Dam Operation Research Articles

Long-term analysis of sediment load changes in the Red River system (Vietnam) due to dam-reservoirs

The sediment regime of the Red River system, the second largest in Vietnam, has undergone changes since the implementation of dams and reservoirs, with implications for downstream river processes. We analyzed long-term datasets of daily discharge and suspended sediment concentrations collected at key gauging stations downstream of the three main tributaries: HB on the Da River, YB on the Red River (main channel), VQ on the Lo River, and ST, the outlet of the Red River system. The results indicated a sharp reduction in the annual sediment load transported by the Red River system, as observed at the four stations. For example, at the ST station, there was a dramatic decline of 91% in sediment load, dropping from 117.9 × 106 ton/yr in the period 2009–2021 to 10.5 × 106 ton/yr in the period 1958–1987. The Red River system experienced two notable declines in sediment load. The first decline occurred from 1988 to 2008, which can be attributed to the commencement of Hoa Binh dam's operation in 1988. The second decline has taken place since 2009, coinciding with the utilization of new dam-reservoirs. Meanwhile, an abrupt change in water discharge was observed clearly since the end of 2008 at all four stations. However, the reductions in water discharges were found to be less pronounced when compared to the sediment budget. Based on our analysis, we concluded that the impacts of dam-reservoirs have had a more substantial influence on the system compared to variations in climate, such as air temperature and precipitation.

A two-stage decision-support system for floating debris collection in reservoir areas

The accumulation of floating debris is one of the main challenges of water conservancy projects, which may pollute the vulnerable ecosystem of the reservoir area and impose significant risks on waterway transportation and dam operations. Due to the dynamicity and uncertainty caused by water flow, the collection of floating debris is much more complicated than on-land waste collection. In this paper, we propose a two-stage decision-support system to optimize the task allocation and routing decisions for floating debris collection in the reservoir area, where the first stage is proactive planning based on historical/observed data and the second stage is reactive planning based on real-time data. The primary objective is to minimize the total collection cost while simultaneously ensuring the accumulation areas with high risks are prioritized in the daily collection plan, and both genetic algorithm and simulated annealing algorithm are used to solve the optimization problems. The proposed method is validated with a real-world case study at Wushan County in the Three Gorges Reservoir area. The computational results show that the level of time-dependent penalty cost on service priority, the types of collection ships, and the number and locations of unloading points are important influencing factors to the cost and responsiveness. Furthermore, the proposed two-stage decision-support system can help effectively optimize the operational planning of floating debris collection in reservoir areas.

Development of the hydrological regime of the Uzh River under backwater conditions to minimize the urban environment risks

The impact of high dams with large reservoirs with long-term regulation is covered in the scientific literature quite widely. The information and recommendations on the use of low-head dam for the creation of the low backwater are not enough. Large dams reduce the mean annual flow downstream, the magnitude and frequency of floods, lead to the accumulation of suspended solids, nutrients compounds (nitrogen, potassium, phosphorus), which, together with increasing temperature leads to the “blooming” phenomenon of the reservoir and the overgrowth, create barrier for sediments transferring and fish. The main reason of the deterioration of the water quality is the water retention time in the formed reservoir and anthropogenic pollution, although the literature rarely provides quantitative data of the water retention time for the evaluated reservoir. The environment risks assessment of the impact of the reservoir should include the calculation of the water retention time, the presence of pollutants in the river, which may indicate future negative effects. The hydrological regime of the river after the backwater creation should correspond to the natural flow with the floods passage by the entire width of the river bed, which will significantly improve flood management, sediments transport and washing the river bed. The significant risk is the shallowing of the river downstream, the amount of water discharged into the downstream should be at least 75% of the river flow. Releasing the flow to the downstream with an overflow or through fish passage structures allows to enrich the water with oxygen. In order to preserve biodiversity, it is necessary to create or leave islands and shallow water areas for the needs of waterfowl. To ensure an environmentally friendly regime operation of the low-head dam the crest of the spillway structure should be at the bottom level along the entire cross section. The low-head dam should be provided with automatic control system and communication with the hydrometric station for a quick response to the flow changes in the river.

