Chapter 16 Detecting and forecasting growth in the seeds of change

Publisher Summary This chapter describes an important variation on the basic theme of structural change, and presents case study. The chapter provides a case study of the River Cam, employing it to assist in reflecting on these profoundly difficult questions. The purpose of system identification, or more commonly model calibration, is to detect and to diagnose the possible paths of structural evolution in the observed behavior of the system, and that this may be perceived as deviations from the core, average, structurally invariant characterization of behavior, the customary product of calibration. The chapter proposes that the behavior of water quality in the River Cam is subject to the workings of an unknown process, of potentially growing significance; that this something must generate both oxygen and biochemical oxygen demand (BOD); and that its putative workings are in some way correlated with a declining streamflow and significant excursions of water temperature about some nominal level.