Reservoir Water Level Research Articles

Reservoir Operating Rules to Create Effective Fish Migration Passages in a Reservoir

AbstractLow flow velocity disrupts the potential fish migration passages in a reservoir, and causes reservoirs to become labyrinths for migratory fish. Previous studies showed that fish migration passages in a reservoir can be restored by modifying reservoir operation. However, reservoir operating rules that are specifically designed to support fish migration have not been established, leading to low success for fish migration and high socioeconomic losses. In this research, we established new reservoir operating rules to improve the migration success rate while also reducing socioeconomic losses. Under the new rules, two parameters (reservoir water level and predicted reservoir inflows) were adapted to trigger water releases to open migration passages. The two parameters were optimized by considering hydrological processes, fish migration processes below the dam, the swimming ability of fish, and the socioeconomic benefits provided by the reservoir. We used data from China's Danjiangkou Reservoir to test the effectiveness of the proposed method. We found that the new method can not only improve the migration success rate (from 0.1% to 4.2%), but can also slightly reduce the reservoir's socioeconomic losses (by 3.7%–7.0%). The new method effectively balances the needs of fish migration with the need for socioeconomic development in the areas surrounding dammed rivers.

Assessment and strategies for water supply security risks in the estuarine city Shanghai under normalized extreme climate conditions

Facing the escalation of extreme climate events, estuarine delta cities like Shanghai grapple with significant water supply challenges. This study employs system dynamics and dynamic adaptive policy pathways to assess Shanghai's water supply security risks and responsive strategies in 2022–2050, amidst extreme climate conditions. Utilizing data from 2000 to 2021, we constructed a system dynamics model to predict future water demand under various development modes. Focusing on the unusual 2022 drought in the Yangtze River Basin, we simulated 15 scenarios, including economy, population, water efficiency, and reservoir levels, to identify the extent and timing of potential water supply risks, then proposed pertinent dynamic adaptive strategies to address them. Our findings suggest that the 2022 drought significantly reduced Shanghai's water supply capacity, leading to a notable deficit. Under scenarios of accelerated economic growth, water supply security risks are heightened, with projections indicating a reduction of days of supply available to merely 33–67 days, and escalating water shortage amount to 592–896 million m3 by 2050. Short-to-medium-term recommendations include optimizing both local and transit water resources, strengthening emergency water reserves, enhancing water use efficiency, and maintaining stable reservoir water levels. For the long term, expanding water storage infrastructure and promoting integrated water resource management within the Yangtze River Delta is key to establishing a resilient and diversified water supply system, effectively mitigating future water security risks. This study provides a scientific basis and reference for the sustainable management of water resources in estuarine cities confronting normalized extreme climate conditions. It offers valuable insights for policymakers and actionable suggestions for urban planners.

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.

Artificial neural network-based water distribution scheme in real-time in long-distance water supply systems

ABSTRACT Hydraulic models of long-distance water supply systems are usually used to regulate valves and pumps to realize the expected water distribution. Establishing and calibrating the hydraulic model is time-consuming and requires many engineering parameters, which are usually uncertain. This paper proposes a metamodel based on artificial neural networks (ANNs) to replace the computationally costly hydraulic model. The metamodel is designed to bypass the modeling and calibration processes of the hydraulic model and directly estimate the target state of valves and pumps to realize real-time water distribution. The proposed approach uses the water levels of reservoirs and the flow demands of water plants as input data to the ANN. The metamodel's output prescribes the opening of regulating valves and the speed of pumps. A realistic case study is presented to validate the accuracy and efficiency of the approach. The results show that ANN is feasible as a state predictor to realize real-time water distribution in practical water supply projects.

Watching the Grand Ethiopian Renaissance Dam from a distance: Implications for sustainable water management of the Nile water.

Increased demands for sustainable water and energy resources in densely populated basins have led to the construction of dams, which impound waters in artificial reservoirs. In many cases, scarce field data led to the development of models that underestimated the seepage losses from reservoirs and ignored the role of extensive fault networks as preferred pathways for groundwater flow. We adopt an integrated approach (remote sensing, hydrologic modeling, and field observations) to assess the magnitude and nature of seepage from such systems using the Grand Ethiopian Renaissance Dam (GERD), Africa's largest hydropower project, as a test site. The dam was constructed on the Blue Nile within steep, highly fractured, and weathered terrain in the western Ethiopian Highlands. The GERD Gravity Recovery and Climate Experiment Terrestrial Water Storage (GRACETWS), seasonal peak difference product, reveals significant mass accumulation (43 ± 5 BCM) in the reservoir and seepage in its surroundings with progressive south-southwest mass migration along mapped structures between 2019 and 2022. Seepage, but not a decrease in inflow or increase in outflow, could explain, at least in part, the observed drop in the reservoir's water level and volume following each of the three fillings. Using mass balance calculations and GRACETWS observations, we estimate significant seepage (19.8 ± 6 BCM) comparable to the reservoir's impounded waters (19.9 ± 1.2 BCM). Investigating and addressing the seepage from the GERD will ensure sustainable development and promote regional cooperation; overlooking the seepage would compromise hydrological modeling efforts on the Nile Basin and misinform ongoing negotiations on the Nile water management.