" Iraqi-Turkish relations after 2014 and their future "

Turkey worked to restore its political relations with Iraq after the government of Mr. "Haider Al-Abadi" won the confidence of Parliament in 2014، but this relationship faced a set of thorny issues، including the terrorist ISIS occupation of the city of Mosul and its control over a third of the country's area، and the Turkish military intervention in Regions of northern Iraq under the pretext of protecting national security، in addition to the water crisis and the decrease in the level of the Tigris and Euphrates rivers due to the operation of the Turkish dams.

Dam System and Reservoir Operational Safety: A Meta-Research

Dams are critical infrastructure necessary for water security, agriculture, flood risk management, river navigation, and clean energy generation. However, these multiple, and often conflicting, objectives introduce complexity in managing dam operations. In addition, dam infrastructure has been evolving as complex systems-of-systems with multiple interacting components and subsystems, all susceptible to a wide range of uncertainties. Such complexities and uncertainties have triggered extensive research initiatives focused on dam systems and reservoir operational safety. Focusing on the latter, this paper meta-researches (conducts research-on-research) previously published studies to identify the critical research gaps and propose future research directions. In this respect, this paper first performs a quantitative analysis of the pertinent literature, using text mining and subsequent topic modeling, to identify and classify major and uncover latent topics in the field. Subsequently, qualitative analysis is conducted to critically review the identified topics, exploring the concepts, definitions, modeling tools, and major research trends. Specifically, the study identified seven topics: optimization models; climate change; flood risk; inflow forecasting; hydropower generation; water supply management; and risk-based assessment and management. The study also presents three main research gaps associated with the limitations in modeling concepts, modeling tools capabilities, and the lack of resilience-guided management of dam operational safety. Overall, this study presents a road map of the currently available dam and reservoir operational safety research and associated knowledge gaps, as well as potential future research directions to ensure the resilience of such critically important infrastructure, especially in the age of climate change.

The role of water management and river morphology on stranding pool formation

Fish can be stranded in pools during flow recessions that may occur naturally or as a result of dam operations. Past studies have recommended dam operation guidelines that only consider water surface elevation (WSE) recession rate to reduce fish stranding potential. Here, we holistically consider the role of flow, WSE recession rate, and river-floodplain topography under unregulated and regulated flow regimes to predict the potential of stranding pool formation. The proposed methodology leverages advances in two-dimensional (2D) surface hydraulic (HD) modeling and high-resolution topobathymetric LiDAR surveys. We applied this method to the South Fork Boise River (SFBR), Idaho, USA. We developed a 2D HD model supported by meter-resolution topobathymetric data to simulate channel and floodplain hydraulics and stranding pool formation for different flow scenarios.Comparison between modeled and fieldsurveyed stranding pool locations shows good match, supporting the use of this method to predict stranding pool potential. Results show that potential for stranding pool formation (number of pools and their surface area) increases with flow for the same flow recession rate. Contrary to expectations, our model predicts that unregulated flows have a considerably higher number of potential fish stranding pools than for regulated flows in the SFBR. The reach-average WSE recession rates were higher for unregulated (0.07 to 0.09 cm/h) than for regulated (0.02 to 0.04 cm/h) flow based on daily mean flows. Our study has shown the importance of river and floodplain morphology and hydraulics to predict fish stranding pool locations and analyze impacts of flow regulations on fish stranding. This approach may provide helpful information to identify potential fish stranding pools and mitigation and to manage for fish stranding issues in regulated and unregulated river systems.

