Robust Planning of Environmental Management Systems with Adjustable Conservativeness under Compound Uncertainty

Abstract

A factor that impedes the practicability of environmental models is a lack of confidence in system performance stability in the face of uncertainty. This paper presents the development and application of a fuzzy radial interval programming (FRIP) approach for identifying waste diversion plans under uncertainty. FRIP allows uncertain parameters in the formats of radial intervals, conventional intervals, and fuzzy sets to be directly communicated into the optimization process. It can be protected against numerous input fluctuations, generating robust solutions that remain optimal in spite of divergent subjective judgments and changing objective conditions. More importantly, such conservativeness in solutions is proactively adjustable by changing protection levels of constraints according to site-specific features and stakeholders’ expectations, avoiding a significant adverse effect on the system optimality. Other capacities of FRIP include a prior quantification of risks associated with solutions, fulfillment of uncertain management goals, and flexibility in the constraints, so that higher public acceptance and easier implementation of the generated schemes can be achieved. A computationally tractable interactive solution algorithm was also proposed for FRIP. The developed methodology has been applied to a representative waste-management case. More than 20 sets of interval solutions were obtained under varied protection levels, asserting that FRIP could help managers make robust and flexible decisions without sacrificing the economic interests to any great extent. The sensitivity analysis of fluctuation radii further verified their significant impacts on the system. FRIP was also compared to potential alternative models to demonstrate its superiority.