A simple infiltrometer automated with a user‐friendly pressure datalogger

AbstractWe have constructed a new, simplified constant‐head infiltrometer automated with a self‐contained water level datalogger (HOBO U20L‐01) repurposed to measure changes in gas pressure inside an inverted bottle reservoir. Our field tests of six of these infiltrometers confirmed that recorded changes in gas pressure were strongly correlated with changes in water level in the infiltrometer reservoir (R2 = 0.9998). Further, by using the derived experimental calibration function, we were able to obtain accurate near‐steady‐state infiltration rates. This infiltrometer is cheaper and lighter than current commercially available infiltrometers. It can be easily assembled with materials readily available in most hardware stores, and its user‐friendly datalogger does not require any programming knowledge. This infiltrometer is compatible with various ponding infiltration methods, and its generic design allows for modifications with locally available materials to meet diverse research needs.

Reservoir Slope Stability Analysis under Dynamic Fluctuating Water Level Using Improved Radial Movement Optimisation (IRMO) Algorithm

External water level fluctuation is the major trigger causing reservoir slope failure, and therefore it is of great significance for the safety assessment and corresponding safety management of reservoir slopes. In this work, the seepage effects stemming from fluctuating external water levels are given special analysis and then incorporated into the rigorous limit equilibrium method for assessing the stability of reservoir slope. An advanced metaheuristic intelligent algorithm, the improved radial movement optimisation (IRMO), is introduced to efficiently locate the critical failure surface and associated minimum factor of safety. Consequently, the effect of water level fluctuation directions, changing rates, and soil permeability coefficient on reservoir stability are investigated by the proposed method in three cases. It is found that the clay slope behaved more sensitively in stability fluctuation compared to the silty slope. With the dropping of external water, the higher dropping speed and lower soil permeability coefficient have worse impacts on the slope stability. The critical pool level during reservoir water dropping could be effectively obtained through the analysis. The results indicate that the IRMO-based method herein could effectively realise the stability analysis of the reservoir slope in a dynamic fluctuating reservoir water level, which could provide applicable technology for following preventions.

Seepage and Stability Analysis of Earth Dams’ Downstream Slopes, Considering Hysteresis in Soil–Water Characteristic Curves under Reservoir Water Level Fluctuations

Fluctuations in reservoir water levels have a significant impact on the seepage and slope stability of earth dams. The varying rate of the water level and soil–water characteristic curve (SWCC) hysteresis are the main factors affecting the seepage and the stability of dam slopes; however, they are not adequately considered in engineering practices. In this study, the SEEP/W module and the SLOPE/W module of Geo-studio were employed to analyze the seepage features and the stability of downstream slopes, taking into account the water level fluctuation rate and the SWCC hysteresis. The results reveal that the pore water pressure of the representative point forms a hysteresis loop when the water level fluctuates, which becomes smaller as the water level variation rate increases. Within the loop, the pore water pressure with a rising water level is greater than the value when the water level is dropping, and the desorption SWCC derives greater pore water pressures than the adsorption SWCC. Similarly, the safety factor (Fs) curves under the condition of water level fluctuations also form a hysteresis loop, which becomes smaller as the variation rate of the water level increases. When the water level fluctuation rate increases to 4 m/d, the two curves are tangent, meaning that the Fs with a rising water level is always greater than the value when the water level is dropping. The desorption SWCC derives a lower Fs value than the adsorption SWCC as the water level draws up, but this initiates no evident difference in the Fs value when the water level draws down. These findings can be used to inform the design and operation of earth dams under fluctuating water levels.

