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This paper proposes a multi-reservoir operating policy for water supply by combining target storage curves with the hedging rule. The curves are derived to solve the allocation problem of joint demand. There are three steps in the proposed methodology: Firstly, the optimal release schedule using dynamic programming to solve a long-term operation model is established, from which the suitable forms of target storage curves are identified. Secondly, a simulation and optimization model is built to identify the key points of the curves with the hedging rule based on aggregated reservoir using improved particle swarm optimization (IPSO). Finally, synthetic inflow series is used to test and verify the efficiency of the proposed rule. The water-supply multi-reservoir system located in the Liaoning province of China is employed as a case study to verify the effect of the proposed operating policy and the efficiency of target storage curves. The results indicate that the proposed operating policy is suitable to handle the multi-reservoir operation problem, especially for periods of drought. The target storage curves also show improved performance for distribution of system storages.

This study was conducted for parameter sensitivity analysis of an eco-friendly fire-fighting device, the sand-ejecting fire extinguisher, by means of experiments and CFD-DEM coupling simulations. The paper presents a total of nine impeller design schemes. Simulations were carried out to reproduce the sand ejection process with each scheme. The results show that the gas flow field has an effect on the ejection process under the windless environment, so the sand ejection characteristic analyses are based on DEM calculations. The phenomenon that a greater number of blades could provide longer ejection distance is also found in the simulation process. Radial and forward schemes may be more suitable for gas-station fires while backward schemes not because of the sand accumulation character. The CFD-DEM calculation shows that increasing the sand mass flow could extend the ejection distance but is more susceptible to ambient wind.

An environmental water supplement through reservoir regulation is an important way to restore the deltaic coastal wetland. In order to quantify the impact of the reservoir on the deltaic coastal wetland ecosystem, this article proposes a quantitative analysis method for the ecological impact and contribution rate of the reservoir, which compares the ecological status in two scenarios with the presence or absence of the reservoir during the assessment period, and reveals the reservoir’s impact on and contribution rate to the ecological status and environmental water supplement conditions. The results show that during 2000–2019, through the regulation of the Xiaolangdi Reservoir, the average annual drying up days at the Lijin section reduced by 81.15 days, the average annual assurance rate of ecological base flow at the Lijin section increased by 20.60%, and the volume of water flowing into the sea from April to June increased by 2.37 billion m³. During 2008–2015, the Xiaolangdi Reservoir increased the environmental water supplement of the Yellow River Delta by 19.95 million m³. Compared with the flow and water withdrawal during 1980–1999, the natural flow of the Yellow River decreased by 10.59% and the measured flow in the lower reaches decreased by 22.15%, and the water withdrawal in the lower reaches increased by 0.32 billion m³ during 2000–2019, which is detrimental to provide environmental water to the Yellow River Delta wetland and coastal areas. The Xiaolangdi Reservoir reversed the adverse effects of flow and water withdrawal and ensured the continuous ecological improvement in the Yellow River Delta and coastal areas, providing the respective contribution rate of 187.85%, 137.24%, and 125.83% to the prevention of drying up at the Lijin section, the increase in the assurance rate of ecological base flow at the Lijin section, and the increase in the volume of water flowing into the sea in the critical period.

The Yellow River Basin is of great significance to China’s economic and social development and ecological security. The Yellow River Basin is not only an important ecological barrier but also an important economic zone. In this article, natural hydrological conditions were taken as a reference, a habitat simulation model of the key sections of the Yellow River was constructed based on the MIKE 21 model, and an ecological water requirement assessment method for river ecological integrity combined with habitat simulation and features of the hydrological reference group was established, which took account of the survival and reproduction of indicator species. The suitable flow rates for the spawning period (i.e., April to June) of Silurus lanzhouensis in Lanzhou (LZ) and Cyprinus carpio in Longmen (LM) were 350–720 and 260–400 m3/s, respectively. Therefore, high pulse flow with a low flow peak should be guaranteed in mid- to late April. The peak flow should be at least approximately 1,000 m3/s to ensure that fish receive spawning signals, with a high pulse flow process occurring 1–2 times in May to June. The annual ecological water requirement of the Lanzhou and Longmen section was 9.1 × 109–11 × 109 and 4.7 × 109–11.3 × 109 m3. The model quantitatively simulated the changes in ecological water requirement of indicator fishes in key sections of the Yellow River, and an effective and realistic tool for ecological water requirement accounting of the Yellow River was provided.

The accuracy of the habitat simulation method is often questioned due to limited simulated elements and indicator species. This study established an environmental flow assessment method by coupling fish habitat simulation with hydrological reference system. The environmental flow obtained through the habitat simulation method was corrected by the statistical characteristics of natural flow regime. The environmental flow of the Huayuankou section in the Lower Yellow River was assessed. The results show that the environmental flow demand of the Huayuankou section is 7.9 - 15.4 billion m3/y without consideration of sediment transport. An environmental baseflow of 220 - 400 m3/s is required throughout the year. One to two high flow pulses are needed in the rising-water season to trigger spawning, followed by flow events of 350 - 500 m3/s with more than 1 week duration to create the spawning grounds.

