Water Replenishment Research Articles

Transport and accumulation of floating marine litter in the Black Sea: insights from numerical modeling

IntroductionFloating marine litter (FML) is a global problem with significant risks to marine life and human health. In semi-enclosed basins like the Black Sea, slow water replenishment and strong input from European rivers create conditions that can lead to the accumulation of FML. This study aims to validate and utilize an FML dispersion and accumulation numerical model. Additionally, it assesses the influence of Stokes drift on the accumulation patterns of marine litter in the Black Sea, focusing on the contribution from the main river discharge points.MethodsNumerical Lagrangian modeling adapted to the regional domain in the Black Sea was employed to simulate the dispersion and accumulation of FML. Three scenarios were conducted: two involved homogeneous particle release, one considering Stokes drift, and the other excluding it. The third scenario involved particle release from the nine main river basins.ResultsThe southwest coast of the Black Sea exhibited a high density of FML in all scenarios. This finding is likely attributed to the cyclonic circulation, significant FML input from the Danube River, and other northern rivers. Notably, the consideration of Stokes drift significantly impacted the residence time of particles in offshore waters and the percentage of particles washing up on the shore. Including Stokes drift increased the percentage of beached particles from 45.5% to 75.5% and reduced the average residence time from 99 to 63 days. These results align with recent literature, which emphasizes the importance of accounting for Stokes drift to avoid overestimating residence times.DiscussionThe model's findings provide valuable insights into FML accumulation patterns in the Black Sea. The eastern region near the Georgian coast and the northwestern Black Sea were identified as high-density areas, corroborated by observational data. This research underscores the significance of considering Stokes drift when modeling FML transport, particularly concerning marine litter accumulation and potential impacts on coastal regions.

Simulation of Water Quality in a River Network with Time-Varying Lateral Inflows and Pollutants

Non-point source pollution inflow is one of the main causes of water quality decline in urban river networks. In this paper, aiming at the problem of non-point source pollutant transport in river network, the lateral outflow term in the Saint-Venant equation is improved from the previous constant to the time-varying flow process, and a mathematical model considering the time-varying source and sink term is established. Based on the initial rainfall intensity, surface confluence and non-point source pollutant concentration, a method for calculating the time-varying lateral pollutant input of nodes and tributaries with linear increase and exponential decay in the initial rainfall period is proposed. Based on the principle of proximity, the watershed is divided into districts. According to the principle of elevation, the non-point source pollutants are allocated to the calculation nodes of adjacent rivers in a certain proportion and incorporated into the model calculation so as to improve the mathematical model of river network water quality and apply it to the simulation of river network water quality in Maozhou River Basin. Verified by the measured data, the NSE values of the improved model are 0.805 and 0.851, respectively, indicating that the model has reliable hydrodynamic and water quality simulation accuracy, indicating that the model can be applied to the calculation of non-point source pollutants in the basin. Based on the improved model, the variation of COD concentration in the Maozhou River of Shenzhen before and after optimized water replenishment was calculated, and the time variation and spatial distribution law of the sudden drop of water quality in the river network caused by the inflow of non-point source pollution in the initial rainfall runoff and the rapid recovery after optimized water replenishment were revealed.

Effects of Tectonic Setting and Hydraulic Properties on Silent Large-Scale Landslides: A Case Study of the Zhaobishan Landslide, China

