of Manival

general view

« PROJECT » EVENT FUNCTIONS

<figure><img src="image_319.png" /></figure>

<figure><img src="image_320.png" /></figure>

EGU 2019.
Vienna

<figure><img src="image_321.png" /></figure>

■ solid material **temporary retention with dredging** ⇒ **included**

■ solid transport **regulation area, without open check dam**

⇒ **not included**

<figure><img src="image_322.png" /></figure>

The torrent of Sainte-Marthe

6

6
## « PROJECT » EVENT FUNCTIONS

<figure><img src="image_323.png" /></figure>

<figure><img src="image_324.png" /></figure>

<figure><img src="image_325.png" /></figure>

EGU 2019,
Vienna

* solid material temporary retention with dredging ⇒ **included**

* solid transport regulation area ⇒ **not included**

* open check dam **changed** in consolidation dam for regulation
  ⇒ **included, for memory**

<figure><img src="image_326.png" /></figure>

The torrent of
Les Arches

<figure><img src="image_327.png" /></figure>

6

## « PROJECT » EVENT FUNCTIONS

<figure><img src="image_328.png" /></figure>

<figure><img src="image_329.png" /></figure>

<figure><img src="image_330.png" /></figure>

EGU 2019,
Vienna

* solid material temporary retention with dredging ⇒ **included**

* solid transport **modulation/regulation** ⇒ **included**

<figure><img src="image_331.png" /></figure>

open check dam, with one large slot

<figure><img src="image_332.png" /></figure>

general view

The torrent of Saint-Bernard,
© A. Perret

<figure><img src="image_333.png" /></figure>

6

## « PROJECT » EVENT FUNCTIONS

<figure><img src="image_334.png" /></figure>

<figure><img src="image_335.png" /></figure>

<figure><img src="image_336.png" /></figure>

EGU 2019,
Vienna

* solid material temporary retention with dredging ⇒ **included**

* solid transport modulation/regulation ⇒ **included**

* debris flow breaker ⇒ **included**

<figure><img src="image_337.png" /></figure>

open check dam, with large slots

<figure><img src="image_338.png" /></figure>

The torrent of
Riou Sec

general view

<figure><img src="image_339.png" /></figure>

6

## « PROJECT » EVENT FUNCTIONS

<figure><img src="image_340.png" /></figure>

<figure><img src="image_341.png" /></figure>

<figure><img src="image_342.png" /></figure>

EGU 2019,
Vienna

* solid material temporary retention with dredging ⇒ **included**

* solid transport modulation/regulation ⇒ **included**

* debris flow breaker ⇒ **included**

* woody debris trapping
  ⇒ **included, for torrents with a specific basin**

<figure><img src="image_343.png" /></figure>

The torrent
of tributary,
with piles

YES

<figure><img src="image_344.png" /></figure>

The torrential river of La Béoux

NO

<figure><img src="image_345.png" /></figure>

6
## OUTPUTS AND FEEDBACK METHODOLOGY

<figure><img src="image_346.png" /></figure>

<figure><img src="image_347.png" /></figure>

EGU 2019.
Vienna

<figure><img src="image_348.png" /></figure>

* in France, first sediment traps after WWII and last inventory in 1997
  → inventory updating

* implementation decrease since 2000s
  maintenance experience puts on light technical problems? design difficulties? too expensive?
  → field feedback

1. Bibliography: several potential functions

2. GIS general inventory

3. A more detailed inventory and general feedback

4. In-depth feedback on specific facilities

<figure><img src="image_349.png" /></figure>

## FRENCH INVENTORY: SYNTHESIS

<figure><img src="image_350.png" /></figure>

<figure><img src="image_351.png" /></figure>

EGU 2019.
Vienna

<figure><img src="image_352.png" /></figure>

* 330 sediment traps

→ 79 % in the **Northern Alps**

→ 25% in **public forests** managed by ONF/RTM, 75 % managed by **local municipalities**

→ 50 % with a **basin retention volume < 1,000 m³**
22 % : > 1,000 m³ and < 5,000 m³
26 % : > 5,000 m³ and < 50,000 m³
8 facilities : > 50,000 m³ and < 350,000 m³