Mass media are important sources of information about water issues that significantly influence civil life. This paper presents a content analysis approach to contextualize the water issues reporting of the People's Daily. The intent of our approach is to uncover the reporting pattern of water issues and the relationship between government policies and their news reports. Using the newspaper with the second widest circulation in China, the content analysis approach reveals that the document frequency of water issues had shown a flat trend since the 1970s. Water-related articles were given more significance by providing additional front pages. The results suggest that newspapers have been focusing more on the recreational function and protection of water since the 1980s. The results also show that there was a relative shortage of coverage on certain types of water-related central government documents. Lacking persistence was another feature of policy propaganda. These factors could work against public engagement in water issues and undermine the public's understanding of and confidence in water management measures. We believe these results could help water resource managers to interpret media content of water issues and improve the propaganda of their policies, which would contribute to better administration of water resources.

Eco-compensation is the most important form of compensatory conservation in China. However, this compensatory mechanism is criticized for vague definition and massive government participation. For better understanding of eco-compensation in China, this paper compares theories and practices of compensatory mechanisms in China and abroad. The analysis of theoretical backgrounds shows that eco-compensation in China is a combination of 'ecological compensation' and 'payments for ecosystem services'. Ten compensatory projects in China and abroad are assessed to reveal characteristics and problems of eco-compensation in China. The results show that compensatory projects in China lagged behind mature foreign compensatory projects in clarity of property rights, responsibility fulfillment, executive efficiency, effectiveness, sustainability and equality. The massive participation of the government is the major reason for the poor performance of compensatory projects in China. However, government participation is necessary at the present stage in China for the income gap and beneficiaries' low willingness to pay. For the improvement of eco-compensation in China, suggestions are given on the choice of non-market valuation methods, the creation of property rights and the establishment of market mechanisms.

Analytical optimal hedging rules are derived for two-objective reservoir operation based on the characteristics of economic and multilevel environmental water demands. This approach is employed to balance current and future economic and environmental water demands using a two-period model. According to the marginal values of utilities, the derived three-step hedging rule curves (THRCs) consist of three steps and six stages. The Huaihe River basin of China is taken as an example to regress the THRCs from a two-objective optimization model. Results show that the derived THRCs can be regressed from the optimal release decision, thereby confirming the derivations and theoretical analysis. The shapes of the THRCs are sensitive to the weight parameters of the objectives and capture the core concern of multiobjective reservoir operation. The THRCs tend to widen and flatten the stages with increasing storage capacity, which implies more water storage and more consideration for future demands.

Global freshwaters are severely depleted. Provision of improved water infrastructure technologies and innovation can address challenges posed by water shortages to environmental sustainability. China’s South-to-North Water Diversion Project has generated extensive debates over sustainability of water resources system in the northern drier region, which faces severe water scarcity hindering ecosystems, agriculture, industries and livelihoods. Some arguments extend the views that large infrastructure projects can have negative implications for biodiversity conservation and ecosystem goods and services. However, this study strengthens the opposite view, as such projects would resolve increasing environmental challenges northern China has been facing over many decades due to severe water shortages. The project empowers connectivity among individuals, community, and organizations that the sustainability of goods and services such as energy, irrigation and water supply are perceived, and livelihoods and the standard of peoples’ living is improved. A resilient, robust and adaptive water infrastructure framework can overcome the challenges of water shortages by meeting a long term social, economic and environmental goals for water resources systems in northern China. Such framework can also identify the thresholds of change and the threats associated with environmental sustainability.

Dynamic explicit finite element analysis is practical and significant to study vehicle spiral rolling. By means of HyperMesh and LsDyna, numerical simulation is achieved with deformation, posture and acceleration obtained. During spiral rolling process, vehicle roof comes much close to occupant head step by step, so vehicle roof should be intensified and optimized moderately. Initial impacting velocity is set as 80km/h, dummy does not leave the seat until the rolling ends with safety belt adopted. While, without safety belt, dummy detaches or contacts vehicle for several times, head and neck have relatively large deflection and bending. Without the protection of the safety belt, the injury of head, neck and chest during spiral rolling goes beyond the regulation requirements for safety, serious casualties will occur consequentially.

Adopting high performance buffer is the foundation of the landing gear on the helicopter. Based on established models on Adams/Aircraft, a novel type of series double cavity buffer on the landing gear is investigated by dynamic simulation. Corresponding simulation and analysis are achieved, which is helpful for farther structure optimization. It is shown that compared with single cavity buffer, the series double cavity buffer can reduce effectively the acceleration, vertical force and tire force of the landing gear. Under the same condition, vertical force and tire force of the landing gear increase with the initial pressure increase of the high pressure grade buffer in the series double cavity buffer.