Zhuoyue Peng

Optimizing the spatial pattern of its carbon storage is of great significance for increasing the carbon storage capacity of regional ecosystem and maintaining regional carbon balance. Although the existing research has achieved remarkable results in regional carbon storage assessment and multi-scenario simulation studies, there are still obvious deficiencies in determining specific carbon storage optimization areas for developed regions and formulating targeted low-carbon development strategies. Taking the economically developed Jiangsu section of the Yangtze River Basin (JS-YRB) as an example, combined with InVEST and PLUS models, the carbon storage and its spatial distribution pattern of the study area in 2030 were predicted under three different scenarios: natural development, cropland protection and ecological protection. The pattern of carbon storage in the study area was optimized by a Bayesian belief network (BBN) with decision optimization ability. The results showed that: (1) From 2000 to 2020, the carbon storage in the study area exhibited a decreasing trend, with a total reduction of 47.98 × 106 t. The primary reason for these decreases was the conversion of cropland and forest land to built-up land. (2) In 2030, under the ecological protection scenario, the carbon storage in the study area would be 390.58 × 106 t, showing an upward trend, while under the other two scenarios, the carbon storage would show a downward trend. (3) Key variables and key state subsets were selected by BBN, and the study area would be divided into four types of optimal zones: ecological protection area, cropland protection area, water conservation area and economic construction area. The findings can provide a reference for the sustainable development of land use within the watershed and contribute to advancing the watershed’s efforts toward achieving the carbon neutrality goals.

Water resources of water transfer projects are not only used to solve the water scarcity problem in the water-receiving area but also to change the regional carbon absorption capacity. Using the water-receiving area of the Jiangsu-Shandong section of the East Route of the South-to-North Water Diversion Project (ER-SNWDP) of China as a case study, this study explored the dynamic variation in carbon stocks in response to water diversion project in the context of carbon neutrality. The results showed that (1) After the ER-SNWDP came into operation, there was a trend of growth in water area. Based on multi-scenario simulation, under the ER-SNWDP scenario, built-up land expansion would be curbed, forest and grassland reductions would be alleviated, and water areas would increase significantly compared to the natural variation scenario. (2) Due to the implementation of the project, the research area had better carbon sequestration capacity. Under the natural variation scenario from 2015 to 2025, the carbon stock would decrease by 1228.35 × 10⁴ t. However, under the ER-SNWDP scenario, there would be an increase of 262.84 × 10⁴ t. In addition, the water resource allocation of ER-SNWDP may affect the spatial distribution of carbon stocks. In the northeast region, particularly in the Binzhou and Dongying areas with large water transfer volumes, the increase in carbon stocks was significant, and the center of gravity of increase also tended to tilt these areas. (3) Land use had the highest explanatory power and driving force for spatial variation in carbon stocks. According to the results of the interaction factor analysis, the strongest interaction factor after 2005 was “land use ∩ nighttime lights”, indicating that the interaction between socio-economic factors and land use factors gradually amplified the impact on the spatial variation of carbon stocks. This study provides a scientific basis for future land use planning, promotes the rational and optimal allocation of water and carbon resources, and provides a prospective reference for water resources to cope with climate change and achieve carbon neutrality.

跨流域调水工程是缓解区域水资源短缺、保障经济社会可持续发展的重要手段，这一过程也改变了受水区生态系统的碳汇效益，因此合理制定碳生态补偿标准对于实现区域生态系统的可持续管理具有重要意义。论文基于能值理论和InVEST模型，选取南水北调东线工程受水区济南市为研究对象，结合2005—2020年的土地利用数据、水资源数据及碳密度数据，定量分析跨流域调水对受水区碳储价值的影响，并提出碳生态补偿标准。研究结果表明：① 在跨流域调水背景下绘制受水区的能量系统图，计算得济南市2020年能值/货币比率为8.57×1011 seJ/＄，基于能值理论得南水北调工程实施下济南市碳储能值价值增加0.174亿元；② 基于CA-Markov和InVEST模型对济南市自然增长情景和调水情景下的碳储量变化进行模拟和核算，结合碳固持价值、通货膨胀率和市场贴现率，计算得济南市得益于南水北调工程的碳储价值为1.04亿元；③ 建议南水北调实施下受水区济南市的碳生态补偿标准为0.174亿元至1.04亿元之间。跨流域调水受水区碳生态补偿核算方法的研究有助于推动生态补偿多样化实现，促进水源区和受水区生态经济的协同可持续发展。

The operation of hydraulic projects within plain river networks to mitigate floods can alter river network connectivity patterns, subsequently affecting flood processes. This study employed the MIKE 11 model to simulate flood processes under three different river network connectivity scenarios. Based on the simulations, we propose a method to evaluate flood intensity severity by integrating three flood characteristic indices: Slope of the Flow Duration Curve (SFDC), Rising Climb Index (RCI), and Flashiness Index (FI). These indices assess the overall magnitude of change, the rate of rise, and process fluctuations, respectively. Results indicate that changes in river network connectivity significantly impact RCI and SFDC, more than FI. Compared to the natural river network connectivity mode, changes in urban or watershed river network connectivity resulted in a significant decrease in RCI values by 3–37% or 18–38% across various return periods, with the rate of change in RCI values increasing as the return period lengthened. The impact of urban river network connectivity changes on SFDC within the Changzhou urban area was more pronounced under high-magnitude storm conditions, causing a 61% reduction. Furthermore, changes in watershed river network connectivity had a larger effect on SFDC under low-magnitude storm conditions than under high-intensity storms. Over 80% of the rivers under natural connectivity conditions exhibited flood intensity severity of Level III or higher, particularly in the Chenshu–Qingyang area. The alterations in connectivity significantly decreased flood intensity severity, with 85% to 91% of rivers showing the lowest flood intensity severity of Level I. Under a 100-year rainstorm scenario, flood risk shifted from within the flood protection envelope to outside it in the Changzhou urban area. The results will provide an important scientific basis for regional flood management in plains with dense rivers.

