Spillways on River Levees


The English translation of a previous French handbook on river levees is now ready. It can already be pre-ordered as a physical book, and it will be available as an open access ebook from October 1st.

More information on : https://www.quae.com/produit/1720/9782759232857/spillways-on-river-levees

See also the flyer.

02812_SpillwaysHD 

A new paper on levee investigations is available

Dear collegues

My new paper on levee investigations <A new levee control system based on geotechnical and geophysical surveys
including active thermal sensing: A case study from Poland >

is available next 50 days in Engineering Geology journal for free.

link to download    https://authors.elsevier.com/c/1dXbq38lpFrmC

Best regards,

Krzysztof Radzicki

FLOODrisk conference papers available online

The repository for the FLOODrisk conference papers is now open. You can find read and download all the conference papers in it. https://repozitorium.omikk.bme.hu/handle/10890/15138

There are different ways to brwose the papers, by author, title or subject. The main web site for the conference is sill open, and the program by sessions (https://hub.floodrisk2020.net/programme/) may help you identify papers of interest for your own activity.

Peat soil – often breaks

https://www.ad.nl/alphen/dijkdoorbraak-zet-weilanden-in-reeuwijk-onder-water-rivierkreeft-zou-niet-de-boosdoener-zijn~af466319/

In the west of the Netherlands a peat “dike” failed today

The original soil is the core of the dike, the surrounding soil has subsided and oxidized.

The dike probably failed due to the fact it dried out, the recent abundant rainfall is only the trigger.

The polder consists of agricultural land

A first step in trying to understand and document what occurred between July 12th and July 23rd in the Meuse river basin, and the effects on the Netherlands

A first step in trying to understand and document what occurred between July 12th and July 23rd in the Meuse river basin.

This was an exceptional weather event. However it was correctly predicted.

In Germany in the Eifel region (mainly tributaries to the Rhine) they had 3 months of rainfall in 36 hours and in Belgium in the Ardennes (tributaries to the Meuse river) they had 2 months of rainfall in 24 hours. People had been warned in most cases. Both the emergency services and the public clearly underestimated the consequences. There was no clear messaging.

 

Messaging should be timely, specific, in the language people speak, and should be understandable. People have to be able to relate to previous events to understand the predicted event, to be able to take the proper measures so stay safe.

Institutional changes are often needed after a flood. Especially when the time needed for a flood alert and a proper response is extremely short. In the Netherlands, the tidal hydrologists were merged with the meteorologists in the same organisation after the 1953 flood (for storm surges). The Czech Republic has set up centres where the emergency services were added to a team of hydrologists and meteorologists to cope with flash floods since the 2003 flood event.

 

Most of the damage in the Netherlands is from overland flow/flash floods from streams in valleys. In Germany and Belgium, this was also the case.

Institutional errors were made in the messaging to the public, in the construction and operation of reservoirs and probably in spatial planning. The Netherlands has very clear spatial planning rules for major rivers, but is rather bad at the enforcement of these rules. The Netherlands can learn a lot from Belgium, where they have recently enforced spatial planning rules in flood prone areas vigorously.

 

In the Netherlands at the gauging station Sint Pieter (near Maastricht), at km 10 on the Meuse River in the Netherlands a discharge of 3260 m3/s was measured. This is the highest discharge measured since the start of formal measurements in 1911. Other high is discharges this century all occurred in the winter:  December 22nd of 1993, 3120 m3/s. January 1st 1926 ~3000 m3/s and January 1995 2870 m3/s.

The previous highest summer discharge was about 1000 m3/s in 1980.

 

In the Netherlands in one town, Valkenburg the direct damage is about 200 million euros and the indirect damage is about the same amount. In Germany and Belgium, damages are a lot higher. The damages to the railway systems is already above one billion euro’s.

 

This extreme discharge on the Meuse River has a return period of about 100 years (for the winter statistics) at km 10 Borgharen[1]. However, this was a summer discharge. Rijkswaterstaat, KNMI and Deltares are, currently investigating what the relationship is between climate change and this flood event.

 

The flood wave was exceptionally short and high. This means that the water levels downstream corresponded with return periods of 25 years (Venlo, km 108) and 10 years at Gennep (km 155)

 

The measures of the large project the Meuse Works were largely effective. The Meuse Works was a complex project. It was a mixture of sand and gravel mining project including landscaping afterwards, room for the river measures and heightening and strengthening of dikes constructed hastily in 1995 and 1996.

The dikes constructed in 1995 and 1996 after the floods of 1993 and 1995 removed 40 % of the flood plain from the river. Some of these dikes have been built perpendicular to the flow of the river. So these dikes obstruct the flow of the river.

