Search Results (45)

Freshwater resources are scarce in tropical island areas. Treating rainwater to produce drinking water through biological slow filtration (BSF) technology can significantly alleviate the problem of freshwater shortages. The characteristics of the filter material are the key factors determining the decontamination performance of BSF technology. However, most existing studies focus on a single filter material. This study was conducted using volcanic rock and coconut shell activated carbon to compare their pollutant removal characteristics in slightly polluted rainwater during the early stage of BSF operation (from the start of operation to day 6, with the first sampling time being 48 h after operation) and during the stable stage (26 days later) and further explore the influence of their mixing ratio. The results show that in the early stages of operation, the pollutant removal performance of volcanic rock and coconut shell activated carbon is better than that of quartz sand. Among them, coconut shell activated carbon showed average removal rates for NH₃-N, TOC, and Cr(VI) that were 6.72, 8.46, and 19.01 percentage points higher than those of volcanic rock, respectively, but its average turbidity removal rate decreased by 5.00%. The removal effect of the mixed filter material was enhanced through the synergistic adsorption mechanism, but most of the improvements were within the standard deviation range and did not exceed the removal range of the single filter material. When the mixing ratio was 1:3, the average total organic carbon removal rate of the filter material was 71.51 ± 0.64%, approximately 0.96 percentage points higher than that of coconut shell activated carbon (70.55 ± 0.42%). While coconut shell activated carbon showed the best removal effect among all single filter materials, this improvement was still within the standard deviation range. Full article

This study employed the HYDRUS-2D model to simulate soil water movement and water productivity (WP) in an apple–soybean alley cropping system in the Loess Plateau region, Shanxi Province, China, under four irrigation methods: mulched drip irrigation, subsurface drip irrigation, bubbler irrigation, and rainwater-harvesting ditch irrigation, with varying water management treatments. Field experiments provided 2022 data for model calibration and 2023 data for validation using soil water content (SWC) measurements, achieving R² = 0.80–0.87 and RMSE = 0.011–0.017 cm³·cm⁻³, confirming robust simulation accuracy. The simulation results indicated that different irrigation methods had a significant impact on the soil water distribution. Mulched drip irrigation enhanced the water content in the surface layer (0–20 cm), while subsurface drip irrigation increased the moisture in the middle soil layer (20–40 cm). Bubbler irrigation was most effective in replenishing both the surface (0–20 cm) and middle (20–40 cm) layers. Rainwater-harvesting ditch irrigation significantly improved the soil water content in both the surface (0–20 cm) and middle (20–40 cm) layers, with minimal changes observed in the deep layer (40–120 cm). Furthermore, soil water variations were significantly influenced by the water uptake of tree roots. In 2022, soil moisture initially increased with distance, then decreased, and subsequently increased again, while in 2023, it increased initially and then stabilized. When the irrigation amount was limited to 75% of the field capacity in the 0–60 cm soil layer, water productivity (WP) reached its optimum, with values of 4.79 kg/m³ (2022) and 5.56 kg/m³ (2023). Based on the simulation results, it is recommended that young apple trees be irrigated using subsurface drip irrigation with a soil layer depth of 30 cm, while soybeans should be irrigated with mulched drip irrigation. Both crops should be irrigated at the podding and filling stages of soybeans, and the irrigation amount should be limited to 75% of the field water capacity in the 0–60 cm soil layer. This study was designed to aid orchard growers in precision irrigation and water optimization. Full article

Major earthquakes and rainfall may occur at the same time, necessitating further investigation into the dynamic characteristics and responses of reinforced soil retaining walls subjected to the combined forces of rainfall and seismic activity. Three sets of shaking table tests on model retaining walls were designed, a modular reinforced earth retaining wall was utilized as the subject of this study, and a custom-made device was made to simulate rainfall conditions of varying intensities. These tests monitored the rainwater infiltration pattern, macroscopic phenomena, panel displacement, tension behavior, dynamic characteristics, and acceleration response of the modular reinforced earth retaining wall during vibration under different rainfall intensities. The results indicated the following. (1) Rainwater infiltration can be categorized into three stages: rapid rise, rapid decline, and slow decline to stability. The duration for infiltration to reach stability increases with greater rainfall. (2) An increase in rainfall intensity enhances the seismic stability of the retaining wall panel, as higher rainfall intensity results in reduced sand leakage from the panel, thereby diminishing panel deformation during vibration. (3) Increased rainfall intensity decreases the shear strength of the soil, leading to a greater load on the reinforcement. (4) The natural vibration frequencies of the three groups of retaining walls decreased by 0.21%, 0.54%, and 2.326%, respectively, indicating some internal damage within the retaining walls, although the degree of damage was not severe. Additionally, the peak displacement of the panel increased by 0.91 mm, 0.63 mm, and 0.61 mm, respectively. (5) The amplification effect of rainfall on internal soil acceleration is diminished, with this weakening effect becoming more pronounced as rainfall intensity increases. These research findings can provide a valuable reference for multi-disaster risk assessments of modular reinforced soil retaining walls. Full article

