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•An ER indicator system for WLTZs was developed based on the D-C-R process chain.•ER’s variation effect in WLTZs was consistent with river basin’s flow direction.•Low-value ER areas ...continuously aggregated and eroded at the water-land interface.•WLTZs’ ER was substantially influenced by land use types and water system gradients.
Water-land transition zones (WLTZs) are quintessential, complex human-land systems where aquatic and terrestrial environments intermingle, playing a pivotal role in bolstering global ecological resilience (ER). Human terrestrial production activities have encroached upon ecologically sensitive aquatic areas, weakening the inherent ER patterns in WLTZs. To address these issues, we developed an ER assessment process chain across the disturbance-carrying-recovery (D-C-R) dimensions. Applied it to the Dongting Lake region, this model diagnosed the spatiotemporal variations in ER from 2000 to 2020 and revealed the stress mechanisms of various driving factors. The results indicate: (1) The ER spatial pattern in the Dongting Lake region featured a radiating enhancement structure originating from a low-value core in the central plain’s lake network area, displaying distinct water-land gradient variations. Areas with declining ER levels were mainly distributed around the main body of the lake, water system runoff areas, and near governmental centers. (2) The spatiotemporal differentiation effects of ER manifested as an east–west axial development trend, tending toward polarization. The spatiotemporal aggregation effect appeared as L-L clustering and cold spots in the north, gradually expanding toward the peripheral forest areas. (3) Factors related to land use were the dominant drivers of spatiotemporal changes in ER. Simultaneously, the nonlinear interaction intensity among these driving factors showed a significant annual increase. This research framework can be extended to assess ER in similar regions, potentially offering policy recommendations for the ecological protection and sustainable management of WLTZs.
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•An integrated model chain for diagnosing and predicting PLES conflicts was created.•Frequent conversions of land use types have intensified the degree of PLES conflicts.•Conflict ...high-value zones constantly gather and worsen at the water-land interfaces.•Future PLES conflict patterns in lake network regions will grow more unbalanced.•The SD scenario is the optimal choice for reducing conflicts in lake network regions.
The disorderly expansion of human production-living construction activities into aquatic ecological sensitive areas has triggered severe production-living-ecological space (PLES) conflicts. However, research on the risk-triggering mechanisms of PLES conflicts in lake network regions and multidimensional scenario simulation techniques is relatively lacking. To address these issues, this study constructs an integrated model chain by coupling the Markov-GMOP-PLUS model to achieve a quantified diagnosis and simulated regulation of spatial conflict strength index (SCSI) under sustainable development goals. Applying it to the Dongting Lake region reveals that: (1) The overall PLES exhibited a distribution pattern where “ecological space encompasses production space, with living space interspersed within”. The category conversion mainly reflected the encroachment of agricultural production space on the plain water ecological space, with a conversion area of up to 899.48 km2. (2) The distinctive “high in the north, low in the south” PLES conflict pattern was closely aligned with the land use structure and water system distribution, with conflict hotspots persistently clustering in the core lake network regions amid rapid urbanization. Among these, the growth rate of severe conflicts in the last ten years was 3.86 times that of the previous ten years. (3) The sustainable development scenario showcased the most effective conflict mitigation by curtailing production-living space expansion and ecological space encroachment. This scenario reversed the growth trend in conflict high-value zones and the reduction trend in low-value zones, with change rates of −3.30 % and 7.05 %, respectively, compared to 2020. This study provides a scientific basis for formulating sustainable land-use policies in lake network regions.
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•A carbon budget accounting model was established for terrestrial space.•The spatial–temporal variation patterns of the MRYRUA were explored.•The territorial space was functionally ...zoned using the carbon balance index method.•A carbon balance regulatory mechanism was proposed by combining trend predictions.
