Abstract:

The Yangtze River is the largest river in China. The section of the Yangtze River flowing through Hubei Province accounts for approximately one-sixth of the total length of the Yangtze River. It is the only province where the mainstream of the Yangtze River flows over thousand kilometers. The water ecological security of the Yangtze River mainstream cities directly affects the high-quality development of this region. The Yangtze River mainstem in Hubei flows through eight cities and states: Enshi Tujia and Miao Autonomous Prefecture, Yichang City, Jingzhou City, Xianning City, Wuhan City, Ezhou City, Huangshi City, and Huanggang City. This study used economic, social, and ecological environment data released by the Hubei Provincial Bureau of Statistics and the China Economic and Social Big Data Research Platform for 2008-2022. Based on the DPSIR model, a water ecological security evaluation index framework covering 25 indicators was established. The entropy weight method and comprehensive evaluation method were used to assess the influencing factors and their spatio-temporal evolution characteristics of water ecological security in the mainstream cities of the Yangtze River in Hubei Province. The gray prediction model was adopted to predict the development trend over the next five years. The results showed that: 1) The water ecological security of the cities in the mainstem of the Yangtze River Basin in Hubei Province is influenced by the driving force, influence, and state subsystem, with weights of 0.23, 0.27, and 0.29, respectively, indicating that they are the main systems influencing the water ecological security of the cities in the main stem of the Yangtze River Basin in Hubei Province. Ecological environment water consumption and total sewage treatment are the main influencing indicators, with corresponding weights of 0.22 and 0.17, respectively. GDP per capita, total value of agricultural, forestry, animal husbandry, and fishery production, per capita water resources, surface water resources, and end-of-year storage volume of large- and medium-sized reservoirs are secondary influence indicators, with corresponding weights of 0.04, 0.04, 0.05, 0.06, and 0.08, respectively. 2) In the subsystem scores, the five subsystems showed a fluctuating but steadily improving trend, and the state and response subsystems fluctuated considerably. The scores of different subsystems in the urban agglomerations varied greatly; for example, Wuhan had the highest scores in the driving force and influence subsystems, and Enshi Prefecture had the highest scores in the pressure, state, and response subsystems. 3) During the period of 2008-2022, the water ecological safety of the eight prefectural-level cities of the Yangtze River mainstream in Hubei Province improved to a certain extent, and only Ezhou and Huangshi fluctuated between the moderately warned level and only Ezhou City and Huangshi City fluctuated between moderate warning level and severe warning level, and are in the high-risk zone. Among them, Wuhan, Enshi and Yichang in the upper reaches of the Yangtze River are in a better state of water ecological safety than the other cities. Overall, spatial water ecological safety shows a pattern of “some first-developed cities take the lead in improving water ecological safety, and later-developed regions gradually follow”. 4) From 2023 to 2027, the water ecological safety grades of cities in the Yangtze River mainstream will show an upward trend. Among them, Wuhan City had the best water ecological safety level, maintaining a safe state; Enshi Prefecture and Yichang City rose from a moderate warning state to a warning state; Ezhou City rose from a severe warning state to a moderate warning state; Huanggang City, Jingzhou City, Xianning City, Huangshi City, and four cities in the water ecological safety in a moderate warning state gradually tended to the state of an early warning. In 2023-2027, the water ecological safety of Hubei Province is in a middle state of warning and gradually tends toward an early warning state. In Hubei Province (2027), the water ecological security comprehensive evaluation value shows a slowly rising trend, which is still in a state of warning, and water ecological security must be further improved. The urban agglomeration of the Yangtze River mainstem in Hubei Province should be oriented toward green and sustainable development, use scientific and technological innovation to promote industrial optimization, and implement green innovation-driven projects to alleviate water ecological pressure and enhance the modernization of water governance in the Yangtze River Basin. Simultanously, according to the development plan and functional positioning of Hubei Province, with the development belt along the river as the axis, and the “Wuhan Metropolitan Area” and “Yichang-Jingzhou-Jingmen” Metropolitan Area as the core, we will optimize the distribution of the province's industrial layout and the allocation of population and resource elements, and make every effort to promote the high-quality development of new townships and the construction of the national science and technology innovation base and the construction of a national science and technology innovation base and continuously improve the water ecological safety level. In future research, we should combine the new dynamics of Yangtze River protection, comprehensively analyze the Yangtze River water ecosystem from multiple dimensions and levels, continuously improve the framework of assessment indices, and devote ourselves to accurately revealing the key controlling factors affecting water ecological security, in-depth investigation of their functioning mechanisms, and sorting out the intrinsic correlation between the factors, to build a more solid theoretical foundation for the realization of the sustainable development goal of the region and the maintenance of the Yangtze River water ecosystem health and stability. In this way, we can build a more solid theoretical foundation and provide practical guidance for the region to realize the goal of sustainable development and to maintain the health and stability of the Yangtze River water ecology. The results of this study will provide scientific references for the protection of the Yangtze River, improvement of the quality of the water ecosystem, and promotion of sustainable economic and social development of the region.

Key words: water ecological safety evaluation, spatiotemporal pattern, drive-pressure-state-impact-response (DPSIR) model, entropy weighting method, gray prediction model

摘要：

湖北省是长江干流流经里程超千里的唯一省份，长江干流城市水生态安全直接影响该区域高质量发展。基于DPSIR模型，评估湖北省长江干流8个城市群在2008-2022年期间，水生态安全影响因素及其时空演化特征，并采用灰色预测模型预测未来5年的发展趋势。结果表明，1）湖北省长江流域干流城市水生态安全受驱动力、影响、状态三大子系统的影响。生态环境用水量、污水处理总量为主要影响因子，人均GDP、农林牧渔总产值、人均水资源量、地表水资源量和大中型水库年末蓄水量为次要影响因子。2）在子系统得分中，武汉市驱动力、影响子系统得分最高，恩施州压力、状态、响应子系统得分最高。3）2008-2022年间，湖北省长江干流8个地级市水生态安全都得到了一定的提升，仅鄂州市、黄石市在中度警告和重度警告间波动，处于高风险区。整体而言，湖北省长江流域水生态安全综合得分从中度预警上升至预警状态，呈向好趋势，但内部空间差异较大。4）2023-2027年，湖北省长江流域水生态安全状况将进一步改善，但仍有城市水生态安全处于中度-预警状态，需因地制宜采取措施对水资源进行保护，对水污染进行控制，并调整产业结构，以提升水生态安全水平。

关键词: 水生态安全评价, 时空格局, 驱动力-压力-状态-影响-响应（DPSIR）模型, 熵权法, 灰色预测模型