TRADE-OFF DECISIONS IN STREAMFLOW FORECASTING FOR MULTIOBJECTIVE RIVER BASINS - THE OTTAWA RIVER CASE
by
I. Corbu¹ and P.C.K. Lau¹


ABSTRACT

Two major objectives, i.e., energy generation and flood protection where Identified in the operation of the Ottawa River Basin during the spring freshet season. These two objectives are often conflicting and a methodology is necessary to determine an acceptable trade-off. The paper describes the maximum net benefit methodology that allows decision-makers to identify the "best trade-off" alternative and the corresponding reservoir regulation plan and streamflow forecast to be used as a guideline for the operation of the river.

RÉSUME

On a établi que I'exploitation du bassin de la riviera des Outaouais pendant les crues du printemps devait viser deux principaux objectifs: la production d'énergie et la lutte contre I'inondation. Ces deux usages sont souvent incompatibles et il s'avère nécessaire d'avoir recours à une méthodologie pour arriver à une solution acceptable. On présente donc la méthodologie du bénéfice net maximal qui permet aux décideurs de trouver la meilleure solution, et d'établir en conséquence Ie plan de régularisation des réservoirs et les prévisions de débit qui devront orienter I'exploitation de la rivière.

INTRODUCTION

Operational decision-making during periods of high runoff, in particular the spring freshet period, represents a complex and challenging problem in the management of large multi reservoir, multiobjective river systems. In many cases, such river systems are operated with a view of achieving "satisfactory" levels and/or flows for more than one interest. Such is the situation on the Ottawa River, where for some decision makers (DMs) the primary objective is to maximize the energy generation and consequently to keep the forebays high and to have full reservoirs at the end of the freshet season. For other DMs, however, the primary objective is to minimize the risk of flooding and consequently to keep the reservoir levels low during the freshet. These two objectives are often conflicting and, consequently, an economical and politically acceptable trade-off methodology is necessary to determine the regulated river flow forecast needed for the operation of the system.
The purpose of this paper is to present the maximum net benefit methodology that allows DMs to identify the "best trade-off" alternative between energy generation and flood-reduction interests in the case of the Ottawa River. This method was proposed by Ontario Hydro to the Ottawa River Regulation Planning Committee (ORRPC) which developed a Runoff Forecasting Model (RFM) and a River Regulation Model (RRM) to provide guidance for the integrated operation of the reservoirs and hydraulic generating stations located in the Ottawa River Basin (ORRPC, 1980). The method allows water resource managers to automatically compute the “best trade-off” alternative and the corresponding reservoir regulation plan and streamflow forecast over the spring freshet season.

Revue Canadienne des Ressources en Eau / Vol. 9, No. 4, 1984
Canadian Water Resources Journal / Vol. 9, No. 4, 1984