This means that at some locations especially at Maastricht the observed river levels were a lot higher than in 1993, while the recent discharge in 2021 was only about 100 m3/s higher (an effect of less than 10cm). At other locations, the increased river flow was also influenced by changes in the relationship between the tributaries in the Netherlands and the main river. In the Meuse Valley the Netherlands seem to be protecting a lot of pasture and seem to forget the cities and the national infrastructure (highways and railways).

 

The Water Management Centre for the Netherlands (WMCN) correctly predicted the water levels in the Meuse River, both the expected water levels and the time of the peak discharge at each spot of the river. There were 21 bulletins, during the peak discharge three to four (if a correction was needed) per day. Some figures were manually adjusted because of backflow due to flow from the tributaries, also some recent room for the river measures were not included in the model and due to weirs which were being refurbished and could not be completely opened. Instead of waiting for corrected data, the regional water authority in Limburg carried out their own predictions, which were more erroneous than those from Rijkswaterstaat (especially in the timing of the peak). These alternative “facts” also caused confusion within the teams responsible for crisis management.

 

Normally new models go on line on or before October 1st the start of the winter season. The new model (not yet online) is currently being tested at Deltares has already been corrected for the room for the river measures and can use real data for the flow from tributaries (instead of statistical relations).

 

The national committee on floods provides information on the impact of the flooding. The national government and the water boards provide the input for this information.

 

The regional water authority in Limburg[2] and Rijkswaterstaat were heavily involved in the flood fighting. Rijkswaterstaat had to sandbag a spot on a canal dike which had flooded a village (Meersen). The local population also initiated a number of measures. Sandbags were often placed where dike had not been reinforced yet to comply with the new standards, to combat piping and probably also slope stability or to reinforce mobile flood barriers (against uplift). Some people built their own dikes to protect their houses in the flood plain (e.a. at Horn for ten houses). There the temporary dike made up of not compacted top soil and plastic foil failed. The municipality had helped. The regional water authority was not involved. None of the sandbags had an influence on the water levels downstream in the provinces of North-Brabant (with the city of ‘s Hertogenbosch) and Gelderland where you have the largest population densities. This was also due to the very short discharge wave, less than a week.

 

Other regional water authorities and Rijkswaterstaat personnel assisted in the Limburg. The request for assistance was done through the union of water boards / union of regional water authorities (https://www.uvw.nl/). All assistance was coordinated through STOWA (from their vacation locations abroad).

The national committee on floods (LCO) also provided personnel from the Crisis Team for Flood Defences. The men and women from the military were very effective in sand bagging an eroded weir maintained by Rijskwaterstaat and in sandbagging a number of dikes for the regional water authority. After the floods they have started removing fallen trees from the tributaries to the Meuse.

 

Every flood wave on a river causes damages both above the water line and below the water line. Some of the damage has been tackled through emergency measures as sandbags. The winter season will start within two and half months. This means all dikes, structures and the riverbed have to be inspected and the most important damages have to be repaired before October 1st 2021. Some of the damages occurred to structures where we knew there was an issue for over twenty years.

One example is the sluice gate of the “Zuid Willemsvaart” a 19th century structure. This set of gates is too low. More than 2 meters of water overtopped the gates.

This canal is directly connected to the Albert Canal in Belgium. There is no flood risk in the Netherlands, which is why this problem had not yet been tackled. However houses in Genk (50 km away) in Belgium along the canal were flooded due to increased discharges from Belgium and the Netherland to the canal. Our water systems do not stop at the border. Closer cooperation is needed.

 

The Meuse river and the tributaries reacted differently to the extreme rainfall event than we expected. This means we need to look into flood risk for the whole river system including the tributaries. Cooperation with Belgium and Germany is advised. For the Netherlands this means we have to look at the main river from Eijsden (km 0) until Keizersveer (km 250) and we should not forget cross border flooding.

 

This flood is a good warning for everyone who has built in the flood plain since 1995. There are more than 2500 houses now when in 1995 there were only a few hundred. People are not protected and by law should not get their damages reinbursed from the disaster fund if the house was built after 1995.

 

Since 2017 all flood defences are allowed to fail at a certain agreed level. For each and every flood defence this protection level has been described in the water act (in the last update from 2014), see the Fundementals on Flood Defences[3]. This means that a number of the measures prepared since 2010 for the Meuse river, the “systeem maatregelen” no longer seem fit for purpose. These measures were devised as a compensation for the fact that formally the 45 former “dike rings” / dike systems along the Meuse will no longer be considered part of the flood plain. As mentioned before this removes 40% of the flood plain from the river and endangers cities like Maastricht. The Netherlands seem to want give pastures almost the same level as protection as neighbouring cities. The former provincial government (2 years ago) wanted to correct this. The current provincial government seems not to want any changes.

 

Due to climate change, a larger part of the valley will become flood prone. A 6000 m3/s means about 60 km2 should be included in the formal flood plain. Floods in this area also protect the cities downstream by lowering the design water levels by about 30 cm. This will require new spatial planning measures, since the population has to be informed of this flood risk.

