Large lake sluice operations during an extreme rainfall season greatly affect circulation and water quality dynamics of a shallow eutrophic lake

Zhaoliang Peng; Yihui Zhang; Jinge Zhu; Weiping Hu; Gang Liu; Hui Zhang; Rui Gao

doi:10.1016/j.scitotenv.2021.146756

Large lake sluice operations during an extreme rainfall season greatly affect circulation and water quality dynamics of a shallow eutrophic lake

Sci Total Environ. 2021 Aug 10:781:146756. doi: 10.1016/j.scitotenv.2021.146756. Epub 2021 Mar 26.

Authors

Zhaoliang Peng¹, Yihui Zhang², Jinge Zhu², Weiping Hu², Gang Liu³, Hui Zhang³, Rui Gao⁴

Affiliations

¹ State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China. Electronic address: zlpeng@niglas.ac.cn.
² State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China.
³ Lake Chaohu Administration Bureau in Anhui Province, Chaohu 238000, China.
⁴ Lake Chaohu Administration Bureau in Anhui Province, Chaohu 238000, China; Lake Chaohu Research Institute, Hefei 238000, China.

PMID: 33798898
DOI: 10.1016/j.scitotenv.2021.146756

Abstract

Large hydraulic infrastructures have been constructed globally to address water challenges. Past studies have well documented their effects on downstream aquatic ecosystems, which have included disrupting hydrological regimes as well as nutrient delivery, cycling and mediating processes that affect primary production. However, how these infrastructure operations affect lake ecosystems where the infrastructures are situated remains poorly understood. In the present study, we used a three-dimensional hydrodynamic-biogeochemical lake model to quantify the potential effects of large lake sluice operations under extreme high water levels on current structure and water quality parameters of Lake Chaohu in China. We designed and simulated multiple operation strategies based on actual operation curves during the 2016 extreme rainfall season. The model successfully captured the water quality dynamics of Lake Chaohu during both the calibration and validation phases. Our results indicate that higher lake water release rates led to overall accelerations of the current velocity; however, the deceleration of along-shore current velocity along the shorelines was also evident. Higher release rates also resulted in rapid rises ammonium nitrogen (NH₄-N), total nitrogen (TN) and total phosphorous (TP) concentrations in the eastern lake basin, as well as a lake-wide rise of chlorophyll-a (Chla) concentration. When the lake sluice was operated at its full capacity, mean concentrations of these four parameters increased by 5.21%, 5.58%, 9.6% and 7.46%, respectively. Modeling results demonstrate that the effects of lake sluice operations were still quite pronounced for four months after the operations. Modeling results also revealed that higher release rate during the operation phase may help decease TN and TP concentrations during the subsequent period. This study provides a useful perspective on how to support the planning and operation of large infrastructures in the face of climate change induced extreme events.

Keywords: Current structure; Extreme events; Lake sluice; Operation strategies; Shallow lake; Water quality.