Assessment of Climate Change Impacts on Water Quality in a Tidal Estuarine System Using a Three-Dimensional Model

Wen-Cheng Liu,Wen-Ting Chan

doi:10.3390/w8020060

Abstract

Climate change is one of the key factors affecting the future quality and quantity of water in rivers and tidal estuaries. A coupled three-dimensional hydrodynamic and water quality model has been developed and applied to the Danshuei River estuarine system in northern Taiwan to predict the influences of climate change on water quality. The water quality model considers state variables including nitrogen, phosphorus, organic carbon, and phytoplankton as well as dissolved oxygen, and is driven by a three-dimensional hydrodynamic model. The hydrodynamic water quality model was validated with observational salinity distribution and water quality state variables. According to the analyses of statistical error, predictions of salinity, dissolved oxygen, and nutrients from the model simulation quantitatively agreed with the observed data. The validated model was then applied to predict water quality conditions as a result of projected climate change effects. The simulated results indicated that the dissolved oxygen concentration was projected to significantly decrease whereas nutrients will increase because of climate change. Moreover, the dissolved oxygen concentration was lower than 2 mg/L in the main stream of the Danshuei River estuary and failed to meet the water quality standard. An appropriate strategy for effective water quality management for tidal estuaries is needed given the projected persistent climate trends.

Highlights

Estuaries are among the world’s vital aquatic resources
The regional climate is subtropical with the temperature varying between 10 and 35 ̋ C, and the annual precipitation in the region ranges between 1500 mm and 2500 mm, with the majority falling in late spring (May) to early fall (October)
Our study demonstrated that the dissolved oxygen would decrease as a result of climate change, which reduces the streamflow during dry seasons

Summary

Introduction

Estuaries are among the world’s vital aquatic resources. They provide food resources and a habitat for ecologically and economically important fish and shellfish species, recreational regions, educational and scientific experiences, and other important ecosystem services [1,2,3,4,5]. Two ecosystem services that estuaries provide are water filtration and habit protection. The adverse impacts include impaired water quality, habitat loss, and diminished resources [11]. These perturbations result in declining water quality and deleterious changes in ecosystem structure and tropic dynamics [12,13]. The deleterious water quality subsequently produces the problems of odor, aesthetics, human pathogens, and increased public

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