 

Two years ago the province of Limburg has drafted a good plan to tackle this issue by removing or lowering the status of 22 of 45 dikes systems along the river. This means the province focusses on the cities and towns along the river, which need extra protection. It is easier and more acceptable to evacuate a village of 1000 people than a city of 20 000. The population who live along the river initiated these plans, they prefer a good view, and a few scares, and maybe a flood than huge dikes in front of their houses. This situation is different from Amsterdam (Durgerdam) where a few hundred people do not want to reinforce a dike (because it is next to their house) but the dike protects more than half a million people.

The Delta commissioner in his response to the plans by the province does not seem to understand that the cities of Maastricht and ‘s-Hertogenbosch are at stake, including the national infrastructure (highways and railroads). If the Meuse valley is to remain liveable and climate proof urban developments should be planned in the main cities and towns and not in the flood plain which is still largely empty.

 

The problems in the tributaries to the Meuse River have been neglected for a long time. Every ten to twenty years there is a flood event. People get used to it, but the impact of these flood events will increase over time and due to climate change. At a certain point people, start dying in large numbers, as we can see in Belgium and Germany. E.g. people expected a larger discharge with water levels about 3 meters higher than normal, not 7 meters. Planners have to think through the worst credible floods. An event with a return period of 1000 years is not un-imaginable. You have to know if the event is deadly or not before you allow a new urban development or even the construction of one single house, which is not adapted for a flood event.

 

Another reason why the impact of the floods were higher may be the construction of reservoirs for rainfall events with return periods of 10 and 25 years in the tributaries to the Meuse River in the Netherlands. When there is a rainfall event the managers of the water systems should – discharge – the hold on to the water in fields, then use reservoirs and then again discharge. In this way the tributaries react naturally to the high precipitation event and they discharge into the main river the Meuse before the peak flows have reached from the Ardennes in Belgium[4].

 

As a researcher, a large flood event is also an event to learn from:

  • What is the impact of climate change? If we cool the climate by two degrees in our climate model for the data of week of July 15th (1 degree more than the current change in temperature), will the same precipitation event be seen?
  • Understanding why this precipitation caused this particular flood wave.
    • Looking into the precipitation events just weeks before and after the event,
      • Can we see a pattern?
      • Were the systems and the soil full or empty?
      • Was this the worst case, if we move the precipitation event 50 km to the west, to coincide with a larger part of the Meuse basin, what will happen?
    • Understanding how the flow wave moves through the river
      • This was an event with a short duration, the upstream areas in the Netherlands and Belgium were hit the worst, in the downstream areas the discharge wave was uneventful
      • Why do datasets for the same model of the river, provides such immense differences in design wate levels (sometimes almost a meter), is this the effect of the discharge wave and the relationship with the tributaries?
      • Should we consider both the height and width of discharge waves in the probabilistic modelling for determining hydraulic boundary conditions?
    • Understanding the relationship between the tributaries and the river
      • Due we understand the relationship for each tributary,
      • Was this the worst case?
      • How can we modify the relationship to reduce damages? Is this wise with expected climate change?
    • What happened below the water level
      • Was there a large bed flow
      • Where can we observe sedimention and erosion
      • Do we understand why this happened
      • Is this a reason to worry,
        • Are control structures in danger due to erosion or debris?
        • Are flood defences in danger due to erosion (deep scour holes can destabilise a dike)
        • Are flood defences in danger due to sedimentation and debris, because of higher water levels
      • Where do we see damage to structures and flood defences, can we explain the reason they were damaged?.
        • Is damage only due to overtopping, e.g. for a weir
        • Where was piping and seepage observed ?
      • In 2007-20014 chocking points on the river were modelled, did they occur, or was the flood wave too low at these sites?

 

[1][1] The Meuse rivier starts at kilometer 0 on the border at Eijsden in the Netherlands, this is about at km 700 if you start counting at the source in France on the Langres Plateau. the nuber stop at about 60 km before the sea in the Amer, the Rhine/Meuse Estuary.

[2] https://www.waterschaplimburg.nl/

[3] https://www.enwinfo.nl/publish/pages/183541/grondslagenen-lowresspread3-v_3.pdf

[4] Actualisatie beschrijving laterale toestroming Maas, Rolf van der Veen, 2018 and Van regen tot Maas. Grensoverschrijdend waterbeheer in droge en natte tijden’  Marcel de Wit, Uitgeverij Veen Magazines (ISBN 978-90-8571-230-5).

A new document on “Methods and techniques for reinforcing and repairing protection levees”

A new report has been approved by the CFBR Executive Board, and is published on the French  committee’s website, “Documentation” tab:

Methods and techniques for reinforcing and repairing protection levees

This is the deliverable of the CFBR “Levees” Working Group. It is made up of two parts:
– a first, “General framework”: https://www.barrages-cfbr.eu/IMG/pdf/recueil_confortement_digues_partie_1.pdf
– a second, “Technical data sheets”: https://www.barrages-cfbr.eu/IMG/pdf/recueil_confortement_digues_partie_2.pdf

This accomplishment is the result of many years of work. At the moment this document is only available in French, but the working group  is now starting the process of translation into English, with the aim to have a first part ready for the Marseille ICOLD congress.

