Reservoir Construction Research Articles

Open pit limit optimization considering the pumped storage benefit after mine closure: a case study

Repurposing a closed mine as lower reservoir is a cost-effective way for the construction of pumped storage hydropower (PSH) plant. This method can eliminate the expenses of mine reclamation, reservoir construction, and land acquisition, resulting in significant cost savings and benefits for the PSH project, known as the PSH benefit. The construction of PSH plants within a closed mine is divided into surface mode and semi-underground mode in this paper. Through a general comparison of two in-situ cases, the finding highlight that the surface mode can achieve a larger potential installed capacity and lower construction cost. Furthermore, the PSH benefit is quantified and internalized as an economic parameter in the ultimate pit limit (UPL) optimization by allocating it into unit ore. Taken an undisclosed open-pit iron mine as example, the UPL is optimized by considering the PSH benefit. The internalized PSH benefit is calculated to be 6.59 CN¥/t when the installed capacity is 2000 MW, and ore amount within the optimized UPL is increased by 1.4%. The results indicated that the PSH benefit does influence the shape and size of UPL, but not significantly. Besides, converting several bottoms in a single open-pit into lower and upper reservoirs presents more challenges for UPL optimization, which further explorations is needed.

Water Reservoirs in North-Western Hispania Roman Gold Mining: Technology, Chronology and Paleoenvironmental Evolution

ABSTRACT Water reservoirs located on the mining fronts were essential for the operation of Roman gold mining. They served purposes such as the extraction and washing of gold deposits, and the final disposal of waste. The history of a Roman gold mine is intricately linked to its hydraulic network. Therefore, dating the construction, usage, and abandonment layers of water reservoirs enables us to comprehend the evolution of mining operations. In this paper, we present a methodological approach consisting of the opening of archaeological sondages in the water reservoirs to understand their stratigraphy and operating phases, together with sampling to obtain chronological and pollen information. We present the work carried out in four case studies located in various mining areas in the northwest of the Iberian Peninsula. Results indicate that water reservoirs serve as paleoenvironmental archives, facilitating the chronological unravelling of mining operations and the landscape reconstruction from the period immediately preceding the onset of mining operations to their abandonment. Results also have highlighting some of the challenges when interpreting radiocarbon results. We conclude that the archaeological analysis of hydraulic mining infrastructure is an effective methodology for understanding the evolution of mining landscapes.

Network of Soil Fungi and the Microfauna Community under Diverse Anthropic Disturbances under Chrysopogon zizanioides Planting in the Reservoir

The reservoir coastal zone is the transitional zone between the terrestrial ecosystem and the aquatic ecosystem. Soil is an essential part of the terrestrial ecosystem and vital for life on Earth. To understand the composition and diversity of the soil eukaryotic microbial community under the background of artificial planting of Chrysopogon zizanioides in various habitats after reservoir construction, including the original habitat (OH), the hydro-fluctuation belt (HB), and the road slope (RS), and to analyze the interaction between the main groups of eukaryotic microorganisms, this study conducted 18S rDNA amplification high-throughput sequencing of the soil eukaryotic microbial community. The study found that the dominant phylum of eukaryotic microorganisms in the three habitats was consistent, but there were significant differences in the community and diversity of eukaryotic microorganisms in the three habitats. The differences in fungal communities between sample sites were greater than those of soil microfauna. Correlation analysis showed that nitrogen, phosphorus, and organic matter were significantly correlated with eukaryotic microbial diversity, with alkaline-hydrolyzed nitrogen and total phosphorus significantly correlated with fungal communities and pH and water content correlated with soil microfauna. Co-occurrence network analysis found that the interactions between fungi and the correlation between fungi and soil microfauna dominated the eukaryotic microbial community, and the interactions between eukaryotic microbes in different habitats were dominated by positive correlations. After the construction of the reservoir, the newly formed hydro-fluctuation belt reduced the types of interrelationships between fungi and microfauna compared to the original habitat. The road slope provided protection of the supporting project for the reservoir construction, although there was also planted vegetation. Eukaryotic microbes declined significantly due to the damage to and loss of the organic layer, and the decline in microfauna was the most significant, resulting in a simple structure of the soil food web, which affects the function and stability of the soil ecosystem.

