Investigation of Water Temperature Variations and Sensitivities in a Large Floodplain Lake System (Poyang Lake, China) Using a Hydrodynamic Model

Abstract

Abstract:Although changes in water temperature influence the rates of many ecosystem processes in lakes, knowledge of the water temperature regime for large floodplain lake systems subjected to multiple stressors has received little attention. The coupled models can serve to derive more knowledge on the water temperature impact on lake ecosystems. For this purpose, we used a physically-based hydrodynamic model coupled with a transport model to examine the spatial and temporal behavior and primary causal factors of water temperature within the floodplain of Poyang Lake that is representative of shallow and large lakes in China. Model performance is assessed through comparison with field observations and remote sensing data. The daily water temperature variations within Poyang Lake were reproduced reasonably well by the hydrodynamic model, with the root mean square errors of 1.5-1.9 • C. The modeling results indicate that the water temperature exhibits distinct spatial and temporal variability. The mean seasonal water temperatures vary substantially from 29.1 • C in summer to 7.7 • C in winter, with the highest value in August and the lowest value in January. Although the degree of spatial variability differed considerably between seasons, the water temperature generally decreases from the shallow floodplains to the main flow channels of the lake. As expected, the lake water temperature is primarily affected by the air temperature, solar radiation, wind speed and the inflow temperature, whereas other factors such as cloud cover, relative humidity, precipitation, evaporation and lake topography may play a complementary role in influencing temperature. The current work presents a first attempt to use a coupled model approach, which is therefore a useful tool to investigate the water temperature behavior and its major causal factors for a large floodplain lake system. It would have implications for improving the understanding of Poyang Lake water temperature and supporting planning and management of the lake, its water quality and ecosystem functioning.

Assessing the thermal regime of poorly monitored reservoirs with a combined satellite and three-dimensional modeling approach

“…It was applied in Lake Geneva for understanding phytoplankton distributions in the epilimnion (Soulignac et al 2018), and in a large tropical hydroelectric reservoir, Intumbiara Reservoir, Brazil, for investigating the impacts of winter cold front passages on the heat balance and diurnal mixed layer dynamics (Curtarelli et al 2014). It has also been used for validating simulated surface temperature in a very large and shallow lake, Lake Poyang, China (Li et al 2017) and in a small lake, Lake Rotoehu, New Zealand (Allan et al 2016). Satellite images have been also assimilated in 3D hydrodynamic models of large lakes, for example Lake Geneva (Baracchini et al 2020) and Lake Erie (Ye et al 2020) as well as medium-sized reservoirs, for example Eagle Creek reservoir (Javaheri et al 2016).…”

Effects of a Proposed Hydraulic Project on the Hydrodynamics in the Poyang Lake Floodplain System, China

“…Although vertical water temperatures at the four gauging stations reacted with relatively complex responses, the PLHP tended to decrease the vertical temperature during the initial period (e.g., 5 September; <1.0 °C) and increase the temperature during other times within the storage period (e.g., 15 September and 25 September; up to 1.0 °C). This is an expected outcome given that the effect of the PLHP on the flow pattern of the lake may exert substantial effects on the water temperature during the initial period, while the meteorological forces may play a critical role in influencing the vertical water temperature due to a gradually increase in the water level of the lake [38]. The outcomes from this study provide an important insight regarding the role of the PLHP on the flow behaviors of Poyang Lake, but the PLHP may significantly reduce the water supply for the main stem of the Yangtze River during this storage period (i.e., September-October).…”

On the Hydrodynamic Behavior of the Changed River–Lake Relationship in a Large Floodplain System, Poyang Lake (China)

“…The changing characteristics of lake variations and the potential causes are rather complex and multifactorial, which drew worldwide attention with multiple extensive studies. It is expected that the hydrodynamic fields, inundation extent, lake area and storage, and lake-floodplain interactions may be disturbed or altered throughout the whole system [53][54][55][56][57], due to climate change and human activities [54,[58][59][60]. Several studies were carried out to investigate the interactions of the Yangtze River and the lake, and how modifications to the Yangtze River basin and local catchment affect the hydrological and hydrodynamic conditions of the lake [26][27][28][29][30][31][32][34][35][36][37]39].…”