Assessment of the Divergent Influence of Natural and Non-Seasonal Hydrological Fluctuations on Functional Traits and Niche Characteristics of Plant Guilds along the Xiangxi River, China

The reservoir water level fluctuation zones (RWLFZs) and the natural riparian zones (NRZs) are two riparian ecosystems with dramatically opposite hydrological rhythms that notably influence the plant guilds. However, little is known about the discrepancies of the functional traits and niche characteristics of plant guilds in the RWLFZs and NRZs under different flooding rhythms. The aims of this study were to assess the divergent influence of natural and non-seasonal hydrological fluctuations on functional traits and niche characteristics of plant guilds. The results showed that 78 vascular plant species were identified in the riparian zones of the Xiangxi River basin. The dominant species were annuals in the two riparian ecosystems and their percentage increased temporally from 65.79% in the NRZs to 67.34% in the RWLFZs. Compared with the NRZs, the specific leaf area, vegetation coverage and the aboveground biomass in the RWLFZs significantly increased by 74%, 27% and 19.6%, respectively, while the water-use efficiency of the RWLFZ decreased by 59.6% and there was no significant difference in the net photosynthetic rate between them, which showed that annuals in the RWLFZs adopted the R adaptation strategy of being fast-growing with a short lifespan and quickly acquiring and investing resources by altering leaf morphology, including expanding the leaf area. The Simpson dominance index of RWLFZs was significantly higher than that of NRZ. Thus, counter-seasonally hydrological alterations had significant effects on functional traits of dominant species in the RWFLZs. Moreover, the highly adaptable and widely distributed species with larger niche breadths and high important values usually had a higher niche overlap value in the RWLFZs than in the NRZs, which showed that the competition in the plant communities after experiencing anti-seasonal flooding was much more intraspecific than interspecific and would facilitate the expansion of species niches. Our findings imply that the species with large niche breadths and high important values should be prioritized in ecological restoration efforts in the newly formed hydro-fluctuation zones of the TGR.

Operational effects on aquatic carbon dioxide and methane emissions from the Belo Monte hydropower plant in the Xingu River, eastern Amazonia

Operational demands and the natural inflow of water actively drive biweekly fluctuations in water levels in hydropower reservoirs. These daily to weekly fluctuations could have major effects on methane (CH4) and carbon dioxide (CO2) emissions via release of bubbles from reservoir bottom sediments (ebullition) or organic matter inputs, respectively. The impact of transient fluctuations in water levels on GHG emissions is poorly understood and particularly so in tropical run-of-the-river reservoirs. These reservoirs, characterized by high temperatures and availability of labile organic matter, are usually associated with extensive CH4 generation within bottom sediments. The aim of this study is to determine how water level fluctuations resulting from the operation of the Belo Monte hydropower plant on the Xingu River, eastern Amazon River Basin, affect local CO2 and CH4 emissions. Between February and December 2022, we monitored weekly fluxes and water concentrations of CO2 and CH4 in a site on the margin of the Xingu reservoir. Throughout the study period, fluxes of CO2 and CH4 were 118 ± 137 and 3.62 ± 8.47 mmol m−2 d−1 (average ± 1SD) while concentrations were 59 ± 29.77 and 0.30 ± 0.12 μM, respectively. The fluxes and water concentrations of CO2 were clearly correlated with the upstream discharge, and the variation observed was more closely associated with a seasonal pattern than with biweekly fluctuations in water level. However, CH4 fluxes were significantly correlated with biweekly water level fluctuations. The variations observed in CH4 fluxes occurred especially during the high-water season (February–April), when biweekly water level fluctuations were frequent and had higher amplitude, which increased CH4 ebullition. Reducing water level fluctuations during the high-water season could decrease ebullitive pulses and, consequently, total flux of CH4 (TFCH4) in the reservoir margins. This study underscores the critical role of water level fluctuations in near-shore CH4 emissions within tropical reservoirs and highlights significant temporal variability. However, additional research is necessary to understand how these findings can be applied across different spatial scales.

Physical Model Test of Deformation Self-Adaptive Mechanism of Landslide Mass

Reservoir impoundment induces a large amount of cumulative deformation of landslide body, leading to damage to the geological environment. Due to many yearly cycles of reservoir water fluctuation, the cumulative deformation of landslides tends to be stable, showing a self-adaptive deformation phenomenon. The study of the self-adaptive deformation mechanism is very important for evaluating landslide stability and achieving the safe operation of hydropower stations. To study the mechanism of self-adaptive deformation, two sets of physical models were used to monitor the groundwater, earth pressure, and cumulative deformation of landslide under periodic fluctuations of the reservoir water level. The results showed that the soil consolidation compaction, release of sliding stress, and increase in permeability are the three main factors of the self-adaptive deformation of landslide accumulation. The overall permeability decreased first and then increased, the front permeability increased greatly, and the middle and rear permeability decreased. The main factors that affected the permeability change were deformation and seepage force.