Attribution of Runoff Variation in Reservoir Construction Area: Based on a Merged Deep Learning Model and the Budyko Framework

This study presents a framework to attribute river runoff variations to the combined effects of reservoir operations, land surface changes, and climate variability. We delineated the data into natural and impacted periods. For the natural period, an integrated Long Short-Term Memory and Random Forest model was developed to accurately simulate both mean and extreme runoff values, outperforming existing models. This model was then used to estimate runoff unaffected by human activities in the impacted period. Our findings indicate stable annual and wet season mean runoff, with a decrease in wet season maximums and an increase in dry season means, while extreme values remained largely unchanged. A Budyko framework incorporating reconstructed runoff revealed that rainfall and land surface changes are the predominant factors influencing runoff variations in wet and dry seasons, respectively, and land surface impacts become more pronounced during the impacted period for both seasons. Human activities dominate dry season runoff variation (93.9%), with climate change at 6.1%, while in the wet season, the split is 64.5% to 35.5%. Climate change and human activities have spontaneously led to reduced runoff during the wet season and increased runoff during the dry season. Only reservoir regulation is found to be linked to human-induced runoff changes, while the effects of land surface changes remain ambiguous. These insights underscore the growing influence of anthropogenic factors on hydrological extremes and quantify the role of reservoirs within the impacts of human activities on runoff.

Extending irrigation reservoir histories for improved groundwater modeling and conjunctive water management in two Arkansas critical groundwater areas

Agricultural land managers in the Mississippi Alluvial Plain rely on the Mississippi River Valley Alluvial Aquifer for the majority of the water used for irrigation in the region. Pumping that outpaces recharge has resulted in significant cones of depression in the region, increasing pumping costs and forcing producers to use more surface water, often in the form of constructing on-farm storage reservoirs. At the same time, efforts are underway to improve groundwater models to run scenarios of conjunctive water management in the region. The improved models require accurate depiction of how the system is being managed including the use of on-farm storage reservoirs. This study extends our knowledge of on-farm storage reservoir construction from those established by a previous study that tracked reservoir construction between 1996 and 2015 backward an additional 20 years to 1976. This was accomplished by using older multi-band satellite and aerial imagery. The study area covers portions of two Critical Groundwater Regions in eastern Arkansas. Reservoir construction was classified into five-year bins starting in 1976 and ending in 2015. Details of how older imagery was processed and analyzed are provided. Previously, nearly 50% of the on-farm storage reservoirs had unknown construction dates, but this research study resolved construction dates for 85% and 72% of the reservoirs in the two study areas. Relationships between time and depth to groundwater, reservoir size, previous land use, and saturated aquifer thickness are described and contrasted in the two study areas across the 40-year study period. Use of the information provided will help guide policy and resource allocation for future reservoir construction activities and help improve conjunctive water management of the region. Specifically, the addition of this historic information will allow modelers to further refine groundwater-surface water models and should improve water resources scenarios that include reservoirs as a tool to reduce groundwater decline.

Numerical Analysis of the Overtopping Failure of the Tailings Dam Model Based on Inception Similarity Optimization

The analysis of overtopping dam break caused by extreme rainstorms and other special circumstances is very important in the feasibility analysis of new construction or expansion projects of tailings reservoirs. Reduced-scale physical model tests can directly reflect the topography and dam-break influence range, but the reasonable selection of model dam material is the key to ensure the model’s similarity. Based on the similarity optimization of the limit state of scour inception of sediment particles, a new method for the model material of tailings dams can be proposed, but it needs to be verified by a similar overtopping model test. In this paper, the modeling and numerical calculation analysis of a prototype tailings dam and a similar reduced-scale model are carried out by using FLOW-3D v11.2 numerical software. The calculation results show that the model test scheme optimized by inception similarity can well reproduce the overtopping failure process of the prototype dam.