Deciphering the black box of deep learning for multi-purpose dam operation modeling via explainable scenarios

Operational rules of a multi-purpose dam are hidden due to missing of the records for decision-making processes. This study aims to assess the explainability of a deep learning model for the multi-purpose dam operation of Seomjin River, Juam, and Juam Control dams in the Seomjin River basin, South Korea. In this study, the Gated Recurrent Unit (GRU) algorithm is employed to predict the hourly water level of the dam reservoirs over 2002–2021. First, the GRU models are trained and validated using the local dam input (precipitation, inflow, and outflow) and output (water level) data to examine similarity/singularity in the operational patterns of these three dams. The hyper-parameters are optimized by the Bayesian algorithm. Secondly, the sensitivity test of the trained GRU model to altered input data (−40%, −20%, +20%, and +40%) is conducted to understand how the GRU models facilitate the input data to simulate the target output data (herein, hourly water level), which is known as explainability scenarios. Results show that the trained GRU models predict the hourly water level well across the three dams (above 0.9 of the Kling-Gupta Efficiency). Results from the explainability scenarios show a linear response to the altered inflow rates, but no response to altered precipitation. Furthermore, the GRU models show a site-specific response to altered outflow rates, depending on whether the observed outflow rate-water level relationship is linear or not. This study hints how to decipher the black box of deep learning in multi-purpose dam operation modeling via explainable scenarios.

A deep learning prediction model of DenseNet-LSTM for concrete gravity dam deformation based on feature selection

Dam deformation can comprehensively reflect the operational status of the dam. Thus, it is significant to build a dam deformation prediction model with high accuracy for the operation of concrete gravity dams. The concrete gravity dam is a complex and dynamic system. Based on the current prediction methods, such as the statistical models or machine learning (ML) models, it is a challenge to capture the complicated relationships between deformation and various features, as well as the features and time. As a result, we have proposed a deep learning model called DenseNet-LSTM, which combines the densely connected convolutional Network (DenseNet) and long short-term memory (LSTM) network. Meanwhile, correlation analysis and random forest (RF) are also adopted to evaluate and select deformation features. In the case study, the deformation monitoring data of multiple points at different elevations in the same section of a typical concrete gravity dam in southwestern China are selected to verify the model. For all the monitoring points, the correlation coefficient of the proposed model is more than 0.99. The result shows that the DenseNet-LSTM model can reveal the dynamic evolution process of deformation of the concrete gravity dam. Compared with the CNN-LSTM, LSTM, and ML-based models, the accuracy of the proposed model is higher and its generalization ability is better, which provides new methods for dam safety monitoring.

Impact of interbasin transfer hydroelectric project on downstream aquatic habitat

AbstractThe recent surge of anthropogenic activities like damming is causing a severe threat to the aquatic ecosystem. A scope of minimizing the degradation of biota exists by modifying the dam operation policy. This can be achieved by releasing a minimum environmental flow (EF), which further requires more scientific investigations. The present study investigated the impact of an interbasin transfer hydropower dam on the downstream habitat of an endangered fish species, Tor putitora, using an adaptive modelling framework. The framework consists of coupling a reservoir operation and a hydrodynamic model. This study analyses the scope of releasing different EFs from a hydropower dam to meet the environmental flow requirement (EFR) at downstream with satisfactory power production efficiency. The EFR was estimated using flow duration curve and Tennant's method. A lean period inflow hydrograph was incorporated into the model with a series of alternate EFs. Two scenarios were explored, with 4 and 6 h of peaking hours, along with the three cases of different initial reservoir storage. The total usable area over the river reach of the mentioned fish species was evaluated from the flow parameters simulated by the hydrodynamic component of the model. The power production efficiencies and area utilization rates were assessed in all these cases to prepare an easy‐to‐use decision support tool in a tabular form depicting the possible states of EF. The generalized methodology adopted in this analysis will help the decision‐makers quantify EF to be released from the dam within an acceptable power generation efficiency.