Microplastic pollution responses to spatial and seasonal variations and water level management in a polymictic tropical reservoir (São Paulo, Brazil).

We assessed microplastic (μP) pollution in water and sediment samples during the dry and rainy season (October/2018 and March/2019, respectively) from the Guarapiranga Reservoir in the Metropolitan Region of São Paulo, Brazil, which provides drinking water for up to 5.2 million people. The concentration of mPs varied spatially and seasonally, with the higher concentrations observed near the urbanized areas and during the dry season. Water column concentrations ranged from 150 to 3100 particles/m3 and 0.07-25.05 mm3 plastic/m3 water during the dry season, and 70-7900 particles/m3 and 0.06-4.57 mm3 plastic/m3 water during the rainy season. Sediment samples were collected only during the rainy season, with concentrations ranging from 210 to 22,999 particles/kg dry weight and 0.15-111.46 mm3/kg dry weight. The particle size distribution exhibited seasonal variation, with μPs >1 mm predominating during the dry season, constituting 60-75% of all particles. In terms of quantity, fibers accounted for the majority of microplastics, comprising 55-95% during the dry season and 70-92% during the rainy season. However, when considering particle volume, irregular particles dominated in some samples, accounting for up to 95%of the total amount. The predominant colors of microplastics were white/crystal, black, and blue, with the main compositions identified as polypropylene (PP) and polyethylene terephthalate (PET), suggesting the influence of untreated domesticsewage discharge. Additionally, some additives were detected, including the pigments Fast RED ITR and phthalocyanine blue. The management of reservoir water levels appears to influence the quantity of μPs in the water column. As the water level increases up to 90% of the reservoir capacity during the rainy season, the amount of μPs in the water decreases, despite the higher influx of particles resulting from surfacerunoffcaused by rainy conditions. This suggests a "dilution" effect combined to the polymictic mixing hydrodynamics. Our results may contribute to the creation and improvement of monitoring programs regarding mP pollution and to the adoption of specific public policies, which are still lacking in legislation.

Analysis of cracks development and damage evolution in red sandstone under dry-wet cycles based on temporal and frequency characteristics of acoustic emission

Utilizing the goafs of underground reservoirs (underground buildings) in western coal mines as storage spaces plays a crucial role in ecological environment protection and energy transition in mining areas. Hence, it is crucial to recognize the repeated erosion of reservoir water levels on the deformation and damage mechanisms of the roof and floor rock masses in the underground building dams. This paper intends to study the instability failure mechanisms and precursor responses of red sandstone samples with 0–3 dry-wet cycles during uniaxial loading-unloading under acoustic emission (AE) monitoring. The AE time-frequency features were analyzed, and the crack three-dimensional spatial extension and tensile-shear crack evolution were explored. The b-value and entropy value of AE events were presented for evaluating crack expansion damage status during loading-unloading. The findings suggest that the peak strength, elastic modulus, and crack thresholds of red sandstone exhibit a positive exponential decline with growing dry-wet cycles. Conversely, the peak strain and strain-softening modulus exhibit an opposite trend. With growing dry-wet cycles, AE signals from low-frequency, high-amplitude, and large-scale cracks decline, exhibiting a multi-frequency simultaneous response effect before sample instability. Meanwhile, the proportion and concentration of localization events with energy exceeding 104 aJ rise, and the failure instability gradually shifts from tensile-shear failure to tensile cracks. The sudden decline in b-value and the significant fluctuation in entropy value serve as short-term precursors to imminent rock instability failure, with the system energy following an ordered-disordered-ordered pattern. The research findings offer certain experimental foundation and novel judgment indicators for rock structure safety warning, including the stability of underground building dams, support for water-rich roadways, water hazard prevention, and utilization of abandoned mine spaces.