<figure><img src="image_353.png" /></figure>

Northern
Alps

Pyrenees

Southern
Alps

<figure><img src="image_354.png" /></figure>

7

## FRENCH INVENTORY: SYNTHESIS

<figure><img src="image_355.png" /></figure>

<figure><img src="image_356.png" /></figure>

EGU 2019.
Vienna

<figure><img src="image_357.png" /></figure>

* 330 sediment traps

→ 79 % in the Northern Alps

→ 25% in public forests managed by ONF/RTM, 75 % managed by local municipalities

→ 50 % with a basin retention volume > 1,000 m³

→ Mainly built between 1980 and 2000

Number of sediment
traps built over time

<figure><img src="image_358.png" /></figure>

Pyrenees

Northern Alps

Southern Alps

<figure><img src="image_359.png" /></figure>

7

## FRENCH INVENTORY: SYNTHESIS

<figure><img src="image_360.png" /></figure>

<figure><img src="image_361.png" /></figure>

EGU 2019.
Vienna

<figure><img src="image_362.png" /></figure>

* 330 sediment traps

→ 79 % in the Northern Alps

→ 25% in public forests managed by ONF/RTM, 75 % managed by local municipalities

→ 50 % with a basin retention volume > 1,000 m³

→ Mainly built between 1980 and 2000

→ Almost entirely **temporary retention** and/or **modulation/regulation**

- only 1 debris flow breaker

- almost 5 woody debris trapping

<figure><img src="image_363.png" /></figure>

7
## OUTPUTS AND FEEDBACK METHODOLOGY

<figure><img src="image_364.png" /></figure>

<figure><img src="image_365.png" /></figure>

<figure><img src="image_366.png" /></figure>

EGU 2019.
Vienna

* in France, first sediment traps after WWII and last inventory in 1997
  → inventory updating

* implementation decrease since 2000s
  maintenance experience puts on light technical problems? design difficulties? too expensive?
  → field feedback

1. Bibliography: several potential functions

2. GIS general inventory

3. A more detailed inventory and general feedback

4. In-depth feedback on specific facilities

## GENERAL FEEDBACK: METHODOLOGY

<figure><img src="image_367.png" /></figure>

<figure><img src="image_368.png" /></figure>

<figure><img src="image_369.png" /></figure>

EGU 2019.
Vienna

330 sediment traps

→ 164 with a basin volume > 1,000 m³ (considered as significant)

→ 137 in the Alps (availability of ONF/RTM officers)

→ 115 detailed inventory sheets (some work remains...)

<figure><img src="image_370.png" /></figure>

<figure><img src="image_371.png" /></figure>

8

## GENERAL FEEDBACK: METHODOLOGY

<figure><img src="image_372.png" /></figure>

<figure><img src="image_373.png" /></figure>

<figure><img src="image_374.png" /></figure>

EGU 2019.
Vienna

330 sediment traps
→ 115 detailed inventory sheets

<figure><img src="image_375.png" /></figure>

* GOVERNANCE

* NATURAL HAZARDS
  (phenomena, watershed description, historical event, project event, granulometry)

* ELEMENTS-AT-RISK

<figure><img src="image_376.png" /></figure>

9

## GENERAL FEEDBACK: METHODOLOGY

<figure><img src="image_377.png" /></figure>

<figure><img src="image_378.png" /></figure>

<figure><img src="image_379.png" /></figure>

EGU 2019.
Vienna

330 sediment traps

→ 115 detailed inventory sheets

<figure><img src="image_380.png" /></figure>

* TECHNICAL COMPONENTS
  (upstream, sediment trap, downstream)

* MAINTENANCE
  ORGANIZATION AND HISTORY
  (modifications, dredging, etc.)

<figure><img src="image_381.png" /></figure>
## GENERAL FEEDBACK: METHODOLOGY

<figure><img src="image_382.png" /></figure>

<figure><img src="image_383.png" /></figure>

EGU 2019.
Vienna

<figure><img src="image_384.png" /></figure>

330 sediment traps

→115 detailed inventory sheets

<figure><img src="image_385.png" /></figure>

<figure><img src="image_386.png" /></figure>

<figure><img src="image_387.png" /></figure>

<figure><img src="image_388.png" /></figure>

* IDENTIFIED MALFUNCTIONS (observed or expected)

* REFERENCES (studies, data, etc.)

<figure><img src="image_389.png" /></figure>

8

## IDENTIFIED MALFUNCTIONS: SYNTHESIS

<figure><img src="image_390.png" /></figure>

<figure><img src="image_391.png" /></figure>

EGU 2019.
Vienna

<figure><img src="image_392.png" /></figure>

* No identified malfunction: 58 % (on 115 sediment traps)

* Main identified malfunctions (on 48 sediment traps)

→ basin too frequently filled (46 %)

potential causes: mechanic obstruction, wood logs clogging

potential consequences: sediment deficit and downstream incision

<figure><img src="image_393.png" /></figure>

<figure><img src="image_394.png" /></figure>

The torrent of Lavanchion

<figure><img src="image_395.png" /></figure>

9

## IDENTIFIED MALFUNCTIONS: SYNTHESIS

<figure><img src="image_396.png" /></figure>

<figure><img src="image_397.png" /></figure>

EGU 2019.
Vienna

<figure><img src="image_398.png" /></figure>

* No identified malfunction: 58 % (on 115 sediment traps)

