HYDROLOGICAL PROCESSESHydrol[ Process[ 03\ 1198Ð1109 "1999#

Copyright © 2000 John Wiley & Sons, Ltd.

TELEMAC modelling system: an overview

Jean!Michel Hervouet�Laboratoire National d|Hydraulique\ EDF\ Direction des Etudes et Recherches\ 5 Quai Watier\ 67390 Chatou\ France

As a result of steady improvements in hardware and algorithms\ numerical simulation is increasingly amajor research area in hydrology[ Meanwhile\ rising environment!related problems\ and in particular water!use issues\ raise more and more complex and multidisciplinary questions[ Consequently\ the applicationrange for numerical analysis is becoming wider and the requirements placed upon it are ever more exacting[This high rate of development involves signi_cant e}orts aimed at four major goals\ namely]

0[ modelling of physical processes and algorithmic research^1[ user interfaces and adaptation to technological developments^2[ documentation and quality control^3[ model validation[

This necessary evolution towards what is sometimes called {hydroinformatics| is costly and the time whencomputer programs could be written by one person in the duration of a study or a thesis is now over[ In thefuture we must work on a long!range basis\ know how to preserve the acquired experience while rapidlytaking advantage of the latest advances in science\ and address users from various origins by setting upintersoftware communications] thus the concept of a modelling system rapidly emerges[ The TELEMACsystem is one such suite of environmental simulation software that has developed as a result of these researchpressures[ The di}erent papers in this special issue give an idea of the system|s range of application and it isperhaps appropriate in this introduction merely to give a bridge overview of its main components[

The TELEMAC system consists of a whole processing chain for the calculation of water\ solute andsediment motions in the ~uvial\ coastal\ estuarine\ lacustrine and groundwater domains[ Classically\ itcomprises {pre!processors| for digitizing the data and describing the problem\ simulation programmes and{post!processors| for displaying and analysing the results[ One of the key assets of the system is the use ofthe _nite element theory\ which comprises a rigorous theoretical framework and a ~exibility for describingcomplex geometries[ This latter point will become apparent in view of the various applications illustrated inthe following papers[ The digital simulation programs are as follows[

0[ TELEMAC!1D provides the hydrodynamics] horizontal depth!averaged velocities and water depth[ Itsolves the De Saint!Venant "or shallow water# equations in two dimensions[ Applications of TELEMAC!1D include ~oods "see the paper by Asaro and Paris#\ dam breaks "Hervouet# and tides "Malcherek#[Many physical phenomena are taken into account\ such as friction\ turbulence\ wind velocity\ variationsof atmospheric pressure\ lunar and solar tide!generating forces\ submerged dykes\ weirs and culverts\ etc[

1[ TELEMAC!2D solves the three!dimensional Navier!Stokes equations with a free surface and a hydro!static pressure assumption[ TELEMAC!2D is able to deal with the e}ects of a vertical density resultingfrom temperature and:or salinity ~uctuations[ Common applications are the study of temperature plumesin rivers or in the sea[ Di.cult problems such as the simulation of a salt wedge\ or the turbidity maximum

� Correspondence to] Dr J[ M[ Hervouet\ Laboratoire National d|Hydraulique\ EDF\ Direction des Etudes et Recherches\ 5 QuaiWatier\ 67390 Chatou\ France[ E!mail]J!M[HervouetÝedf[fr

J[!M[ HERVOUET

Copyright Þ 1999 John Wiley + Sons\ Ltd[ Hydrol[ Process[ 03\ 1198Ð1109 "1999#

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in an estuary can also be tackled[ The paper by Kopmann and Markovsky illustrates just such anapplication of TELEMAC!2D[

2[ The water quality programs\ SUBIEF!1D and SUBIEF!2D\ use the results of the ~ow computationsdelivered by TELEMAC!1D and 2D to simulate the movement of dissolved substances and:or suspendedsediments[ Any water quality model composed of a set of interacting substances subject to advection\di}usion and sink:source terms can be easily parameterized[ This is achieved in the SUBIEF architectureusing a simple ASCII _le to describe the model[ This is then pre!processed and the relevant computersource code is generated automatically and linked to the SUBIEF software libraries[

3[ Sediment transport models have also been developed to use the results of the ~ow computation toundertake simulation of bed!load and suspended!sediment transport[ The SYSIPHE software o}ersvarious bed!load transport formulae\ such as Engelund!Hansen\ Einstein!Brown and Bijker[ Sedimenttransport in three dimensions can also be treated directly in TELEMAC!2D "see the paper by LeNormant#[

4[ Underground saturated and non!saturated ~ows are dealt with in two and three dimensions with twoprograms\ ESTEL!1D and ESTEL!2D\ recently developed at the University of Bristol "Desitter et al[#and based on Darcy|s law and Richard|s equation[ Thanks to a formal analogy between porosity in theRichard|s equation and water depth in the transport equation for pollutants and tracers\ SUBIEF!1Dcan be readily used with a velocity _eld computed by these programs "Lucille et al[#[

5[ Other programs deal with wave simulation\ which although not falling within the scope of this journalspecial edition are mentioned here for completeness[ ARTEMIS models wave changes induced byrefraction\ di}raction and re~ection by obstacles\ wave breaking and bottom friction in the vicinity of ashore[ TOMAWAC and COWADIS are third generation spectral wave codes that model the mainphysical processes creating and acting upon the waves[

6[ All the physical phenomena treated by modules of the TELEMAC system generally interact\ e[g[ thehydrodynamics may generate sediment transport\ which modi_es the topography and hence has anin~uence on the hydrodynamics[ Means of communication are thus necessary between the di}erent partsof the system[ The {external coupling| approach has been chosen with a software application calledCALCIUM\ based on the message passing language\ PVM[ Two programs running concurrently on thesame or on di}erent machines may exchange data through simple read and write statements[ Compatibilityis naturally ensured even if the two programs are developed separately[ More recently\ parallelism basedon domain decomposition has also been implemented "see the paper by Hervouet#[

The TELEMAC system was developed initially at the Laboratoire National d|Hydraulique\ a departmentof the research branch of Electricite� de France[ It is now a joint e}ort of several research teams in Europeand this is exempli_ed by the variety of papers presented hereafter[ Pioneers were the Universities ofHannover in Germany\ Bristol in England\ and Coimbra in Portugal[ The system is also being used anddeveloped in European projects such as MAST\ MAST1\ MEDCOAST\ COSINUS\ PCECOWATER\SASME\ SEDMOC and ELTRAMOS[

The system is now a common platform enabling industrial studies and multidisciplinary research\ it israpidly evolving both in its conventional _elds and towards new applications[ With their support\ suggestionsand remarks\ with the developments and ideas they contribute\ users are now the main evolution factor[Being at the crossroads of their knowledge and diversity is an exciting situation\ and not disappointing themis a challenging commitment[ Despite the variety of topics discussed hereafter\ we all have the feeling ofliving the same scienti_c adventure[ Our wish is that by reading the papers that follow you will catch someof this feeling[