As China’s largest cross-regional urban agglomerations, the middle reaches of the Yangtze River urban agglomerations (MRYRUA) possess both significant societal carbon source volume and ecological carbon sequestration capacity. Nevertheless, with the uncontrolled expansion of urban energy consumption activities and the industry migration from eastern coastal regions to inland cities, the carbon budget pattern of territorial space is increasingly unbalanced in the MRYRUA. To achieve low-carbon regulation, this study utilized land use and energy consumption data from 31 cities within the MRYRUA to establish a “carbon source-carbon sink” quantification and spatiotemporal exploration model, revealing the spatial-temporal variation of carbon budgets from 2005 to 2020. Furthermore, we developed a carbon balance indicator analysis system by employing the carbon offset rate (COR), carbon productivity (CP), Gini coefficient, ecological support coefficient (ESC), economic contribution coefficient (ECC), and functional zoning was performed. Finally, using the GM (1,1) model, we derived the carbon budget pattern for 2050 and explored the differentiated regulatory mechanisms under the carbon balance perspective. The results indicated that: (1) The MRYRUA’s territorial carbon budgets have increased annually, displaying a spatial distribution pattern with the highest values in the central region, followed by the northwest, and the lowest in the southeast near water bodies. The spatiotemporal differentiation effects manifest as an east–west axial development trend, with spatiotemporal clustering effects demonstrating a propensity for outward dispersion from the northern hot spot radiation core. (2) The MRYRUA’s COR has consistently remained below 10% and decreased annually, while the CP has shown a yearly increase at an accelerating rate. The ESC and ECC exhibit evident spatial heterogeneity among cities. In response to the carbon emission economic benefits and carbon sequestration ecological carrying capacity reflected by carbon balance indicators, each city was classified into low-carbon economic zones, carbon intensity control zones, carbon sink functional zones, and high-carbon optimization zones. (3) From 2020 to 2050, the polarization trend of the carbon budget pattern continues to intensify. Subsequently, we have established a differentiated territorial spatial carbon balance regulatory mechanism. This mechanism strengthens the leading role of low-carbon economic zones in the green low-carbon transition, moderately retains the carbon sink functional zones in the southeast with solid carbon fixation capabilities, and promotes the transition of the northern carbon intensity control zones and high-carbon optimization zones to low-carbon economic zones. The research findings provide a scientific basis for formulating territorial spatial planning policies from a carbon neutrality perspective.
Urban rainstorms and flood disasters are the most common and severe environmental problems worldwide. Many factors influence rain-flood control simulation, forming a complex network system of ...interconnected and mutually constraining elements. In terms of spatial scale selection, existing research on rain-flood disaster risk largely relies on a single-scale infrastructure index system and has not yet focused on urban “gray-green-blue” spatial scale simulations for rain-flood storage. Regarding research methodology, applying system dynamics methods to the simulation of rain-flood storage and disaster prevention planning in watershed cities is still in its initial stages. System dynamics models can simulate the feedback interactions among various sub-elements in the coupled mega-system, fully addressing complex issues within the system structure that involve multiple variables, non-linear relationships, and numerous feedback loops, thereby compensating for the inadequacies of traditional linear models in the collaborative management of rain-flood risks. Taking the Changsha Guitang River Basin as an example, this paper constructs a system dynamics model covering four dimensions: natural environment, socio-economics, internal structure, and policy development. It aims to derive the optimal planning scheme for gray-green-blue spatial coordination in rain-flood storage by weighing four different development scenarios. The simulation results show: (1) Simply changing the surface substrates without considering rainwater discharge and the plan that emphasizes the construction of municipal drainage facilities will see the capacity gap for rain-flood storage-space construction continue to widen by 2035. This indicates that the plans mentioned above will struggle to bear the socio-economic losses cities face during rain-flood disasters. (2) The plan of combining gray and green infrastructures sees the rain-flood storage construction capacity turn from negative to positive from 2024, rising to 52.259 billion yuan by 2035. This reflects that the plan can significantly reduce the rainwater volume in the later stages of low-impact development infrastructure construction, mitigate rain-flood disaster risks, and reduce government investment in rain-flood disaster risk management, making it a relatively excellent long-term rain-flood storage space planning option. (3) The rain-flood regulation space planning scheme, under the combined effect of the urban “gray-green-blue” network system, sees the capacity for rain-flood storage construction turn positive a year earlier than the previous plan, reaching 54.232 billion yuan by 2035. This indicates that the scheme can not only effectively respond to extreme flood and rainstorm disasters but also maintain ecological environment benefits and mitigate the socio-economic losses caused by disasters, making it the optimal choice for future government disaster management planning. The research results provide a theoretical framework and practical insights for territorial spatial planning, rain-flood control management, and resilient city construction in watershed areas.
