Water Level Reduction Research Articles

Very‐Near‐Field Coseismic Fault Pressure Drop and Delayed Postseismic Cross‐Fault Flow Induced by Fault Damage From the 2018 M6.3 Hualien, Taiwan Earthquake

AbstractEarthquakes can produce rock damage, poroelastic deformation, and ground shaking that modify fault zone hydrogeologic properties. Coseismic and postseismic hydrologic response to the ruptured fault can serve as constraints on hydrogeologic property changes. Here, we document fluid pressure responses to the 2018 M6.3 Hualien, Taiwan earthquake and model the postseismic fault zone hydrology inferred from very‐near‐fault data. Two groundwater wells located ∼180–250 m from the fault damage zone experienced 10–15 m of groundwater level decline followed by a prolonged (>6 months) recovery. Poroelastic models indicate that strain dilation in the fault's hanging wall can produce water level reductions of several meters. However, the model cannot explain groundwater level change in the footwall nor the delayed postseismic recovery, suggesting fault zone damage played a primary role in both the coseismic and postseismic water level reductions. Fluid flow models incorporating the effects of coseismic fault damage on the temporal evolution of hydrologic fault properties show enhanced hydraulic anisotropy after the earthquake. The best‐fit models show that while both vertical hydraulic conductivity and specific storage likely increased within the fault zone, the horizontal hydraulic conductivity is low, suggesting the fault zone behaves as a hydraulic barrier to cross‐fault flow with modeled diffusivities as low as ∼10−3 m2/s. High‐fidelity hydrologic measurements in the very‐near‐field of fault zones (e.g., within a few hundred meters) may be a useful tool to constrain the spatial and temporal evolution of fault zone properties before, during, and after rupture.

Fish Health Altered by Contaminants and Low Water Temperatures Compounded by Prolonged Regional Drought in the Lower Colorado River Basin, USA.

The goal of this study was to assess health of male Common Carp (carp, Cyprinus carpio) at four sites with a wide range in environmental organic contaminant (EOC) concentrations and water temperatures in Lake Mead National Recreation Area NV/AZ, US, and the potential influence of regional drought. Histological and reproductive biomarkers were measured in 17-30 carp at four sites and 130 EOCs in water per site were analyzed using passive samplers in 2010. Wide ranges among sites were noted in total EOC concentrations (>10Xs) and water temperature/degree days (10Xs). In 2007/08, total polychlorinated biphenyls (tPCBs) in fish whole bodies from Willow Beach (WB) in the free-flowing Colorado River below Hoover Dam were clearly higher than at the other sites. This was most likely due to longer exposures in colder water (12-14 °C) and fish there having the longest lifespan (up to 54 years) for carp reported in the Colorado River Basin. Calculated estrogenicity in water exceeded long-term, environmentally safe criteria of 0.1-0.4 ng/L by one to three orders of magnitude at all sites except the reference site. Low ecological screening values for four contaminants of emerging concern (CEC) in water were exceeded for one CEC in the reference site, two in WB and Las Vegas Bay and three in the most contaminated site LVW. Fish health biomarkers in WB carp had 25% lower liver glycogen, 10Xs higher testicular pigmented cell aggregates and higher sperm abnormalities than the reference site. Sperm from LVW fish also had significantly higher fragmentation of DNA, lower motility and testis had lower percent of spermatozoa, all of which can impair reproduction. Projections from a 3D water quality model performed for WB showed that EOC concentrations due to prolonged regional drought and reduced water levels could increase as high as 135%. Water temperatures by late 21st century are predicted to rise between 0.7 and 2.1 °C that could increase eutrophication, algal blooms, spread disease and decrease dissolved oxygen over 5%.

Effects of changed water regime on the toxicity of silver nanoparticles (AgNPs) in tadpoles of Fejervarya limnocharis.