Unlike strong earthquake-triggered or heavy rainfall-triggered landslides, silent large-scale landslides (SLL) occur without significant triggering factors and cause unexpected significant disaster risks and mass casualties. Understanding the initiation mechanism of SLLs is crucial for risk reduction. In this study, the mechanism of the Zhaobishan SLL was investigated, and the SLL was jointly controlled by weak-soil (fractured rock mass) and strong-water (abundant water replenishment) conditions under the impact of active tectonism and complex hydraulic properties. Strong tectonic uplift, high fault density, and historical earthquakes led to weak-soil conditions conducive to the Zhaobishan SLL. The combined effect of unique lithology, antiform, and cultivated land contributed to the water replenishment characteristics of extensive runoff confluence (3.16 times that of the landslide body) and supported long-distance groundwater replenishment, thereby forming strong-water conditions for the landslide. The amplified seepage amount caused the strength of the soil mass on the sliding surface to decrease to 0.4 times its initial strength, eventually triggering the Zhaobishan SLL, which occurred 4.6 days after the peak rainfall. Moreover, the landslide deposits have accumulated on the semi-diagenetic clay rock, thereby controlling the subsequent recurring debris flows in the Lengzi Gully. To reduce disaster risk of SLL in vulnerable mountainous regions, the water confluence area behind the main scarp of the landslides and the hysteresis characteristics between landslides and peak rainfall should be further considered, and recurring debris flows following massive landslides also should be focused.

Study on the simulation of reservoir water environment and the optimization of ecological water replenishment effect: Taking Luhun Reservoir as an example

Abstract With global climate change and extreme weather events, water scarcity and environmental degradation are becoming increasingly prominent. Ecological replenishment is one important measure to enhance water quality in reservoirs. To address the severe pollution and ecological degradation problems of the Luhun Reservoir, this paper uses MIKE21 software to construct a coupled hydrodynamic-water quality model. Six recharge scenarios were designed to compare and explore the enhancement of reservoir water quality for these scenarios. The water quality status of these options was evaluated using the single-factor index method and the combined pollution index method. The results show that due to the ecological replenishment, the pollutant concentration leads the phenomenon of gradient diffusion to the center of the reservoir, and the average improvement rate of water quality is up to 40.22%. Schemes 2 and 5 have the lowest integrated pollution index. The most significant improvement in water quality was achieved at the same total recharge conditions, using 0.5 times the flow rate and two times the recharge time of the actual recharge project. The study results provide theoretical and technical support for the future management of the reservoir water environment.

Water replenishment to maize under heat stress improves canopy temperature and grain filling traits during the reproductive stage

The occurrence of heat often exacerbates drought stress by increasing atmospheric vapor pressure deficit and decreasing transpiration efficiency. Water replenishment to increase soil water content (SWC) could be an effective measure for improving crop resilience in heat. However, field observational evidence and the underlying mechanism for the mitigation were still limited. For this, two widely adopted maize hybrids (ZD958 and XY335) were planted in 2019 and 2020 in North China Plain with three growth environments during the reproductive stage: Normal field conditions (NC), High-temperature episodes (HT) and High-temperature together with elevating SWC (HT-W). Averagely, high temperature reduced grain yield by 21.6-65.1% in HT treatment compared with NC treatment. In HT-W treatment, grain yield was improved by 11.8-13.5% while SWC was elevated by 27.6–51.5% in 0–80 cm soil profile compared with HT treatment. In HT-W treatment, water replenishment to maize under heat stress improved canopy temperature and grain filling traits. The daily maximum canopy temperature was reduced by 1.0–3.1 °C. The effective grain-filling period (Pf) was extended by 1.0–1.6 days and the mean grain-filling rate (Gmean) was increased by 8.2%-10.5%. The improvement of Gmean and Pf for ZD958 was greater than XY335. Furthermore, the significant correlations between SWC in 0–20 cm soil profile and Gmean, and between SWC in 40–80 cm soil profile and Pf for both hybrids were observed. As a result, the fresh weight, volume, and water content of the grain were significantly improved in HT-W treatment compared with HT treatment. Overall, per unit increase in SWC (0–80 cm) decreased the daily maximum canopy temperature by 0.3 °C, increased dry matter accumulation by 1.5%, and grain yield by 2.1%. The information obtained from this study will be helpful to develop efficient management to protect against heat stress in the field.

Effects of supplemental irrigation on grain yield and water and nitrogen efficiencies of winter wheat in the North China Plain.