Webinar on Animal Burrowing – feedback

It was good to see so many at the workshop 30 June (67 people in total). Some presentations are already on the website (see https://lfd-eurcold.inrae.fr/index.php/wg-webinar-1/), the others will follow as soon as possible.

The speakers were excellent and we are very grateful to them. Hopefully we will be able to have another event later this year. In the meantime, if you want to be kept up to date on news from the Working Group please sign up for membership to the website (see https://lfd-eurcold.inrae.fr/index.php/web-site-instructions/).

FLOODrisk online conference 22-24 June 2021

The FLOODrisk conference starts tomorrow. A very attractive program including plenary sessions, parallel sessions ans special sessions has been prepared; see it here : https://hub.floodrisk2020.net/programme/

Join us and let’s share knowledge and experiences!

Webinar on Animal Burrowing (30/6/21) – Final program

The webinar on Animal Burrowing will take place on June 30.

11:00 CET          Welcome
11:05                  1. English perspective on managing badgers in embankments (Paul Arnold, EA)
11:20                  2. Detection of cavities in levees and forelands caused by beavers (Torsten Heyer, TU Dresden; Michael Arndt, Secon Systems)
11:40                  3. Experiences with the beaver during high water 2021 (Wijnand Evers, Waterboard Drents Overijsselse Delta)
11:55                  4. A glimpse of another animal active in and around levees (Heleen Keirsebelik, UAntwerpen)
12:00                  Exchanging thoughts and experiences on animal activity on levees
12:25                  Feedback on webinar and poll for future topics

Please send an email to patrik.peeters@mow.vlaanderen.be to receive a MS Teams-invitation!
Adrian, Patrik & Rémy

2019 Japan flood reports are published

The reports of levee failures, etc. in 2019 Typhoon Hagibis is published in English by the Japanese Geotechnical Society. The reports are open access.
https://www.sciencedirect.com/journal/soils-and-foundations/vol/61/issue/2#article-22
Including, “Levee damage and bridge scour by 2019 typhoon Hagibis in Kanto Region, Japan”
https://www.sciencedirect.com/science/article/pii/S0038080621000226

Backslope erosion by overtopping at the Naka River levee (Photo : Hirotoshi Mori)

A WG webinar on animal activity on levees

We are very pleased to announce the first webinar of the Working Group on Levees and Flood Defences of the European Club of ICOLD, about animal activity on our levees, which will be held June 30th from 11:00 to 12:30 CET. Please email Patrik if you want to attend. He will send you an appointment which you can also forward to any others you think would be interested.  Three presenters will be given the floor to share experiences and expertise with respect to prevention, detection, assessing severity, repairing, regulation and any other issue related to animal activity challenging the integrity of levees, in particular from the levee managers’ point of view. After these presentations, a large part of the session will be devoted to discussion and further exchanges between all of the participants.

Please email  Adrian/Patrik/Rémy by Friday 4 June

  1. If you would like to be a presenter for the 30 June webinar. Presentations will be up to 15 minutes long. Depending on the number of responses we may have to select who will be a speaker.
  2. We are considering organising a second knowledge sharing session in autumn of this year. Let us know what topics you would like to hear about it.

Adrian Rushworth

Patrik Peeters

Rémy Tourment

Photo source and copyright : https://commons.wikimedia.org/wiki/File:Badger-badger.jpg

Special session in the FLOODrisk conference on risk based decision making for levees

During the FLOODrisk 2020 conference (happening in June 2021) , a special session  ‘Risk Informed Decision Making for Levees and Flood Defences’ will take place virtually on Tuesday 22 June 2021 from 13:30 to 15:00. This special session is organised by EUCOLD LFD WG and ICOLD TC members.

Special Session: Risk Informed Decision Making for Levees and Flood Defences

For more information visit the Special Session Hub. To access this page, you will need to be registered online. If you haven’t done so yet, tou need to  Register Now Here.

Grass roots

Very interesting post in Linkedin about grass roots, which shows we still have a lt to learn on this topic :  link

Discovery of ancient levee in the Netherlands

Near the town of Vlaardingen, remnants have been found of an ancient construction that probably served as a low levee. The construction was about 1 metre in height, at least 20 metres long, and consisted of a dual construction consisting of wooden piles and braided willow branches, that was subsequently filled with earth.

The levee was probably constructed over 2000 years ago, during the 2nd century BC. As such, it is probably the most ancient levee discovered so far in the Netherlands.