Climate change is viewed as one of the important causes of the amphibian population decline. Aspects of climate change like increase in water temperature and drying up of habitats have been underrepresented. The expanding production and usage of metal nanoparticles like silver nanoparticles (AgNPs) make them likely to end up in aquatic ecosystems. To arrive at a realistic assessment of the impact of AgNPs in a warming world, we have investigated the effects of temperature on the acute toxicity of AgNPs in tadpoles of Fejervarya limnocharis at 24, 48, 72 and 96h of exposure. The various aspects of sub-lethal toxicities of AgNPs with increase in temperature were also investigated. Besides, the effects of habitat desiccation on the sub-lethal toxicities of AgNPs in the tadpoles were analysed. The LC50 values of AgNPs at four different time points were found to be significantly different between the two different temperatures. Alterations in survival pattern, life history traits, amplifications in genotoxic potential and oxidative stress were observed with increased water temperature following AgNP exposure. The phenomenon of habitat desiccation was also found to significantly affect the toxicity of AgNPs with respect to alterations in mortality rate, time to metamorphosis and morphometric parameters of metamorphosed tadpoles. The findings suggest that changed water regime such as increased water temperature as well as reduction in water level accelerated the toxic effects of AgNPs in F. limnocharis tadpoles which is likely to affect their natural populations.

Paleoenvironmental factors controlling organic-rich formations deposition in the Babouri-Figuil Basin (Northern Cameroon)

The Babouri-Figuil Basin is an intracratonic basin (half-graben) in northern Cameroon that is genetically connected to the Benue Trough from Nigeria, and is an area of interest in terms of petroleum prospectivity. Recent studies highlighted the presence of organic-rich formations in the basin. However, none of these works have identified factors that governed the accumulation of organic matter (OM) in the sediments. The main objective of this work is the characterization of these formations through palynofacies and organic geochemical techniques (total organic carbon - TOC, total sulfur, insoluble residue and biomarkers), in order to determine the organic facies, their depositional environments and the main drivers for organic enrichment in the basin. The current study reveals that black shale and massive claystone lithologies constitute the main organic-rich formations in the basin, with TOC reaching up to 26.08 wt%, being characterized by a dominance of bacterially-derived amorphous OM. Palynofacies and biomarker data revealed that these formations are positively associated with anoxic conditions and a partly highly saline and stratified lake water column. The deposition of organic-rich formations in the Babouri-Figuil Basin was mainly controlled by restriction conditions which developed in connection with the regional tectonic framework. The Lower Cretaceous rifting episode in the West and Central African Rift System (WCARS) basins led to the formation of accommodation space, a reduction in water levels, and the development of anoxic conditions within the basin, facilitating the deposition of organic-rich formations. Therefore, the organic enrichment of the Babouri-Figuil Basin has been predominantly controlled by its tectonic evolution, particularly during the syn-rift phase. This phase created favorable conditions for the deposition and preservation of OM, including the establishment of anoxic conditions. Additionally, the paleoclimate (arid conditions), the development of bacterial biomass, and the basin's paleogeography all played a significant role in this process. The organic-rich formations of the Babouri-Figuil Basin show characteristics of prospective petroleum source rocks (high organic content, high proportion of oil-prone kerogen, significant thickness and lateral extension). The combination of organic-rich formations with sandstone deposits above and extensive claystone/shale deposits on top can indicate the presence of an oil play in the basin. A detailed study with broader sampling is needed to investigate thoroughly the variation of organic facies and the influence of paleoenvironmental factors that control the deposition of thick source rock intervals.

Experimental study on controlling basement leakage for urban flooding mitigation

Intense summer rainstorms can result in short-term urban flooding, leading to localized groundwater level rise and subsequent floor cracking and leakage in basements. Rational control of the surrounding water level is crucial for addressing existing basement leaks caused by short-term urban flooding. In this study, a combined approach of interception and seepage control using waterproof curtains and negative-pressure wells is proposed. Four different scenarios were considered, and experimental and numerical investigations were conducted on a 1.2 m × 1.2 m × 1.1 m model. The study analyzed the influence of factors such as water content, pore water pressure, soil properties, waterproof curtain insertion depth, and length of the filter section in the negative-pressure well on controlling the upward water level in the basement.The results showed that the installation of waterproof curtains alone can impede rainwater infiltration into the basement, delaying its penetration by approximately 48 h. The combined approach of interception and seepage control outperformed the sole use of waterproof curtains, with the reduction in water level becoming smaller as the insertion depth of the waterproof curtain increased. The reduction in water level decreased at a slower rate with increasing waterproof curtain insertion depth. The recommended waterproof curtain insertion ratio was equal to or greater than 83.5 %, while the filter section length ratio in the negative pressure well should be less than 64 %. Compared to natural seepage drainage, negative-pressure pumping could maintain the basement floor's water content within the initial range 32 h earlier. The water-blocking and depressurization effect is best in sandy soil and worst in clay. Water-blocking and depressurization provide a new approach for controlling the uplift caused by summer urban waterlogging, especially offering a new method for controlling leaks in the basement.