Sweet cherry (Prunus avium L.) is a valuable fruit crop for fresh consumption. Due to its early availability in season, it achieves relatively high prices on the market. Self-fertile cultivar Lapins is one of the world’s leading sweet cherry varieties. Intensive cherry production seeks for new technologies such as using more adaptable rootstocks and microbiological products that could help plants adopt more sustainable growth in different soils/climates. The aim of this work is to determine the substrate properties, vegetative growth, leaf chlorophyll and mineral content of maiden trees grafted on three different rootstocks due to the application of growth-promoting rhizobacteria. A pot experiment was carried out on one-year-old maiden trees of cv. Lapins grafted on SL 64, MaxMa 14 and Gisela 5 and grown in 12 L plant pots filled with commercial substrate. Plant growth-promoting rhizobacteria Azospirillum brasilense was added by watering the plants with 1.12 g L⁻¹ per pot once a month (T₁) or every two months (T₂) from March to September with seven treatments in T₁ and four treatments in T₂. At the same time, control (C) plants were watered with rainwater. Plant height, trunk circumference and leaf chlorophyll content index (CCI) were measured. In addition, shoot growth and internode number were measured in three development stages (BBCH 34, 39 and 91). The substrate and leaf samples were collected and analyzed in the laboratory in accordance with established procedures. Data were processed by ANOVA and the Tukey test. Results have showed that rootstock affected substrate electrical conductivity (EC); nitrate (NO₃⁻), phosphorous (P₂O₅), calcium (Ca) and magnesium (Mg) content, including mineral nitrogen (N) content; tree height, circumference, shoot length and internode number; the leaf chlorophyll content index (CCI); and leaf potassium (K), Ca and Mg content. Furthermore, treatment significantly affected the CCI, average internode length, ammonia (NH₄⁺) and Ca content in the substrate and leaf N, Ca and Mg content. Rhizobacteria A. brasilense can be used as an additional biofertilizer in sustainable agricultural practices for obtaining healthier sweet cherry maiden trees, but microbial biotechnology rules must be respected. Full article

In order to address the increasingly prominent issues of water resource protection and agricultural non-point source pollution in the Erhai Lake Basin, this study conducted a two-year field experiment in Gusheng Village, located in the Erhai Lake Basin. In 2022, two irrigation treatments were set up: conventional flooding irrigation (CK) and controlled irrigation (C), with three replicates for each treatment. In 2023, aiming to enhance the utilization rate of rainwater resources and reduce the direct discharge of dry-farming tailwater from upstream into Erhai Lake. The paddy field was used as an ecological storage basin, and the water storage depth of the paddy field was increased compared to the depth of 2022. Combined with the deep storage of rainwater, the dry-farming tailwater was recharged into the paddy field to reduce the drainage. In 2023, two water treatments, flooding irrigation with deep storage and controlled drainage (CKCD) and water-saving irrigation with deep storage and controlled drainage (CCD) were set up, and each treatment was set up with three replicates. The growth and physiological index of rice at various stages were observed. Nitrogen leaching of paddy field in surface water, soil water, and groundwater under different water treatments after tillering fertilizer were observed. The research results show that the combined application of organic and inorganic fertilizers under organic planting can provide more reasonable nutrient supply for rice, promote dry matter accumulation and other indices, and also reduce the concentration of NH₄⁺-N in surface water. Compared with CK, the yield, 1000-grain weight, root-to-shoot ratio, and leaf area index of C are increased by 4.8%, 4.1%, 20.9%, and 9.7%, respectively. Compared with CKCD, the yield, 1000-grain weight, root-to-shoot ratio, and leaf area index of CCD are increased by 6.5%, 3.8%, 19.6%, and 21.9%, respectively. The yield in 2023 is 19% higher than that in 2022. Treatment C can increase the growth indicators and reduce the net photosynthetic rate to a certain extent, while CCD rain-flood storage can alleviate the inhibition of low irrigation lower limit on the net photosynthetic rate of rice. Both C and CCD can reduce nitrogen loss and irrigation amount in paddy fields. CCD can reduce the tailwater in the Gusheng area of the Erhai Lake Basin to Erhai Lake, and also can make full use of N, P, and other nutrients in the tailwater to promote the formation and development of rice. In conclusion, the paddy field rain-flood storage methodology in the Erhai Lake Basin can promote various growth and physiological indicators of rice, improve water resource utilization efficiency, reduce direct discharge of tailwater into Erhai Lake, and decrease the risk of agricultural non-point source pollution. Full article

