Dams and overtopping: a polyhedral relationship

Abstract

This paper discusses the different elements playing a role in causes and consequences of dam overtopping: the river basin, the reservoir, the dam and the spillway, the riverbed and the territory downstream of the reservoir. The risk is presented as the key concept linking all these elements, causes and consequences of the dam overtopping. The perspective of the different stakeholders is also considered, especially that of the dam owner, who is responsible for making a decision about what to do if a dam overtopping problem arises. The different attitudes of the dam owner are mainly characterized by the definition of the damage adopted when considering the risk as a basis for an informed decision taking. The social and economical risk are defined as characteristic of the extreme opposite positions, considering only damage to others, casualties and environmental damage (social risk), or considering only the cost for the dam owner, including cost in compensation for casualties and environmental damage, (economical risk). The legalist position is also considered, of the dam owner that seeks to comply with the regulations, irrespective of the risk except in the countries where risk considerations are already part of the legal framework for decision-making. Three key questions that the dam owner must answer to solve an overtopping problem are analyzed: a) Do I really have a problem? b) What different ways can I solve my overtopping problem; and, c) How do I choose the best solution for me? Finally, an ideal process for solving an overtopping problem on a rational and informed way is proposed, including the perspective and position of the particular dam owner. The general process should be adapted for every particular case in order to be feasible in practice and as efficient as possible.