Clarifying the trade-offs/synergies of ecosystem services is crucial for achieving a win-win situation in economic development and ecological conservation. Past studies have lacked research on ...ecosystem service functional management zones that integrate socio-economic factors and ecological conservation, particularly based on predictive scenarios. Based on the above, this study innovatively established a multi scenario simulation model and framework (EST-EMZ) for the study of ecosystem service (ES) trade-off/synergy and ecological management zoning, combining remote sensing and socio-economic data from 2000 to 2020 in the Chang-Zhu-Tan Metropolitan Area (CZTMA). The model evaluates the dynamic trade-offs/synergies among different ecosystem services under various scenarios, aiming to seek the optimal management approach for enhancing the functionality and optimizing the structure of ESs in the future of the CZTMA. The results indicate the following: (1) From 2000 to 2020, the Ecosystem Service Value (ESV) of the CZTMA gradually declined from 601.57 billion yuan to 584.65 billion yuan. Under the three future scenarios, the ESV also decreased, with the Ecological Conservation Scenario (ECS) experiencing the most minor decline, and the Economic Priority Scenario (EPS) witnessing the most substantial decrease. (2) In the historical period and the 2030 predicted scenarios, there is a predominant synergy among paired ESs in the CZTMA. Throughout the study period, the region’s dominant ecosystem service bundle (ESB) is the high-service ecological regulation bundle, primarily located in the northeastern, western, and southern areas dominated by forests. (3) Based on ESV and urbanization intensity (UI), five different ecosystem management zones were identified: water balance zone (WBZ), coordinated improvement zone (CIZ), ecologically weak zone (EWZ), ecological conservation zone (ECZ), and ecological derivative zone (EDZ). Corresponding management and protection strategies for ecosystem services were proposed. The research findings offer potential solutions for optimizing land use and managing the trade-offs of ESs in metropolitan areas.
The water-town settlements in the East River Delta of China engage with the aquatic environment, establishing a comprehensive cultural–ecological system. However, rapid urbanization challenges the ...structural integrity of water-town settlements. Focusing on the East River Delta as the study area, we utilized the Normalized Difference Water Index (NDWI), settlement morphology indicators, systematic clustering, and graph classification methods. We conducted a quantitative analysis of the spatial characteristics of water-town settlements at various scales, followed by formulating a sequence encoding based on landscape factors and constructing a settlement landscape spatial map. We characterized the landscape spatial structure of water-town settlements formed through the gradual evolution of morphological water network structures, retracing a prototype of water-town settlement landscape spatial structures. Results: ① Water-town settlements exhibit distinct uniformity in the landscape spatial features. The settlement landscapes conform to water network patterns, with streets and alleys aligning with water bodies. Crucial elements, including docks, bridges, and waterside farmland, are integral to this landscape. ② Water-town settlements undergo three progressive differentiation phases based on their location. The spatial distribution of settlements reveals three distinct landscape features influenced by the delta’s dynamic interplay between water and land. ③ Various regions exhibit three typical settlement layouts: upstream settlements are mainly clustered and linear, while midstream and downstream settlements, characterized by linear and strip-like features, align with the river’s course. These research findings offer preliminary insights into landscape spatial prototypes, contributing valuable perspectives to the conservation and design of water-town settlements.
