Statistical insights into the water exchange process in the Yangtze-Poyang System: The YPWES model

Abstract

Study RegionThe Yangtze-Poyang river-lake system (YPRLS) which includes the Poyang Lake, and the middle reach of Yangtze River basin. Study FocusThe water exchange in the YPRLS is complex and vital to the dynamic of it, thereby requiring well simulation. Nevertheless, existing numerical models have shortages in accuracy, efficiency and revealing potential relationships. Thus, for providing an accurate and efficient statistical model as a fundamental tool for investigating the effects of changing environment on the YPRLS, we developed the Yangtze-Poyang water exchange statistic (YPWES) model. In this study, the YPWES model was employed to simulate the water exchange in the YPRLS from 1971 to 2016 and improve our understanding of the backflow from the river to lake (BRL) in the YPRLS.New Hydrological Insights for the Region: Based on a physic-based lumped framework, the established YPWES model is basically more accurate and efficient than nine existing models. Meanwhile, 93% of the BRL event will occur when the value of discharge identification function (DIF) is 9.2–10.0 m, while the threshold range of the DIF corresponding to the BRL event occurrence was smaller after 2003 because the discharge-stage relationship changes with the Yangtze River streamflow when the BRL event occurs. Our work provides a valuable model and may help to investigate the cause and influence of the water exchange in the YPRLS.