Aiming at unbalanced coordination of irrigation and fertilization of winter wheat in the eastern North China Plain, this study investigated the effect of fertigation on wheat grain yield, grain quality, and water use efficiency (WUE) and nitrogen use efficiency (NUE) in seven irrigation and nitrogen (N) fertilization treatments. Under the field conditions, the traditional irrigation and fertilization method (total N amount of 240 kg ha-1 , application of 90 kg ha-1 at sowing irrigation at jointing and anthesis, with topdressing N of 150 kg ha-1 at jointing) was used as the control (CK). There were six fertigation treatments to compare with CK. For the fertigation treatments, the total amount of N application was set to 180 kg ha-1 and 90 kg ha-1 was applied at sowing and the remaining N fertilizer was applied through fertigation. The fertigation treatments included the combination of three fertigation frequencies (S2: at jointing and anthesis; S3: at jointing, anthesis, and filling; S4: at jointing, booting, anthesis, and filling) and two soil water replenishment depths (M1: 0-10 cm; M2: 0-20 cm). The six treatments were S4M2, S4M1, S3M2, S3M1, S2M2, and S2M1. Compared with CK, three and four irrigations (S3 and S4) maintained higher soil and plant analyzer development value and photosynthetic rate after anthesis. These treatments increased soil water extraction while reducing crop water consumption during the whole growing season, promoted the assimilation and translocation of dry matter into the grain after anthesis, and increased the 1000-grain weight. These fertigation treatments also significantly increased WUE and NUE. At the same time, the high grain protein content and grain protein yield were maintained. Compared with the CK, high wheat yield was maintained by S3M1 (drip irrigation fertilizer at the jointing, anthesis, and filling, and the depth of the moisture replenishment is 10 cm). This fertigation treatment significantly increased yield by 7.6%, WUE by 30%, NUE by 41.4%, and partial factor productivity from applied N by 25.8%; grain yield, grain protein content, and grain protein yield also performed well. Consequently, S3M1 treatment was suggested to be a good practice for reducing irrigation water and N input in the eastern North China Plain. © 2023 Society of Chemical Industry.

Driving mechanism of water replenishment on DOM composition and eutrophic status changes of lake in arid and semi-arid regions of loess area

Water replenishment can be a key factor in driving lake eutrophication status. In arid and semi-arid regions of China, water replenishment for a lake has been widely carried out for not only improving water environmental quality, but also maintaining ecological system function. However, it is still unclear in terms of mechanism by which water replenishment drives lake eutrophication status. In this study, fluorescence excitation-emission matrix spectroscopy (EEMs) combined with multiple statistical analysis models (including parallel factor analysis, correlation analysis, redundancy analysis, and partial least squares structural equation modeling) was utilized to reveal potential driving mechanism and causality between water replenishment, dissolved organic matter (DOM) fractions and eutrophic status of Lake Shahu in China. Based on variations of DOM fractions, fulvic-like substances could be accumulated during the replenishment period, while nutrients carried along the replenishment might conduce to increase microbial activities during the non-replenishment period. This should be contributed to an alteration of prominent component from fulvic-like substances to tyrosine-like substances during the replenishment period to non-replenishment period. According to partial least squares structural equation modeling, two potential indirect paths were finally revealed, i.e., water replenishment derived the eutrophic status of Lake Shahu: water replenishment → microbial activity → algae → eutrophication, and water replenishment → microbial activity → eutrophication. This supposed that the water replenishment should indirectly drive the algae and eutrophication of the lake by promoting the transformation of DOM fractions. In addition, natural conditions could indirectly contribute to the eutrophication of the lake through impacting the algae growth. These findings should be conducive to trace the alteration of DOM fractions in lakes by water replenishment and in recognizing potential driving mechanisms of water replenishment on eutrophication of lakes by changing DOM fractions. This could provide basic theoretical support for policymakers to regulate and treat the eutrophication of lakes.

