Variation of Lake-River-Aquifer Interactions Induced by Human Activity and Climate Change in Poyang Lake Basin, China

Strong spatiotemporal variations in regional water cycle in low-lying flat Fluvial-Lacustrine plain are the consequence of anthropogenic and climatic influences. Quantification of the lake-river-aquifer interactions and estimation of spatial patterns and temporal dynamics remain a challenge for understanding the exchange between surface water and groundwater (SW-GW). Selected case study of Gan-Fu plain (GFP) of Poyang Lake Basin, China, in combination with hydrological dynamic monitoring and the setup of an elaborate regional three-dimensional groundwater flow numerical model enabled the identification of the surface water process between lake and rivers and quantification of inflow or outflow between SW-GW for different scenarios considering human activity and climate change. Three scenarios of (a) S-1, under average surface water level (SWL) and recharge from precipitation (RP) from 1956 to 2003, (b) S-2, under average SWL from 2003 to 2010 and RP from 1956 to 2003, and (c) S-3, under average SWL and RP from 2003 to 2010 in response to climate change, were designed based on historical monitoring data. The results demonstrate that the TGD impoundments incurred water level drops with a maximum estimate of 3 m at the outlet of Poyang Lake in late-October, which exacerbated the evacuating effects of Yangtze River, intensifying the droughts in abnormal decline in lake stage and SWL in rivers flowing into the lake. The hydrologic drought influenced the spatiotemporal variations in regional groundwater regimes, especially in the area of "bank storage", where is the riparian zone and lakeshore area, resulting in a groundwater storage reduction of 36.7×10⁶m³ in November. However, the recharge reduction from precipitation due to climate change only accounted for 3.2×10⁶m³, which is not significant in comparison with hydrologic influences contribution from human activity.