**2. Problem statement**

Once the potential risks and losses as a result of rupture accidents on a dam can reach large scales a safe project and adequate construction as well as a correct operation on dams are concerns of Brazilian and worldwide engineers. Additionally, an effectively done monitoring on large dams is essential for the safety of its structure. By aiming the safety of the dams, International Guidelines and many helpful discussions about this subject have been proposed and conducted, such as the one from the [1].

In Brazil, guidelines that aim the safety of the dams were published by the *Comitê Brasileiro de Grandes Barragens* (Brazilian Committee on Large Dams), see [2]. The *Comissão de Constituição e Justiça e Cidadania do Congresso Nacional)* (The Constitutional, Justice and Citizenship Committee of the National Congress) approved, on 06/23/2009, the proposal that requires the Executive Power to establish a National Policy on Dams Safety. Its aim was to endow the Public Power with a permanent instrument for the inspection of over 300 thousand dams in the country. The text that has been questioned is the surrogate for the Law Project 1181/03 [3]. The original proposal, the Law Project 1181/03, (*Projeto de Lei – PL 1181/03)*, written by Leonardo Monteiro, defines safety guidelines for the construction of dams and landfills of industrial liquid wastes.

The concerns about the Brazilian Constitutional Public Powers is due to the recent rupture of the Dam of Câmara, (in the State of Pará - PA), in 2004; the rupture of the diversion structure of the Dam of Campos Novos, (in the State of Santa Catarina - SC), in 2006; the rupture of the Dam of Algodões I, (in the State of Piauí - PI), in 2009; and other accidents of smaller magnitude.

According to [4], the catastrophes have been opportune signs for the examination of the criteria of the existing projects and for the selection of more efficient methods and monitoring safety of dams.

In [5] show a table which contains the estimative for the most common causes of ruptures on dams. Among them, the following are highlighted: problems of the foundation; inappropriate spillway; structural problem; different declinations; extreme low-pressure; rupture of landfills; defective materials; incorrect operation; actions of war, and earthquakes. All these problems can be diagnosed with the monitoring of the dam instrumentation, with exception of the last two ones, which percentage of frequencies sum just 4%.

According to [6], the global experience shows that the expenses in order to guarantee the safety of a dam are little when compared to the costs of its rupture. The author quotes the importance of the use of a database of instrumentation for supporting the preliminary analysis of the readings in order to detect problems.
