A computer-based system for modelling the stage-discharge relationships in steady state conditions

Abstract

Abstract In order to support the effort of Environment Canada directed to the automation of surface water quantity data management, an Intelligent Decision Support System (IDSS), to be used to create, develop and maintain stage-discharge (S-D) rating curves, is in the final stage of development. Environment Canada is the agency responsible for establishing gauging stations and monitoring streamflow in Canada. Hydraulic data such as stage and discharge are measured at these stations and used for the development of S-D rating curves. These in turn are cross-referenced with continuous water level recordings to generate daily stream discharges. The current procedure for establishing S-D curves used by Environment Canada is subjective, due to the manual labour involved in the plotting of measurements, analysing of data points and decision making to alter or update an existing curve. The IDSS computer system is based on the concept of representing rating curves with mathematical models or equations. The paper describes the main characteristics of the modelling module of the IDSS. Linear regression is the modelling technique used within the IDSS together with power and Box-Cox transformations introduced to achieve linearity of the data. Within the module presented in the paper, the generation of multiple S-D curves is combined with comprehensive statistical and multi-objective analyses in order to select an optimal mathematical model or equation.