Code 1583 - preliminary steps for studies to assess the safety of an earth dam in terms of use and lowering the reservoir level for public supply during the water crisis

The spring 2021 climate forecast report from the National Institute of Meteorology (INMET) and the National Institute for Space Research (INPE) indicated an increased possibility of below-average rainfall in almost the entire region of the state of Paraná, which is consistent with the historical trend of decreasing rainfall in the Paraná River basin since the 1990s, with an intensification in the 2000s. This led to a water emergency situation in Paraná, which was decreed by the state government in 2020 and 2021. The Curitiba region depends on the Curitiba and Metropolitan Region Integrated Supply System (SAIC). Due to the intense drought in 2020 and 2021, SAIC's reservoirs suffered a significant reduction in stored water levels and volumes, reaching 28% of their total capacity in August 2020. This was the biggest water crisis in the last 90 years in the history of the state of Paraná, with several reservoirs reaching levels close to historic lows, but maintaining constant discharges in order to maintain power generation or public supply. In these cases, with the reservoirs at lower levels and with a smaller volume, the variation in the water level on the upstream slope of the earth dam varies differently from the levels when the dam and reservoir are in normal operation or outside of a water crisis. In view of the atypical behavior of reservoir levels, and based on good dam engineering practice, when the operating regime changes or the reservoir water level drops, the safety aspects of these structures should be reassessed through geotechnical analyses for conditions of rapid lowering, in order to learn how these structures behave under these conditions. This article sheds light on the important stages of this thorough technical investigation of the extensive documentation of a project like this, data on instrumentation and performance, how they were built and behaved during the construction and filling of the reservoir, knowledge of geotechnical parameters of the materials of the dam massif and foundation, recorded field observations made at the time of preliminary investigation during the design, project and construction phase; obtaining hydro-meteorological data from the region, in order to obtain the "as-built" geometry of the structure, with the aim of modeling the typical section reliably to the structure in the field in order to infer this numerical model and vice versa, and obtain results on its performance during this atypical period.

Pit Lake Slope Stability under Water Level Variations

This paper presents the results of a geotechnical investigation regarding the slope stability in a pit lake, emphasizing the impact of water level variations. Advanced analysis techniques were utilized for this study. The research was performed by using fully coupled flow-deformation analyses. For the fully coupled approach, Bishop’s effective-stress equation was used, and for the description of soil hydraulic behavior, the Van Genuchten’s model was applied. The analysis of slope stability associated with reservoir water level changes revealed that the slope tended to become unstable as the water level decreased; the stability factor was negatively related to the rate of water level reduction. Concerning the water level fluctuations, the analyses revealed that the soil mass seemed to become less stable as the rate of water level change increased. Under a specific range of rates of water level variation, the safety factor became higher as the number of fluctuations increased. Additionally, the simulation results concerning the water level rising indicate that the pressure due to the external water level acts on the slope surface with a positive impact on the stability factor. The results obtained reflect the effects under a specific site condition, but they can be used as a reference for evaluating slope stability in a pit lake design.

Investigating the Impact of Large Lakes on Local Precipitation: Case Study of Lake Urmia, Iran