* Main identified malfunctions (on 48 sediment traps)

→ basin too frequently filled (46 %)

→ lateral bypass of the structures (27 %)

potential causes: too low dike slope

potential consequences: new flow direction towards elements-at-risk

<figure><img src="image_399.png" /></figure>

Böll et al., 2008P

<figure><img src="image_400.png" /></figure>

9

## IDENTIFIED MALFUNCTIONS: SYNTHESIS

<figure><img src="image_401.png" /></figure>

<figure><img src="image_402.png" /></figure>

EGU 2019.
Vienna

<figure><img src="image_403.png" /></figure>

* No identified malfunction: 58 % (on 115 sediment traps)

* Main identified malfunctions (on 48 sediment traps)

→ basin too frequently filled (46 %)

→ lateral by pass of the structures (27 %)

→ facility located too upstream along the channel (21 %)

potential causes: topographic or land ownership constraints

potential consequences: downstream solid material recovery

<figure><img src="image_404.png" /></figure>

The torrent of Saint-Chaffrey

<figure><img src="image_405.png" /></figure>

9
## IDENTIFIED MALFUNCTIONS: SYNTHESIS

<figure><img src="image_406.png" /></figure>

<figure><img src="image_407.png" /></figure>

EGU 2019,
Vienna

<figure><img src="image_408.png" /></figure>

* **No identified malfunction: 58 %** (on 115 sediment traps)

* **Main identified malfunctions** (on 48 sediment traps)

→ basin too frequently filled (46 %)

→ lateral by pass of the structures (27 %)

→ facility located too upstream along the channel (21 %)

→ **lack of regular dredging**

potential causes: too expensive

potential consequences: reduction of retention volume capacity

<figure><img src="image_409.png" /><figcaption>The torrent of Claret</figcaption></figure>

<figure><img src="image_410.png" /></figure>

9

## IDENTIFIED MALFUNCTIONS: SYNTHESIS

<figure><img src="image_411.png" /></figure>

<figure><img src="image_412.png" /></figure>

EGU 2019,
Vienna

<figure><img src="image_413.png" /></figure>

* **No identified malfunction: 58 %** (on 115 sediment traps)

* **Main identified malfunctions** (on 48 sediment traps)

→ basin too frequently filled (46 %)

→ lateral by pass of the structures (27 %)

→ facility located too upstream along the channel (21 %)

→ lack of regular dredging

→ **structural failure** (15 %)

<figure><img src="image_414.png" /><figcaption>The torrent of
Saint-Bernard</figcaption></figure>

<figure><img src="image_415.png" /></figure>

9

## MODIFICATIONS: ONE EXAMPLE

<figure><img src="image_416.png" /></figure>

<figure><img src="image_417.png" /></figure>

EGU 2019,
Vienna

<figure><img src="image_418.png" /></figure>

* **from two horizontal slits to one large slot**

<figure><img src="image_419.png" /><figcaption>The torrent of Claret, 2018 modification</figcaption></figure>

<figure><img src="image_420.png" /></figure>

10

## OUTPUTS AND FEEDBACK METHODOLOGY

<figure><img src="image_421.png" /></figure>

<figure><img src="image_422.png" /></figure>

EGU 2019,
Vienna

<figure><img src="image_423.png" /></figure>

* **in France, first sediment traps after WWII and last inventory in 1997**
  → **inventory updating**

* **implementation decrease since 2000s**
  maintenance experience puts on light technical problems? design difficulties? too expensive?
  → **field feedback**

1. Bibliography: several potential functions

2. GIS general inventory

3. A more detailed inventory and general feedback

4. **In-depth feedback on specific facilities**

<figure><img src="image_424.png" /></figure>
## IN-DEPTH FEEDBACK ON EXISTING STRUCTURES