 

See https://nos.nl/artikel/2373863-mogelijk-oudste-dijkje-van-nederland-ontdekt-in-vlaardingen.html  for some pictures.

FLOODrisk conference

The FLOODrisk international conference on Food Risk management, postponed from 2020, is now scheduled from 21st to 25th June 2021 online. You can find all details here: https://floodrisk2020.net/news/floodrisk2020-virtual-conference-information/ 

Registration is open.

EGU virtual conference – Submissions deadline January 20th.

I received from a colleague  this information that I wanted to share with you:

DO NOT FORGET THAT… Is that time of the year were we get crazy and excited about submitting abstracts for EGU ! Deadline for abstract submission is extended to the 20th of January 2021, 13:00 CET. This 2021 promises an even more exciting event as we started our session on “Advances in modelling, failure assessment and monitoring of levees and other flood defences”. We want to start this session as a tradition for dikes and other flood defences practioners and researchers to have the opportunity to meet in a yearly basis and share our findings and relate to other world known flood risk experts. Please submit your abstract and contribute to the start of this hopefully yearly tradition for flood risk and flood resilience enthusiasts.  Please feel free to forward the invitation to any dike enthusiast who you think may be interested either in submitting something or attending to the session. Looking forward to your abstract submission !

In situ overflowing experiments at Living Lab Hedwige-Prosperpolder by POLDER2C’s

POLDER2C’s has started with the execution of levee overflow tests near the Dutch-Belgian border. Besides well-maintained levee sections, we aim to test anomalies like presence of a cliff, animal burrows and a tree.

https://www.vrt.be/vrtnws/nl/2020/11/13/dijken-doel/

https://polder2cs.eu/

Patrik Peeters
Flanders Hydraulics Research

Presentation of the French version of the ILH

The French association of levee managers France Digues organises a presentation of the French edition of the International Levee Handbook. Because of the COVID19 situation, this event, which was supposed to happen in Paris as a physical meeting, will beheld online so more people will potentially be able to attend. More details here : Programme de la matinée JT Guide ILH  and inscriptions here : Formulaire d’inscription

Reflections on the ICOLD LE TC meeting September 2020

The ICOLD Levees Technical Committee (LE TC) 2020 met over the last three days of September for our 2020 meeting. These are some of my personal reflections.

The current restrictions in response to COVID19 were overcome by having a teleconference on each of the days. I think the importance of Levees worldwide was seen by the range of countries that joined the meeting despite the large time differences for some. We were also pleased to Welcome Michael Rogers, the current President of ICOLD, to one of our meetings. Each day had a different theme.

Day 1: On the Monday we considered the Levees situation report. The report is well developed containing information, including a section with detailed information about levees within many countries. The version of the Levee Situation Report tabled at the meeting was approved.

Day 2: The focus for Tuesday was the dams-levees comparison report. Chapter include design, construction and inspections. Draft chapters were considered with feedback for the authors. The report is developing into a useful source and signpost for information and will help learning across dam and levee practitioners.

Day 3: The Wednesday meeting considered general topics. I particularly noted the importance of effective national backing groups to support TC members as the reports are nearing completion. It was also an opportunity for suggestions for future bulletins.

I was again impressed by the importance of levees across the world combined with the knowledge and enthusiasm of those managing them.

Adrian Rushworth

Webinar on International Levee Databases

Last week TU Delft hosted a webinar on their International Levee Performance Database, as well as similar initiatives from France and the USA. The webinar also discussed the applications of such databases and the necessity for closer collaboration in developing them.

Over 150 participants joined online from around the world, representing private consultancies, academic and research institutes and local and national authorities.

A recording of the event can be found through the below link, as well as links to videos on the use of the ILPD;

Webinar:                                                                                                         https://www.youtube.com/watch?v=lVSmvdaCVCE
ILPD in general:                                                                                           https://youtu.be/p4B6biRk0EM
Assessment and design (In Dutch,with English subtitles)  https://youtu.be/3wQk77_vuiU
Crisis management:                                                                                   https://youtu.be/eecNYsiJh6k
Data Science:                                                                                                 https://youtu.be/k2_IcEISeWA

We hope to continue this initiative, and welcome any comments or suggestions through our email: leveefailures@tudelft.nl.

I.S. Rivers conference

The 4th International Conference  IS. Rivers will take place from June 21 to 25, 2021.
I.S.Rivers is an international conference focused on research and action in the service of large rivers in Europe and the world, a meeting between scientists and practitioners.
The French National Dams Committee CFBR is a partner of this event. More details here : http://www.graie.org/ISRivers/a_index.php

SafeLevee webinar on failure databases

Dear colleagues,

Over the last 5 years the SAFElevee project team at TU Delft has investigated levee failures and has set up an open-access database (the international levee performance database – ILPD) with over 1500 levee failure and performance cases.

You are warmly invited to attend a webinar on the SafeLevee project and ILPD database.
The event will be held on Friday 25th September from 13.30 – 15.30 CEST, and the program outline is as follows (further details will be made available at a later stage).

