通讯机构：
[Feng, C ] H;Hengyang Normal Univ, Sch Geog & Tourism, Hengyang 421002, Peoples R China.
关键词：
Water security index;Green water;Blue water;Water footprint;Xiangjiang river basin
摘要：
In a changing environment, a comprehensive and accurate water security assessment is critical to regional sustainable development. Most water security assessment studies concentrate on the sustainable use of blue water and less on green water, while the latter is irreplaceable to sustain food production. Considering the vital role that green water plays in maintaining human production and ecosystem stability. Here we incorporate green water into the water security assessment framework, proposing a blue-green water security index (BGWSI) and conducting a case study in the Xiangjiang River Basin (XRB). Two main conclusions are as follows: (a) combining green water to improve the water security assessment framework. The framework expands and extends the connotation of water security assessment and pioneers linking the attributes of water resources, like natural, social, and spatial benefit distances. In this way, the intrinsic connection between human activities and the risk status of regional blue-green water security can be grasped more comprehensively. (b) The case study reveals that the framework is feasible and applicable. The index BGWSI can better reflect the influence of basin green water resource fluctuation, green water footprint dynamics, spatial distance, and other factors on the overall water security risk. Incorporating green water and its related concepts into the water security assessment framework would provide new insight into water security assessment research, and we hope it will provide a more comprehensive reference for conducting regional blue-green water security assessment research. Also, the framework would be popularized and applied in more similar areas of blue-green water security assessment studies, which may contribute to accurately identifying the actual status of regional water security and promote the development of more scientific water management measures.
通讯机构：
[Feng, C ] H;Hengyang Normal Univ, Coll Geog & Tourism, Hengyang 421002, Peoples R China.
关键词：
river network system evolution;adaptation;urbanization;GTWR model;Xiangjiang River Basin
摘要：
<jats:p>The research focuses on the difficult problem of quantifying the adaptation state of river network system development under rapid urbanization. Based on the river network system data and remote sensing image data of the past 30 years, this study discusses the evolution of the river network system and its adaptability. The geographically and temporally weighted regression (GTWR) model was used to reveal the response of the river network system in the Xiangjiang River Basin to urbanization. The results suggest that the Xiangjiang River Basin has experienced a significant increase in urban land due to the strong disturbance by human activities in the last 25 years. The number indicators of river network system such as overall water surface rate and river network density have decreased by 10.04% and 13.99%, respectively. Drainage structure indicators such as tributary development coefficient and structural stability decreased by 6.89% and 4.40%, respectively. The influence of three-dimensional urbanization on the intensity of river network density change is spatiotemporal heterogeneity during 1995–2020. It shows that population factors have a significant negative impact on the upstream area. The regression coefficient between river network density and per capita GDP in the basin is positive. The regression coefficient of urban land is negative, indicating that urban expansion has a significant negative effect on river network density in Xiangjiang River basin. The analysis of the relationship between urbanization and river network system evolution by using the coordination degree model shows that: in the early stage, the level of urbanization is low, the adjustment capacity and carrying capacity of river network are strong, and the coordination degree of urbanization and river network system is small. The level of urbanization has reached a new height, especially in the upstream central cities such as Chang-Zhu-Tan from 2015 to 2020. At this time, the increase of coordination degree is characterized by the mutual promotion of urbanization and river network development, and the improvement of their adaptive development requirements. This study quantitatively reveals the changing characteristics and influencing factors of the adaptability of river network systems and urban spatial development, which can provide scientific support for regional human–water harmony, flood prevention and mitigation, and green urbanization development.</jats:p>
通讯机构：
[Yang, L ] H;Hengyang Normal Univ, Sch Geog & Tourism, Hengyang 421002, Peoples R China.
