Effects of water level fluctuation on thermal stratification in a typical tributary bay of Three Gorges Reservoir, China.

Juxiang Jin,Senlin Zhu,Defu Liu,Jun Ma,Scott A Wells,Zhengjian Yang,Guolu Yang

doi:10.7717/peerj.6925

Abstract

Xiangxi River is a typical tributary of Three Gorges Reservoir (TGR) in China. Based on field observations in 2010, thermal stratification was significant in most months of the year. Through field data analysis and numerical simulations, the seasonal and spatial variation of thermal stratification as related to the impact of the operation of TGR were investigated. Thermal stratification was most pronounced from April to September in the Xiangxi River tributary. Air temperature (AT) and water level (WL) were the two dominant variables impacting thermal stratification. AT affected the surface water temperature promoting the formation of thermal stratification, and high WLs in TGR deepened the thermocline depth and thermocline bottom depth. These results provide a preliminary description of the seasonal variation and spatial distribution of thermal stratification, which is important for better understanding how thermal stratification affects algae blooms in Xiangxi River.

Highlights

Reservoirs are constructed for multiple purposes, such as hydropower production, flood control, water supply, and commercial fisheries
The process of thermal stratification resulting from the operation of Three Gorges Reservoir (TGR) was studied using both field data analyses and numerical simulations for the period from June to October 2010
The results indicated that water level (WL) and Air temperature (AT) were two main factors which correlated with the thermal stratification

Summary

Introduction

Reservoirs are constructed for multiple purposes, such as hydropower production, flood control, water supply, and commercial fisheries. Serious algal blooms have occurred in many tributaries of Three Gorges Reservoir (TGR) in China since its impoundment (Liu et al, 2012; Zhuan-xi et al, 2007). These blooms were influenced by water temperature, solar radiation, and nutrients, and by hydrodynamics and thermal stratification (Wu, Liu & Hsieh, 2004; Tufford & McKellar, 1999). Since the surface water temperature is affected by incoming long wave radiation, evaporation, heat conduction and solar radiation, thermal stratification is common in many reservoirs and deep lakes (Ma et al, 2008; Kim & Kim, 2006; Boland & Padovan, 2002).

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Conclusion