Lessons learnt from the application of a participatory modelling approach in the framework of a river restoration project: case of the Gave de Pau River, Hautes-Pyrénées, France

Abstract

Considering the diversity of criteria and stakes, the uncertain and stochastic nature of the physical phenomena and the multi-scale aspects to be taken into account, a river restoration project can be viewed as a complex problem. Many river managers and scientific researchers have been investigating the subject as river restoration projects deal with significant safety, environmental and economic issues. A project manager can hardly be an expert in all the disciplines to consider to come up with the optimal solution that satisfies all the involved dimensions. The integration of both local stakeholders with field experience and technicians and academics with scientific knowledge can hence benefit river restoration projects. The aim of this paper is to present an approach that considers the integration of various stakeholders engaged in river restoration issues to gather their knowledge and define the solutions that offer decent compromise considering all the dimensions involved. To this end, a group of stakeholders identified according to specific selection criteria were engaged in a modeling approach based on Bayesian Networks (BNs). BNs are increasingly being used as tools for decision-making in river management due to their natural ability to adjust to complex multi-criteria systems with multiple interactions. A participatory approach based on BNs that led to the elaboration of causal graphs is introduced in this paper. This study considers the combination of both physical knowledge associated to river systems and the relation constraints to river users and managers. The work is conducted in the framework of the restoration project of the “Lac des Gaves”, an artificial lake that undergone years of sediment extractions over the past century and important flood events that highlighted several numbers of impairments.