With the continuous growth of economic water consumption in arid regions, many endorheic rivers and terminal lakes have desiccated. As an important ecological engineering measure, water transport in arid regions has vital ecological significance for protecting the regional ecological environment and delaying desertification. In this study, Qingtu Lake, the terminal lake of Shiyang River, was selected to analyze the ecological effects of water transport by means of remote sensing interpretations and current year field investigations. The results demonstrated that, in July 2018, the water surface had formed and recovered to 5.68 km2. Additionally, Qingtu Lake formed a spatial gradient distribution in groundwater depth. The depth increased in gradient from the waterside to the desert edge. There was a significant increase in the overall regional vegetation coverage, which mainly occurred in the water areas because of the extensive growth in Phragmites australis, which reached 10.54 km2 in area in 2018. Furthermore, the regional vegetation formed a gradient distribution, which transitioned from hygrophytes to xerophytes. This study can provide guidelines for the protection and restoration of lakes in arid regions.
Water conservancy projects occupy an extremely important status in human development history. Human cognition about water conservancy projects has been in constant evolution along with the changing relationship between humans and nature (water). Based on a literature review, this study provides a systemic summary of the evolution of the human need for water resources and of water conservancy projects, as well as the equilibrium between humans and nature (river and lake ecosystems). More importantly, the transformation of cognition concerning the governance of nature and river and lake ecosystems is reviewed. Taking the perspective of modern rationalism on water conservancy projects, four major changes in human cognition are identified. Further, the most salient water-related issues arising from China’s largest freshwater lake, Poyang Lake, are analyzed and the history and predicament of its governance are described. This is accompanied by a discussion on the countermeasures. Finally, based on the evolution of the human–water relationship and cognitive transformation concerning water conservancy projects, several suggestions are proposed for the planned construction of the Poyang Lake Hydraulic Project. The conclusions of this paper shed new light on the principles of water governance and water conservancy project construction in a new era that has witnessed a growing conflict between socioeconomic development and the water environment. Our suggestions are also valuable for the governance of Poyang Lake.
Abstract:The streamflow and water level complexity of the Poyang Lake basin has been investigated over multiple time-scales using daily observations of the water level and streamflow spanning from 1954 through 2013. The composite multiscale sample entropy was applied to measure the complexity and the Mann-Kendall algorithm was applied to detect the temporal changes in the complexity. The results show that the streamflow and water level complexity increases as the time-scale increases. The sample entropy of the streamflow increases when the time-scale increases from a daily to a seasonal scale, also the sample entropy of the water level increases when the time-scale increases from a daily to a monthly scale. The water outflows of Poyang Lake, which is impacted mainly by the inflow processes, lake regulation, and the streamflow processes of the Yangtze River, is more complex than the water inflows. The streamflow and water level complexity over most of the time-scales, between the daily and monthly scales, is dominated by the increasing trend. This indicates the enhanced randomness, disorderliness, and irregularity of the streamflows and water levels. This investigation can help provide a better understanding to the hydrological features of large freshwater lakes. Ongoing research will be made to analyze and understand the mechanisms of the streamflow and water level complexity changes within the context of climate change and anthropogenic activities.
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