A coupled modeling approach to predict water quality in Lake Taihu, China: linkage to climate change projections

Abstract

Climate change is expected to impact water quality and ecosystem health in water bodies. In this study, a modeling framework was developed to assess the response of environmental variables to climate change scenarios in Lake Taihu, China. A coupled hydrodynamic-water quality-sediment flux model was employed to simulate water quality processes under future climate scenarios projected from a general circulation model (GCM) forced by the Representative Concentration Pathway 8.5 (RCP 8.5). The results showed that the climate change impacted physico-chemical parameters and biological interactions in Lake Taihu. The annual average water temperature increased by 0.96, 2.09, and 3.2 C by the 2020s, 2050s, and 2080s, respectively. Daily temperature stratification tended to occur earlier and the period of stratification increased, especially in summer during calm wind conditions. The sediment flux increased and dissolved oxygen (DO) concentration decreased with climate change. Additionally, climate change increased the onset time, duration, and areas of algal blooms. The results showed that the blooms activation time advanced approximately six days per decade. The onset time of algal blooms of 2080s was in February and March and the elevated concentration of chlorophyll a lasted until late autumn in the west lake region. The chlorophyll a concentration in summer did not increase substantially (about 10À15 mg/L). Overall, water management strategies and ecological restoration plans in Lake Taihu, mainly based on nutrient load reduction and hydrodynamic modification, should incorporate anticipated effects of climate change.

Predicting Impact of Climate Change on Water Temperature and Dissolved Oxygen in Tropical Rivers

“…Similarly, the impact of climate change on the DO concentration in the tropical rivers shows that DO concentrations declined in the tropical rivers in parallel with water temperature increase and a similar relationship has been discussed by others [15,56]. It was observed that the water temperature and DO concentration along the river section varied independently of climate variability.…”

Modeling the effects of external nutrient reductions on algal blooms in hyper-eutrophic Lake Taihu, China

“…The detailed mass conservation equations for each state variable are documented in Craig (2011), Hamrick (1992) and Tetra Tech (2007). A detailed model setup, calibration and validation process with respect to hydrodynamics and water quality variables in Lake Taihu can be found in the supplementary material (Li et al, 2011b;Tang et al, 2015). The previous results showed that the model reproduced the main features of wind-driven circulation, water level and water quality state variables quite well.…”

“…The benthic flux rates (i.e., PO 4 3− , NH4 + , NO 2 − -NO 3 − and SOD) in different lake regions were set according to the previous field experiments in Lake Taihu (Hu et al, 2006; Jiang et al, 2008;Luo et al, 2006;Tang et al, 2015;Trolle et al, 2009). The results clearly indicated that external nutrient reduction is critical to help mitigate eutrophic status but the amount of reduction needed to achieve the goal seems much higher than modeled in this study.…”

“…The Lake Taihu eutrophication model initially developed by Tang et al (2015) based on the Environmental Fluid Dynamics Code (EFDC) was used to simulate the hydrodynamic, nutrient cycling and biological processes in the lake. The EFDC model was initially developed by the United States Environmental Protection Agency (Hamrick, 1992).…”

Climate Sensitivity of Phosphorus Loadings to an Urban Stream

“…; Tang et al. ). Climate scientists report with high confidence that the U.S. will experience a significant increase in the number of hot days by the end of the 21st Century (Gleason et al.…”