 These IWA specialist groups are a fantastic opportunity for people to meet, to share knowledge, to share experience, and to build new projects together. Sometimes we learn new methods, new approaches from other groups that we can import in our own field, reciprocally we can export some IDs, some concepts, some tools and models that could be helpful for the other specialist groups. And some issues today are at the frontiers between subsystems. And this is why and how specialist groups can usefully work together. IWA is working globally with urban water systems, urban water systems. So you have drinking water, you have wastewater treatment plants, you have many subfields or subsystems. And urban drainage is one part of this global urban water systems. In practice our group is dealing with more than storm water, because we have storm water either in separate system or in combined system, where you have also a mixing with wastewater. And by extension of the concept we are working on storm water and also sewer systems as a large concept. So we are working on issues starting from rainfall, how the rainfall is now measured, modeled, how it falls over urbanized areas, what is the generated runoff with potential questions related to flooding. And also this is not only a transfer of water, but it's our pollutants transferred. So how these pollutants arrived in the aquatic environments, what are the consequent pollution we can observe, what are the risks. And the idea is to improve our knowledge in this field to better know what are the processes, what happens, how we can model, explain them and find also solutions to reduce the emission of pollutants. And if they are emitted, how can we intercept them before they are entering into the environment, the aquatic environment. And we are working interactively with other parts of the system. For example, the outlet of sewer systems, you have treatment plants. So when we know better what is leaving the sewer systems, we know better what is entering into the treatment plant, how they interact. And simultaneously some discharges in the sewer systems are emitted directly into the aquatic environment. And so we have to interact also with river specialists, how discharges from sewer systems may affect the rivers. And rivers are sometimes used for downstream drinking water resources. So there is globally a loop and a closed system at an urban scale. So like many other specialist groups within IWA, we are not working alone. We try to find interactions with other groups, to find some issues and questions where contributions of different specialist groups may be necessary to progress in understanding, to progress in solutions, to solve the problems.