Identifying the Static and Dynamic Relationships Between Rural Population and Settlements in Jiangsu Province, China

Rapid urbanization has triggered large rural population floating into cities, which in turn affects rural human-land relationships. The actual human-land relationship involves the coupling level of a time point and dynamic change of a time interval. However, few studies have identified the rural human-land relationship from these two perspectives. This study combined static coupling analysis with a dynamic decoupling model to analyze the relationships between rural population and settlements from 2009 to 2018 in Jiangsu Province, China. Although the static coupling degree in Jiangsu Province was relatively high, the decoupling analysis found that the rural human-land relationship in most counties was uncoordinated. There were 11 combination types based on the coupling and decoupling relationships. The most common two types(accounting for 76.74%) were recession decoupling with high-level coupling and strong decoupling with high-level coupling. Although the majority of counties had a high-level coupling degree, an uncoordinated change in rural population and rural settlements was observed in these counties. Counties with relatively reasonable human-land relationships accounted for only 12.79% of the total. The combination features for each type were identified and differential policies were proposed for optimizing human-land relationship in rural areas. This study would contribute to our understanding of the multiple relationships between rural population and settlements involved in different patterns and processes, and expect to provide theoretical and methodological support for promoting rural revitalization and sustainable development in practice.

Mechanism of Structure Variations at Rifted Margins in the Central Segment of South Atlantic:Insights from Numerical Modeling

Rifted margins in the central South Atlantic portray spatial variability in terms of preserved width and thickness,which relates to complex rift-related fault activities.However,there is still a lack of systematic and quantitative explanations for the causes of the variations that are observed along the paired rifts.To elucidate this issue,2D viscous-plastic thermomechanical numerical models are applied to capture the behavior of deformation,in which we investigate the effects of extensional rate,crustal strength and thickness on crust-mantle coupling,and timing of transition from rifting to breakup.Our numerical experiments demonstrate that crust-mantle decoupling accounts for crustal hyperextension,and that incorporating moderate-intensity rheology into lower crust may yield insights into the hyper-extended crust and asymmetric architecture observed in the central South Atlantic.The results also suggest that undulations in lithospheric basement cause asymmetric mantle upwelling.The lower crust of fold belts takes priority to be thermally weakened over craton and induces rift migration simultaneously.A new mechanism for the formation of failed rift is described,where the mechanical decoupling derived from thermally weakened lower crust gives access to dual rift migration.These results reinforce the interpretation on how crustal rheology shapes margins architectures and highlight the first-order effects of crust-mantle coupling.