A Diverting Structure's Effects on a River Flow Time Series

A step-by-step summary of an empirical time series analysis of the effects of a newly constructed dam on river flow rate is given. A model of river flow rate for the 522 weeks of data is built through the transfer function/intervention model development processes of Box-Jenkins/Box-Tiao. Analysis indicates a rainfall variable has a significant influence on the pre-dam flow rate but not on the post-dam flow rate. The model also reflects a differing relationship of rainfall to pre-dam flow rate depending on the season of the year. Physical interpretations of model parameters and determination of implied mean flow rates suggest that the final model provides a sound basis for some public policy decisions that might focus on the dam.