Hydrological problems, such as flood disasters, can be caused by the influence of urbanization on river network structures in plain areas. Taking the main urban region of Zhengzhou city as the research area, based on six remote sensing images from 1992 to 2015, the modified normalized difference water index method and a land-use transfer matrix were used to reconstruct river network data to study the temporal and spatial changes in the river system. In addition, the analytic hierarchy process and the entropy weight method were used to construct pattern indexes of the river system to quantitatively evaluate the inner relationship between the urbanization process and the river network structure in the plain area. The results showed that the percentages of arable land, forest and grassland, water, and unused land in Zhengzhou that was transferred to construction land from 1992 to 2015 were 59.10%, 51.05%, 29.83%, and 58.76%, respectively. In the past 34 years, the morphological indices, structural indices, and connectivity indices of the river system experienced a trend of high to low, and then increased, with the structural indices being significantly correlated with construction land use (p < 0.05). The regression equation R² between urbanization level and river length, water area, river network density, water surface rate, connection rate, and connectivity ranged from 0.677 to 0.966, which could well reflect the response relationship between urbanization and the river network. In addition, the outflow was greater than the inflow, which has destroyed the natural structure of the channel.

Water temperature, as one of the important water environment impact factors, has a significant impact on the survival and development of aquatic organisms. We selected water temperature data (1959–2017) from four key hydrological stations in the Yangtze River: Cuntan, Yichang, Hankou, and Datong. We analyzed the characteristics and variability of the Yangtze River hydrothermal regime by the Mann-Kendall method, wavelet analysis, and by the IHA-RVA method to analyze hydrothermal regime variations of the Yangtze River, and the response mechanisms of fish to variations in hydrothermal regimes were explored. The results show that (1) The annual average water temperature of the Yangtze River is warming, and Cuntan Station, Yichang Station, Hankou Station, and Datong Station have a sudden increase in temperature in 2002, 1995, 2003, and 2004, and the periodicity analysis demonstrates that Cuntan, Yichang, and Datong stations all have main periods of 24~32 years; (2) The overall variations of 32 hydrothermal indicators at Cuntan Station and Yichang Station reached 65% and 61%, which are close to the height variation; (3) With the construction of the Three Gorges Dam, the stagnant cooling effect caused the arrival date of the upper reproduction water temperature of “The four major fish species” to be delayed by about 23 days, and the stagnant heat effect caused the arrival date of the Chinese sturgeon reproduction upper limit water temperature to be delayed by about 30 days.

Changing environments have intensified drought impacts on terrestrial ecosystems. By integrating meteorological and multi-platform remote sensing observations spanning 2000–2020, this investigation employed spatiotemporal analysis and correlation analysis to investigate multi-dimensional drought characteristics and their impacts on ecosystem patterns and net primary productivity (NPP) across the Yellow River Basin. The meteorological drought center was predominantly located in the midstream region, with the most intense drought persisting for 32 months (January 2000–May 2002) and shifting 419.18 km in 2003. Human activities dominated land use transformation: cropland decreased by 8523.48 km², built-up land increased by 4550.79 km², and severely ecologically degraded areas rose to 28.61%. Forestland and cropland showed continuous upward trends in EQI and LUE, while grassland and unused land exhibited severe interannual fluctuations and slow improvement. Land use type determined coupling differences between climatic and ecological indicators. Under human intervention, cropland formed unique correlations: −0.9 between SPEI-12 and CWSI, −0.8 between SPEI-12 and TVDI, and 0.9 between CWSI and TVDI. These findings indicate that human activities critically regulate drought–ecosystem feedbacks, highlighting the need for land use-tailored management approaches.