Block 1: SAFElevee, the international levee performance database and its use for levee managers

  • Introduction to the program, SAFElevee project and International Levee Performance Database
  • The use of levee performance information for levee managers (design, crisis management etc.) – 4 short videos on this theme have been prepared by HKV consultants and will be shown
  • Open discussion on use by levee managers with contributions from Rijkswaterstaat and other levee managers and participants.

 

Block 2: International collaboration in collecting, sharing and analysing levee failures

  • Short Introduction (Bas Jonkman, TU Delft)
  • Presentations by other similar database initiatives (EDF, France and others)
  • Panel and open discussion on future use and sharing of levee failure and performance data

Please confirm your attendance by emailing leveefailures@tudelft.nl, and feel free to share with others you think may be interested. More details will be provided to attendees prior to the event, including a detailed agenda and access details.

Free ICFM webinar on flood events China, JP, USA (26 Aug)

Under the title “The Flood Challenge to Resilience” ICFM will share the experience with (i) major flooding in China that affected/s millions of people and hundreds of river basins; (ii)  flooding in Japan caused by truly extraordinary amounts of rain falling over the island of Kyushu; and (iii) flooding in Michigan (US) that interacted with aging infrastructure and resulted in failure of two dams.

Three highly regarded speakers – Professor Jun XIA, Professor Toshio KOIKE and Dr. Molly FINSTER –  will introduce these topics and set the stage for the discussion by the audience. See the webinar invitation/registration page at www.icfm.world/Webinars.

Building a resilient flood protection system, including to overtopping. Summer 2019: creating openings in an existing railway

History of the project

On the left bank of the south of the Rhône river (in France), between the cities of Tarascon and Arles, a railway embankment has performed for many years as a flood protection structure although it was not a role falling under its owner (the French National Railway company) responsibility. In December 2003, because of breaches in appurtenant embankments, the north of the city of Arles was flooded for many weeks.

Fig. 1: breaches on appurtenant embankments in 2003

In the aftermath of this centennial flood, the State and local authorities have put in place a vast flood prevention plan at the scale of the catchment area, called Plan Rhône, which notably provides for the complete renovation of the levees of the Rhône Delta over 20 years. Among this ambitious program, was decided the creation of a levee resistant to overtopping up to the 100 year flood, parallel to the railway embankment, and the creation of 10 openings (concrete structures) in the railway in order for it to be “hydraulically transparent” (see Fig. 2). This segment of levee and the reinforcement of the rest of the system against all other deterioration and failure mechanisms allows the whole levee system to withstand floods up to the 1000 year with a 50 cm margin (the crest level of the levees not-resistant to overtopping). Floods above the protection level (100 year) will flood the protected area in a controlled way and with many times less water volume and speed than any previous scenario with the same probability (see Fig. 3). A second line levee will prevent the flood going over the new levee to reach the densely inhabited suburbs of Arles.

Fig. 2: schematics of. the future overtopping resistant levee and the railway embankment with the transparency structures

Fig. 3: compared modelled consequences of the historic flood (1856 – 250 years event) before and after the project (Source: SYMADREM)

References  on the design of the system: 

Cheetham, M., Mallet, T., Chastel, E., Tourment R., Robustelli, P., Pelt, P., - - 2015. Building a resilient system of defence against flooding from the Rhône. Proceedings of the Institution of Civil Engineers-Water Management, vol. 168, n° 2, p. 74-84

Cheetham, M., Tourment, R., Pelt, P. - 2016. Risk assessment and economic appraisal of protection methods for the Tarascon-Arles railway embankment. 3rd European Conference on Flood Risk Management FLOODrisk 2016 17/10/2016-21/10/2016, Lyon, FRA. E3S Web Conf. Volume 7, 2016. 3rd European Conference on Flood Risk Management (FLOODrisk 2016). 8 p.

Summer 2019

During the summer of 2019, over two periods of barely more than 48 hours, five out of the ten opening structures(like the one in figure 4)  were put in place in the railway embankment. The planning of these operations started years in advance, as it involved the disruption of the rail traffic on a major line of train transport for both passengers and goods. The five other ones are being constructed now at a short distance along on the side of the railway embankment and will be put in place during the summer of 2020. During each of these sequences of non-stop operation, the following steps have to be successively completed:

  • Cutting the rails
  • Creating an opening in the embankment (Fig.5),
  • Adding a layer of material to support the structure,
  • Moving the concrete structure in its final place and checking its proper placement (Fig. 6), as well as smaller parts on each side, also prefabricated (Fig. 7),
  • Filling the space between the embankment and the concrete with new embankment and compacting it (Fig. 8)
  • Adding railway ballast
  • Repairing the rail line and setting it to ensure its performance (Fig.9)

The hazard of a flood happening during these crucial phases was considered and measures were taken to minimize the risks, including being able to close the embankment openings in case of a flood not foreseen when the operation started.

