Identifying potential systemic changes in a regulated river: A diagnostic methodology based on whiteness property of innovation sequences

Abstract

Traditional hydrologic routing schemes are structured in reference to a pre-assumed time-invariant inflow-storage-outflow function. In light of this, potential systemic changes, arising from river regulation, cannot be accommodated in such a static model structure. As such, a diagnostic methodology is developed in this study to examine the presence of potential systemic changes and recognize time spans in which the adopted inflow-storage-outflow function is inadequate to represent the functional behaviour of the system. This is done objectively by developing a two-step change-points detection algorithm based on the whiteness property of the innovation sequence. Using four carefully designed numerical experiments, our findings reveal that the proposed methodology (a) detects the non-stationary behaviour in streamflow time series associated with systemic changes objectively, (b) tracks the pathway of structural evolution of a hydrologic routing model properly, and (c) identifies time periods automatically wherein a river routing model structure needs to be updated.