Environmental fate of microplastics in alpine and canyon-type river-cascade reservoir systems: Large-scale investigation of the Yalong River in the eastern Qinghai-Tibet Plateau

Reservoirs are regarded as potential collection sites for microplastics (MPs), and ample water resources in plateau regions provide favorable natural conditions for hydroelectric power generation. However, research on the impact of cascade reservoir construction in the plateau region on the fate of MPs within the watershed is limited. In this study, the Yalong River, an alpine canyon river in the eastern Qinghai-Tibet Plateau, was selected as the research area. This study explored the distribution of MPs at various depths in water, sediment, and riverbank soil as well as the formation of “MP communities” within the river-cascade reservoir system. Furthermore, the effects of dam construction on MPs' migration in different environments were analyzed. The results revealed that the abundance of MPs in the water and sediment within the cascade reservoir area (CRA) was significantly higher than that in the river area (RA) (P < 0.001). Additionally, the trend of increasing MPs in water with decreasing altitude was notably slower in CRA. Regarding shape, the proportion of fibers in the water within the CRA was significantly lower than that in the RA, with a smaller vertical migration rate in the water than in the sediment. The proportion of MPs < 500 μm in the water within the CRA was significantly higher than that in the RA. High-density MPs were notably deposited in the reservoir sediments. The analysis of the MP communities revealed that the construction of cascade dams led to relative geographical isolation between different sampling sites, reducing the similarity of MP communities in the CRA. This study established a theoretical foundation for understanding the impact of cascade dam construction on the fate characteristics of MPs and their potential risks in plateau areas.

Water quality's responses to water energy variability of the Yangtze River.

River energy serves as an indicator of pollutant-carrying capacity (PCC), influencing regional water quality dynamics. In this study, MIKE21 hydrodynamics-water quality models were developed for two scenarios, and grid-by-grid numerical integration of energy was conducted for the Yangtze River's mainstream. Comparison of predicted and measured values at monitoring points revealed a close fit, with average relative errors ranging from 5.17 to 8.37%. The concept of PCC was introduced to assess water flow's ability to transport pollutants during its course, elucidating the relationship between river energy and water quality. A relationship model between Unit Area Energy (UAE) and PCC was fitted (R2 = 0.8184). Temporally, reservoir construction enhanced the smoothness of UAE distribution by 74.47%, attributable to peak shaving and flow regulation. While this flood-drought season energy transfer reduced PCC differences, it concurrently amplified pollutant retention by 40.95%. Spatially, energy distribution fine-tuned PCC values, showcasing binary variation with energy changes and a critical threshold. Peak PCC values for TP, NH3-N, and COD were 2.46, 2.26, and 54.09 t/(km·a), respectively. These insights support local utility regulators and decision-makers in navigating low-carrying capacity, sensitive areas, enhancing targeted water protection measures for increased effectiveness and specificity.

Combining Satellite Images and the Hydraulic Engineering Archive to Map the Processes of Reservoir Construction in Xinjiang

Reservoirs are essential hydraulic facilities for water resource allocation in Xinjiang. Since the 1950s, many reservoirs have been constructed for oasis water resource utilization in Xinjiang, enhancing the storage capacity of water resources. There are a few intact and open reservoir archives containing both geolocations and hydraulic attributes, such as the reservoir completion year, which can facilitate our understanding of the correlation between hydraulic engineering and oasis expansion. This paper mapped all the reservoirs of Xinjiang using Sentinel-2 MSI images from 2022. It associated their attributes with the reservoir’s extent, such as the capacity, area, complete year, altitude, etc., by consulting historical almanac data to establish a full elemental dataset with both geographic and attribute information. Furthermore, the spatial variability and historical process of the reservoirs were discussed against geomorphic information and oasis evolution. The results showed that 804 reservoirs were mapped cumulatively in Xinjiang up to 2022, and 1960–1980 and 2005–2010 are the rapidly developed periods. The construction history of the reservoirs indicates that reservoirs’ locations have the spatial tendency to shift from being in oasis plain areas to mountainous areas, and the newly built reservoirs showed a trend of miniaturization in area and maximization in volume.

Allowable Pillar Width for Salt Cavern Gas Storage Based on Triangular Well Layout: A Case Study in China