The openings are temporarily closed until the new levee is completely built, in order to keep ensuring the current protection level (Fig. 10). Afterwards stilling basins can be added (Fig. 11)

Marseille 2021 ICOLD Congress

During the Marseille 2021 ICOLD congress, one of the field trips will be organised in this area and the whole complex system will be presented: overtopping resistant levee, opening structures, second line of defence and flood water management.

Fig. 4: one of the opening structures and the equipment used to move it

Fig. 5: open railway embankment

Fig. 6: moving the structure and controlling its placement

Fig. 7a & 7b: additional prefabricated concrete structures for the bottom of the slopes of the embankment

Fig. 8a, 8b & 8c: placing and compacting the new material between the existing embankment and the concrete structure

Fig. 9: the specific engine in charge of placing the railway ballast in order to ensure performance of the rails

Fig. 10: concrete slabs to temporarily close the openings until the new levee is operational

Fig. 11: a stilling basin in construction

Fusion of information from geophysical and geotechnical investigations for levee assessment

The identification of levees constitutive materials, as well as the detection of possible interfaces and anomalies, are crucial for site characterization. During investigation campaigns, complementary geophysical and geotechnical methods are usually used. These two sets of methods yield data with very different spatial scales and different levels of incompleteness, uncertainty and inaccuracy. On the one hand, geophysical methods are generally non-intrusive and provide physical information on large volumes of soils but with significant potential uncertainties. These uncertainties are due in particular to the integrative and indirect aspects (relative to the parameters related to failure modes limit state equations) of the methods as well as to the resolution of the inverse problems. On the other hand, geotechnical investigation methods are intrusive and provide more local information but also more accurate and very often directly related to parameters related to failure modes limit state equations. An important issue to improve the characterization of subsoils and existing levees is to be able to combine acquired geophysical and geotechnical data, while taking into account their respective uncertainties, inaccuracies and spatial distributions. The complementarity of these two sets of methods is often underused since the uncertainty and inaccuracy associated with each method are rarely considered. Furthermore, results are usually only graphically superimposed and considered with an expert opinion instead of being mathematically merged. These works propose a specific methodology in order to manage conflictual information and different levels of uncertainties and inaccuracies from different investigation methods, expanding geotechnical information between borehole positions. It presents a new way of mathematically combining data from these two types of information sources, taking into account the specificities of each kind of method. This new methodology considers the framework fixed by the theory of belief masses and improves the characterization of lithological sets within levees and their foundation. It provides information on the level of conflict between information sources while proposing a confidence index associated with the results.

By: Théo Dezert

Figure 1: Section of a levee with representation of lithological materials having the highest belief mass values after fusion process between electrical resistivity, granulometry and CPT data (left) and their associated belief mass values (right).

Figure 2: Levee modeled resistivity longitudinal section obtained by inverting Wenner-Schlumberger apparent resistivity data
Figure 3 : ISBT vertical profiles for each CPT test and associated soil classes
Figure 4 : Representation of the levee section displaying borehole positions in dashed lines and associated ISBT (white dotted line) and particle size distribution (white solid line) corresponding classes

 

References :

Journal articles:
  • Dezert, T., Fargier, Y., Lopes, S. P., & Côte, P. (2019). Geophysical and geotechnical methods for fluvial levee investigation: A review. Engineering Geology, 105206.
  • Dezert, T., Lopes, S. P., Fargier, Y., & Côte, P. (2019). Combination of geophysical and geotechnical data using belief functions: Assessment with numerical and laboratory data. Journal of Applied Geophysics, 170, 103824.
Conference papers:
  • Dezert, T., Fargier, Y., Palma-Lopes, S., & Côte, P. (2019, September). Levee Characterization by Means of Data Fusion of In-Situ Geophysical and Geotechnical Information. In 25th European Meeting of Environmental and Engineering Geophysics (Vol. 2019, No. 1, pp. 1-5). European Association of Geoscientists & Engineers.
  • Dezert, T., Fargier, Y., Palma-Lopes, S., & Cote, P. (2018, September). Application of Belief Functions to Levee Assessment: chapter X in: Belief Functions: Theory and Applications.

https://hal.archives-ouvertes.fr/hal-01891806/

  • Dezert, T., Lopes, S. P., Fargier, Y., & Cote, P. (2018, September). Geophysical and Geotechnical Data Fusion for Levee Assessment-Interface Detection with Biased Geophysical Data. In 2nd Conference on Geophysics for Mineral Exploration and Mining (Vol. 2018, No. 1, pp. cp-566). European Association of Geoscientists & Engineers.

https://www.earthdoc.org/content/papers/10.3997/2214-4609.201802536

ICOLD Meeting 2020 New Delhi

UPDATE (4 March) : the meeting has been postponed due to the Coronavirus epidemic. The new dates are: Sat. 26 Sept. – Th. 01 Oct. 2020.
The dates for the WG workshop and meeting are on Sunday 27th and Monday 28th respectively.


