Study on Spatial and Temporal Distribution Characteristics of Coordinated Development Degree among Regional Water Resources, Social Economy, and Ecological Environment Systems

A new interpretable streamflow prediction approach based on SWAT-BiLSTM and SHAP

Streamflow is a crucial variable for assessing the available water resources for both human and environmental use. Accurate streamflow prediction plays a significant role in water resource management and assessing the impacts of climate change. This study explores the potential of coupling conceptual hydrological models based on physical processes with machine learning algorithms to enhance the performance of streamflow simulations. Four coupled models, namely SWAT-Transformer, SWAT-LSTM, SWAT-GRU, and SWAT-BiLSTM, were constructed in this research. SWAT served as a transfer function to convert four meteorological features, including precipitation, temperature, relative humidity, and wind speed, into six hydrological features: soil water content, lateral flow, percolation, groundwater discharge, surface runoff, and evapotranspiration. Machine learning algorithms were employed to capture the underlying relationships between these ten feature variables and the target variable (streamflow) to predict daily streamflow in the Sandu-River Basin (SRB). Among the four coupled models and the calibrated SWAT model, SWAT-BiLSTM exhibited the best streamflow simulation performance. During the calibration period (training period), it achieved R2 and NSE values of 0.92 and 0.91, respectively, and maintained them at 0.90 during the validation period (testing period). Additionally, the performance of all four coupled models surpassed that of the calibrated SWAT model. Compared to the tendency of the SWAT model to underestimate streamflow, the absolute values of PBIAS for all coupled models are below 10%, which indicates that there is no significant systematic bias evident. SHapley Additive exPlanations (SHAP) were used to analyze the impact of different feature variables on streamflow prediction. The results indicated that precipitation contributed the most to streamflow prediction, with a global importance of 29.7%. Hydrological feature variable output by the SWAT model played a dominant role in the Bi-LSTM's prediction process. Coupling conceptual hydrological models with machine learning algorithms can significantly enhance the predictive performance of streamflow. The application of SHAP improves the interpretability of the coupled models and enhances researchers' confidence in the prediction results.

The role of the environmental subsystem in sustainable urban development: Evidence from megacities in China

Conflicts in urban subsystems have severely hindered the realization of sustainable development, among which the most serious is the conflict between the environmental subsystem and urban development. Differing from studies considering individual environmental elements, this paper innovatively investigates the quantitative relationship between overall environmental performance and other development dimensions to understand the quantitative role of the environmental subsystem in sustainable urban development. Taking the nine megacities in China as an example, this paper first develops the performance variables of four urban subsystems, including the environment, by entropy method and analyzes the conflict or coordination level between the environment and other subsystems through the coupling coordination degree model (CCDM). Then, the interaction mechanism is further analyzed by the fully modified ordinary least square (FMOLS) and vector error correction model (VECM). This paper tries to provide a new reference for management and decision-making by focusing on the whole environmental subsystem rather than separate elements, which is of theoretical and practical significance. The main conclusions are as follows: (1) The coordination level between the environment and other urban subsystems is low; (2) 1 % rise in the economic and resource performance can respectively lead to 0.2014 % and 0.1388 % declines in the environmental performance; (3) 1 % increase in social performance can bring a 0.3738 % rise in environmental performance; (4) Improving environmental and resource subsystems' performance is the priority; (5) Coordinating urban subsystems is the key to long-run sustainable development. Despite the case studies on megacities in China, we hope to provide a new reference for cities worldwide with concentrated populations, rapid growth, and complex development contradictions.

Adaptability of water resources development and utilization to social-economy system in Hunan province, China

The interplay of water resources with social-economy spheres involves a reciprocal feedback mechanism. With the acceleration of the construction process of modernized water networks in Hunan Province, investigating the adaptation status of the "Water-Social-Economy " composite system (WSE) is crucial for promoting sustainability. This study clarifies the connotation of the adaptability of WSE, and the quantitative analyses were conducted through coupling coordinative degree, harmonious development capacity, and the evolution of development lag types among the 14 cities of Hunan Province from 2005 to 2020. The results show that: (1) The development index of the water resources subsystem (WRS) showed a "downward-fluctuation-upward" trend, while the development index of the social-economy subsystem (SES) showed signs of great improvement, the former didn't catch up with the latter. (2) The coupling coordination degree of WSE developed well, and reached the coordinative development stage by 2020, but the unbalanced spatial pattern between north to south and east to west still exists and is further intensified. (3) The development ability of WSE improved while the harmony ability reduced, and the development rate of WRS and SES hasn't achieved dynamic synchronization. Finally, the policies and suggestions to improve the adaptability are put forward, which is of instructive significance for the sustainable development of water suitability.

