Abstract
The paper proposes a method for modelling tunnel network flow between reservoirs and creeks above hydro power plants in short term hydro optimization. A method for handling pressure constraints in nodes in the tunnel network is also included. The method is applied on a plant below a reservoir and a creek, with a rigorous minimum pressure constraint in a tunnel. A comparison of the presented method with a manual adjustment method for handling the minimum pressure constraint shows a 3.3% increase in objective value of the original total sale.