The dense river network and large population in the southern region of China are vulnerable to flooding stress, which challenges the construction of human settlements. This paper analyzes the causes ...of flood risk and the dilemma of human settlement improvement in river-network cities, introduces the principle of resilience to human settlements, and conducts a quantitative study on the resilience of human settlements in river-network cities with the goal of flood risk management. Taking Yueyang city, a river-network city in the Yangtze River Basin, as the empirical research object, we conduct a flood resilience zoning of the human settlements based on the flood risk assessment model and use the GIS spatial overlay method to correct the resilience of the current human living space against the territorial spatial planning of Yueyang city. Ultimately, we propose a strategy for optimizing human settlements under flood risk management. The results show that (1) the highest-risk and high-risk areas of Yueyang city were mainly located in Dongting Lake and its interconnected water system, the southwest local area and the southeastern fringe, while the low-risk and lowest-risk areas were mainly located in the northeast local area and the northwestern fringe, with low flood stress risk. (2) The spatial system of human settlement resilience was constructed based on the flood risk assessment level. Among them, the human settlement flood resilience zoning of Yueyang city was divided into five categories from low to high: human settlement control zone, restriction zone, buffer zone, construction zone and expansion zone; the flood resilience zoning of Yueyang city’s current living space was divided into three categories from low to high: structure adjustment zone, flood restriction zone and development stability zone. (3) The specific control implementation and execution of the human settlements in Yueyang city mainly focus on the interrelationship between the risk of flooding in the watershed and the development of human activities through zoning regulation and collaborative management to optimize the human settlements. The study results can provide positive intervention and guidance for constructing urban and rural territorial spatial prevention planning and improving human living quality in river-network cities in China.
Direct-ink-writing (DIW)-based 3D-printing technology combined with the direct-foaming method provides a new strategy for the fabrication of porous materials. We herein report a novel method of ...preparing porous SiC ceramics using the DIW process and investigate their mechanical and wave absorption properties. We investigated the effects of nozzle diameter on the macroscopic shape and microstructure of the DIW SiC green bodies. Subsequently, the influences of the sintering temperature on the mechanical properties and electromagnetic (EM) wave absorption performance of the final porous SiC-sintered ceramics were also studied. The results showed that the nozzle diameter played an important role in maintaining the structure of the SiC green part. The printed products contained large amounts of closed pores with diameters of approximately 100-200 μm. As the sintering temperature increased, the porosity of porous SiC-sintered ceramics decreased while the compressive strength increased. The maximum open porosity and compressive strength were 65.4% and 7.9 MPa, respectively. The minimum reflection loss (
) was -48.9 dB, and the maximum effective absorption bandwidth (EAB) value was 3.7 GHz. Notably, porous SiC ceramics after sintering at 1650 °C could meet the application requirements with a compressive strength of 7.9 MPa, a minimum R
of -27.1 dB, and an EAB value of 3.4 GHz. This study demonstrated the potential of direct foaming combined with DIW-based 3D printing to prepare porous SiC ceramics for high strength and excellent EM wave absorption applications.
Large-scale short carbon fibre-reinforced silicon carbide (Csf/SiC) ceramic matrix composites (CMCs) have important applications in the field of aerospace engineering. This study proposed the use of ...material extrusion based additive manufacturing to fabricate large-scale Csf/SiC CMC preforms. In this paper, we determined how the key material extrusion parameters, including solid loading, nozzle diameter and layer height impact the stability of the additively manufactured Csf/SiC CMCs. The solid loading significantly influenced the stability of the Csf/SiC CMCs, and the slurry with 50 vol.% solid loading was better for additive manufacturing. The layer height played a significant role in the void formation in CMCs. It was appropriate for structure retention to set the layer height as 60–75% of the nozzle diameter. The effect of angle from vertical on the stability of out-of-plane structure was also investigated. When the angle was over 40o, the out-of-plane structure additively manufactured without supports tended to collapse. Large-scale Csf/SiC CMC preforms with out-of-plane structures were finally successfully fabricated. This study is believed to provide some fundamental understanding for the fabrication of large-scale fibre-reinforced ceramic matrix composites.
