An inexact fuzzy nonlinear optimization model for supporting decisions of river water quality management

This paper developed an inexact fuzzy nonlinear programming (IFNP) model for supporting decisions of water quality management under uncertainty. Methods of interval and fuzzy programming were integrated within a general frame to address uncertainties in the left- and right-hand sides of the nonlinear constraints. Uncertainties in water quality, pollutant loading, and system objective were reflected through the developed IFNP model. A case study for water quality management planning in the Changsha section of the Xiangjiang River was then conducted for demonstrating applicability of the developed IFNP model, It was also indicated that the proposed method was effective in dealing with IFNP problems; uncertainties can be communicated into optimization process and generate reliable solutions for decision variables and objectives; the decision alternatives can be obtained by adjusting different combinations of the decision variables within their solution intervals.