System dynamics modelling to simulate regional water-energy-food nexus combined with the society-economy-environment system in Hunan Province, China

Nexus approaches provide an efficient way to analyze the dynamic evolution of the water-energy-food nexus (WEFN), yet there is a need to close the science-policy divide by making simulation models more practically relevant. This study incorporates society, economy and environment systems (SEE) into the WEFN, simulating a broad environmental system. A system dynamics model is constructed to simulate and dynamically track the development of the WEF-SEE system in Hunan Province, China. The developed model is applied to assess WEF-SEE system trajectories from 2021 to 2035 against nine policy goals formulated by the Hunan Provincial Government. Baseline results suggest that Hunan Province will have a surplus of grain production and will be in a state of "self-sufficiency" in water resources. The energy security situation is not as optimistic, with imports being required to meet demand. The sustainable development of the WEF Nexus will be constrained by resource shortages. As the future development of Hunan Province outpaces environmental protection policies, water pollution and CO₂ emissions and are expected to increase. Intra-system trade-offs and synergies under the impacts of different policies indicate that the implementation of an indicative policy has the intended impact within its particular subsystem, but may lead to trade-offs in other subsystems. Due to system interconnectedness, the simultaneous implementation of multiple policies may increase or hinder progress towards certain goals. For example, expanding planting area increases food production, but increase agricultural water demand and water pollutant discharge, counter to water security goal and environmental protection goals. Cross-system impacts must be considered when choosing policies. This study advances environmental system analysis and evaluation, and contributes to practical policy recommendations, providing useful insights for Hunan Province, especially considering potential trade-offs and synergies. Such information could lead to more effective, holistic environmental policy formulation.

Digital finance and regional green innovation: evidence from Chinese cities

Digital finance realizes the combination of finance and technology, makes up for many deficiencies of traditional finance, and brings opportunities for green and innovative development. However, systematic research on regional digital finance and green innovation is still lacking. Based on this, this study aims to analyze the impact of digital finance on the regional level of green innovation. For the analysis, the fixed-effect model, the mediating effect model, and the moderating effect model are used to perform regression on the panel data of Chinese cities. The results show that digital finance can significantly improve the level of regional green innovation. Improving the level of regional green financial services is its main mechanism, but the intermediary role of industrial structure optimization and upgrading fails to pass the test. In addition, the results of heterogeneity analysis show that digital finance plays a greater role in promoting green innovation in areas with high levels of traditional financial supply and Internet infrastructure construction. It is worth noting that digital finance does not really play the role of universal benefit, widening the regional green innovation gap. The main contributions of this study are to prove the positive effect of digital finance on green innovation at the regional level, clarify its transmission mechanism and urban heterogeneity analysis, and find that the current digital finance cannot bridge the gap of regional green innovation.

The impact of fiscal decentralization, green energy, and economic policy uncertainty on sustainable environment: a new perspective from ecological footprint in five OECD countries

The paper explores the short-run and long-run asymmetric impact of fiscal decentralization, green energy, and economic policy uncertainty on environmental sustainability proxied by ecological footprint. Using the Nonlinear Autoregressive Distributed lag (NARDL) approach in selected five OECD countries, we find that ecological footprint responds to positive and negative fiscal decentralization asymmetrically in the long run and short run. However, the nature of the response varies significantly across countries. The result also suggests that green energy is a major factor in reducing the ecological footprint in all countries except Canada. Finally, economic policy uncertainty plays a negative and significant role in the ecological footprint in the UK, USA, and Germany while insignificant in Australia and Canada. Implications for effective environmental policies are discussed.

