Changes in the level of the Yangtze River caused by anthropogenic water regulation have major effects on the hydrological processes and water cycle in surrounding lakes and rivers. In this study, we obtained isotopic evidence of changes in the water cycle of Yangtze River during the two drought years of 2006 and 2013. Isotopic evidence demonstrated that the δ18O and δD levels in Yangtze River exhibited high spatial heterogeneity from the upper to lower reaches, which were controlled by atmospheric precipitation, tributary/lake water mixing, damming regulation, and water temperature. Both the slope and intercept of Yangtze River evaporative line (δD = 7.88 δ18O + 7.96) were slightly higher than those of local meteoric water line of Yangtze River catchment (δD = 7.41 δ18O + 6.01). Most of the river isotopic values were located below the local meteoric water line, thereby implying that the Yangtze River water experienced a certain degree of evaporative enrichment on isotopic compositions of river water. The high fluctuations in the isotopic composition (e.g., deuterium excess [d‐excess]) in the middle to lower reaches during the initial stage of operation for the Three Gorges Dams (2003–2006) were due to heterogeneous isotopic signatures from the upstream water. In contrast to the normal stage (after 2010) characterized by the maximum water level and largest water storage, a relatively small variability in the deuterium excess was found along the middle to lower reaches because of the homogenization of reservoir water with a longer residence time and complete mixing. The effects of water from lakes and tributaries on the isotopic compositions in mainstream water were highlighted because of the high contributions of lakes water (e.g., Dongting Lake and Poyang Lake) efflux to the Yangtze River mainstream, which ranged from 21% to 85% during 2006 and 2013. These findings suggest that the retention and regulation of the Three Gorges Dams has greatly buffered the isotopic variability of the water cycle in the Yangtze catchment, thereby improving our understanding of the complex lake–river interactions along the middle to lower reaches in the future. 相似文献
Water resources provide the foundation for human development and environmental sustainability. Water shortage occurs more or less in some regions, which usually causes sluggish economic activities, degraded ecology, and even conflicts and disputes over water use sectors. Game theory can better reflect the behaviors of involved stakeholders and has been increasingly employed in water resources management. This paper presents a framework for the allocation of river basin water in a cooperative way. The proposed framework applies the TOPSIS model combined with the entropy weight to determine stakeholders’ initial water share, reallocating water and net benefit by using four solution concepts for crisp and fuzzy games. Finally, the Fallback bargaining model was employed to achieve unanimous agreement over the four solution concepts. The framework was demonstrated with an application to the Dongjiang River Basin, South China. The results showed that, overall, the whole basin gained more total benefits when the players participated in fuzzy coalitions rather than in crisp coalitions, and \(\left\{ {NHS_{Fuzzy} \,and\, SV_{Crisp} } \right\}\) could better distribute the total benefit of the whole basin to each player. This study tested the effectiveness of this framework for the water allocation decision-making in the context of water management in river basins. The results provide technical support for water right trade among the stakeholders at basin scale and have the potential to relieve water use conflicts of the entire basin. 相似文献
Particulate matter (PM) originated by road transport constitutes an urgent task for megacities and pedestrians are supposed to be the first batch of innocent victims that exposed to and inhaled the polluted air. Footbridges have become a promising resolution to land tension, the location and design of them should be more considered in order to provide a more desirable walking system to pedestrians. In this study, three groups of PM [i.e., 0.3–0.9 μm (sub-fine), 0.9–2.5 μm (fine) and 2.5–10 μm (coarse)] were measured at different traffic scenario related footbridges (i.e., upstream of the on-ramp, downstream of the on-ramp, and signalized intersection) along an urban artery in Hong Kong, and their traffic volume composition, multifractality and cross-correlation behavior were investigated thereafter. Multifractal detrended fluctuation analysis and multifractal detrended fluctuation cross-correlation analysis were used simultaneously to quantify the persistency of different PM groups and interaction between them. The results indicate that although the particle concentration at intersection above footbridges presents the lowest, it has the highest emission rate and the strongest multifractality and cross-correlation behavior, especially the finer ones. Hence, it is suggest that the nature ventilation style of footbridges should avoid to be built above the signalized intersection due to the long persistency of particles and active interaction between different particle groups. 相似文献
