Global Sensitivity Analysis of a Water Quality Model in the Three Gorges Reservoir

Abstract

Global sensitivity analysis is the key to establishing advanced and complex water quality models and measurements of ecological parameters. In this paper, the Sobol's sensitivity analysis method was applied to a quantitative analysis of the important factors governing a water quality model, which has been developed to simulate algal dynamics in Caotang Bay, one of the tributary bays in the Three Gorges Reservoir, China. The analysis focused on the response of chlorophyll-a and dissolved oxygen to 11 parameters. The results show that chlorophyll-a is influenced mainly by the maximum phytoplankton growth rate, the lower optimum temperature for algal growth, the phosphate half-saturation constant, and the phytoplankton linear mortality rate; while dissolved oxygen is influenced mainly by the maximum phytoplankton growth rate, the lower optimum temperature for algal growth, the phytoplankton basal respiration rate, and the detritus remineralization rate. These parameter sensitivities change with time and have a marked seasonal pattern. The parameter sensitivity differences between a shallow lake or reservoir and a deep reservoir suggest that mechanisms of cycling in nutrients and dissolved oxygen are different.

Study of the Water Quality of a Tropical Reservoir

“…In this study, the Ecological Risk Index (ERI) was used as a fast and practical tool for environmental risk assessment in ALMD. This methodology is proposed by Håkanson [19] and suggests the classification of contamination in a waterbody and the identification of the toxic substances in order to take actions for the control and mitigation of this contamination [40][41][42]. The Ecological Risk Index is based on the Equations (6) and 7:…”

Water Residence Time in a Typical Tributary Bay of the Three Gorges Reservoir

“…It has dramatically changed the aquatic ecosystem from a continuous lotic ecosystem to a huge reservoir, which exhibits complex hydrodynamic processes [27][28][29][30]. As a consequence, increasingly serious eutrophication and algal blooms usually occurred in spring and autumn in tributary bays in the TGR which were induced by multiple factors, including the ecological and hydrodynamic environment change [31][32][33][34]. The decline of ecological health and ecosystem services function for river basins has become a worrying environmental problem [35,36].…”