Modeling and Optimal Control of Networks of Pipes and Canals
  This paper deals with the optimal control of systems governed by nonlinear systems of conservation laws at junctions. The applications considered range from gas compressors in pipelines to open channels management. The existence of an optimal control is proved. From the analytical point of view, these results are based on the well posedness of a suitable initial boundary value problem and on techniques for quasidifferential equations in a metric space. 
R.M. Colombo, G. Guerra, M. Herty, V. Sachers