Water Chemical Characteristics and Water Quality Evaluation of the River under the Ecological Water Replenishment: A Case Study in the Yongding River Basin in North China

Water Chemical Characteristics and Water Quality Evaluation of the River under the Ecological Water Replenishment: A Case Study in the Yongding River Basin in North China

Responses of the Siberian crane population to temporal and spatial hydrological variations in stopover sites in northeast China

The Siberian crane (Grus leucogeranus), a critically endangered species, is used as an indicator species for ecosystem stability because of its sensitivity to the environment. The distribution of Siberian cranes has shown dramatic fluctuations on an order of magnitude at the main stopover site (Jilin Momoge National Nature Reserve) since the present century, which poses a great challenge to the conservation of endangered species. Research on the threshold values of key factors of the Siberian crane in stopover habitats and the relationship between the Siberian crane and hydrological temporal and spatial fluctuations can promote endangered species conservation. The response of population changes and distribution patterns of Siberian cranes to hydrological temporal and spatial patterns of wetlands was analyzed from 1984 to 2020. The results showed that population changes and distribution patterns of Siberian cranes were highly correlated with hydrological temporal and spatial patterns in the study area, and their variation trend was the same. However, there were obvious stage migration changes in the core activity area of the Siberian crane (1984–2000, 2001–2010 and 2010–2020). The habitat characteristics of fragmentation, dispersion and complex shape of water bodies changed from steady to dramatic fluctuations and then leveled off in the core activity area of Siberian cranes during the 37 years of migration transit. This was closely related to the early agricultural reclamation and the later ecological water replenishment project in the study area. In addition, the trend of the water pattern index of the spatial distribution of Siberian crane active habitat was also closely related to their habitat selection preference. When the perimeter area fractal dimension of water (1.27–1.40), landscape division index (0.73–0.95) and aggregation index (80.97–91.36) are within a certain stable threshold, the stopover habitat of the Siberian crane is suitable. This study will provide scientific guidance for the conservation of the Siberian crane population and the development of wetland restoration projects.

Human Health Risks due to Exposure to Water Pollution: A Review

Water resources are crucial in developing any area as they serve as a major source of potable, agricultural, and industrial water. Water contamination, caused by natural and anthropogenic activities, poses a significant threat to public health globally. This review synthesizes data from various studies published in national and international journals, as well as reports from governmental and non-governmental organizations. Our primary objective is to understand and review previous research on water pollution, contamination types, and the effects of water contamination on public health. Water pollution studies generally involve a scientific understanding of the biological, chemical, and physical processes that control the movement of contaminants in the underground environment. The nature and severity of health consequences vary based on several factors, including the chemical composition, duration of exposure, and concentration of pollutants. This work highlights the human health risks associated with current research topics such as anthropogenic, geogenic, microplastics, pharmaceuticals, and heavy metals. A section on remedial measures and mitigation strategies is included to emphasize sustainable approaches to water conservation, replenishment, and sustainability. However, there is a lack of comprehensive knowledge regarding the distribution, toxic effects, and human health risks associated with different sources of contamination. This review thus establishes links between multiple sources of pollution, their toxicity to human health, and approaches to health risk assessment.

Research on the purification enhancement of ecological ponds: Integrating water cycle optimization and plants layout

The hydrodynamic conditions of ponds are generally poor, which seriously affects the long–term water quality guarantee. In this research, the numerical simulation method was used to establish an integrated model of hydrodynamics and water quality for the simulation of the plant purification effect in ponds. Based on the flushing time using the tracer method, the purification rate of plants was introduced to consider the purification effect of plants on water quality. In–situ monitoring was carried out at the Luxihe pond in Chengdu, and the model parameters such as the purification rate of typical plants were calibrated. The degradation coefficient of NH3–N in the non–vegetated area was 0.014 d−1 in August and 0.010 d−1 in November. In areas with vegetation, the purification rate of NH3–N was 0.10–0.20 g/(m2·d) in August and 0.06–0.12 g/(m2·d) in November. The comparison of the results in August and November showed that due to the higher temperature in August, the plant growth effect was better, and the degradation rate of pollutants and the purification rate of pollutants by plants were higher.The flushing time distribution of the proposed Baihedao pond under the conditions of terrain reconstruction, water replenishment, and plant layout was simulated, and the frequency distribution curve of flushing time was used to evaluate the results. Terrain reconstruction and water replenishment can significantly improve the water exchange capacity of ponds. The reasonable planting of plants can reduce the variability of the water exchange capacity. Based on this combined with the purification effect of plants on NH3–N, the layout plan of Canna, Cattails, and Thalia in ponds was proposed.

