Sudden channel shifting of wandering rivers poses significant challenges for river engineering, flood control strategies, and the security of water resources. This study proposes a novel analytical model to quantitatively assess such channel shifts based on the cusp catastrophe theory. Utilizing bathymetric data from 93 river sections collected biannually between 2015 and 2019, a comprehensive investigation of channel instability in the wandering reach of the Lower Yellow River was conducted. The results show that both lateral and longitudinal stabilities in the Huayuankou-Gaocun section were generally favorable. For the most part of the selected sections demonstrated a propensity for gradual change. Out of the 93 sections, totally 45 were identified as being susceptible to sudden channel shifts. These vulnerable sections were predominantly located in two highly active reaches—Xiaodabin-Jinglonggong and Huayuankou-Zhaolanzhuang—during the period from 2015 to 2017, excluding the 2018–2019 non-flood season. In the latter non-flood period, nearly half of the sections in the downstream reach from Jinglonggong displayed instability. Our findings are consistent closely with empirical observations from the Lower Yellow River. Additionally, the changed flow and sediment conditions in the 2015–2019 and the efficiency of guide works have significant effects on the stability of river channels.

The disturbance in river ecosystems caused by reservoirs and dams has become a critical topic, attracting increasing attention. However, the extent to which reservoir and dam construction and operation impact downstream river ecosystem health and ecosystem service functions is not fully understood. This research examines the Xiaolangdi Reservoir and the Lower Yellow River (LYR) ecosystem in China as a case study. We analyzed the complex material and energy flows in the LYR ecosystem using emergy theory and developed a set of emergy-based indicators for the quantitative assessment of river ecosystem health and services under reservoir operation interference. The results indicate that the total natural capital and environmental endowments of the LYR ecosystem have remained relatively stable after the operation of the Xiaolangdi Reservoir, with an increase in renewable emergy input. The ecosystem’s vigor decreased slightly, while the biomass emergy diversity index remained stable. However, the total emergy inputs increased significantly, with external feedback inputs becoming the most important emergy source for the LYR ecosystem. The resilience of the LYR ecosystem improved, with a significant increase in emergy density and a decrease in the emergy sustainability index. These findings suggest that although the river ecosystem continues to provide supporting services to human society, the extent of these services has diminished compared to pre-perturbation levels. In this research, a methodology for analyzing the impact of key reservoir operations on the ecosystem health and services of a large river is proposed to provide support for large river sustainable development studies.

In historical regional cropland reconstruction in floodplains and delta areas, changes in the river system and the historical distribution of settlements are important to the spatial–temporal dynamic process of historical land reclamation. This paper takes the Yellow River Delta as the research area, combines historical data with field investigation, and analyzes the influence of river system change and delta formation on settlement establishment and land reclamation. The results revealed the following. (1) The development timing of the Yellow River determines the order of deposited land by old river courses and the settlement or resettlement process of the village. Since 1855, approximately 90% of new villages have been located within the 1–5 km buffer of the Yellow River channels. Two peak tides for village establishment along the Yellow River corresponded to the fluvial periods and the 20 ± 10 yr after the river silted out. It took over 100 years for the cultivation range to advance 5 km from the coastline of 1820 to the sea for the lengthy desalination and subsequent freshwater-driven dilution of the newly deposited land. (2) It is necessary to introduce the locations of the settlements, distance from the river courses, and coastline change to the cropland distribution model by setting parameters for different buffer zone distances. This paper provides data and theoretical parameters for cropland construction in the Yellow River Delta suitable for the floodplains and delta areas. The relevant findings can provide valuable references for land use policy formulation, agricultural development planning, and management practices in delta regions.

The lower reaches of the Tarim River (Chala-Taitma Lake) is a typical ecologically fragile and sensitive area in the arid river basin. By 2017, 17 ecological water conveyances have been continuously implemented in this area, and the accumulated ecological water supply has exceeded 6.11 billion m³. It’s necessary to know changement of the Taitema Lake after ecological water transportation. This study investigate the dominant ecological processes on emergy analysis methods and analysis the renewable emergy changement of the Taitema Lake. The results are as follows: (1) Water is the dominant ecological factor in the region, and water resource metabolism is the dominant process in the region's ecosystem evolution. The evolution from desert to lake and wetland ecosystem is the main pattern of ecological water transportation in this area.(2) According to the calculation of the renewable emergy of the Taitema Lake in 2016, the total renewable emergy input is 3.53 x 1020 sej, in which the solar emergy takes up the largest proportion of the total emergy input, which is up to 74.39%.(3) Before 2000, the renewable emergy input in this region tended to decrease. By 2000, there was a significant growing. After 2000, the renewable emergy of the Taitema Lake shows a increasing trend.