 The monitoring of dams, okay, this presentation is, I'm the first talker, he lead you for various firm, an important dam owner in Portugal. It is the main energy supplier and twice a colleague of mine at LNEC. In dams, there are a long history of monitoring because a lot, there are a lot of years with the monitoring of dams. The main motivation was the large number of dams. Dam are structures with high consequences in the case of an accident. So there is a little values of probability of occurrence of an accident, but they have huge consequences with lots of life sets. So there is, from the beginning of the construction, a great interest in the monitoring. There was also some incidents requiring the expensive repair works. Let's, in dams, mainly for instance in hydroelectric systems, it is very expensive to not operate. So an adequate monitoring that can avoid the no operation is very important. Also the number of dams in operation is increasing in the aging. So we have the aging of dams. The dams, a lot of dams are being older than the design provision. And also there are important contribution from the development of science and technology to understand the behavior of this monitoring. Only to understand the consequences here, you are, an image of the consequences have a known accident in dams. For this reason, in most and a number of countries, there are specific legislation concerning the safety of dams. In Portugal, there is a decree law, a regulation for safety of dams. The first version is almost 25 years and it was revised in 2007. And it identifies the main entities that are responsible for the monitoring and safety of dams. The main responsibility is the dam owner. But for this kind of works, it is important to involve public entities because in case of an accident, it is a public emergency. So it involves the dam owner, Portuguese authority for dams, LNEC. LNEC works like a technical advisor and the LNEC as continuous, a long time knowledge of the behavior of the dams because from this legislation, the LNEC must know and investigate the behavior of the dams from construction during all the life of these structures. And also national civil defense service. And this is a decree law that is also supported by Codes of Practice with recommendations for the design, the construction and the observation in these patients. So there is a legal framework that concerning these activities. So the main principle of safety control is like the other structures. We have the reality, we have the monitoring and we have the predicted values with numeric or empirical models. And this from the confrontation comparison from monitoring with prediction that we decide about the behavior of the dam. Here is, I'm sorry because the picture is not very well but it is an image of the monitoring system of a concrete dam. You can see devices for measuring the displacements, strange temperature, et cetera. And here you can see a graph with the number of sensors or instruments in each dam. As you can see, the bigger dams have a lot of instruments. So this is because they are important structures. But the smaller dams have a smaller number of instruments. The monitoring systems are designed specifically for each dam, taking into account the recommendations of the codices of practices. Now I gave two examples that I think that illustrate the interesting of monitoring. The first example is a concrete arch dam in Portugal that from the beginning it is a dam that was 50 years old with a lot of cracking. It is a medium high dam, but it was very damaged. It was a lot of cracking. It was this picture as a few years. And you can see that, namely here in the middle of the banks that there are a lot of cracking with water in these dangers. So in the year you can see in a zoom in in that zones. And this was an image of the structures. It was affected by alkali silica reactions in the concrete. And it was identified by the monitoring systems here. It is, we have some points which displacement are observed by geotechnical methods. And here you can, it is represented an arch of the dam and evolution of the displacements a long time. And you can see that all the dam was going upstreams with one millimeter per year during 40 years. So this was a sign of something was wrong. And so 20 years ago or 25 years ago some concerning about the dam, there was some concerning and it was thinking to abandon the dam but with monitoring and another studies to understand this behavior, it was possible. This is a representation of some numerical studies taking that was developed during the 90s. It was understood the evolution of the swelling and it was possible to maintain the dam in operation during more 20 years. With all time with the dam operating with this for production of electricity which was very important. So it is a case here later the dam a few years ago the dam was demolished and substituted for foreign UN. Here you can see in the back the remains of the old dam. This was the spillway the dam was here and this is a new dam that was built down downstream. It was an example of how the monitoring could contribute to the extension of the life of the structures helping the delay of the construction of the new one. Only with a continuous assessment of the dam safety condition it was possible to achieve this objective. Another example, I think in dams in the safety control of dams the old accidents gives always good lessons that are important to learn. Here is a known accident, it was in Italy. Vagion Dam, it is in the north of Vanessa. It was a very high dam and it was built north of Venus in the year 1960. In what happened, it was not in the dam, this is important to understand, the dam, but it was in the reservoir. It happened a huge landslide and all the mountain goes to inside the reservoir and originates a wave that overtop of the dam is destroyed, literally some village. I can use some explanation, I don't want to be very technical but it was not a good zone to make the reservoir because this was some sliding plans. And what happened here, it is like a movie. It is very interesting because the Italians have an interesting side with these pictures. Here it is the beginning, you can see here the dam, the village downstream and what happened, it was this bank, this mountain was not stable and with the rise of the water it was, it originates a sliding of all this mass in the reservoir and the originating a wave, a flooded wave 100 meters over the dam, it was, this is an estimation because I measured, of course, and also a wave upstream for another village and here it was a small valley and here there was some village and what happened, it was a huge disaster with around 2,000 deaths. Here what is interesting is that it was not, the system was monitored, they knew that something was wrong but they could not predict what happened. Here, I'm sorry, you can see that in three years before, they had a small landslide here but then in the accident it was all of this area and it was not possible to, they did not predict it. They had some, this was the first slide, this is the level of the water in the reservoir and they have some measurements and piezometers and so on but they could not avoid the accident because they did not take an adequate response to the monitoring system and so, and they had, this was before the accident, there was cracks in the mountain. This is the small landslide and then it was all of this. So this was the result. Here is one village was totally destroyed. And these pictures, in the left it is the dam before the accident. These are pictures of the dam nowadays. It is there, only this, you can see only this zone of the crest was damaged, but the dam is there. So I think that this give us some lessons. One is that we must not look only on the main structures because here the main structures work to behave well but we must have an overall view of all the problems for all the projects. And another important thing is that monitoring, in monitoring it is not sufficient to only monitor. It's necessary to understand what we are seeing and to take proper decisions. Here it is easier to talk about this after but this is an important issue I think. And in this case it is a limit case of course, the cost of an adequate monitoring with proper decision method was not comparable with the cost of not doing nothing. So only to finish, in the dams we are, the monitoring are very linked to safety problems because we can have these consequences. And so we are investing in new technologies for continuous with automated monitoring systems and so on because this is the main problem. And this is, we have in the case of ADP a good collaboration and they make a lot of investment in monitoring in these activities as they must do also by by law. Thank you. Thank you very much for a very interesting presentation. The third now presentation is by