Warning waves to protect human beings in bypassed river reaches of hydropower schemes

River reaches located downstream of a hydropower plant are conductive to sudden variations in flow discharge. Warning waves constitute a useful non-structural measure to warn users of the downstream river reaches of an imminent increase in discharge. However, determining the up-stream release hydrograph to generate a suitable warning wave is an inverse problem, intricate to solve. We present here a two-model strategy, in which a kinematic analytical model provides valuable insights to guide the solution of a 2D computational model.