Poyang Lake Water Level Research Articles

Effect of Three Gorges Dam on Poyang Lake water level at daily scale based on machine learning

Effect of Three Gorges Dam on Poyang Lake water level at daily scale based on machine learning

Water level reconstruction and characteristic diagnosis of China's largest freshwater lake for the past five hundred years

The water-level variation of Poyang Lake, China's largest freshwater lake, has an important influence on the ecological and environmental protection of the middle reaches of the Yangtze River area. In addition, water-level variations will directly affect the lake's migratory bird habitat and migratory bird wintering. The reconstruction of the long-term Poyang Lake water-level variation series has important mitigation and adaptation significance for ecological protection and socio-economic development in the lake area. In this study, the historical records of drought floods from three representative regional stations of Poyang Lake were collected, and an OLS-PLS model was constructed for reconstruction. In this way, the water levels from the three regional stations were reconstructed for the past 500 years. The relationship between the water levels of the three regional stations and the Poyang lake water levels was analyzed using the partial least square (PLS) method, with R2 = 0.490 (p < 0.001). The variations in water levels from 1500 to 2000 were then reconstructed based on this model, with a low relative bias of −0.19%. According to the results, there were nine periods of high water levels and nine periods of low water levels, among which 1604–1619 was the most obvious period of high water levels during the past 500 years and 1633–1647 was the most obvious period of low water levels. The results of the accumulated anomaly and the moving t-test revealed that a mutational point of water levels shift from high to low occurred in the year 1600. As can be seen from the results of the wavelet power spectrum, there were variations in the water levels with cycles of 2–4 years, 6–8 years, 10–12 years, 20 years, 38 years, and 128 years. The results of this study can be used for lake area ecological environment management and to mitigate the adverse effects of flood and drought disasters in the future.

Forecasting performance of support vector machine for the Poyang Lake's water level.

The growth of forecasting models has resulted in the development of an excellent model known as the support vector machine (SVM). SVMs can find a global optimal solution equipped with kernel functions. This research trains and tests the SVM network and constructs the support vector regression prediction model by using hydrologic data. Six hydrologic time series were calculated by different kernel functions (namely, linear, polynomial, radial basis function (RBF)), to determine which kernel is the more suitable hydrologic time series in practice. A new solution is presented to identify the good parameter (C; g) by using grid-search and cross-validation. Results prove that linear SVM is a superior model to polynomial and RBF and produced the most accurate results for modeling hydrologic time series behavior as complex hydrologic phenomena. The case study also shows that the calculation errors were correlated with data characteristics. More stable raw data will result in a more accurate result, whereas more random data will result in a more inaccurate result. Model performance could also be dependent on base data nonlinearity.

The Study on the Relationship of the Poyang Lake Water Level and the Water Area by Using MODIS Data from 2000 to 2012

Based on the MODIS data from 2000 to 2012 and the water level data of the Poyang Lake, this paper extracted the water area of the Poyang Lake and got the long time seasonal changing characteristics of the water area and analyzed the relationship between the water level and the water area with the use of the historical water level data of the Poyang Lake. The results provide scientific basis for the building of the Poyang Lake Ecological Economic Zone and the researching of the seasonal change of water resource.

Has the Three‐Gorges Dam made the Poyang Lake wetlands wetter and drier?

The Three‐Georges Dam holds many records in the history of engineering. While the dam has produced benefits in terms of flood control, hydropower generation and increased navigation capacity of the Yangtze River, serious questions have been raised concerning its impact on both upstream and downstream ecosystems. It has been suggested that the dam operation intensifies the extremes of wet and dry conditions in the downstream Poyang Lake, and affects adversely important local wetlands. A floodgate has been proposed to maintain the lake water level by controlling the flow between the Poyang Lake and Yangtze River. Using extensive hydrological data and generalized linear statistical models, we demonstrated that the dam operation induces major changes in the downstream river discharge near the dam, including an average “water loss”. The analysis also revealed considerable effects on the Poyang Lake water level, particularly a reduced level over the dry period from late summer to autumn. However, the dam impact needs to be further assessed based on long‐term monitoring of the lake ecosystem, covering a wide range of parameters related to hydrological and hydraulic characteristics of the lake, water quality, geomorphological characteristics, aquatic biota and their habitat, wetland vegetation and associated fauna.