With the increasing environmental impacts of human activities, the problem of polygenic multipollutants in groundwater has attracted the attention of researchers. Identifying the hydrobiogeochemical characteristics of the surface sewage that replenishes groundwater is crucial to addressing this problem. The input of polygenic multipollutants into groundwater leads to not only the mechanical superposition of pollutants but also the formation of secondary pollutant types. The evolution of polygenic multipollutants is influenced by aquifer characteristics, carbon sources, microbial abundance, etc. Therefore, this study took a sewage leakage point in Northwest China as the research object, carried out a controlled laboratory experiment on the impact of sewage discharge on groundwater, and, combined with long-term field monitoring results, determined the main hydrobiogeochemical processes of polygenic multipollutants and their secondary pollutants. The results showed that the redox environment and the gradient change in pH were identified as the most critical controlling factors. In oxidative groundwater during the early stage of vertical infiltration, sewage carries a substantial amount of NH₄⁺, which is oxidized to form the secondary pollutant NO₃⁻. As O₂ is consumed, the reduction intensifies, and secondary pollutants NO₃⁻, Mn (IV), and Fe(III) minerals are successively reduced. Compared with the natural conditions of rainwater vertical infiltration, the reaction rates and intensities of various reactions significantly increase during sewage vertical infiltration. However, there is a notable difference in the groundwater pH between sewage and rainwater vertical infiltration. In O₂ and secondary pollutant NO₃⁻ reduction, a large amount of CO₂ is rapidly generated. Excessive CO₂ dissolves to produce a substantial amount of H⁺, promoting the acidic dissolution of Mn (II) minerals and generation of Mn²⁺. Sewage provides a higher carbon load, enhancing Mn (II) acidic dissolution and stimulating the activity of dissimilatory nitrate reduction to ammonium, which exhibits a higher contribution to NO₃⁻ reduction. This results in a portion of NO₃⁻ converted from NH₄⁺ being reduced back to NH₄⁺ and retained in the groundwater, reducing the denitrification’s capacity to remove secondary NO₃⁻. This has important implications for pollution management and groundwater remediation, particularly monitored natural attenuation. Full article

With high-speed urbanization, ecological space is seriously shrinking, and lagging drainage facilities contradict the ecological needs of citizens. In particular, water-scarce cities are faced with frequent stormwater disasters, such as excessive accumulation of rainwater, peak runoff and water pollution, which threaten the safety of the urban water ecological environment. This paper combined the actual construction content of the sponge city project with a whole process policy evaluation framework to examine whether the projects solve these problems and to find different approaches to the results. Utilizing entropy fuzzy comprehensive evaluation provides a systematic standard for the evaluation system. The research shows that the sponge city project can achieve a good governance effect, including constructing a suitable scheme for urban hydrological characteristics, effectively improving the rainwater treatment level of different types of water-scarce cities, and alleviating the ecological contradiction of urban water environment. The stages of policy formulation, policy implementation and policy results achieve a good degree of completion. On one hand, sponge city projects transform the infrastructure at key locations, aiming at improving the rainwater interception capacity of the streets; on the other hand, restoring original natural waters improves the capacity of water conservation and forms a sustainable ecosystem between the city and nature. Full article

