Under the background of ecological civilization construction, high-quality development and the establishment of territorial spatial planning system, it is of great practical significance to explore the synergistic relationship and improvement path among ecological protection, economic transformation and social transformation in trans-boundary regions for the implementation of regional or metropolitan integration development strategy in the new era. This article aims to improve the overall benefits of ecology, economy, and society, and comprehensively uses the entropy method and the coupling coordination degree model to analyze the development of the ecological, economic, and social subsystems and the level of coupling and coordination in the cross-border region of Pukou-Nanqiao, i.e., Nanjing-Chuzhou, from 2005 to 2019. Through analysis, it is found that the comprehensive development index of the two places basically shows a consistent growth trend, and the degree of coupling and coordination between regions and various subsystems has also developed to a higher level, but there is still a certain distance to the target stage of high-quality coordination, and the ecological subsystems. There are multiple regressions and fluctuations in the coordination degree between time and economic subsystems. It is necessary to formulate planning response strategies with regional coordinated development as the core content. The technical path proposed in this paper can provide a reference for the evaluation and improvement of the development level of transboundary regions at the meso-micro scale.

With rapid socio-economic development, the relationship between city and lake has experienced complicated and diversified changes, which brings potential challenges to regional sustainable development. To optimize the relationship between urban development and lake protection, this study, taking Hefei-Chaohu Lake in the Yangtze River Delta (YRD) as an example, established the evaluation index system of city-lake symbiosis, and analyzed the development levels and variations of Hefei and Chaohu Lake from 2005 to 2019, based on the theoretical analysis of city-lake symbiosis. Consequently, the symbiotic pattern of Hefei and Chaohu Lake was identified by introducing Lotka-Volterra model, and the variation trend of Hefei and Chaohu Lake symbiotic level was measured using symbiotic coordination degree model. The main conclusions and suggestions are as follows: (1) During the study period, the city subsystem showed a steady upward trend, and the level of each indicator gradually changed from great differences to balanced development. Although the level of scientific and technological innovation showed the fastest increasing trend, it was still lower than the other indicators. In order to further improve the level of scientific and technological innovation, it is suggested to enhance both the industrial transformation-upgrading and green innovation capability of Hefei. (2) During the study period, the lake subsystem showed a fluctuating upward trend, and the trend slowed down since 2014. The water ecological environment has been improved significantly compared with the levels of water pollution prevention and water resource security. However, the growth rates of all the three indicators have slowed down in recent years. Thus, comprehensive management and protection of Chaohu Lake is still one of the top priorities in the near future. (3) Although the results of the identification of symbiotic pattern show that Hefei and Chaohu Lake have already stepped into the stage of mutualistic symbiosis, the low value of symbiotic coordination degree indicates that both the city and the lake are still in the early stage. In addition to the improvement of the levels of both the city subsystem and the lake subsystem, it is suggested that the linkage and integration between Hefei and Chaohu Lake should be further enhanced to reach the high level of mutualistic symbiosis, and realize the harmonious development between human and nature. The study provides a reference for symbiotic pattern recognition and high-quality development of other city-lake systems in the YRD.

Following the rapid process of urbanization and transfer of many rural labors, cropland use presents new characteristics in the undeveloped area of the Yangtze River Delta. Studies on cropland use from the perspective of farmers are significant to rural governance and agricultural high-quality development. This study took villages in the cities of Yancheng and Nantong as case studies and used the methods of questionnaires and structural equation models (SEM) to analyze the behavioral intention and its influence mechanism. The results show that behavioral intension of cropland use in Northern Jiangsu province had great differences among farmers with different cropland scales. The behavioral intention was mainly affected by the individual farmer and its family characteristics and cropland resource endowment. The policy perception and usage of technology and capital indirectly and weakly influenced the behavioral intention. It is urgent to carry out classified management and guidance of farmers, promote scale operation of cultivated land, strengthen skills training and policy learning, and explore new models of agricultural services for accurate and efficient management of cultivated land, agricultural high-quality development and rural revitalization.