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Ye X.,Southwest University | Ye X.,CAS Nanjing Institute of Geography and Limnology | Zhang Q.,CAS Nanjing Institute of Geography and Limnology | Liu J.,Water Research Institute of Shandong Province | And 3 more authors.
Journal of Hydrology | Year: 2013

Under the background of global climate change and local anthropogenic stresses, many regions of the world have suffered from frequent droughts and floods in recent decades. Assessing the relative effect of climate change and human activities is essential not only for understanding the mechanism of hydrological response in the catchment, but also for local water resources management as well as floods and droughts protection. The Poyang Lake catchment in the middle reaches of the Yangtze River has experienced significant changes in hydro-climatic variables and human activities during the past decades and therefore provides an excellent site for studying the hydrological impact of climate change and human activities. In this study, the characteristics of hydro-climatic changes of the Poyang Lake catchment were analyzed based on the observed data for the period 1960-2007. The relative effect of climate change and human activities was first empirically distinguished by a coupled water and energy budgets analysis, and then the result was further confirmed by a quantitative assessment. A major finding of this study is that the relative effects of climate change and human activities varied among sub-catchments as well as the whole catchment under different decades. For the whole Poyang Lake catchment, the variations of mean annual streamflow in 1970-2007 were primarily affected by climate change with reference to 1960s, while human activities played a complementary role. However, due to the intensified water utilization, the decrease of streamflow in the Fuhe River sub-catchment in 2000s was primarily affected by human activities, rather than climate change. For the catchment average water balance, quantitative assessment revealed that climate change resulted in an increased annual runoff of 75.3-261.7. mm in 1970s-2000s for the Poyang Lake catchment, accounting for 105.0-212.1% of runoff changes relative to 1960s. However, human activities should be responsible for the decreased annual runoff of 5.4-56.3. mm in the other decades, accounting for -5.0% to -112.1% of runoff changes. It is noted that the effects of human activities including soil conservation, water conservancy projects and changes in land cover might accumulate or counteract each other simultaneously, and attempts were not made in this paper to further distinguish them. © 2013 Elsevier B.V. Source


Shi Y.-Z.,Dalian University of Technology | Shi Y.-Z.,Water Research Institute of Shandong Province | Peng Y.,Dalian University of Technology | Zhou H.-C.,Dalian University of Technology
Dalian Ligong Daxue Xuebao/Journal of Dalian University of Technology | Year: 2012

Due to the superior forecasting performance, relevance vector machine (RVM) was applied to mid-and long-term runoff forecasting, and based on the phase space reconstruction, the runoff relevance vector machine forecasting model was established. Firstly, the runoff time series was reconstructed in the phase space, and the reconstructed series was as the proposed model input; Secondly, the particles swarm optimization (PSO) algorithm was applied to identifying the model parameters and chaotic properties of time series. The EM algorithm was used to estimate hyper-parameters in the inherent cycle, RVM was compared with widely used least squares support vector machine (LSSVM) and auto-regressive moving average model (ARMA). The test results show that the model has good generalization ability; Finally, in terms of the uncertainty of hydrological processes, the scheduling staffs consider the uncertainties in forecasting, and quantitatively estimate the risks and benefits in decision-making based on the uncertainty of RVM output values and the probability forecast interval. Source


Ye X.,Southwest University | Ye X.,Key Laboratory of Lake Science and Environment | Liu J.,Water Research Institute of Shandong Province | Zhang Q.,Key Laboratory of Lake Science and Environment
ISWREP 2011 - Proceedings of 2011 International Symposium on Water Resource and Environmental Protection | Year: 2011

Water resources management in the Poyang Lake basin have raised the concern of how human activities affect the local hydrological cycle. To address this concern and related issues, a distributed hydrological model-WATLAC (A Water Flow Model for Lake Catchments), was applied to the Poyang lake watershed to study the hydrological response to different landuse change scenarios. Simulations of canopy interception, evapotranspiration and stream flow were modelled and compared from four different extreme landuse change scenarios which were constructed from the landuse 1996 of the Poyang Lake basin. Major results from the modelling study indicate that through interactions of vegetation with soil and surface waters, land-use change can modify the local hydrological cycle and exert a strong biological control of the annual distribution of streamflow in the basin. Due to the discrepancy and great variation of Leaf Area Index, simulated annual interception and evapotranspiration by the scenario of forest land is much larger than the scenarios of agriculture, shrub and grass lands, while stream flow is relative smaller. The increase of forest cover after returning agricultural lands to forest in Poyang Lake basin can effectively reduces the local flood risk in the lake area. © 2011 IEEE. Source


Liu J.,Water Research Institute of Shandong Province | Ye X.,Southwest University | Zhang Q.,Key Laboratory of Lake Science and Environment
ISWREP 2011 - Proceedings of 2011 International Symposium on Water Resource and Environmental Protection | Year: 2011

Based on the monthly runoff series (1955-2003) of the three gauging stations in Poyang Lake watershed, the wavelet transform method was adopted to analyze the temporal trend and periodic variation of the streamflows in the watershed. Result from Multi-Resolution Analysis (MRA) using the Db3 wavelet function indicates that the long-term trend of streamflow in the Poyang Lake watershed show ascends before 1998 while descends thereafter, and the descending rate is slower than that of rising rate. Causes for this mainly come from the long-term uptrend of precipitation and downtrend of actual evapotranspiration, and both trends turn over at 1998. Periodicity analysis from continuous wavelet transform (CWT) revealed that there exist 25-26 years' first dominant periods and 8 years, 3-4 years' sub-dominant periods at all three stations. According to the variation of periodicity, it can be anticipated that the Poyang Lake watershed will be in the relative arid climate in the next 10 years, and the higher frequency and severity of droughts will persist. The watershed will enter into a humid climate and high-flow period at about 2018. © 2011 IEEE. Source


Ye X.,Southwest University | Ye X.,CAS Nanjing Institute of Geography and Limnology | Liu J.,Water Research Institute of Shandong Province | Li X.,CAS Nanjing Institute of Geography and Limnology | Zhang Q.,CAS Nanjing Institute of Geography and Limnology
Journal of Hohai University | Year: 2013

The Ganjiang River is the largest inflow branch of Poyang Lake. In this study, the characteristics of hydrological and climate variability of the Ganjiang River Basin over the last 50 years were analyzed, and the effects of climate variability and human activities on water resources variation of the river basin were investigated based on a coupled water and energy budget analysis. The results show that, with the depth of runoff in the 1960s as a reference value, the variations of depth of runoff in the Ganjiang River in other periods were mainly caused by climate variability, while the effect of human activities was relatively small. The quantitative analysis based on the evaporation rate function further reveals that there is a large difference between the effects of climate variability and human activities on runoff variations in different periods, and climate variability always leads to an increase of runoff, while human activities play a complementary role at different levels. Source

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