In a world grappling with the severe effects induced by climate change, one of the most significant concerns affecting agriculture is the gradual decline in water quality for irrigation associated with reduced rainfalls and the consequent increase in soil salinity. This issue is particularly crucial for grapevine cultivation (Vitis vinifera L.) and the associated winemaking industry. The aroma of the resulting wines and the yield parameters can be influenced both directly by water quality and indirectly due to the effects exerted by salinity on the microbiota, which directly impacts plant health. To gain insights into this topic, our study aimed to analyse the changes induced in the microbiota of both the rhizosphere and the carposphere due to salt stress using a metabarcoding approach, focusing on Vitis vinifera cv. Glera. The control plants were irrigated with rainwater, while the treated plants were irrigated with water containing salt (NaCl). Our findings revealed significant differences in the microbiota (both fungi and bacteria) of the rhizosphere and carposphere between the two treatments. For instance, the Shannon diversity index (i.e., alpha diversity) was lower in the treated plants compared to the control not-treated ones, whilst the beta diversity did not show any differences. Several microbial phyla exhibited better resilience to this abiotic stress (e.g., Ascomycota, Saccharomycetes, Acidobacteria, Proteobacteria, Bacteroidetes), shedding light on their impact on crucial bacterial and fungal groups essential for the subsequent winemaking stages. Additionally, the salt stress negatively affected the yield parameters. This study contributes valuable insights to the viticultural community, providing a deeper understanding of the complex interplay between soil characteristics, microbial communities, and their influence on productivity. Full article

A field study was conducted to assess the effect of tillage systems (TSs) and manure rates (MRs) on sunflower growth and yield at the University of Limpopo Experimental Farm (Syferkuil) which is on sandy loam soils and University of Venda Experimental Farm (UNIVEN) clayey soils, both located in Limpopo Province of South Africa for 2021/2022 and 2022/2023 cropping seasons. The experimental design was a split plot with three replications. The main plot was the tillage treatments: conventional (CON) and in-field rainwater harvesting (IRWH), while the subplots were the manure treatments: viz. poultry and cattle manures at rates of 20 and 35 t ha⁻¹⁰, plus a control (no manure application). The IRWH is a tillage technique that collects rainwater on a 2 m wide runoff strip into the 1 m wide basin where it infiltrates deep into the soil beyond the evaporation zone but is available for crop use. The results revealed that at Syferkuil IRWH had a significant increase (p < 0.05) on grain yield, head diameter, head dry matter and aboveground dry matter yield in both cropping seasons, whereas at UNIVEN, the significant increase was obtained on grain yield, head diameter, aboveground dry matter, plant height and stem girth during both cropping seasons. The effect of manure rate significantly increased with the application rate, with poultry manure at the highest rate of 35 t ha⁻¹ significantly recording high mean values of grain yield, head diameter, head dry matter, aboveground dry matter, plant height and stem girth at both sites during the two cropping seasons. The increase in leaf area index and 100 seed weight by IRWH and manure rate application varied across the growing stages and cropping seasons with no consistent trend. At Syferkuil, TS and MR interaction was significant on head diameter and on aboveground dry matter at flowering stage in the first cropping season, whereas at UNIVEN, it was significant on head diameter in the first cropping season. Therefore, these results suggest that IRWH combined with poultry manure (35 t ha⁻¹) can be adopted to improve sunflower crop yield under similar management and environmental conditions. In the absence of poultry manure, farmers may opt to use cattle manure at a rate of 35 t ha⁻¹ for better improved yield. Full article