Russian-Asian trade caravans of the 18th–19th centuries: features of organization and everyday life on the road

The study covers transport issues of economic relations between Russia and Asian states in the 18th19th centuries. The paper attempts to systematize the accumulated information about the mechanism of the trade caravan as an important element of the everyday work of merchants engaged in international trade in the period under study. The article describes the key tasks of entrepreneurs in organizing a caravan. Being the main customers of the caravan services, the merchants tried to take into account all the nuances of preparing goods for shipment, from the selection of management and working personnel to the purchase of fastening gear. Emphasis is placed on the elements of everyday life of the caravan personnel, such as the rules for placing cargo on pack animals and caring for them, the gastronomic arsenal of caravaners, recreation conditions, replenishment of water and provisions during the movement. The article describes the principles of selection of caravan masters, their functions and powers. In the course of the study, a number of differences between Russian and Asian caravans were discovered, which existed mainly in the status of caravan masters, the way the owners of the goods travelled and how meals were organized. The source base of the study, formed by unpublished archival materials, narratives of merchants and travelers who traveled in the 18th19th centuries on pack animals across the Asian steppes and deserts and participated in the everyday camp life, made it possible to recreate the microenvironment of the caravan travel as a unique logistical phenomenon.

Improving mass transfer in anion exchange membrane water electrolysis by ordered gas diffusion layer

For tight assembly electrochemical gas evolution devices, such as anion exchange membrane water electrolysis (AEMWE), bubbles blocking gas diffusion layer (GDL) channels is one of the key reasons for cell performance degradation under high current densities. To enhance mass transport in GDLs at high current densities, herein we report a 3D printed Ni GDL (GDL3D print) with straight-through pores and three-dimensional periodic structures. Due to its periodic structures and high hydrophilicity, GDL3D print is more conducive to the rapid escape of bubbles and timely replenishment of water, showing higher mass transfer efficiency and lower ohmic resistance. Therefore, compared with the commercial nickel foam (NF), GDL3D print exhibits better cell performance not only in 1 mol/L KOH solutions but also in pure-water-fed AEMWE, and the cell voltage of AEMWE using GDL3D print as the anode GDL is only 1.8 V at 1 A cm−2. This work provides a useful guidance for GDL design for tight assembly electrochemical gas evolution devices.

Rainfall Interception by Mature Coastal and Interior Forests in British Columbia

Interception of rainfall by forest canopies and its evaporation back to the atmosphere is an important component of the hydrological balance. We quantify the influence of six mature forests at two coastal and one southern interior locations in British Columbia on interception loss. Drainage from the canopy was measured with throughfall troughs and stemflow collars that emptied into tipping buckets monitored by data loggers. Interception loss was evaluated on an event basis and summed to monthly and seasonal totals. The throughfall coefficients increased with a decrease in canopy volume with values of 0.3 for the south coast forest, 0.5 for the north coast forests, and 0.6 for the southern interior forests. The respective saturation capacities were 2.0, 1.1, and 0.6 mm. The average evaporation rates during events varied from 0.05 to 0.3 mm h-1 at all sites. Consequently, for large events, interception loss was dominated by evaporation and replenishment of water in storage during the event. Increasingn event size increased interception loss, which tended to plateau at large events. The coastal forests had throughfall 75±2 percent, stemflow 1±0.2 percent, and interception loss 24±2 percent of the May to November rainfall. The respective values for the interior forests were 72±3 percent, 0.05±0.05 percent, and 28±3 percent of the late May to October rainfall. The similarity between coastal and interior sites in the partitioning of the seasonal rainfall resulted from the differing distributions of event size and similar evaporation rates of intercepted water during events.