<figure><img src="image_425.png" /></figure>

<figure><img src="image_426.png" /></figure>

EGU 2019.
Vienna

<figure><img src="image_427.png" /></figure>

* choice of sediment traps → a dozen in the Alps

* geographic distribution

* functions distribution

* malfunctions distributions

* modifications distributions

* group of specialists, local technicians, writer

<figure><img src="image_428.png" /></figure>

The torrent of Claret, before 2018
modification, Pernet A. ©

11

## IN-DEPTH FEEDBACK ON EXISTING STRUCTURES

<figure><img src="image_429.png" /></figure>

<figure><img src="image_430.png" /></figure>

EGU 2019.
Vienna

<figure><img src="image_431.png" /></figure>

* choice of sediment traps

* group

* field information gathering: several scales

1. Watershed scale, including elements-at-risk

2. Sediment trap within its environment

3. Sediment trap components
(failure mode analysis)

<figure><img src="image_432.png" /></figure>

11

## IN-DEPTH FEEDBACK ON EXISTING STRUCTURES

<figure><img src="image_433.png" /></figure>

<figure><img src="image_434.png" /></figure>

EGU 2019.
Vienna

<figure><img src="image_435.png" /></figure>

* choice of sediment traps

* group

* field information gathering: several scales

* feedback report

<figure><img src="image_436.png" /></figure>

11

## EXAMPLE: STORY OF A CONTINUOUS ADAPTATION

<figure><img src="image_437.png" /></figure>

<figure><img src="image_438.png" /></figure>

EGU 2019.
Vienna

<figure><img src="image_439.png" /></figure>

Torrent of Saint-Bernard

<figure><img src="image_440.png" /></figure>

Channel (end of 19th century) :

* bridges (highway, significant roads)

* housing

→ main problem : boulders transferred by debris flows

<figure><img src="image_441.png" /></figure>

12
### EXAMPLE: STORY OF A CONTINUOUS ADAPTATION

#### Torrent of Saint-Bernard

<figure><img src="image_442.png" /></figure>

<figure><img src="image_443.png" /></figure>

EGU 2019,
Vienna

<figure><img src="image_444.png" /></figure>

<figure><img src="image_445.png" /></figure>

© A. Pernet

1987 – 1<sup>st</sup> sediment trap
ONF-RTM
Vertical bars

<figure><img src="image_446.png" /></figure>

12

### EXAMPLE: STORY OF A CONTINUOUS ADAPTATION

#### Torrent of Saint-Bernard

<figure><img src="image_447.png" /></figure>

<figure><img src="image_448.png" /></figure>

EGU 2019,
Vienna

<figure><img src="image_449.png" /></figure>

<figure><img src="image_450.png" /></figure>

© A. Pernet

1987 – 1<sup>st</sup> sediment trap
ONF-RTM
Vertical bars

1990 – too frequently filled
→ basis of bars was cut

<figure><img src="image_451.png" /></figure>

1993 – two consecutive
debris flows
→ one slot is effective

<figure><img src="image_452.png" /></figure>

12

### EXAMPLE: STORY OF A CONTINUOUS ADAPTATION

#### Torrent of Saint-Bernard

<figure><img src="image_453.png" /></figure>

<figure><img src="image_454.png" /></figure>

EGU 2019,
Vienna

<figure><img src="image_455.png" /></figure>

<figure><img src="image_456.png" /></figure>

© A. Pernet

1987 – 1<sup>st</sup> sediment trap
ONF-RTM
Vertical bars

1990 – too frequently filled
→ basis of bars was cut

<figure><img src="image_457.png" /></figure>

12

1995 – 2<sup>nd</sup> downstream sediment trap
Highway manager

1993 – two consecutive
debris flows
→ one slot is effective

<figure><img src="image_458.png" /></figure>

### EXAMPLE: STORY OF A CONTINUOUS ADAPTATION

#### Torrent of Saint-Bernard

<figure><img src="image_459.png" /></figure>

<figure><img src="image_460.png" /></figure>

EGU 2019,
Vienna

<figure><img src="image_461.png" /></figure>

<figure><img src="image_462.png" /></figure>

© A. Pernet

1987 – 1<sup>st</sup> sediment trap
ONF-RTM
vertical bars

1990 – too frequently filled
→ basis of bars was cut

<figure><img src="image_463.png" /></figure>

1993 – two consecutive
debris flows
→ one slot is effective

<figure><img src="image_464.png" /></figure>

12
## CONCLUSION

<figure><img src="image_465.png" /></figure>

<figure><img src="image_466.png" /></figure>

<figure><img src="image_467.png" /></figure>

Listea

EGU 2019,
Vienna

* **A global feedback approach** for sediment traps

⇒ **Steps:** Inventory, (selection,) general feedback, (selection,) in-depth feedback

⇒ **Several scales:** watershed, sediment trap, components

⇒ **Several domains:** Hydraulic engineering, civil engineering, failure mode analysis

