Abstract
Understanding the spatial-temporal dynamics of evapotranspiration in relation to climate change and human activities is crucial for the sustainability of water resources and ecosystem security, especially in regions strongly influenced by human impact. In this study, a process-based evapotranspiration (ET) model in conjunction with the Global Land Surface Satellite (GLASS) LAI dataset was used to characterize the spatial-temporal pattern of evapotranspiration from 1982 to 2016 over the Gan River basin (GRB), the largest sub-basin of the Poyang Lake catchment, China. The results showed that the actual annual ET (ETa) weakly increased with an annual trend of 0.88 mm year−2 from 1982 to 2016 over the GRB, along with a slight decline in annual potential ET (ETp). On an ecosystem scale; however, only the evergreen broadleaved forest and cropland presented a positive ETa trend, while the rest of the ecosystems demonstrated negative trends of ETa. Both correlation analysis and sensitivity analysis revealed a close relationship between ETa inter-annual variability and energy availability. Attribution analysis illustrated that contributions of climate change and vegetation greening on the ETa trend were −0.48 mm year−2 and 1.36 mm year−2, respectively. Climate change had a negative impact on the ETa trend over the GRB. However, the negative effects have been offset by the positive effects of vegetation greening, which mainly resulted from the large-scale revegetation in forestland and agricultural practices in cropland. It is concluded that large-scale afforestation and agricultural management were the main drivers of the long-term evolution of water consumption over the GRB. This study can improve our understanding of the interactive effects of climate change and human activities on the long-term evolution of water cycles.
Highlights
Climate change and human activities have altered the global hydrological cycle at multiple spatiotemporal scales
The purpose of this study is to investigate the evolution of eco-hydrological processes and the driving mechanism in the Poyang Lake basin (PLB) during the past several decades
Over the past several decades, climate change and human activities have largely altered the hydrological regimes in the Basin of Poyang Lake (PLB), the largest freshwater lake of China, posing a hydrological regimes in the Basin of Poyang Lake (PLB), the largest freshwater lake of China, posing potential threatthreat to water resources sustainability and ecosystem security
Summary
Climate change and human activities have altered the global hydrological cycle at multiple spatiotemporal scales. Due to the tremendous heterogeneity in climate and geographical conditions in different regions, responses of the hydrological cycle to the environmental changes are region-dependent. The annual runoff of major rivers in north China has shown a decreasing trend, aggravating the existing water shortage in this region [1,2,3]. For most rivers in south China, the impacts of seasonal pattern changes in hydrological variables are more prominent than those of the. Due to the seasonal asymmetry of the changes in precipitation, the upper Yangtze River basin has witnessed both an increase in summer runoff and a significant decrease in autumn runoff over the past decades, which posed a certain threat to the water security and ecological environment [5]. Climate variability has been revealed to increase security risks with respect to water supply and food production (Intergovernmental Panel on Climate Change (IPCC) Fifth
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