Long-Term Water Temperature Variations in Daya Bay, China Using Satellite and In Situ Observations

Jing Yu,Chunhou Li,Danling Tang,Xiaoping Jia,Lijun Yao,Pimao Chen

doi:10.3319/tao.2009.05.26.01(oc)

Abstract

Daya Bay is a shallow, semi-enclosed bay in the northern section of the South China Sea. The present study analyzed variations of water temperature in Daya Bay over the past 21 years (1985 - 2005) using Advanced Very High Resolution Radiometer (AVHRR) satellite remote sensing data and in situ observations. Results showed that AVHRR readings of sea surface temperature (SST) increased by 0.07 degrees C y(-1). Linear regression analysis for monthly SST anomalies (SSTA) showed a shift from negative to positive from 1995 - 1996, when the Daya Bay nuclear power station commenced operations in 1994. The slope of linear regression analysis for SSTA nearly doubled from 0.05 (1985 - 1993) to 0.09 (1994 - 2005). Monthly AVHRR images showed a thermal plume from the power station and revealed the increase of SST over 21 years. In situ observations in water temperature also showed an increasing trend for the same period (1985 - 2005). Variations in water temperature in Daya Bay were connected with climatic perturbations and increasing human activity including thermal discharge from nuclear power stations and the rapid economic development around the bay area.

Highlights

Daya Bay is located in the northern section of the South China Sea (SCS; Fig. 1a)
Linear regression analysis for sea surface temperature (SST) showed an ascending trend with a slope of 0.07 over the past two decades, indicating that SST increased by 0.07°C y-1 (Fig. 2a)
An increase in water temperature in Daya Bay was observed through both satellite remote sensing and in situ observations, coinciding with the increase of human activities such as thermal discharge from nuclear power stations in the bay area, and global warming

Summary

Introduction

Daya Bay is located in the northern section of the South China Sea (SCS; Fig. 1a). It was one of the major aquacultural areas in the Guangdong province because of its excellent water quality and rich biological resources (Xu 1989). Since the late 1980s, economic development in industry, aquaculture, and agriculture in the area has rapidly expanded. The first large-capacity commercial nuclear power unit in China, the Daya Bay nuclear power station (DNPS), commenced operation in early 1994. Near the DNPS, another nuclear power station, the Lingao nuclear power station (LNPS), has been in operation since 2003 (http://www.cgnpc.com.cn). The two nuclear power stations have been continuously discharging thermal water to Daya Bay since their operation (http://www.cgnpc.com.cn)

Results

Discussion

Conclusion