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 timescale 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.

The Three Gorges Reservoir, serving as a crucial ecological barrier for the middle-lower Yangtze River basin, faces substantial threats to watershed ecosystems from sediment-associated heavy metal, threatening aquatic ecosystems and human health via bioaccumulation. Leveraging the legislative framework of the Yangtze River Protection Law, this study analyzed sediment cores (0–65 cm) collected from 12 representative sites in the Three Gorges Reservoir using 2020 Air–Space–Ground integrated monitoring data from the Changjiang Water Resources Commission. Concentrations of nine heavy metals (Cd, Cu, Pb, Fe, Mn, Cr, As, Hg, and Zn) were quantified to characterize spatial and vertical distribution patterns. Source apportionment was conducted through correlation analysis and principal component analysis (PCA). Contamination severity and ecological risks were assessed via geo-accumulation index (I_geo), potential ecological risk index (RI), and acute toxicity metrics. The findings indicated substantial spatial heterogeneity in sediment heavy-metal concentrations, with the coefficients of variation (CV) for Hg and Cd reaching 214.46% and 116.76%, respectively. Cu and Pb showed surface enrichment, while Cd exhibited distinct vertical accumulation. Source apportionment indicated geogenic dominance for most metals, with anthropogenic contributions specifically linked to Cd and Hg enrichment. Among the metals assessed, Cd emerged as the primary ecological risk driver, with localized strong risk levels (E_i > 320), particularly at FP and SS sites. These findings establish a scientific foundation for precision pollution control and ecological restoration strategies targeting reservoir sediments.

In the middle and lower reaches of the Hanjiang River in February 2018, another serious diatom bloom occurred. The Changjiang Water Resources Commission promptly initiated an emergency plan to use the cascade reservoirs at the middle and lower reaches of the Hanjiang River to carry out water scheduling. At the same time, six monitoring sections were set up to daily monitor in the middle and lower reaches of the Hanjiang River. From 9 February to 18 March, this bloom had lasted more than 30 d. It is the longest since the record was recorded. The emergency dispatch measures adopted during the outbreak of the diatom bloom have stopped the further development of diatom bloom and played a good role. Analysing the causes of diatom bloom can provide a more comprehensive basis for further optimizing emergency dispatch. This paper analyzes the key hydrological factors that occur in this diatom bloom and proposes a water dispatching optimization plan and specific countermeasures. However, to permanently solve the diatom bloom problem, it is necessary for local environmental protection departments to work actively under the current requirements of the river chief system. Comprehensive protection of the Hanjiang River water ecological environment, completely solve the watershed problem of non-point source pollution.

The 2017 Hanjiang autumn flood appeared to have higher surface water levels at the same discharge rate than previously at the Huangzhuang gauging station. It is seriously impacted the flood control. This paper analyses the 2000–2017 data from the Huangzhuang reach in the Hanjiang River, including surface water levels, the surface water fall, erosion-deposition variation and the engineering activities. A comparison of the 2016–2017 data with the 2000–2015 data in the Huangzhuang reach, revealed that the surface water levels were about 1.47 and 0.13 m higher in the high and intermediate discharge ranges, respectively. In the low discharge range, the 2016–2017 and 2010–2015 surface water levels were similar. However, a comparison of the 2016–2017 with the 2000–2009 data in the low discharge range, shows that the surface water levels were 0.28–0.4 m lower. The surface water fall in the Zhuandouwan–Huangzhuang's reach decreased in 2016–2017 for discharges above 5000 m³ s⁻¹, whereas in the Huangzhuang–Datong reach the opposite was found. For other time periods and discharge ranges the fall decreased. In the Datong-Shayang reach the fall reduced in 2014–2015 relative to other periods in 2000–2017 in the discharge range above 5000 m³ s⁻¹. The erosion-silting analysis for the Huangzhuang reach showed scouring of local river deposits due to bridge engineering. However, near the bridge the substantial silting was found. The collated surface water level and scouring-silting data suggest that reduced surface water levels during low discharge are mainly due to the overall river erosion. The increased surface levels in the high discharge range are due to local river siltation, especially because of the increased water resistance as response to bridge engineering.