A numerical investigation of freshwater and sediment discharge variations of Poyang Lake catchment, China over the last 1000 years

Abstract

The Poyang Lake catchment, an important sub-catchment of Changjiang, experienced ‘Little Ice Age’ (LIA) and accelerating intensity of human activities during the last 1000 years. As such, the area and time period serve as a perfect case to study the variations in water and sediment discharge under combined natural and anthropogenic impact. Simulation results of the model HydroTrend indicate that the annual average cumulative water discharge of the five rivers entering Poyang Lake over the last 1000 years is 103.65 ± 1.80 km3, and climate change is the dominating factor determining water discharge variations over time. Influenced by the LIA (AD 1451–1850), the total water discharge of the five rivers was reduced by 10%. Sediment load discharging into Poyang Lake by the five rivers was only 9.21 ± 0.43 Mt yr−1 between AD 1000 and 1700, when the anthropogenic impact on the landscape was still low. However, with the human activities accelerating during the past 300 years, the sediment load entering Poyang Lake underwent a drastic change. Because of intensified soil loss, the total sediment load entering Poyang Lake during AD 1800–1950 increased by 58.7%, compared with AD 1000–1700. After AD 1950, the sediment load variation is mainly reflected by the combined impact of dam emplacement and soil erosion. As sediment interception by dams continuously increased over time, the total sediment load entering Poyang Lake during AD 1990–2000 is only 60.9% of that of the highest riverine sediment flux during AD 1951–1980, which is almost equal to that of the lowest level during AD 1000–1700. The sediment load of many rivers in the world exhibited similar variation trends as that of Poyang Lake under combined impact of climate change and human activities. Better understanding the mechanisms of these variation trends is helpful to analyzing the formation and evolution of an estuary-shelf sedimentary system over the Holocene.

Precipitation changes recorded in the sedimentary total organic carbon isotopes from Lake Poyang in the Middle and Lower Yangtze River, southern China over the last 1600 years

“…In addition, the reconstructed water discharge of Lake Poyang showed a similar trend with the change of the sedimentary TOM δ 13 Corg values in core PYC13-3 in the last millennium (Fig. 3a, 3d) (Gao et al, 2015). The low sedimentary TOM δ 13 Corg values generally correspond with high water discharge of the 5 rivers around Lake Poyang in the period of 1050 to 1350 AD (Fig.…”

“…3). In addition, the δ 13 Corg record was also compared with variations in the water discharge of Lake Poyang based on numerical simulation for the last 1000 years (Gao et al, 2015) and the fragmentary historical document (Ma et al, 2004;Hu and Lin 2012) to prove the effectiveness of our result.…”

“…In this study, we evaluate the climatic significance of the carbon isotopes of TOM from the lake-sediment from Lake Poyang in the Middle and Lower Yangtze River zone, assisted by modern meteorological (precipitation and temperature) and hydrological data (volume of runoff) collected over the past 50 years, and water discharge of 5 rivers around Lake Poyang over the last millennium based on numerical simulation (Gao et al, 2015) and the organic carbon records from a sediment core. On this basis, the precipitation variability in the Middle and Lower Yangtze River recorded by the total organic carbon isotopes of a sedimentary core from Lake Poyang was reconstructed to better understand the local hydrological changes and their forcing factors in the monsoon-dominated southeastern region of China during the last 1600 years.…”

Suspended sediment transport dynamics in rivers: Multi-scale drivers of temporal variation

“…Increase in sediment loads can result from a greater sediment supply, e.g. as a result of soil erosion due to intensification of land use, mining and mineral exploitation or construction works (Fan et al, 2012;Fuchs et al, 2011;Gao et al, 2015;Mohr et al, 2014;Sun et al, 2015;Zhang et al, 2009). …”

Frequency and magnitude variability of Yalu River flooding: Numerical analyses for the last 1000 years

“…The model can simulate past (10 0 -10 5 years) behavior of small and medium-sized rivers (10 2 -10 5 km 2 ) by incorporating historical data on climate (meteorological data and high-resolution modeled climate data), basin properties (river networks, topography, glacier equilibrium-line) and human activity (reservoirs and deforestation) (Syvitski et al, 1998;Kettner and Syvitski, 2008). The model has successfully estimated the long-term flux of freshwater and sediment to the coastal ocean in drainage basins across the world, including the Danube, Rhône, and Po basins in Europe (Kettner 2009, McCarney-Castle 2012, Poyang Lake (Mainland China) and the Lanyang River (Taiwan) in Asia (Syvitski et al, 2005;Gao et al, 2015), and several Greenland river systems (Overeem and Syvitski, 2010). Model performance on flood magnitude and frequency has also been successfully tested in the flood-dominated Eel River in northern California (Syvitski and Morehead, 1999).…”