Spatiotemporal Evolution of Water Resource Utilization and Economic Development in the Arid Region of China: A “Matching-Constraint” Perspective

Water resources are the most important guarantees for sustainable socioeconomic development in arid regions. However, serious water scarcity puts great pressure on the sustainable development of the northwest arid region of China. Based on the “matching-constraint” perspective, this study used the Gini coefficient, imbalance index, and growth drag model of water resources to quantify the spatiotemporal evolution of water resource utilization (WRU) and economic development (ED) in the northwest arid region from 2009 to 2019. The results showed the following: (1) The matching degree of WRU and ED in Gansu and Xinjiang from 2009 to 2019 was poorer than that in Ningxia, Shaanxi, and Qinghai. Cities with the high matching type of WRU and ED were dominant, with a proportion of 60.78%. (2) During the study period, the growth drag of water resources showed an “N-shaped” change of “rising–declining–rising” and a spatial pattern of “decreasing from inland to coastal” in the northwest arid region. The average growth drag coefficients for the five northwestern provinces were as follows: Xinjiang (2.22%), Gansu (1.61%), Ningxia (1.41%), Qinghai (1.01%), and Shaanxi (0.84%). The total percentage of low and medium constraint type cities was 74.51%. (3) Based on the urban “matching-constraint” types, the WRU status was divided into four zone types: Zones I and IV had relatively well-allocated water resources; however, zone IV had more significant water resource constraints, with the growth drag coefficient ranging from 1.10% to 2.30%. An imbalance between WRU and ED existed in Zones II and III; moreover, the water resource constraints of these two zones were also significant, with growth drag coefficients ranging from 0.12% to 1.47% and 1.03% to 2.90%, respectively. Additionally, we explored the driving mechanisms of WRU and sustainable ED in the northwest arid region. Policy recommendations are proposed for the optimal use of water resources, capital, and labor for different types of cities.

Coordination evaluation and obstacle factors recognition analysis of water resource spatial equilibrium system

The comprehensive evaluation analysis of water resource spatial equilibrium (WRSE) system is a fundamental and crucial facet to construct national water resource network system and implement socio-economy equilibrium development strategy in China. To clearly understanding of the structural relationship of WRSE system, we firstly proposed the definition of WRSE system from the perspective of coordination variation between water resource carrying pressure and support force subsystems in this study, then, the multi-dimensional connection cloud and coupling coordination degree approaches were applied to construct integrated evaluation model (MCCD) of WRSE system, and finally, the obstacle degree model was utilized as well to recognize the primary influence factors which resulted in the variation of WRSE system. Eventually, it can be revealed from the application results of MCCD model that, the overall situation of WRSE system in Anhui Province, China was improved obviously during the past 10 years, with the average coupling coordination degree (CCD) increased from 0.58 in 2011 to 0.68 in 2018. In addition, water resources availability per capita (S₁) and agricultural irrigation quota (P₈) were the two primary indicators causing the variation of water resource carrying support and pressure force subsystems. The above application analysis results were reliable and consistent with the evolution trend of actual historical observed statistics, and could also provide scientific decision-making basis for the implementation of prediction and regulation schemes of WRSE system.

Study on water resources carrying capacity in Zhuanglang River Basin

With the rapid development of China's social economy, the phenomenon of unbalanced regional economic development is increasingly obvious. The shortage of water resources in northwest China is an important constraint to local development. The study on the water resources carrying capacity of the Zhuanglang River Basin plays an important role in the development of local economy; thus, we evaluate the water resources situation of Zhuanglang River Basin by using hydrology-related calculation method, combining with field investigation, visiting relevant departments, and referring to relevant data. Meanwhile, the water resources carrying capacity of 3 counties and 12 townships in the Zhuanglang River Basin in the current year are studied and analyzed based on methods such as fuzzy comprehensive evaluation model and quantitative calculation. Results indicate that the carrying capacity of water resources in Zhuanglang river basin can mostly meet the needs of township, but it is necessary to further optimize the water resources carrying capacity of the Zhuanglang River Basin from the four systems of water resources, society, economy, and ecology in the future. Besides, the results of quantitative calculation show that the maximum economic scale that water resources can withstand in most areas of the Zhuanglang River Basin is the overall well-off level, that is, the per capita domestic water is 80L/(d· person), and the per capita GDP is 10000 yuan/person. But there is still a certain gap to achieve the level, when the people are well-off in an all-round way, the two indexes are correspondently raised to 120L/(d· person), and the per capita GDP is 30,000 yuan/person.