Urban rainstorms and flood disasters are the most common and severe environmental problems worldwide. Many factors influence rain-flood control simulation, forming a complex network system of interconnected and mutually constraining elements. In terms of spatial scale selection, existing research on rain-flood disaster risk largely relies on a single-scale infrastructure index system and has not yet focused on urban “gray-green-blue” spatial scale simulations for rain-flood storage. Regarding research methodology, applying system dynamics methods to the simulation of rain-flood storage and disaster prevention planning in watershed cities is still in its initial stages. System dynamics models can simulate the feedback interactions among various sub-elements in the coupled mega-system, fully addressing complex issues within the system structure that involve multiple variables, non-linear relationships, and numerous feedback loops, thereby compensating for the inadequacies of traditional linear models in the collaborative management of rain-flood risks. Taking the Changsha Guitang River Basin as an example, this paper constructs a system dynamics model covering four dimensions: natural environment, socio-economics, internal structure, and policy development. It aims to derive the optimal planning scheme for gray-green-blue spatial coordination in rain-flood storage by weighing four different development scenarios. The simulation results show: (1) Simply changing the surface substrates without considering rainwater discharge and the plan that emphasizes the construction of municipal drainage facilities will see the capacity gap for rain-flood storage-space construction continue to widen by 2035. This indicates that the plans mentioned above will struggle to bear the socio-economic losses cities face during rain-flood disasters. (2) The plan of combining gray and green infrastructures sees the rain-flood storage construction capacity turn from negative to positive from 2024, rising to 52.259 billion yuan by 2035. This reflects that the plan can significantly reduce the rainwater volume in the later stages of low-impact development infrastructure construction, mitigate rain-flood disaster risks, and reduce government investment in rain-flood disaster risk management, making it a relatively excellent long-term rain-flood storage space planning option. (3) The rain-flood regulation space planning scheme, under the combined effect of the urban “gray-green-blue” network system, sees the capacity for rain-flood storage construction turn positive a year earlier than the previous plan, reaching 54.232 billion yuan by 2035. This indicates that the scheme can not only effectively respond to extreme flood and rainstorm disasters but also maintain ecological environment benefits and mitigate the socio-economic losses caused by disasters, making it the optimal choice for future government disaster management planning. The research results provide a theoretical framework and practical insights for territorial spatial planning, rain-flood control management, and resilient city construction in watershed areas. Full article

To investigate the impact of advanced microphysics schemes using single and double moment (WSM6/WDM6) schemes, numerical simulations are conducted using Weather Research and Forecasting (WRF) model for a severe mesoscale convective system (MCS) formed over the Korean Peninsula. Spatial rainfall distribution and pattern correlation linked with the convective system are improved in the WDM6 simulation. During the developing stage of the system, the distribution of total hydrometeors is larger in WDM6 compared to WSM6. Along with the mixing ratio of hydrometeors (cloud, rain, graupel, snow, and ice), the number concentration of cloud and rainwater are also predictable in WDM6. To understand the differences in the vertical representation of cloud hydrometeors between the schemes, rain number concentration (Nr) from WSM6 is also computed using particle density to compare with the Nr readily available in WDM6. Varied vertical distribution and large differences in rain number concentration and rain particle mass is evident between the schemes. Inclusion of the number concentration of rain and cloud, CCN, along with the mixing ratio of different hydrometers has improved the storm morphology in WDM6. Furthermore, the latent heating (LH) profiles of six major phase transformation processes (condensation, evaporation, freezing, melting, deposition, and sublimation) are also computed from microphysical production terms to deeply study the storm vertical structure. The main differences in condensation and evaporation terms are evident between the simulations due to the varied treatment of warm rain processes and the inclusion of CCN activation in WDM6. To investigate cloud–aerosol interactions, numerical simulation is conducted by increasing the CCN (aerosol) concentration in WDM6, which simulated comparatively improved pattern correlation for rainfall simulation along with intense hydrometer distribution. It can be inferred that the change in aerosol increased the LH of evaporation and freezing and affected the warming and cooling processes, cloud vertical distribution, and subsequent rainfall. Relatively, the WDM6 simulated latent heating profile distribution is more consistent with the ERA5 computed moisture source and sink terms due to the improved formulation of warm rain processes. Full article

In the case of rapid urban development, the impact of extreme climates on the world is gradually increasing, resulting in frequent flood events. However, Taiwan is still in the stage of urban development, and it is necessary to develop more roads. Therefore, determining how to reduce the impact of road engineering on the environment is one of the major issues currently faced. Therefore, a demonstration road of a general pavement and a permeable pavement was built in Dahua North Street, Taoyuan City, Taiwan, and rainwater was stored in a central irrigation ditch and a permeable pavement through an innovative construction method for reuse in agricultural irrigation. In addition, monitoring instruments and management systems were built, and the flow law formula was established, with R² greater than 0.9. The actual discharge and peak discharge of the permeable pavement and general pavement were analyzed. According to the data analysis results, it can be seen that the permeable pavement can effectively reduce the peak discharge of 60~75%, which not only can achieve the benefit of low-impact development but also can reuse rainwater. The patent application can be used as an example for the application of permeable pavement in Taiwan in the future. Full article