The present paper reviews the conceptual framework and development of the Bayesian Maximum Entropy (BME) approach. BME has been considered as a significant breakthrough and contribution to applied stochastics by introducing an improved, knowledge-based modeling framework for spatial and spatiotemporal information. In this work, one objective is the overview of distinct BME features. By offering a foundation free of restrictive assumptions that limit comparable techniques, an ability to integrate a variety of prior knowledge bases, and rigorous accounting for both exact and uncertain data, the BME approach was coined as introducing modern spatiotemporal geostatistics. A second objective is to illustrate BME applications and adoption within numerous different scientific disciplines. We summarize examples and real-world studies that encompass the perspective of science of the total environment, including atmosphere, lithosphere, hydrosphere, and ecosphere, while also noting applications that extend beyond these fields. The broad-ranging application track suggests BME as an established, valuable tool for predictive spatial and space–time analysis and mapping. This review concludes with the present status of BME, and tentative paths for future methodological research, enhancements, and extensions. 相似文献
The control of soil pollution in China has become an issue, and in this study, a compound contaminated site was selected and focus on the site and its nearby environment, organochlorine pesticides (OCPs) were investigated in both soil (top and deep soil) and air samples. The main pollutants in top soils at site are dichlorodiphenyltrichloroethane (DDTs, 0.05–104 mg/kg d.w., avg: 14.5 mg/kg d.w.) and hexachlorobenzene (HCB, 0.02–4.85 mg/kg d.w., avg: 0.72 mg/kg d.w.) which is in accordance with its production history. As for the deep soils, ΣOCPs at site were found concentrated at workshops especially the technical pesticide workshop (5.29–22.1 mg/kg d.w., avg: 9.15 mg/kg d.w.) and the history DDTs’ workshop (4.00–64.8 mg/kg d.w., avg: 20.4 mg/kg d.w). Around site, OCPs were mainly concentrated at layers of −20 cm and the −40 cm and decreased with distance being far away, at 5000 m, the ΣOCPs was comparable with normal agriculture soil (22.1−91.4 ng/g d.w., avg: 55.4 ng/g d.w.). ΣOCPs in the air samples ranged 64.6–823 ng/m3 (avg: 459 ng/m3) at site and 9.93–176 ng/m3 (avg: 50.8 ng/m3) around site which are all dominated with DDTs and HCHs. Soil–air exchange fugacity was calculated to judge the transportation of the OCPs and the results showed soils at the site and its nearby areas (within 5000 m) are releasing most of the OCPs into air, and accordingly through evaluation, inhalation was found to be the major source for human health risk, which is a great threat to the workers at site and the nearby residents.
A numerical modeling study of the influence of the lateral flow on the estuarine exchange flow was conducted in the north passage of the Changjiang estuary. The lateral flows show substantial variabilities within a flood-ebb tidal cycle. The strong lateral flow occurring during flood tide is caused primarily by the unique cross-shoal flow that induces a strong northward (looking upstream) barotropic force near the surface and advects saltier water toward the northern part of the channel, resulting in a southward baroclinic force caused by the lateral density gradient. Thus, a two-layer structure of lateral flows is produced during the flood tide. The lateral flows are vigorous near the flood slack and the magnitude can exceed that of the along-channel tidal flow during that period. The strong vertical shear of the lateral flows and the salinity gradient in lateral direction generate lateral tidal straining, which are out of phase with the along-channel tidal straining. Consequently, stratification is enhanced at the early stage of the ebb tide. In contrast, strong along-channel straining is apparent during the late ebb tide. The vertical mixing disrupts the vertical density gradient, thus suppressing stratification. The impact of lateral straining on stratification during spring tide is more pronounced than that of along-channel straining during late flood and early ebb tides. The momentum balance along the estuary suggests that lateral flow can augment the residual exchange flow. The advection of lateral flows brings low-energy water from the shoal to the deep channel during the flood tide, whereas the energetic water is moved to the shoal via lateral advection during the ebb tide. The impact of lateral flow on estuarine circulation of this multiple-channel estuary is different from single-channel estuary. A model simulation by blocking the cross-shoal flow shows that the magnitudes of lateral flows and tidal straining are reduced. Moreover, the reduced lateral tidal straining results in a decrease in vertical stratification from the late flood to early ebb tides during the spring tide. By contrast, the along-channel tidal straining becomes dominant. The model results illustrate the important dynamic linkage between lateral flows and estuarine dynamics in the Changjiang estuary. 相似文献