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Interbasin water-transfer schemes provide an engineering solution for reconciling the conflict between water demand and availability. In the context of climate change, which brings great uncertainties to water resource distribution, interbasin water transfer plays an increasingly important role in the global water–food–energy nexus. However, the transfer of water resources simultaneously changes the hydrological regime and the characteristics of local water bodies, affecting biotic communities accordingly. Compared with high economic and technical inputs water-transfer projects require, the environmental and ecological implications of water-transfer schemes have been inadequately addressed. This work selects the largest water-transfer project in China, the South-to-North Water Diversion (SNWD) Project, to critically review its eco-environmental impacts on donor and recipient basins, as well as on regions along the diversion route. The two operated routes of the SNWD Project represent two typical water diversion approaches: The Middle Route uses an excavated canal, while the East Route connects existent river channels. An overview of the eco-environmental implications of these two routes is valuable for the design and optimization of future water-transfer megaprojects.

Abstract Subsonic jet nozzles, commonly used in passenger aircrafts, generate significant noise that travels both downstream and upstream due to large-scale or fine-scale turbulence in the jet plume. To reduce jet noise, a novel wall treatment method, termed the wavy inner wall (WIW), is proposed. With this method, the smooth inner wall near the exit of the nozzle is replaced by treated walls that carry small wavy patterns. Numerical simulations were conducted to investigate the effects of the WIW treatment. Large eddy simulations (LES) were used to predict the unsteady flow field and the far-field noise, followed by the analogy method proposed by Ffowcs Williams and Hawkings. To better understand the mechanism behind the noise reduction achieved by the WIW treatment, the shear-layer instability, radial and azimuthal auto-correlation functions, turbulent kinetic energy, and acoustic source term from the Tam-Auriault (TA) jet-noise model were analyzed. Results indicated that the WIW treatment advances the onset of jet flow instability in the shear-layer, leading to the early breakdown of jet shear-layer and production of different scales of downstream turbulent structures. As a result, the distribution and production of turbulent kinetic energy are affected, and the generation and emission of jet noise are controlled. The WIW treatment enables the control of fine scale turbulence, resulting in the reduction of mid- to high-frequency noise in the far field, while ensuring a low thrust loss. This feature makes the WIW method a promising approach for jet noise control.

Three anaerobic reactors for treating starch wastewater as the Anaerobic Digester (AD), Up-flow Anaerobic Sludge Blanket (UASB) reactor, and Internal Circulation (IC) reactor, were assessed in terms of energy supply and economic factors pertaining to biogas production. For all three reactors, more than 90% of heat loss was derived from the substrate heating loss. When the Chemical Oxygen Demand (COD) of wastewater exceeded 15,000mg/L, the UASB and IC reactors produced excess energy and achieved an economic surplus throughout the year. The UASB and IC reactors reached energy equilibrium throughout the year when the influent COD was 11,195.44mg/L, and 9,844.67mg/L, respectively. The economic equilibrium of the UASB and IC reactors was achieved for influent COD of 12,984mg/L and 11,561mg/L, respectively. The energy and economic equilibria of the AD could not be achieved throughout the year with influent COD concentrations ranging from 5,000mg/L to 20,000mg/L.