A COMPUTER-BASED SYSTEM FOR MODELING THE STAGE-DISCHARGE RELATIONSHIPS IN STEADY-STATE CONDITIONS

In order to support the effort of Environment Canada directed to the a utomation of surface water quantity data management, an Intelligent De cision Support System (IDSS), to be used to create, develop and mainta in stage-discharge (S-D) rating curves, is in the final stage of devel opment. Environment Canada is the agency responsible for establishing gauging stations and monitoring streamflow in Canada. Hydraulic data s uch as stage and discharge are measured at these stations and used for the development of S-D rating curves. These in turn are cross-referen ced with continuous water level recordings to generate daily stream di scharges. The current procedure for establishing S-D curves used by En vironment Canada is subjective, due to the manual labour involved in t he plotting of measurements, analysing of data points and decision mak ing to alter or update an existing curve. The IDSS computer system is based on the concept of representing rating curves with mathematical m odels or equations. The paper describes the main characteristics of th e modelling module of the IDSS. Linear regression is the modelling tec hnique used within the IDSS together with power and Box-Cox transforma tions introduced to achieve linearity of the data. Within the module p resented in the paper, the generation of multiple S-D curves is combin ed with comprehensive statistical and multi-objective analyses in orde r to select an optimal mathematical model or equation.