The travel time of flood waves in the Upper Tekapo River, caused by opening of the Lake Tekapo control gates, was investigated in relation to the operation of this river as an element of the Waitaki hydro scheme. It is envisaged that better knowledge of the parameters that cause variability in the time taken for water to travel down the river will lead to more efficient and reliable operation of this part of the hydro scheme. An integrated approach was used, including analysis of hydrological data, fieldwork, computational modelling and laboratory modelling. It was found that the variability observed in the travel times can be attributed to a number of parameters, not all of which can be directly measured. Although travel times were reproduced with reasonable accuracy by a computational model, the potential for the model to be used as a predictive tool for improving the hydro scheme's control system is limited by the difficulty in modelling the initial and antecedent conditions for flow events, particularly for incipient flows. The effect of depression storage in the river bed on the propagation of a flood wave, both in terms of the effect on travel time and the interaction between the wave front and the ponded water, was investigated in the laboratory. The volume of water initially stored in the river bed was shown to have an effect on the flood wave travel time. While this result could be applied qualitatively to the Upper Tekapo River, it was not possible to scale the quantitative results. Overall, the results of this study add to the understanding of unsteady flow in the Upper Tekapo River. They are likely to be useful both for the operation of the river with its current control system, and as a basis for increasing the efficiency with which water is used for energy generation by refining the control strategy.