Large lakes face considerable challenges due to human activities and climate change, impacting local weather conditions and ecosystem sustainability. Lake Urmia, Iran’s largest lake and the world’s second-largest saltwater lake, has undergone a substantial reduction in water levels, primarily due to drought, climate change, and excessive irrigation. This study focuses on the potential repercussions on local climate conditions, particularly investigating the impact of moisture sources, evaporation from lake surfaces, and evapotranspiration from agricultural activities, on local convection rainfall. The prevailing westerly winds in the basin suggest a hypothesis that this moisture is transported eastward within the basin, potentially leading to local precipitation as it ascends to higher altitudes near the eastern basin border. To validate this hypothesis, climate data from 1986 to 2017 from the Sarab meteorological station (east of the lake basin, influenced by local precipitation) and Saqez meteorological station (south of the basin, unaffected by local precipitation) were analyzed. The impact of lake water level reduction was assessed by categorizing data into periods of normal lake conditions (1986–1995) and water level reduction (1996–2017). Additionally, the MSWEP global precipitation product was used to examine the precipitation distribution in the entire basin over the entire period and sub-periods. The findings indicate Lake Urmia’s significant influence on convective rainfall in the eastern basin, especially during the summer. Despite decreasing lake levels from 1996 to 2017, convective rainfall in the eastern basin increased during the summer, suggesting intensified agricultural irrigation, particularly in hot seasons.

Impact of design aspects on iron removal efficiencies from coal mine drainage in full-scale lagoons

In response to the potential ecological problems caused by coal mine drainage, passive Mine Water Treatment Schemes (MWTS), consisting of settlement lagoons and aerobic wetlands, are developed to remove iron and other contaminants prior to discharge into the environment. Existing research has examined individual design aspects separately, addressing the effect of lagoons' design on treatment performance. However, long-term research lacks data on the design aspects of full-scale mine drainage lagoons, to ensure consistent iron removal and optimal treatment of the mine drainage. This study analysed and assessed the design aspects of five full-scale lagoons, alongside monthly iron concentrations spanning over a period of twelve years, aiming to evaluate lagoon treatment performance based on different design aspects. Correlation and regression analyses were conducted to offer a better understanding of the potential relationships between iron removal efficiencies and the various design aspects of lagoons.Results indicated that the mean iron removal efficiencies of the lagoons studied, ranged from 25.12% to 92.85%, being impacted by the different design features. The correlation and multiple regression analysis results suggest that operational Water Levels, Surface Area, Aspect Ratio, layout and number of inlets and outlets, as well as shape of the lagoons affected iron removal (R2 0.78, p-value <0.05). Lagoons with larger aspect ratio were observed to have performed better in removing iron. In addition, a reduction in operational water level was observed to lead to increased iron removal. Furthermore, the result of the regression analysis demonstrated that the age of the lagoon significantly affects its treatment performance. Overall, lagoons with mid-mid configuration, multiple inlets and outlets and aspect ratio of 4 are found to allow for better flow and contaminant spread within the system, ensuring better adsorption and optimal removal of iron, although subject to regular ochre removal. This study offers valuable insights to lagoons design engineers, research scientists, policy makers and MWTS operators to optimize treatment performance.

The impact of rock filtration heterogeneity on fresh groundwater reserve prediction calculations in the Nefteyuganskoye field

In hydrogeology, filtration heterogeneity of rocks usually means heterogeneity of waterconductivity of an aquifer. Methods for determining water conductivity are primarily designed forhomogeneous aquifers. However, natural hydrogeological objects are often heterogeneous, whichcan complicate the interpretation of experimental data from hydrodynamic studies and lead toerrors in calculating groundwater reserves. The article shows the impact of rock filtration hetero-geneity on reserve calculation forecasts. The studies, including hydrodynamic testing (clusterpumping), were carried out at the Nefteyuganskoye field, which is one of the major fresh ground-water deposits of the Latitudinal Ob region. The experimental data from four experiments wereinterpreted using the Theis model. The parameters of the aquifer are determined: coefficient ofwater conductivity and pressure conductivity factor. The article presents predictive calculations forthe reduction of water levels in the center of a large well. The forecast was conducted for threeoptions, taking into account the filtration heterogeneity of the aquifer in the field. Consequently,the impact of filtration heterogeneity on the forecast calculations was determined. The calculationerror in estimating groundwater reserves at the Nefteyuganskoye field could be as high as 51 %.The article suggests conducting long-term hydrodynamic studies in subsurface areas with filtrationheterogeneity to obtain reliable field parameters. This will cover the disturbance of an aquifer with alarger size than the filtration heterogeneity of rocks.