Investigation of water quality and aquatic ecological succession of a newly constructed river replenished by reclaimed water in Beijing

The potential to create new ecosystems in rivers is possible through the use of reclaimed water as a replenishment source, although the long-term effects of this method are unknown. In this study, the water quality and aquatic ecological evolution of a newly constructed river replenished by reclaimed water in Beijing (the Jing River) were investigated, and the conventional water quality, phytoplankton indicators, and submerged plant growth conditions from October 2018 to December 2020 were analyzed. Spearman's correlation and redundancy analysis between possible influential environmental factors and algal indicators were conducted. The results show that the major water quality indicators could meet the water quality standards for landscape water. There were seven phyla present, including 322 species of phytoplankton. The phytoplankton density increased, followed by a decreasing trend. Phytoplankton densities at each monitoring site reached 10 × 106 to 25 × 106 cells/L in 2019 before decreasing in 2020, then ranging from 8 × 106 to 20 × 106 cells/L. Phytoplankton growth was influenced by changing water quality and ecosystems. Consequently, the submerged plant coverage rate gradually increased from 2018 (0%) to 2020 (26.27%–37.06%), as did biodiversity. Through the implementation of ecological restoration measures in the Jing River, the reclaimed water environment evolved into a more natural water environment, which could provide some reference for similar areas to use reclaimed water as a water replenishment source.

Spatiotemporal variations and tradeoff-synergy relations of ecosystem services under ecological water replenishment in Baiyangdian Lake, North China

Understanding dynamic variations of ecosystem services (ESs) and their tradeoff-synergy relations under ecological water replenishment (EWR) is conducive to the formulation of effective eco-environmental management strategies. In this study, spatiotemporal variations of three leading ESs, namely habitat quality, carbon storage and water yield services influenced by EWR in Baiyangdian Lake, North China from 1991 to 2019, were investigated using the “Integrated Valuation of Ecosystem Services and Tradeoffs” (InVEST) model, and their tradeoff-synergy relations were quantitatively assessed with correlation analysis methods. Our results showed that habitat quality had continuously declined, whereas it got a steady improvement after the year of 2015. Total carbon storage was relatively stable, and the volume of total water yield and precipitation showed the same variation trend. Overall, EWR promoted the maintenance and improvement of ESs. Tradeoff-synergy relations among ESs varied with time and space. Temporally, there was an obvious synergistic relation between habitat quality and carbon storage services. Spatially, these two ESs were synergistic in the southern, central and eastern parts of the lake, while they had a tradeoff relation in the north; and there were no tradeoff-synergy relations between the water yield service and these two services. This study confirmed the importance of zoning management and comprehensive multi-factor management based on spatial and temporal differences of ESs, and can offer a scientific basis for adaptive eco-environmental management strategies for wetland restoration.

Analysis and prediction of the changes in groundwater resources under heavy precipitation and ecological water replenishment

Abstract Identifying the influence of heavy precipitation and ecological water replenishment (EWR) on groundwater resources is essential for groundwater resources management and risk prevention. This study innovatively developed a groundwater resource analysis and prediction model integrated with the water level fluctuation method, correlation analysis, and machine learning method under the influence of heavy precipitation and EWR. Water level fluctuation method results showed that compared with January 1, 2021, the groundwater resources of the study area increased 4.46 × 108 m3 on August 28. Compared with small flow of EWR, heavy precipitation was the main contributor to the rise in the groundwater level. Correlation analysis found that elevation, specific yield, and permeability coefficient show positive correlations with groundwater resource recharge. Machine learning results showed that among the water level prediction models of 35 monitoring wells, extreme gradient boosting (XGB) and random forest (RF) performed best in 30 wells and five wells, respectively. The increase in groundwater storage predicted deviated from the actual value by only 0.6 × 107 m3 (prediction bias of 1.3%), indicating that the model prediction performance was good under the heavy precipitation condition. This study can help to better understand the change trend of groundwater resources under the conditions of heavy precipitation and EWR.