Ecological compensation for inter-basin water transfer is an effective way of coordinating regional ecological environment protection and balancing the interest relationship between the water-source area and the water-receiving area. However, there are still some deficiencies in the research on the evolutionary game analysis and the compensation behavior of stakeholders. To this end, a replication dynamic model of evolutionary game analysis was established to analyze the behavior and mutual influence of the governments of the water-source area and the water-receiving area. We examined the dynamic evolution process of each strategy, discussed the stability of the evolution result, and calculated the penalty amount of the superior supervision department through the market value method and the willingness-to-pay method. The results show that in the process of independent selection of local governments, the social optimal environmental protection strategy (protection, compensation) will not reach a balanced and stable state, and the constraint elements of the superior supervision department must be introduced. If the penalty amount is greater than the maximum value between the wealth lost in the water-source area due to ecological protection and the money the local residents in the water-receiving area is willing to pay, the optimal stability strategy can be achieved most easily. Taking Yangzhou, the water-source area of the east route of the South-to-North Water Transfer Project, and Jinan, the water-receiving area, as an example, it is calculated that the loss cost of Yangzhou is 1.304 billion RMB (USD 189 million), and Jinan is willing to pay 1.753 billion RMB (USD 254 million). Therefore, in order to stabilize the optimal strategy (protection, compensation) between the governments of Yangzhou and Jinan, the penalty amount of the superior supervision department should be greater than 1.753 billion RMB (USD 254 million). Our results could provide a reference for regulating the relationship between stakeholders and promoting the innovation of ecological compensation system for inter-basin water transfer.

In the context of global warming, changes in extreme-precipitation events are becoming increasingly complex, and investigating the spatial and temporal variation characteristics of extreme precipitation is extremely important for scientific water-resource planning, preventing new climate risks and maintaining ecosystem balances. Based on the daily precipitation from 1960–2017 at 15 meteorological stations in the Jianghuai region, the extreme-precipitation indices were calculated. The variations in 12 extreme-precipitation indices were detected by using the Mann–Kendall test in the Jianghuai region. The periodicity of indices was examined by wavelet analysis detecting significant time sections. Through the cross wavelet transform and wavelet coherence analyses, the nonlinear connections between extreme precipitation and atmospheric circulation were explored. The results indicate significant increasing trends in the max one-day precipitation amount (Rx1day), extreme wet days (R99p), and simple precipitation intensity index (SDII). The intensity of extreme precipitation increased significantly. The variation in extreme precipitation showed different trends in different regions, with a greater likelihood of increasing extreme-precipitation intensity and frequency in the southern region compared to the central and northern regions. The period of most oscillations of the indices tend toward be on a time scale of 2–4 years and are in the 1990s. The number of heavy precipitation days (R10 mm) and number of very heavy precipitation days (R20 mm) had, mainly, periods of 5.84 years. Additionally, there were significant resonance periods between the extreme-precipitation indices and the atmospheric circulation index; however, there were obvious differences in time domains. The North Atlantic Oscillation (NAO) and East Asian summer monsoon (EASM) had the most significant effect on the duration of extreme precipitation; Atlantic Oscillation (AO) and EASM had the most significant influence on the extreme-precipitation intensity. The results of the study can provide a scientific basis for water-resource management and disaster prevention and control in the Jianghuai region.

Finding a method to accurately evaluate a water diversion project’s socio-economic impact, which can contribute to planning and decision-making, has become a hot issue in the world. Our paper constructs a computable general equilibrium model of a water diversion project for a water-receiving area to solve this issue, and takes the south-to-north water diversion project in Beijing, China as an example. With comparative analysis of different water supplies, the socio-economic impact of a water diversion project on the water-received area is evaluated quantitatively. The result shows that as the reduction of the water supply from the south-to-north water division project under different policy scenarios, the regional gross domestic product decreases, which means the economic level declines, the proportion of high water consumption by industry declines, the price index rises (which is not conducive to social stability), employment rate falls and unemployment rises, and per capita disposable income falls (reflecting that the quality of people’s living standards is falling). This study provides a theoretical basis to allocate the diverted water and local water reasonably in order to adjust the industry structure according to the local situation, to improve water management, and to reform water market and water price.

Northeastern China is one of the largest industrial and agricultural bases in China, but frequent flooding brings huge losses to the people and country. To forecast floods in northeastern China, we used commensurability forecasting techniques and ordered a network structure chart and butterfly structure diagram. The prediction selected extraordinary flooding years that have occurred in the region since 1856, and it used ternary, quinary, and septenary commensurability calculation models for forecasting. It verified the inevitability of flooding in 2013 and showed that northeastern China would be highly prone to flooding in 2017. The specific locations of flooding would be the second Songhua River or Liaohe River. The ordered network structure and butterfly structure diagram are the extension of commensurability, both of which showed perfect symmetry neatly and orderly, and indicated the great possibility of flooding in northeastern China in 2017. Because of spatial distribution in the region, we also picked up four representative sites in the region to subsidiarily forecast the runoff qualitatively. Except for a site that did not have a significant year, the other three sites showed that the runoff in the second Songhua River would be wet in 2017. The idea of this paper is good in the data-starved area and helpful for improving judgment regarding flood trends.