Techno-economic Comparative Analysis of Floating/On-Ground Solar PV System for Electrification of Gilgel Gibe I Auxiliary Load in Ethiopia

Ethiopia is well endowed with solar energy resources with daily average radiation ranging from 4.5 to 7.5 kWh/m2/day. The significant electricity consumption of the country is reliant on hydropower. This dependence on hydropower makes the country susceptible to weather and climate changes, such as droughts, which can lead to reduced water levels in hydropower reservoir and reduced electricity generation. The application of solar floating photovoltaic (FPV) in the existing hydro reservoir would provide solar electric power to support hydropower generation especially during dry periods, and decrease evaporation losses. This implementation also has the cascading effect of increasing the solar power generation from the PV system by reducing the panel temperature through efficiency gain while saving the land requirement for installing the same PV system. Especially for countries like Ethiopia where agriculture is the key source of economy, optimal usage of land is very important. Thus, in this research, a techno-economic comparative analysis of 4MW Grid-tied FPV and ground-mounted PV system on Gilgel gibe I reservoir in Ethiopia for supplying the auxiliary load of the generation plant is done. The results showed that the proposed FPV system has 6.9% more electricity generating capacity than land-mounted PV system and saves 74,400m3 of water from evaporation annually. The FPV plant will also save the land cost burden, and results the levelized cost of energy (COE) 0.043$/kWh, which is 15.7 % less than land-mounted PV systems. In another way, the proposed FPV system indicated a positive impact on the environment by reducing 993 tons of greenhouse gas emission annually. Thus this research results will offer a clear directions for the concerned stockholders to implement FPV technology on the Ethiopian hydro reservoirs.

Water–Rock Interaction Processes in Groundwater and Flows in a Maar Lake in Central Mexico

Tropical maar lakes are distinct ecosystems with unique ecological features. To comprehend, manage, and conserve these lakes, it is essential to understand their water sources, particularly groundwater, and the hydrogeochemical processes shaping their water chemistry. This research focuses on the maar lake Alchichica in central Mexico, known for harboring 18 new and endemic species and a ring of stromatolites. With groundwater discharge as the primary source, concerns arise over anthropic extraction impacts on water levels and stromatolite survival. Sampling six wells and one piezometer revealed major ion (Ca2+, Mg2+, K+, Na+, Cl−, HCO3−, SO42−) and trace element (Fe, Al3+, SiO2) concentrations. Geochemical evolution was explored through diagrams, geological sections, and inverse geochemical models using the PHREEQC code. Findings indicate groundwater evolving along controlled flow paths, and influencing chemical composition through water–rock interactions. The lake’s unique conditions, resulting from the mixing of two flows, enable stromatolite formation. Water level reduction appears unrelated to evaporation at the sampled sites, suggesting a need for a broader study in a larger area. Analyzing the maar lake’s hydrochemistry provides valuable insights into unique characteristics supporting high endemism in this ecosystem. This research enhances our understanding of groundwater’s geochemical processes and hydrogeochemical evolution in maar lakes, with potential applications worldwide.

Energy Transition: Semi-Automatic BIM Tool Approach for Elevating Sustainability in the Maputo Natural History Museum

Mozambique is experiencing the consequences of a severe energy crisis with economic and social impacts. Its strict dependence on hydroelectric sources is being severely tested by recent droughts that have drastically reduced water levels in dams. However, Mozambique is addressing energy poverty by exploring renewable energy sources thanks to investments in the sector by the European Union. The research concerns an energy analysis profile of the country and the penetration of renewable energy, presenting an energy upgrading scope through a semi-automatic calculation methodology in a Building Information Modeling (BIM) environment. The building under study, located in Maputo, is the Natural History Museum, which plays an important role in biodiversity conservation. Therefore, this paper proposes a BIM methodology for sizing an environmental control system tailored to serve the museum. The proposed system replaces the previous one and includes a photovoltaic system that not only meets the museum’s load but also supplies electricity to the surrounding area. Energy production from renewable sources with a surplus of 30% has been achieved. The proposed digital methodology has identified a maximum gap of 1.5% between the dimensions of the BIM duct and those of a traditional plant design, meeting ASHRAE requirements for environmental control.

