ECONOMIC IMPLICATIONS OF USING THE SOIL CONSERVATION SERVICE (SCS) EQUATIONS FOR OPEN CHANNEL DRAINAGE DESIGN IN THE OTTAWA - ST. LAWRENCE LOWLANDS

Abstract

This study was conducted to estimate and compare the economic costs of constructing and maintaining open channel drainage systems on a representative watershed located in the Ottawa - St. Lawrence lowlands based on the SCS curve number procedure and on observed peak flows. The results indicate significantly higher costs for the design based on the SCS method, ($33 790 compared with only $12 761 for the design based on observed peak flows) primarily because the SCS equations over-predict peak flows. The SCS method over-predicts peak flows leading to an over-designed open channel. This is an inefficient utilization of financial resources both for individuals and society, given that the provincial governments of Ontario and Quebec subsidize the design and construction of drainage systems.In addition, the drainage design based on the SCS equations requires additional land for construction. As such, there is an implicit loss in income, assuming the land is taken out of crop production. In Quebec, the potential...