International Levee Handbook Overview of the handbook Chapter 8 Physical processes and tools for levee assessment and design

Chapter 8 - context

8 Introduction Chapter 8 details the morphological, hydraulic and geotechnical tools to assess performance of a levee It is a toolbox chapter divided into 11 sub- sections

8.1 Principles - overview This section is an introduction of : the key principles discussed in the chapter the issues relating to levee analysis It also provides links with other chapters.

8.1 Principles – detailed example In “analysis issues for levees” sub-section, the following links with “Source – Pathway – Receptor” concept and chapter 8 sections is proposed

8.2 External hydraulic processes - overview This subsection detailed several external hydraulic processes :

8.2 External hydraulic processes – detailed example For each process, several methods are proposed, from simple to more complex ones. Most important or used formula are proposed and detailed. For example, run-up level at two percent exceedance level can be calculated with EuroTop method and Pullen et al (2007) equation

8.3 Internal hydraulic processes - overview This subsection detailed several internal hydraulic processes (flows or pore pressures within the levee and its foundation) caused by hydraulic and mechanic actions :

8.3 Internal hydraulic processes – detailed example This section reminds basic hydraulic laws and effects of permeability and anisotropy on flownet or exit gradients is discussed k 5 x k low permeability foundation unsaturated zone a) Transient flow (permeability of levee body = k) b) Transient flow (permeability of levee body = 5 x k)

8.4 External erosion - overview This section details the effect of movement of water (currents or waves) on levee surfaces and the resistance of protection systems

8.4 External erosion – detailed example Critical concepts (velocity or shear) for erosion are presented For example, grass resistance under wave overtopping conditions is detailed

8.5 Internal erosion - overview This section details all processes that involve soil particles detachment and transport by seepage flow within the levee and its foundation

8.5 Internal erosion – detailed example For example : for suffusion process (8.5.3) different up to date models are proposed such Kenney and Lau (1985) or Fannin and Li (2006) –Kenney et Lau criterion :

8.6 Slope stability - overview This section deals with slope stability analysis, reminds concepts and and gives methods, from simplified methods, design charts to complex design ones

8.6 Slope stability – detailed example For example, Jambu (1973) design charts are provided and steps of the method are explained to evaluate slope stability factor of safety Limits of methods are also discussed

8.7 Settlement - overview This section deals with settlement analysis during levee design or construction processes

8.7 Settlement – detailed example Principles of settlement are reminds and key methods of estimation are developped

8.8 Seismic analysis - overview This section details the two critical design issues when evaluating the seismic performance of a levve : – loss of significant strength of the material and – significant deformations

8.8 Seismic analysis – detailed example For slope stability, pseudo-static and pseudo-dynamic approaches are presented For liquefaction analysis, simplified method is proposed and detailed after discussion of several liquefaction criteria

8.9 Stability of flood walls - overview This section is specific to flood walls stability as structure associated to levees

8.9 Stability of flood walls – detailed example Hydrostatic and dynamic forces on walls are discribed and methods proposed to eveluate them Stability (bearing capacity, sliding, overturning) methods are given

Breach - overview This section gives elements on breach formation processes, soil type erodability and actual methods for modelling breach growth

Breach – detailed example For soil erodability, Hanson et al (2010) research results are presented For breach growth, research results of Verheij (2002) are presented

Flood inundation - overview This section provides guidance on how to relate accuracy of modelling results to the end users

Flood inundation – detailed example Examples of end uses of inundation modelling are given : flood maps for risk analysis, evacuation planning… Type of inundation models, modelling approaches are introduced

Thank you ILH Chapter 8 Team Leads: To download the International Levee Handbook go to: Édouard Durand Cerema Guillaume Veylon Irstea