Shoreline slope influences movements of larval lampreys over dewatered substrate

AbstractLarval lampreys are filter feeders that live for several years burrowed in fine sediments in freshwater streams. Stream side channels and edges, where larval lampreys gather, are vulnerable to natural and human‐caused dewatering. Water level reductions can strand and kill thousands of larval lampreys, in part because many remain burrowed until their habitats are exposed, at which point larvae must emerge and attempt to move over dewatered substrate to locate wetted habitat. Dewatering for restoration efforts or seasonal closures of irrigation canals can be done slowly to reduce lamprey strandings, but in some settings, mechanisms are lacking to control the dewatering rate. Phased dewatering, where water level is reduced in stages separated by periods of static water level, could provide options when dewatering rate cannot be tightly controlled. To guide this phased approach, information is needed on the movement capability of larval lampreys. We examined larval lamprey (Entosphenus tridentatus and Lampetra spp.) movement distance and rate over dewatered substrate at shoreline slopes of 1%, 5%, 10% and 20% in a laboratory setting and modelled results using gamma regression models. Model results suggest both movement distance and movement rate increased with increasing slope and increasing larval length. We used the models to predict minimum distances and rates that 90%, 75% and 50% of medium‐sized (75 mm) lampreys would move over dewatered substrates on slopes of 1%–20%. The models predicted that 50% of larvae could move distances of ≥31 cm at rates of ≥0.7 mm/s on a 1% slope and distances of ≥502 cm at rates of ≥8.6 mm/s on a 20% slope. We present an example scenario of how information on larval movement capabilities and shoreline slope could guide phased dewatering events to limit impacts to lampreys.

Research on Data Acquisition and Regulation Methods of Basement Flashing Pressure Relief System Based on Digital Technology

Abstract This study utilizes digital technology to monitor water pressure changes within basement flashings, facilitating targeted drainage operations. By implementing an active water discharge method, drainage holes are strategically placed around or beneath basements to decompress and reduce water levels, thereby alleviating hydrostatic pressure on underground structures. This approach helps prevent basement uplift. The paper addresses challenges such as high energy consumption and ample data storage in long-term monitoring, introducing an acceleration trigger module and a data correction algorithm based on an enhanced BP neural network. A WOA-BP neural network model was developed using historical data to monitor water pressure efficiently. Our findings indicate that at 0.076MPa, flashing connections begin to fail, progressing to shear damage at 0.085MPa. Consequently, to preserve basement integrity, it is crucial to activate complete drainage when monitored pressure exceeds 0.045MPa to maintain pressures below the critical threshold of 0.076MPa.

Influence of Water Level Reduction in The Caspian Sea on The breeding Behaviour of Sedentary Bird Populations in Gizilaghaj Bay

Influence of Water Level Reduction in The Caspian Sea on The breeding Behaviour of Sedentary Bird Populations in Gizilaghaj Bay

Evaluating the impact of leakage in intermittent water supply networks considering justice index: A case study

Abstract Intermittent water supply (IWS) is one of the effective methods to manage the consumption of urban water networks under water scarcity conditions. However, it is essential to minimize unfair water distribution in this method by defining a proper strategy. This study utilized the EPANET pressure-dependent hydraulic analysis and the gray wolf optimization algorithm to achieve maximum volumetric reliability under different scenarios in a district of the Hamedan urban water distribution network in Iran. The volumetric reliability of the network was evaluated in the IWS condition regardless of justice constraints, with the justice constraint, and by considering the leakage in the IWS network with the justice constraint. The first scenario demonstrated that the reliability decreased by an average of 4.6% for every meter of water level reduction in the tank. The second scenario revealed that the objective function was negligibly affected by the variation of the justice constraint; however, fluctuation of the water level in the tank significantly affected the volumetric reliability. In the third scenario, the objective function value was significantly impacted by leakage, ranging from 0 to 0.3 (representing the absence and presence of leakage in 30% of the nodes, respectively), resulting in an average decrease of about 17%.