Experimental Investigation and Field Evaluation of Anti-Scouring and Protection Material of Earth-rock Dam

Earth-rock dams have important flood control, silt reduction, water supply, and ecological benefits, but extreme rainstorms seriously threatens the safe operation of earth-rock dams. Therefore, based on the self-developed soil stabilizer, the laboratory tests and field evaluation tests for the anti-scouring performance for solidified soil were carried out to achieve the requirements of non-collapse or slow-collapse for the earth-rock dams. Firstly, the basic performance indexes of solidified soil using soil stabilizer and 42.5# P.O Portland cement were compared. Then, clear water scouring and muddy water scouring tests were carried out based on the self-developed anti-scouring test system. Furthermore, an earth-rock dam test dam was built by using the solidified soil as the material, and a field scouring test was carried out to analyze the corresponding hydraulic elements. Finally, a safety inspection of the dam structure was carried out. The results demonstrate that when compared to the results of solidified soil using 42.5# P.O Portland cement under the same contents, the strength and durability of soil stabilizer solidified soil rose by more than 5% and 10%, respectively. The performance of soil stabilizer is better than that of 42.5# P.O Portland cement. After 10 hours of approximately 15 m/s water flow scouring through the experiment test, the performance of the solidified soil under the higher content of soil stabilizer can meet the design requirements of anti-scouring performance. The field test results show that the maximum scouring depth is less than 2 cm, and the average scouring depth is less than 0.8 cm. The monitoring results show that the displacements are less than 5 mm, and the dam structure is safe and stable. It is recommended that the content of soil stabilizer should be higher than 20% to meet the overflow safety requirements of small and medium earth-rock dams.

Changes in Dissolved Inorganic Carbon Across Yangtze River Regulated by Dam and River‐Lake Exchange

AbstractThe boom in dam construction and continuous river‐lake exchange has had a profound impact on the transmission and transformation of riverine dissolved inorganic carbon (DIC). An in‐depth understanding of the change mechanisms of DIC concentrations and sources driven by dam operation and lake recharge is crucial for regulating greenhouse gas emissions and evaluating the impact of DIC on the global carbon cycle. This study investigated dam‐ and lakes‐driven DIC via the concentration and δ13C of DIC, combined with anions, cations, δD and δ18O in the main stream of the Yangtze River. DIC showed a decreasing trend from upper reach (2,262.31 ± 113.69 μmol kg−1) to lower reach (1,771.61 ± 89.36 μmol kg−1). Carbonate dissolution proportion (from 36.45% to 28.44%) and atmospheric CO2 proportion (from 37.51% to 22.94%) of DIC decreased from upper reach to lower reach, whereas soil CO2 proportion of DIC (from 26.01% to 48.63%) increased. The control of dam operation on DIC biogeochemical process was revealed from different time scales. From the perspective of short‐term seasonal changes (from 2020 to 2021), the mineralization of organic matter in the dry season strengthened CO2 degassing and calcite precipitation, reducing the DIC and increasing the proportion of soil CO2. Meanwhile, longer periods of runoff retention provided sufficient time for water–rock reactions in the wet season and increased the DIC and carbonate dissolution source in the reservoir area. On a long‐term scale (from 2009 to 2021), a decrease in pH driven by sediment mineralization contributed to an annual increase in DIC in the reservoir. The flow of lakes mixed into the mainstream was revealed by the enrichment of δ18O, and river‐communicating recharge decreased the DIC and carbonate dissolution source. We show that dam operation and lake inflow change DIC concentrations and sources and therefore need to be considered in the transmission and transformation processes of DIC in the river‐ocean continuum.