Salt rock, renowned for its remarkable energy storage capabilities, exists in deep underground environments characterized by high temperature and pressure. It possesses advantageous properties such as high deformability, low permeability, and self-healing from damage. When establishing a cluster of salt cavern gas storage facilities, the careful selection of ore column widths between these reservoirs is crucial for minimizing the risk of structural failure, optimizing salt rock resource utilization, and enhancing the construction and operation of gas storage reservoirs. In current practices, square triangular arrangements are commonly used in designing well layouts for reservoir groups to balance stability and economic considerations. This study, conducted in the context of the Jintan salt cavern gas storage project in Jiangsu Province, employed FLAC3D to create a finite element model for proposed gas storage configurations. A comprehensive analysis of the long-term operational safety of salt cavern gas storage with triangular well layouts was carried out. Various indices were examined, covering aspects such as cavern wall displacement, characteristics of the plastic zone, volume shrinkage, safety coefficients, seepage range, pore pressure fluctuations, and seepage volume. The study also considered the mechanical behavior of hexagonal columns within the surrounding rock during extended storage operations, leading to the optimization of allowable widths for these columns. The results indicate that, at operating pressures ranging from 6.5 to 17 MPa, the permissible column width should exceed 1.67 times the maximum cavern diameter to ensure compliance with criteria for long-term stability and containment within a square triangular layout. These findings provide valuable insights into determining the optimal allowable widths of salt cavern columns for positive triangular layouts.

The δ18O and δ2H fingerprint of the Scioto River: A detailed look into seasonal and spatial variations in the context of Ohio rivers

The global expansion and increased intensity of the human footprint causes modification of natural freshwater systems, particularly in densely populated areas. This poses a challenge for society where the water systems that humans rely on for domestic, industrial, and agricultural water are also the most physically and chemically disturbed. There is an urgent need to study hydrologic processes in surface water systems that flow through human-altered landscapes to better manage freshwater resources. Stable water isotopes (δ18O and δ2H) can be used as natural tracers to study the hydrologic patterns of rivers as they flow through these agricultural and urban landscapes. In this work, we investigate the seasonal and spatial hydrologic patterns of the Scioto River in Ohio, USA by analyzing stable water isotopes. Samples were collected over the course of one year (2021) from five locations that transition from intense agriculture to the metropolitan area of Columbus, Ohio. Results show that the Scioto River isotopic composition reflects a dampened seasonal precipitation pattern, where δ18O and δ2H are enriched in summer and depleted in winter. Scioto River transect patterns show that there was greater variability in stable isotopic composition in the upstream, agricultural reaches of the river. As the river flowed through the metropolitan Columbus area two “river-like” reservoirs generated isotopic homogenization along the Scioto without inducing isotopic enrichment, which is commonly observed from evaporation in river-reservoir systems. The Scioto River was put in context with other major Ohio river systems, to show the variability across the state. Isotopic composition differences among and within river systems across the state were induced by a combination of different environmental factors, like precipitation and river baseflow contribution. They were further affected by humans through land use modification and the constructions of dams and reservoirs. Overall, this study underlines the influence that urbanization and intensive agriculture have on rivers. In the context of the current hydrologic changes induced by climate change, this work emphasizes the importance of studying urban river hydrology in the context of joint climatic and human influences.

Refined machine learning modeling of reservoir discharge water temperature

Water temperature is a controlling factor for physical, biological, and chemical processes in rivers, and is closely related to hydrological factors. The construction of reservoirs interferes with natural water temperature fluctuations. Hence constructing a model to accurately and efficiently predict the reservoir discharge water temperature (DWT) is helpful for the protection of river water ecology. Although there have been studies on constructing efficient and accurate machine learning prediction models for DWT, to our knowledge, there is currently no research focused on hourly scales. The study proposed in this paper is based on high-frequency monitoring data of vertical water temperature in front of a dam, water level, discharge flow, and DWT. In this study, six types of machine learning algorithms, namely, support vector regression, linear regression, k-nearest neighbor, random forest regressor, gradient boosting regression tree, and multilayer perceptron neural network, were used to construct a refined prediction model for DWT. The results indicated that the SVR model using the radial basis function as the kernel function had the best modeling performance. Based on the SVR model, we constructed a 1–24 h early warning model and optimized the scheduling of DWT based on changing discharge flow. In summary, a machine learning model for DWT that can provide short-term forecasting and decision support for reservoir managers was refined in this study.

The multiple services of hydropower plants in the context of sustainable electric sector in Brazil

At the worldwide level, the hydroelectricity corresponds to 54% of all renewable electricity, 15% of total electricity generated and only 3% of all total primary energy. In Brazil, hydropower produces 74% of all renewable electricity, 57% of electrical energy and 11% of all total primary energy (EPE, 2023). As all over the world, the construction and operation of large artificial reservoirs until the mid-twentieth century was seen in Brazil by government and by the general public as important infrastructure investment for economic development and improvement of well-being. Nowdays, investments in hydropower plants are re-gaining importance given not only its ability in supporting the transition of the electricity grid to get rid of dependence on fossil fuels but also in the provision of numerous other services. In particular, Brazilian hydropower plants contribute to multiple water resources management services such as flood and drought control, groundwater stabilization, water quality management, river navigation, irrigation, leisure and tourism and aquaculture around the country. The article discusses the multiple services provided to society by hydroelectric power plants within the context of sustainability in Brazil.