Introducing an Innovative Design Approach for Drainage Systems: Facilitating Shallow Aquifer Recharge and Mitigating Flooding

Maringá, in southern Brazil, is undergoing a crisis with the alternation of dry and wet periods and floods caused by heavy rainfall along with the lack of infiltration of the stormwater. Due to a combination of these two opposite factors, the central lake of Ingá Park, which is an important urban park of the city, is suffering from water level reduction. This paper aims to verify if a sustainable drainage system design with infiltration wells can help recharge the surface aquifer. To this end, a stormwater drainage system simulation was conducted using SewerGEMS. Additionally, a calibrated shallow aquifer computational model was run in Visual Modflow Flex considering recharge wells to verify whether rainfall events impact the water levels of the surface aquifer. The results show that the sustainable intervention in a drainage system to increase stormwater infiltration has the potential to effectively recharge the shallow aquifers, while helping, at the same time, the drainage system, which is operating beyond design capacity, and the Ingá Park Lake. Thus, this study demonstrates that the sustainable design of drainage systems can help restore the springs inside the urban park. However, it is important to continuously monitor the wells’ heads and the hydrological variables. Also, for future studies, new models and simulations must be undertaken using the continuous monitoring data already available.

Three-dimensional numerical research on coupling heat transfer characteristics of PRHR HX under different water levels based on the experimental model

The passive residual heat removal system (PRHRs) is an important heat transfer system to ensure the removal of residual heat in non-LOCA conditions occurring in advanced Generation III nuclear reactors. The water level of the In-containment Refueling Water Storage Tank (IRWST) decreases due to long-term water evaporation under accident conditions and the later stages of PRHRs operation. Additionally, the water level also decreases during the water leakage accidents. The reduction of water level contributes to a decrease in the heat transfer area and the passive residual heat removal ability of the core. In order to investigate the coupling heat transfer characteristics of both primary and secondary side in the heat exchanger under different water levels, Three-dimensional numerical simulations of the PRHR HX's operation under different water levels was carried out based on the scaled-down IRWST&PRHR HX experimental model. The fluid flow and heat transfer processes inside and outside the C-type tubes were analyzed in detail. The results indicate that when heat transfer area is reduced by 50%, the overall heat transfer rate is reduced by about 41%, meanwhile the average heat transfer coefficient is about 37.4% higher than that under the full water level condition. It indicates that PRHR HX can maintain high passive residual heat removal capacity even under half water level, which provides an important reference for the design and safe operation of the PRHR HX.

Assessment of Biological Treatment for Ammonia Removal from Water Resources, Egypt

Egypt is depending entirely on the Nile water. The Rosetta branch of the river Nile serves as a vital freshwater source for domestic, agricultural, industrial, fisheries, and recreational purposes in several western Delta governorates of Egypt, with a daily flow averaging 21,500,000 m3/day. The branch faces significant challenges due to escalating ammonia concentrations stemming from agricultural drains along the river, industrial effluents from industrial activities, and fish farming cages. One particular issue arises during low-demand periods when the flow in the Rosetta branch diminishes. Annually, Egyptian authorities close water flows in a series of channels to facilitate maintenance, resulting in reduced water levels. This winter closure has impacted Kafr El Sheikh and El Beheira, located in northern Egypt, as the drainage of industrial wastes during this period has led to a high pollution load of ammonia and other pollutants. The elevated ammonium content has hindered coagulation, encouraged algal growth, and impeded the chlorine breakpoint during water chlorination processes. Laboratory experiments were conducted to investigate the ability of blue-green algae species (Anabaena sp., Scyndesmos sp., Chlorella sp.) and bacteria (Lactobacillus sp.) to uptake ammonia. This study revealed that single algal species achieved a maximum removal percentage of 30% for ammonia concentrations ranging from 5 to 7.5 mg/l, and mixed algal species attained removal percentages between 6% and 12% at constant retention times of 15 to 60 minutes. For single algal species, retention times exceeding 1 hour (2 and 5 hours) resulted in removal percentages ranging from 85% to 100%. For mixed algal species, removal percentages between 9% and 20% were observed for various retention times ranging from 15 minutes to 1 hour. When comparing the use of algal species mixtures, removal percentages of up to 30-50% were achieved. Additionally, the study found that the application of bacterial species (Lactobacillus sp.) to raw water samples with an average ammonia concentration of 7.8 mg/l resulted in a maximum removal percentage of 100% when using a bacterial content of 100-200 ml per 1-liter raw water sample volume, with varied retention times up to 2 hours.