The rising importance of utilizing rainwater as a sustainable and viable alternative water source is evident amid increasing urbanization and the mounting global apprehensions about water scarcity. This research aims to develop a comprehensive and sustainable approach to rainwater treatment by effectively utilizing the recently constructed solar panels at the University of Engineering and Technology (UET) in Pakistan. The study’s distinctiveness lies in its comprehensive examination of treatment plant efficiency under various weather conditions in a water-scarce region. The main objective of this work is to maximize the harvested rainwater in order to provide safe drinking water while lessening the carbon footprint of treatment operations. The proposed University of Engineering and Technology water purification process (UETWPP) method involves a sequence of four essential rainwater filtration stages, namely aeration, absorption, sediment filtration, and finally, UV disinfection, all powered by solar energy. Water samples were collected monthly for a year to assess the quality of untreated and treated rainwater, including physical, chemical, and biological parameters. Multivariate analysis techniques were used to assess these parameters, including the Friedman test and principal component analyses. By reducing the initial set of twenty components down to the four most critical ones identified in the untreated water samples, the interrelationships among these components were investigated. The results indicate that the quality of treated water using the UETWPP process was found to be suitable for human consumption, aligning with the local standards as well as those established by the World Health Organization (WHO), highlighting the effectiveness of the process in transforming rainwater into potable water. Ultimately, this pilot project showcases the viability and economic efficiency of the proposed system, rendering it easily implementable in other regions. Full article

This paper reports the results of an investigation into the influence of precipitation and air temperature on the efficiency of pollutant removal processes and effluent pollutant concentrations in a one-stage constructed wetland with subsurface vertical flow. We studied an on-site constructed wetland system that used Phragmites australis for the treatment of domestic wastewater. The system was located in central Europe, in the south-east of Poland, in a temperate climate zone with transitional features. Physico-chemical analyses of influent and effluent wastewater, as well as measurements of precipitation and air temperature were carried out in the years 2001–2010. It was shown that the pollutant removal efficiency of the treatment plant was significantly higher in the growing season than outside the growing season (the mean efficiency is usually a few percent higher but generally this parameter is highly varied). This indicated that temperature determined the efficiency of the wastewater treatment. We found that the amount of precipitation affected the concentration of pollutants in the effluent. The more rainfall there was, the lower the content of pollutants in the effluent from the treatment plant, which demonstrated that rainwater diluted the concentrations of pollutants in the treated wastewater—thus improving the efficiency of the wastewater treatment plant. Full article

This paper investigates the influence of different vegetation on the permeability of the shallow soil layers of slopes under rainfall infiltration. Firstly, four large slopes are filled in an outdoor natural environment, and the overburdens of the four slopes are Magnolia multiflora, Cynodon dactylon, Magnolia multiflora mixed with Cynodon dactylon, and no vegetation. Secondly, the four slopes are cultivated in an outdoor natural environment for one year. After the vegetation overburdens are matured, the field artificial rainfall test is carried out through a self-developed artificial rainfall device to monitor the water migration law inside the four slopes in real time. Finally, the unsaturated permeability coefficients of the shallow soil layers of slopes are calculated. The results show that the infiltration rate of rainwater in each overburden slope from fastest to slowest is Magnolia multiflora overburden slope, no vegetation slope, Cynodon dactylon overburden slope, and Magnolia multiflora mixed with Cynodon dactylon overburden slope. In the early stage of rainfall, Magnolia multiflora increases the permeability coefficient of the shallow soil layer of the slope, thus weakening the anti-seepage ability of the slope, but the influence of Magnolia multiflora is not obvious in the later stage. Cynodon dactylon and Magnolia multiflora mixed with Cynodon dactylon can significantly reduce the permeability coefficient of the shallow soil layers of the slopes, thereby increasing the anti-seepage ability of the slopes, and the mixed planting of Magnolia multiflora and Cynodon dactylon can minimize the permeability coefficient of the shallow soil of the slope, resulting in the best anti-seepage effect. Full article