Analyzing cultivated land input behavior (CLIB) at the scale of rural households links with cultivated land-use efficiency (CLUE), this study examined the Yimeng Mountain area in northern China, supported by field survey data from 737 rural households. This research systematically analyzed the characteristics of CLIB of different types of rural households, measured the CLUE of different types of rural households by using a data envelopment analysis (DEA) model, and explored the influence of CLIB on CLUE based on the Tobit regression model. The results show (1) significant differences in the characteristics of the CLIB of different types of rural households in the Yimeng Mountain area. Among them, the highest land, labor, and capital inputs were I part-time rural households (I PTRH), followed by full-time rural households (FTRH). In contrast, II part-time rural households (II PTRH) and non-agricultural rural households (NARH) had higher levels of non-agricultural employment; however, their input levels gradually declined. (2) The CLUE of the sample rural households was generally low and had considerable potential for improvement. Regarding the types of rural households, as the degree of part-time employment increased, the CLUE showed an inverted U-shaped trend of first increased and then decreased, namely, I PTRH > FTRH > II PTRH > NARH. This finding indicates that appropriate part-time employment could help to promote investment in agricultural production and improve the CLUE. (3) The CLIB of rural households had significant effects on CLUE; the literacy of the agricultural labor force, yield-increasing input per unit area, per capita household income, share of agricultural income, operation scale of cultivated land, effective irrigation rate of cultivated land, and soil and water conservation rate of cultivated land had positive effects on improving CLUE. Even so, there was still significant heterogeneity in the degree of influence of different rural household types. The study concluded with some policy recommendations from the perspective of different rural household types to provide references for optimizing farming inputs and improving CLUE.

The global demand for sand and gravel is at 50 billion tons per year, far exceeding global resource capacities. It reached 7.6 billion tons in 2021 in the Yangtze River Basin (YRB), China. However, production is severely limited in the YRB. Therefore, the incongruity between the supply and demand of river sand is prominent. Wise management of decreasing sand resources in the YRB has become critical since the Three Gorges Dam became operational in 2003. This study synthesized spatial and temporal changes in sand mining activities and quantities along the Yangtze River and its major tributaries from 2004 to 2020. Results from the study show that the mining amount during the period reached 76.2 million tons annually. At the same time, riverine suspended sediment discharge (SSD) downstream of the Three Gorges Dam decreased largely. SSD reduction leads to riverbed erosion, further limiting the riverine sand and gravel sources for mining. Thus, alternative sand and gravel resources, as well as optimizing supply/demand balance, are necessary for sustainable development. There is an urgent need to assess the relationship between river sand resources and exploitation in the YRB for creating a sand and gravel data management system in order to cope with the increasing incongruity between their supply and demand.

Deltaic channels are significant landforms at the interface of sediment transfer from land to oceanic realms. Understanding the dynamics of these channels is urgent because delta processes are sensitive to climate change and adjustments in human activity. To obtain a better understanding of the morphological processes of large deltaic channels, this study assessed the evolution and response mechanism of the South Channel and South Passage (SCSP) in the Yangtze Estuary between 1983 to 2018 using hydrology, multibeam echo sounding and historical bathymetry datasets. Decadal changes in riverbed volume and erosion/deposition patterns in the SCSP were assessed. The results showed that the SCSP experienced substantial deposition with a total volume of 26.90 × 10⁷ m³ during 1983–2002, but significant bed erosion with a total volume of 26.04 ×10⁷ m³ during 2003–2010. From 2011 to 2018, the estuarine riverbeds shifted from erosive to depositional, even though the deposition was relatively marginal (0.76 ×10⁷ m³). We inferred that the SCSP have most likely changed from a net erosion phase to a deposition stage in response to local human activities including sand mining, river regulation project, and Deep Water Channel Regulation Project). The channel aggradation will possibly continue considering sea level rise and the ongoing anthropogenic impacts. This is the first field evidence reporting that the lowermost Yangtze River is reaching an equilibrium state in terms of channel erosion and, in fact, the Yangtze River Estuary channels are beginning to aggrade. The findings have relevant implications for the management of the Yangtze River and other lowland alluvial rivers in the world as global sea level continues rising and human intervention on estuarine systems persists.