A multifunctional synergy development evaluation model of the impact of the cascade reservoir construction sequence on basins

Considering the mass reservoirs construction, it is important to study the cascade reservoir construction sequence, which directly affects the water and sediment resource allocation, ecological environment restoration, and socioeconomic development of the basin. Thus, we constructed an evaluation index system by comprehensively considering the basin water and sediment discharge index, basin ecological and environmental maintenance index, and basin social and economic development index. The evaluation model was established to assess the impact of the cascade reservoir construction sequence on basin multifunctional synergy development index. The model was applied to evaluate the cascade reservoir construction sequence in the Yangtze and Yellow River Basin of China. The results revealed that: (1) The basin water and sediment discharge index, basin social and economic development index, and basin multifunctional synergy development index benefits gradually increased, the basin ecological and environmental maintenance index benefits progressively decreased in the Yangtze and Yellow River Basin. (2) The basin water and sediment discharge index, and basin ecological and environmental maintenance index of the planned cascade reservoir construction sequence ranked top in the Yellow River Basin; the basin water and sediment discharge index, and basin social and economic development index of the planned cascade reservoir construction sequence ranked top in the Yangtze River Basin. (3) The cascade reservoir construction sequence focused more on basin social and economic development index benefits when the level of national economic development was low, and more on basin water and sediment discharge index benefits when it was high. (4) Reservoir capacity and installed capacity were the main factors influencing the cascade reservoir construction sequence in the Yangtze and Yellow River Basin, respectively. These findings provide useful information regarding the cascade reservoir construction sequence.

Prediction Study on the Impact of Engineering Waste Rocks on Water Quality During Reservoir Construction

The impact of dammed reservoirs on the local ecological environment during the operational phases has garnered significant attention. However, there is limited research on the ecological risks posed by reservoirs during the construction period, particularly regarding the waste rock at the bottom of the reservoir. Based on the results of release experiment, the water quality risks of engineering waste rocks to reservoirs were analyzed by a three-dimensional model using the MIKE 3 FM HD and ECO Lab module. The calculation results showed that as the waste rock yards are inundated, SO42− and Fe3+ in the reservoir are released and gradually affecting the water quality in the area in front of the dam. During the process of water storage, the release of pollutants from the waste rocks at the bottom of the reservoir had a significant impact on the underlying water body after two months and then spread from the bottom to the upper layer of water. After three months of water storage, when the water level of the reservoir reached 867 meters, the pollutants released by the waste rock had an impact on the surface water quality. After four months, the release of pollutants from the waste rock yards essentially ceased, and the pollutants gradually accumulated in the bottom water body in front of the dam after dilution and diffusion. In the future, special attention should still be given to the risk assessment of pollutants in the bottom sediments during long-term operation and management of the reservoir.

Crustal response to water loads and expansion of triggered seismicity around the Xiluodu Reservoir, Southwest China

&lt;p&gt;The transition to low-carbon energy generation requires a diverse portfolio of energy sources. Large hydropower stations play a crucial role in providing eco-friendly energy but can lead to crustal deformation and seismic activity due to reservoir impoundment and discharge. The mechanism behind how impoundment-induced deformation influences reservoir-triggered seismicity remains unclear. We investigate this at the world��s 4&lt;sup&gt;th&lt;/sup&gt; largest hydropower station in Xiluodu, China, using interdisciplinary analyses of relocated earthquakes, geodetic data, and numerical simulations. Geodetic observations confirm both a linear elastic response to hydrologic loading and the transition towards a relaxed and flexural response. Notably, approximately 81% of the earthquakes since impoundment occurred within ~15 km of the subsidence center. These events temporally relate to rapid hydrologic loading/unloading periods, with their spatiotemporal outward migration potentially caused by viscous relaxation of load stresses in the lower crust and upper mantle. The reservoir-induced flexural deformation and subsequent viscous relaxation may control the distribution and expansion of triggered seismicity. This research highlights the urgent need to enhance geohazard monitoring efforts around the subsidence center and emphasizes the vital importance of carefully considering this factor during the construction of large reservoirs to mitigate potential seismic risks.&lt;/p&gt;