Identification of Coupling and Influencing Factors between Urbanization and Ecosystem Services in Guanzhong, China

Urbanization trades off the value of ecosystem services for economic value, either directly or indirectly. Optimizing the synergistic effects of both and identifying the coupled influences associated with human activities are essential for sustainable regional development and policy formulation. In this study, we analyzed the spatial differentiation of regional ecosystem service values and urbanization using ArcGIS 10.2, STATA 15.1, the value coefficient method, the urbanization index model, and the coupled coordination model, assessed their coupled coordination status, and further explored the influencing factors, taking the Guanzhong region of China as an example. The results show that the substrate has an important influence on ecosystem service values, with woodlands being the most important value provider and the largest contribution of regulating service values, with a spatial “center-periphery” ring-band growth distribution. There is a clear hierarchy of urbanization, with the higher the administrative level, the higher the level of urbanization. The overall coupling and coordination of ecosystem services and urbanization is in a non-equilibrium state, with high levels in the south and low levels in the north. Further research on the factors influencing the coupling found that the disposable income of urban residents and the population employed in the tertiary industry had the greatest influence.

Investigation of Dynamic Coupling Coordination between Urbanization and the Eco-Environment—A Case Study in the Pearl River Delta Area

The interaction between urbanization and the eco-environment is usually viewed as an effect–feedback framework. Its coupling system is composed of urbanization and eco-environment subsystems. In this paper, the coupling degree (CD) and the coupling coordinated degree (CCD) are used to reflect the coupling interaction and coupling coordination between the urbanization subsystem and the eco-environment subsystem. Based on the dynamic relative quantities of urbanization and eco-environment data in the Pearl River Delta, CD and CCD values were calculated, and the spatiotemporal evolution trend of coordination was analyzed. The results show that (1) from 2000 to 2015, the nine cities in the Pearl River Delta had high CD values and CCD values. Though they had different performances in different periods, they were all in a coordinated class, including good coordination (GC), moderate coordination (MC), and bare coordination (BC). (2) In terms of temporal evolution, the coupling coordination between urbanization and the eco-environment in the entire Pearl River Delta greatly improved. (3) From the perspective of spatial distribution, the coupling coordination of the central region was higher than that of the peripheral regions, and that of the west bank of the Pearl River was higher than that of the east bank of the Pearl River. These results can help local policy makers enact appropriate measures for sustainable development.

Spatio-Temporal Coordination and Conflict of Production-Living-Ecology Land Functions in the Beijing-Tianjin-Hebei Region, China

Assessment of multiple land use functions promotes both utilization efficiency of land and regional coordination. Different personal and public products and services are offered by various land use types, meaning their functionality varies. Lack of judgment on temporal trends, turning points, or consideration of multi-source indicators like the ecological and air quality index leads to uncertainties in urban multifunctionality evaluation and functional orientation. In this study, the production-living-ecology land use function index system and evaluation process was improved using an entropy weight, triangle model, and coupling coordination degree. The production-living-ecology land use function (PLELUF) is defined from land use multi-functions. The Beijing-Tianjin-Hebei urban agglomeration was the representative area. The model was applied to quantify land use functions and measure spatio-temporal coordination and conflict from 1990 to 2015. Results found that the production and living functions displayed an overall upward trend and the growth rate of production function is larger, doubling from 1990 to 1995, while living function increases steadily. Ecology function remained steady from 1990 to 2000 but increased afterward. Land use function stage became balanced in ecology-living-production after 2005. No function-balanced cities existed in 1990; nine function-balanced cities were found in 2015. The coupling coordination degree increased from a slight conflict to a high coordination. Land use multi-functionality was high in the north and low in the south in 2015; Beijing had the most significant multifunctionality. This study can aid land use zoning and sustainable land management.