* **A formalized support**

⇒ **Exchange** between specialists and field practitioners

⇒ **Information gathering** according to a similar knowledge

⇒ **Help improvement** of design and maintenance guidelines

* **Possible implementation** on other sites

a formalized methodology and reporting tools

<figure><img src="image_468.png" /></figure>

<figure><img src="image_469.png" /></figure>

<figure><img src="image_470.png" /></figure>

Thank you for your attention

<figure><img src="image_471.png" /></figure>

<figure><img src="image_472.png" /></figure>

## ON-STREAM OR STREAM PARALLEL?

<figure><img src="image_473.png" /></figure>

<figure><img src="image_474.png" /></figure>

<figure><img src="image_475.png" /></figure>

Listea

EGU 2019,
Vienna

* **On-stream**

<figure><img src="image_476.png" /><figcaption>Piton et Recking 2016a,
adapted from Zollinger 1983</figcaption></figure>

<figure><img src="image_477.png" /><figcaption>The torrent of Saint-Bernard,
© A. Pernet, 23/05/2018</figcaption></figure>

* **Stream parallel sediment trap**

<figure><img src="image_478.png" /><figcaption>Lefort, 1996</figcaption></figure>

<figure><img src="image_479.png" /><figcaption>The torrent of Renhige,
Piton et Recking 2016a</figcaption></figure>

## « PROJECT » EVENT FUNCTIONS

<figure><img src="image_480.png" /></figure>

<figure><img src="image_481.png" /></figure>

<figure><img src="image_482.png" /></figure>

Listea

EGU 2019,
Vienna

* **solid material permanent retention** ⇒ not included in this inventory

<figure><img src="image_483.png" /><figcaption>The torrent of
Claret</figcaption></figure>

general view, with solid body dam

3

6
SEDIMENT TRAPS: « PROJECT » EVENT FUNCTIONS

<figure><img src="image_484.png" /></figure>

<figure><img src="image_485.png" /></figure>

EGU 2019.
Vienna

<figure><img src="image_486.png" /></figure>

* **Solid material retention dam**

**function:** to stop and store **permanently** transferred solid materials

**check dam openings:** solid or with very small opening

**basin capacity:** sufficiently large

<figure><img src="image_487.png" /></figure>

The torrent of
Claret

* **temporarily solid material retention with dredging**

**function:** to stop and store **temporarily** transferred solid materials until **artificial** dredging

**check dam openings:** grills or slits

**basin capacity:** sufficiently large

<figure><img src="image_488.png" /></figure>

The torrent of
Manival

<figure><img src="image_489.png" /></figure>

5

SEDIMENT TRAPS: « PROJECT » EVENT FUNCTIONS

<figure><img src="image_490.png" /></figure>

<figure><img src="image_491.png" /></figure>

EGU 2019.
Vienna

<figure><img src="image_492.png" /></figure>

* **regulation of solid transport**

**function:** to act on **solid material flow** decreasing its **peak value** and **spreading** it over time

**check dam openings:** preferably, large slot(s)

**basin capacity:** sufficiently large

<figure><img src="image_493.png" /></figure>

The torrent of
Saint-Bernard,
© A. Perret

* **Debris flow breaker**

**function:** to stop and store **temporarily big boulders**

**check dam openings:** large slot(s)

**basin capacity:** limited

<figure><img src="image_494.png" /></figure>

The torrent of
Roua Sec

<figure><img src="image_495.png" /></figure>

6

SEDIMENT TRAPS: « PROJECT » EVENT FUNCTIONS

<figure><img src="image_496.png" /></figure>

<figure><img src="image_497.png" /></figure>

EGU 2019.
Vienna

<figure><img src="image_498.png" /></figure>

* **woody debris trap**

**function:** to stop and store **temporarily** a significant part of woody debris volume
**potential associated function:** to stop and store solid materials

**check dam openings:** piles, inclined grills and vertical bars, nets

**basin capacity:** sufficiently large

<figure><img src="image_499.png" /></figure>

The torrent of
Imbents

⇒ to take into account woody debris already at the design step

<figure><img src="image_500.png" /></figure>

7

MODIFICATIONS

<figure><img src="image_501.png" /></figure>

<figure><img src="image_502.png" /></figure>

EGU 2019.
Vienna

<figure><img src="image_503.png" /></figure>

* **Improvement of design guidelines** based on experience

* **Modification of existing structures**

→ **basin adaptation with low flow channel**

<figure><img src="image_504.png" /></figure>

<figure><img src="image_505.png" /></figure>

The torrent of Manival, 2017-2018 modification

<figure><img src="image_506.png" /></figure>

10
ONF / Direction Forêt et Risques Naturels

Département Risques Naturels

Pôle RTM

9 Quai Créqui - CS 20028

38026 GRENOBLE cedex 1

Champ de certification «cœur de métier» : iso 9001 et 14001