关键词：
Cultivation;Economic and social effects;Ecosystems;Function evaluation;Game theory;Pareto principle;Rivers;Soils;Transpiration;Watersheds;Ecosystem services;Green water;Green water compensation;Green water management;Payment for water-related ecosystem service;Scenarios analysis;Water compensation;Waters managements;Waters resources;Water management
摘要：
Given environmental or hydrological functions influenced by changing river networks in the development of rapid urbanization, a clear understanding of the relationships between comprehensive urbanization (CUB) and river network characteristics (RNC), storage capacity (RSC), and regulation capacity (RRC) is urgently needed. In the rapidly urbanized Tai Lake Plain (TLP), China, various methods and multisource data were integrated to estimate the dynamics of RNC, RSC, and RRC as well as their interactions with urbanization. The bivariate Moran's I methods were applied to detect and visualize the spatial dependency of RNC, RSC, or RRC on urbanization. Geographically weighted regression (GWR) model was set up to characterize spatial heterogeneity of urbanization influences on RNC, RSC and RRC. Our results indicated that RNC, RSC and RRC variables each showed an overall decreasing trend across space from 1960s to 2010s, particularly in those of tributary rivers. RNC, RSC, or RRC had globally negative correlations with CUB, respectively, but looking at local scale the spatial correlations between each pair were categorized as four types: high-high, high-low, low-low, and low-high. GWR was identified to accurately predict the response of most RNC, RSC, or RRC variables to CUB (R-2: 0.6-0.8). The predictive ability of GWR was spatially non-stationary. The obtained relationships presented different directions and strength in space. All variables except for the water surface ratio (Wp) were more positively affected by CUB in the middle eastern parts of TLP. Drainage density, RSC and RRC variables were more negatively influenced by CUB in the northeast compared to other parts. The quantitative results of spatial relationships between urbanization and RNC, RSC or RRC can provide location-specific guidance for river environment protection and regional flood risk management.
期刊：
FRONTIERS IN EARTH SCIENCE,2021年9:677191 ISSN：2296-6463
通讯作者：
Yang, Liu
作者机构：
[Feng, Chang; Yang, Liu] Hengyang Normal Univ, Coll Geog & Tourism, Hengyang, Peoples R China.;[Han, Longfei] Hunan Normal Univ, Sch Geog Sci, Changsha, Peoples R China.
通讯机构：
[Yang, Liu] H;Hengyang Normal Univ, Coll Geog & Tourism, Hengyang, Peoples R China.
关键词：
Water Resources;Blue water;Green water;Climate Change;Parallel parameter calibration method;Prediction uncertainty;SWAT
摘要：
<jats:p>Green water resources, which are fundamental for plant growth and terrestrial ecosystem services, reflect precipitation that infiltrates into the unsaturated soil layer and returns to the atmosphere by plant transpiration and soil evaporation through the hydrological cycle. However, green water is usually ignored in water resource assessments, especially when considering future climate impacts, and green water modeling generally ignores the calibration of evapotranspiration (ET), which might have a considerable impact on green water resources. This study analyzes the spatiotemporal variations in blue and green water resources under historical and future climate change scenarios by applying a distributed hydrological model in the Xiangjiang River Basin (XRB) of the Yangtze River. An improved model calibration method based on remotely sensed MODIS ET data and observed discharge data is used, and the results show that the parallel parameter calibration method can increase the simulation accuracy of blue and green water while decreasing the output uncertainties. The coefficients (<jats:italic>p-factor</jats:italic>, <jats:italic>r-factor</jats:italic>, <jats:italic>KGE</jats:italic>, <jats:italic>NSE</jats:italic>, <jats:italic>R</jats:italic><jats:sup><jats:italic>2</jats:italic></jats:sup>, and <jats:italic>PBIAS</jats:italic>) indicate that the blue and green water projections in the calibration and validation periods exhibit good performance. Blue and green water account for 51.9 and 48.1%, respectively, of all water resources in the historical climate scenario, while future blue and green water projections fluctuate to varying degrees under different future climate scenarios because of uncertainties. Blue water resources and green water storage in the XRB will decrease (5.3–21.8% and 8.8–19.7%, respectively), while green water flow will increase (5.9–14.7%). Even taking the 95% parameter prediction uncertainty (95 PPU) range into consideration, the future increasing trend of the predicted green water flow is deemed satisfactory. Therefore, incorporating green water into future water resource management is indispensable for the XRB. In general, this study provides a basis for future blue and green water assessments, and the general modeling framework can be applied to other regions with similar challenges.</jats:p>