The 2020 ICOLD meeting will be in New Delhi, India, from 4 to 10 April. Registration is now open and the early bird rate ends at the end of January, so hurry if you want to benefit from this reduced rate. Information and registration here : https://www.icold2020.org  The third bulletin is available on line on the same web site.

The Levees Technical Committee of ICOLD (ICOLD LE TC)  will hold a workshop on Monday  6 and a meeting on Tuesday 7. During registration attendees have to indicate which TC workshop and meeting they plan to attend. We invite all our levees community members to register for these TC events, wether a member of the LE TC, of  the EUCOLD LFD WG or simply interested in levees, and to encourage your colleagues and relations to do the same. It is important that we have a large attendance for a wide exchange of information and knowledge, and it is also important to register for logistic reasons (room size).

NB: LE TC members not able to attend are strongly advised to have a colleague from their national dam committee to attend the TC workshop and meeting on their behalf.

new geotechnical software

Rijkswaterstaat has launched new geotechnical software for slope stability on November 28th

This was developed together with Deltares and our dike reinforcement program HWBP (The Slope Stability Project / POV Macrostabiliteit).

Raymond van der Meij from Deltares was the main driving force behind the development. Meindert Van was one of the initiators.

We have merged the knowledge from five different initiatives in the Netherlands on slope stability in the new software.

 

It will be available on the Deltares and on the Rijkswaterstaat website (Helpdeskwater.nl)

It will be in the English language. The software is available to everyone (free of charge). Support for users who assess or design flood defenses in the Netherlands is covered by Rijkswaterstaat. Support for user in other countries will go through Deltares (this is not free of charge).

 

The user manual is available on

https://www.helpdeskwater.nl/publish/pages/169760/user_manual_d-stability_v20_1.pdf

 

Request: information on drought effects (e.g., cracks) in levees

Dear all,

During last month’s EURCOLD Symposium I presented a paper on drought effects on levees; see https://www.researchgate.net/publication/336641742_Mitigating_drought_risk_for_levees_Mitigating_drought_risk_for_levees . For the Sept2020 Floodrisk Symposium, I wish to extend this work and include some more experiences regarding drought effects on levees. However, it turned out to be quite hard to find publications and data (such as drought crack dimensions+position and other properties, drought crack development and recovery, best practices on remedial measures, etc.). Who can help me out, and send me some useful weblinks/publications and/or [summarized] data?

Thanks in advance!

Marcel Bottema

ECMSGE 2019

The XVIIth ECSMGE conference, held in Reykjavik  with the theme “Geotechnical Engineering, ​foundation of the future” on September 1-6, had a lot of content related to levees and also to dams.
​ISSMGE TC201 on “Geotechnical aspects of Dykes and Levees” has some members in common with ICOLD LE TC and EUCOLD LFD WG.  We will in the future continue to exchange information between our ICOLD groups and TC201, as well as encourage actual collaboration (see report).
With the help of Meindert Van for review and of Cor Zwanenburg for a list of levee papers, we produced a report on the conference with links to additional information, that we encourage you to read.

The report is available for download from our “Members only” menu in the web site.

FLOODrisk2020 : last week to submit an abstract

FLOODrisk 2020

Attention – 1 week left to end of abstract submission

We would like to remind you all that the call for abstracts for the 4th European Conference on Flood Risk Management, that will take place in Budapest will close on 16th September 2019.

FLOODrisk2020 is committed to attract, coach and listen to the next generation of scientists and practitioners who will future-proof our research methods and help to improve our flood risk management practice in order to better cope with deep uncertainty and therefore the 4th conference will focus on the issue of Science and practice for an uncertain future.

YOU NOW HAVE LESS THAN 1 WEEK LEFT TO SUBMIT YOUR ABSTRACT on https://floodrisk2020.net/authors-area/

New issue of our LFD WG newsletter

Hello

we have  issued a new issue of our Levees and Flood Defences  Working Group  newsletter. You can find it available for download on our website.

It concentrates on the different levees related conferences of this year: the ICOLD annual meeting, the ECSMGE conference, and the EUCOLD symposium. It also includes a special feature presenting the extreme flood events on the Missouri in the USA.

Thanks to all the contributors, particularly Noah Vroman from USA for the long paper, and Sam Leonard from UK for the editorial task.

I hope you enjoy it.

Rémy

EUCOLD 2019 Symposium

We encourage all our members to attend the EUCOLD Symposium on October 2-4  (https://www.eurcold2019.com) and particularly the two days organized  by our WG (https://www.eurcold2019.com/eucold-wg-lfd) on Sept. 30 and Oct. 1

Please also disseminate this information among your contacts interested in levees and flood defences.