Seepage–Deformation Coupling Analysis of a Core Wall Rockfill Dam Subject to Rapid Fluctuations in the Reservoir Water Level

Core wall rockfill dams are susceptible to cracking at the dam’s crest, as well as collapse and settlement of the rockfill during storage and operation periods, particularly due to rapid fluctuations in the water level in pumped storage power stations. Most studies on the impact of fluctuations in the reservoir’s water level on dam deformation have considered fluctuations of less than 5 m/d, while pumped storage power stations experience much larger fluctuations. Additionally, the seepage and stress fields within the dam’s rock and soil interact and influence each other. Few studies have used the coupling theory of seepage and stress to analyze seepage and deformation in core wall rockfill dams. To address these issues, a finite element model using seepage–stress coupling theory was utilized to investigate the variations in the phreatic line, earth pressure, and deformation of a core wall rockfill dam due to rapid fluctuations in the reservoir’s water level. Additionally, the results of the finite element simulation were compared with and analyzed alongside safety monitoring data. The results indicated that, upon a sudden decrease in the reservoir’s water level, there was a lag in the decline of the phreatic line in Rockfill I, which created a large hydraulic gradient, resulting in a reverse seepage field on the dam’s slope surface and generating a drag force directed upstream. Consequently, a significant concentration of stress occurred on one-third of the upstream slope surface of the dam and the seepage curtain, and the increase in horizontal displacement was substantially greater than the increase in settlement from one-third of the rockfill’s height to the dam’s foundation. The deformation was more sensitive to the lowest water level of the reservoir rather than to the fastest rate of decline. Sudden rises in the reservoir’s water level result in decreased horizontal displacements and settlement of the dam. Amid rapid fluctuations of the reservoir’s water level, changes in the vertical earth pressure were more pronounced at the bottom of the core wall than in its midsection. Compared with the core wall, variations in the vertical earth pressure in the upstream and downstream filter layers were minor at similar elevations. A peak horizontal displacement of 6.5 mm was noted at one-third the height of Rockfill I, with the greatest increase in settlement of 3.5 mm at the dam’s crest. To ensure a project’s safety, it is crucial to control the elevation of the lowest point during a sudden drop in the reservoir’s level and to carefully monitor for cracks or voids within approximately one-third of the dam’s height in Rockfill I and at the dam crest. This study’s results provide a scientific basis for assessing core wall rockfill dams’ health and securing long-term safety at pumped storage power facilities.

The influence of reservoir water level on the hydraulic characteristics of spillway tunnel

Abstract The spillway tunnel for water discharging is very important in water conservancy and hydropower engineering. Spillway tunnel with inclined and elbow part near the outlet can be more easily adapted to the topographic and geological conditions than that near the inlet, and can limit the cavitation damage to the short tunnel near outlet. Therefore, it has been widely used in the case of discharging water with high head and large discharge. Cavitation induced by high speed flow may cause severe damage to the spillway tunnel surface. And aeration is a common measure for surface protection. Study on the hydraulic characteristics of water-air two-phase flow is of great significance for improving aeration effect. In this paper, the velocity, depth of water and Froude Number of spillway tunnel under different reservoir water levels are studied by using VOF method. The results show that the Froude Number decreases at first and then increases as reservoir water level becomes lower.

Forecasting and uncertainty analysis of tailings dam system safety based on data mining techniques

Tailings dams, as critical infrastructure, play a vital role in ensuring the safety and reliability of tailings pond systems. Predicting the trend of tailings dam monitoring parameters helps monitor its operational status and support safety management and decision-making. The traditional time series prediction model focuses on point prediction while neglecting the nonlinear feature of data and the uncertainty of prediction results, which is far from meeting the requirements for risk monitoring and safety management of tailings dam systems. To address this, Deep Auto-Encoder is used to extract and optimize features of multi-dimensional time series; Whale Optimization Algorithm, Long Short Term Memory, and Kernel Density Estimation are used to build a monitoring parameters trend interval prediction model. It can effectively predict and analyze the uncertainty of tailings dam monitoring parameters. Time series data of monitoring parameters are collected from a tailings dam in Anhui, China and modeled to verify the effectiveness of the model. The results show that the hybrid prediction model performs the best in monitoring parameter prediction accuracy and trend. The Root Mean Square Error values of the Whale Optimization Algorithm and Long Short Term Memory prediction for reservoir water level, surface displacement, internal displacement, phreatic line, and beach width are 0.0160, 1.0405, 0.0389, 0.0176, and 0.7525, with errors reduced by 0.37 % to 17.92 % compared to other models. The uncertainty analysis confirms the high reliability of the model. The Kernel Density Estimation effectively forecasts the fluctuation range of predicted values, significantly improving the prediction effectiveness of the monitoring parameters.

