THE COURT OF MIRACLES OF HYDROLOGY

 
     Paris,18-20 June 2008
A scientific workshop

organized at
ENGREF-AgroParistech

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Context

 

 

Articles and conferences on hydrology usually focus on success stories, i.e. case studies where hydrologists have been able to produce so-called ‘successful’ model runs. As a consequence, scientific meetings have become rather stereotyped: failure stories, the salt of scientific progress, have been excluded, and hidden in a secret place.

We postulate here that we can find this secret place, which we will call from now on the court of miracles, by analogy with what was described by Victor Hugo in his famous novel The Hunchback of Notre Dame. The court of miracles was the secret place of Paris, where all the monsters, thieves, beggars of the city were hiding.

The goal of this workshop will be to explore collectively the court of miracles of hydrological modeling.

      How to define hydrological monsters?
 

By hydrological monsters, we mean catchments, hydrometeorological situations and extreme events (flood and low flows) that somehow caused unexpected or apparently unsolvable problems in terms of:

  • measuring and observing

  • behavior understanding and modeling

  • uncertainty quantification

  • decision making in an operational context

    Why should we be interested in the failures of hydrological models?
 

Hydrological models are tools created to helps us better understand the behavior of catchments and to provide predictions, i.e. simulations or forecasts, which are used by engineers, managers and decision makers. All predictions carry their part of uncertainty, and to provide users with an honest assessment of this uncertainty, we need to analyse all results, whether successful or not.

By hiding model failures, by reducing the variability of our results, we believe sometimes that we may increase artificially the a priori confidence of users. This is a short-sighted view: our users, when confronted to the actual variability of possible results, will loose confidence towards hydrological tools. Besides, knowing that an approach is a dead end could be useful to others (if published… which quite never happens).

    Which benefits can we expect from the exploration of the Hydrological Court of Miracles?
 

There are two main reasons for calling for a renewed look at all the outliers discarded from hydrological studies:

  • identifying new ways to improve the predictions of our models. By hiding our failures, we miss the opportunity to learn what was wrong. So the damage is first scientific;

  • regaining the confidence of our model users by a more realistic assessment of model uncertainty. Indeed, the gap between the satisfactory performances published in scientific articles and the actual practice in operational conditions results in a loss of credibility from model end-users.

    Main topics of the workshop
 

Presentations are expected to focus on ‘outlier' catchments or hydrological phenomena, i.e. on those catchments or events which have been shown to be peculiar (in comparison with regional neighbors or usual behavior) and which can be considered as ‘hydrological monsters’. Studies presented during the workshop should focus on measuring, evaluating, understanding and explaining the reasons for hydrological monstrosity, and to investigate how our hydrological models could adapt to the whole range of the hydrodiversity.

The main topics of interest will be the role and processing of outliers in:

  • measurement and observation strategies;

  • regional hydrological studies;

  • extreme hydrological events;

  • rainfall-runoff modeling;

  • model evaluation – strategies and criteria;

  • issues of spatial and temporal variability;

  • non stationarity in catchment behavior;

  • the issue of ungauged basins;

  • quantification of uncertainties;

  • decision making.