Highly Salt-Resistant interfacial solar evaporators based on Melamine@Silicone nanoparticles for stable Long-Term desalination and water harvesting

Interfacial solar-driven evaporation (ISE) is one of the most promising solutions for collecting fresh water, however, poor salt-resistance severely limits the long-term stability of solar evaporators. Here, highly salt-resistant solar evaporators for stable long-term desalination and water harvesting were fabricated by depositing silicone nanoparticles onto melamine sponge, and then modifying the hybrid sponge sequentially with polypyrrole and Au nanoparticles. The solar evaporators have a superhydrophilic hull for water transport and solar desalination, and a superhydrophobic nucleus for reducing heat loss. Spontaneous rapid salt exchange and reduction in salt concentration gradient were achieved due to ultrafast water transport and replenishment in the superhydrophilic hull with a hierachical micro-/nanostructure, which effectively prevents salt deposition during ISE. Consequently, the solar evaporators have long-term stable evaporation performance of 1.65 kg m-2h−1 for 3.5 wt% NaCl solution under 1 sun illumination. Moreover, 12.87 kg m−2 fresh water was collected during consecutive 10 h ISE of 20 wt% brine under 1 sun without any salt precipitation. We believe that this strategy will shed a new light on the design of long-term stable solar evaporators for fresh water harvesting.

A comprehensive study of electrodeposition by response surface methodology with presenting hybrid bi-conductive surfaces for promoting pool boiling

This study investigated the effect of simultaneously changing influential parameters of the electrodeposition method, with proposing an intensified approach for promoting the pool boiling process by creating hybrid bi-conductive surfaces. With the help of surface response methodology (RSM), current density, time, and the number of electrodeposition steps were varied to experimentally study the wickability, porosity, thickness, and maximum heat transfer coefficient (HTC) of fifteen coated samples. Boiling experiments were performed with deionized water at atmospheric pressure. The characteristics of surfaces were studied by conducting scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS), and profilometry tests. The results of three-dimensional graphs showed that with increasing the number of steps, the wickability became independent of time and current density of the electrodeposition process, while the thickness of the porous layer increased. Also, when the porosity peaked, the HTC plummeted, which can be due to the water replenishment obstacles. In addition, experimental correlations for the desired parameters were extracted using the regression model. Finally, by combining electrodeposition and bi-conductive methods in the electrodeposited sample with low-conductive channels of 1.5 mm width and 2.5 mm pitch, heat flux and HTC improved by 62% and 260% compared to the plain sample, respectively.

Water environment characteristics and control countermeasures of typical hilly cities in Southeast China

Abstract Due to population growth and economic development, problems such as uneven distribution of freshwater resources and degradation of water quality are becoming increasingly prominent. Many measures have been adopted to address water resources issues; however, few studies have focused on specific changes in water quality after policy implementation. In this study, Yiwu City, Zhejiang Province, a typical hilly city with a well-developed water system, was selected to analyze the changes in water quality. By analyzing the rainfall series and hydrology characteristics, and water quality characteristics, this paper revealed the water environment characteristics and put forward some suggestions for water management in hilly cities. Results showed that the historical rainfall time distribution is uneven, and the water environment capacity of urban inland rivers exhibits strong variability in Yiwu City. The contents of ammonia nitrogen (NH3-N) and total phosphorus (TP) decreased significantly since the policy implementation of ‘Five water cohabitation’. Urban rivers presented regional pollution and surface source pollution characteristics, and the water quality fluctuated significantly with the increase in rainfall. At the same time, the study confirmed that scientific water replenishment measures can effectively improve water quality, providing reference ideas for the protection and management of China's urban water environment.