2D model of groundwater flow and total dissolved HCH transport through the Gállego alluvial aquifer downstream the Sardas landfill (Huesca, Spain)

The organic pollutants disposed at the Sardas landfill in Sabiñánigo (Huesca, northeastern Spain) by the INQUINOSA lindane factory have reached the Gállego alluvial aquifer and could affect the Sabiñánigo reservoir. The daily oscillations of the reservoir water level produce a tidal effect on the piezometric heads of the aquifer. These oscillations are transmitted in a damped way with a time lag, thus attesting that the silting sediments of the reservoir and the natural silts of the Gállego alluvial are interposed between the reservoir water and the layer of sands and gravels. A 2D finite element groundwater flow and total dissolved hexachlorocyclohexane (HCH) transport model through the Gállego alluvial aquifer is presented here. The flow model was constructed to: (1) Quantify the tidal effect, produced by the daily fluctuations of the reservoir water level on the aquifer; (2) Estimate the hydrodynamic parameters of the layer of sands and gravels; and 3) Estimate the vertical hydraulic conductivity of the silting sediments and silts; and (4) Quantify aquifer/reservoir interactions. The flow model reproduces the dynamics of the tidal effect and attests that groundwater velocity and flow direction changes daily in response to the oscillations of the reservoir level. Model results reproduce the measured well hydrographs and the Darcy velocity derived from tracer tests and confirm the validity of the conceptual model. The transport model of total dissolved HCH simulates the time evolution of the contaminant plume. The computed concentrations of total dissolved HCH and the contaminant mass outflux are very sensitive to changes in the source terms and the distribution coefficient, Kd of HCH. The best fit to the measured HCH plumes in September 2010 and December 2020 is obtained with a Kd ranging from 1 to 3 L/kg. The computed flux of dissolved HCH leaving the Sardas site in 2020 towards the Sabiñánigo reservoir ranges from 0.6 kg/year for Kd = 3 L/kg to 3.1 kg/year for Kd = 1 L/kg. The findings of this study will be most useful for planning and designing remedial and containment actions at the Sardas site and other similar lindane-affected sites.

Trade-driven model of “Hydropower for Rice” cooperation in the Lancang-Mekong River basin

There have been intense conflicts over water resources between upstream and downstream countries in the Lancang-Mekong River Basin (LMRB) over the past years, primarily due to the trade-off relationship between hydropower and rice production. Great potential for transboundary cooperation has been shown, such as China’s emergency water release in 2016 to alleviate downstream severe drought. However, there is still a lack of systematic cooperation pattern. To address this issue, the study proposes a trade-driven model of “Hydropower for Rice” cooperation, and then derives three key political factors including price weight, export rate, and terminal water level of reservoirs. Our results show that (1) The hydropower and rice production under the trade-driven model can approximate the centralized model, and the “Hydropower for Rice” cooperation is feasible. (2) For downstream countries, rice is the main product, and the rice production and economic benefit can be increased with a higher price weight or export rate. Compared to Thailand and Cambodia, Vietnam needs to engage in deeper trade with China. (3) For upstream China, hydropower is the main product, and the economic benefit of riparian countries can be increased with higher export rates. The discharge in the dry season is increased, which is driven by the trade of rice. Additionally, China’s initiative to reduce the terminal water level of reservoir Nuozhadu has the potential to further increase rice production in downstream countries. This study indicates that the transboundary cooperation in LMRB requires joint efforts of upstream and downstream countries.

Smart Water Management Grid

The Smart Water Management Grid (SWMG) lever- age the power of the Internet of Things (IoT) to revolutionize water management, ensuring efficiency, sustainability, and reliability in water distribution systems. By integrating sensors such as level monitoring, pressure monitoring, leakage control, and pH sensors, these grids enable real-time monitoring and intelligent decision-making to optimize water usage and minimize wastage. One crucial aspect of smart water grids is level monitoring, which tracks water levels in reservoirs, tanks, and pipelines. By continuously monitoring water levels, authorities can ensure optimal storage and distribution, preventing shortages or over- flows. Pressure monitoring sensors further enhance efficiency by maintaining optimal pressure throughout the distribution network, minimizing energy consumption and reducing the risk of pipe bursts. Leakage control is another significant feature facilitated by IoT sensors in smart water grids. Advanced leak detection sensors can pinpoint even minor leaks in the system, enabling swift repairs and preventing significant water losses. This proactive approach not only conserves water but also reduces operational costs and mitigates potential damage to infrastructure and the environment. Moreover, integrating pH sensors into the water grid allows for real-time monitoring of water quality. Maintaining proper pH levels is critical for ensuring safe and potable water supply. By detecting variations in pH levels, authorities can promptly identify and address potential contamination issues, safeguarding public health and preventing waterborne diseases.

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.