Functional requirements for an intelligent system for monitoring the impact of beaver activity on ecosystems

The consequences of beaver activity affect the condition of natural and anthropogenic systems. The paper presents a brief description of possible consequences of beaver settlement in the natural territory. The monitoring of the number of individuals, the control of the environment and the possibility of forecasting its changes require the development of specialized software tools. The paper presents a description of the main functionalities of such a system and a list of users to whom they are available. These include the detection of beaver habitats, the prediction of environmental changes due to the construction of dams and reservoirs, and the regulation of animal fishing processes. In addition, lists of data are presented, the use of which will make it possible to realize the presented functionalities. The proposed intelligent system will allow forest specialists to monitor the state of natural areas, to specify the list of measures to ensure the preservation of natural and anthropogenic objects. From the point of view of state management, it is possible to create an up-to-date and constantly updated register of beavers and to control their fishing.

The results of the study on the technical condition of hydraulic structures in reservoirs

The article discusses the results of a study on the technical condition of operated hydraulic structures in reservoirs. During operation, various effects of long-term use, shortcomings in design, construction and operation of reservoirs as well as factors affecting the reliability of their hydraulic systems are manifested. The article also provides main criteria for ensuring reliable operation of reservoir systems.

Determination of the stress-strain state of models of steel cylindrical tanks using the “ANSYS” program

In the world, metal cylindrical shell constructions occupy a leading position in the construction of reservoirs for various purposes, bodies of water pressure generating towers, television towers, chimneys, lighting masts, tower cranes and similar engineering structures. In this direction, in developed countries such as the USA, Germany, Japan, and Russia, special attention is paid to increasing the load-carrying capacity of cylindrical shell structures, ensuring earthquake resistance and priority, reducing metal consumption, preventing the resulting deformations, and thereby ensuring their reliable operation. In this regard, one of the important tasks is to increase the priority of various construction structures, optimize their shape and size, improve existing calculation methods, and develop modern advanced methods of construction preparation and assembly.

Metal(loid) Partitioning and Transport in the Jinsha River, China: From Upper Natural Reaches to Lower Cascade Reservoirs-Regulated Reaches

Riverine contamination of metals and metalloids is a growing global concern. However, our understanding of how cascade reservoirs influence the fate of these pollutants remains limited. In this study, we focused on the Jinsha River, a typical large river polluted with metal(loid)s in Southwest China, to investigate the partitioning and transport of these substances from the upper natural reaches to the lower cascade reservoirs-regulated reaches during both flood and dry seasons. Results revealed that the rapid urbanization and industrial development following the construction of reservoirs led to significant copper (Cu), nickel (Ni), lead (Pb), chromium (Cr), and cadmium (Cd) pollution. Through various analytical techniques such as correlation analysis, principal component analysis, redundancy analysis, and structural equation modeling, we determined that reservoirs had a profound impact on solid-associated parameters, including particulate organic matter (POM), suspended solid concentration (SSC), and median particle diameter (D50). These parameters, in turn, affected the fate of metal(loid)s through processes like sorption-desorption and dissolution-precipitation. High POM concentrations and low SSC and D50 values resulted in the precipitation of most particulate metal(loid)s, thereby reducing their transport across reservoirs. As river water moved downstream across the reservoirs, the percentage of particulate metal(loid)s decreased by 6.1% for arsenic (As), 38.3% for Cu, 74.9% for Ni, 36.8% for Cr, 17.8% for Cd, and 41.9% for Pb, respectively. Furthermore, the cascade reservoirs had cumulative effects on the deposition of particulate metal(loid)s, particularly concerning Cr, Cd, and Pb in the final reservoirs. Human health risk assessments indicated that dissolved As and Pb posed potential non-carcinogenic threats to residents. Despite the fact that reservoirs captured most particulate metal(loid)s, the transport of dissolved As and Pb across the reservoirs still impacted the safety of downstream drinking water. Therefore, in cascade reservoir systems, the concern regarding dissolved metal(loid) pollution remains a priority for future reservoir management.