Preliminary assessment of the suspended sediment dynamics in the Sikkim–Darjeeling Himalayan river

The Sikkim–Darjeeling Himalaya region receives the highest amount of rainfall along the whole southern Himalayan margin and is known for the occurrence of extreme hydrometeorological and geomorphological events. The massive amounts of water and sediment transported each year through the mountain part of the Teesta River drainage system (∼8,150 km2)––the largest river in the region––have been severely impacted by dam construction in recent decades. The aim of the current study was to determine, for the first time in this part of the Himalaya region, the dynamics of suspended sediment transfer at a number of points distributed through the mountainous part of the Teesta River catchment prior to dam construction and preliminarily assess the impact of dam operations on the suspended sediment. Sediment sources were identified using a database of landslide inventories from 1965 to 2019, combined with visual interpretation of satellite imagery from the U.S. Corona programme and Google Earth. Hydrological and sediment data up to the second half of the 1990s were used to reconstruct the discharge and suspended sediment dynamics before direct human intervention in the river channels. The beginning and end of the construction of the reservoirs was determined by analyzing satellite images. The impact of dam operations on the suspended sediment was compiled from the available literature. The results of the current study indicate that the primary sources of sediment are landslides caused by the interaction of rainfall and road undercutting of slopes as well as channel erosion. During extreme rainfall events, the influence of deforested areas in the mobilization and delivery of sediment to the river network increases. The current analysis reveals that reconstruction of the suspended sediment dynamics should take into account the course of extreme events responsible for supplying material to the river network, as well as the long-term remobilization of already deposited sediment in the river channel. It was found that the mean suspended sediment load (SSL) following extreme rainfall, flooding, and landslides in the Teesta River catchment can be up to four times higher than its average values for the same catchment unaffected by such an event, and the effects can be observed for more than a decade afterwards. Under these conditions, the mean suspended sediment yield can reach 12,000 and up to 20,000 t/(km2·y) in individual years, which is among the highest in the Himalaya region and, indeed, the world. The construction of 13 dams in the last 30 years has disrupted the hydrological regime and sediment transport in the Teesta River catchment along 70% of its main course and largest tributaries, and this has resulted in the selective retention of coarser material in the reservoirs and a reduction in the SSL in the Himalayan piedmont. The high density of the dams suggests that further transport of suspended sediment will depend on the efficiency of the water and sediment management at the reservoirs, which may be affected by irregular natural extreme events.

Groundwater-surface water interactions in a semi-arid irrigated agricultural valley: A hydrometric and tracer-aided approach

The purpose of this study was to assess hydrological controls (e.g., rainfall, irrigation practices, river discharge, dam operation, evaporation) on surface (SW)- ground water (GW) interactions in an irrigated valley within semi-arid Patagonia Argentina (−65.49 W, −43.29 S). We combined different sampling designs (watershed/sub-watershed scales, longitudinal and monthly samplings) from 2015 to 2019 to investigate the temporal and spatial variation of hydrometrics, electrical conductivity (EC) and stable isotope composition of surface and ground water. Results showed that plant transpiration in the upper basin, evaporation in the middle basin and the reservoir dynamics modified water salinity and left an imprint in stable isotopes. Water tables in the irrigated valley were high (0.5–2 m level from soil surface) and presented higher salinity than river water. Groundwater salinity, temporal variation of water table levels and stable isotopes suggested that groundwater is subjected to evaporation, is recharged from field seepage and, at a lesser extent, from local rainwater. River salinity increased downstream of the irrigated valley during the whole study period (3 years), showing the effects of agriculture and urbanization. EC also responded to the opening and closing of irrigation channels. EC and daily discharge statistical analysis revealed that groundwater recharge the stream below a threshold discharge of 26 m.s−1; with river salinity increasing linearly as daily discharge decrease. This study illustrates the deep modifications that agricultural systems, mainly surface irrigation, produce on semiarid watersheds. Given that SW and GW components are currently not isolated and flow regulation and irrigation practices are playing a critical role in soil quality and river chemistry at low flow conditions, a conjunctive water management strategy must be implemented in order to prevent further land and water quality degradation.

Applying flow convergence routing to control sediment erosion and deposition locations in a dam's backwater zone

Despite studies showing that dams have significant effects on the sediment dynamics and evolution of a river upstream of a dam, the knowledge of relationships between river topography and sediment transport in a dam's backwater zone has hardly been applied in reservoir sedimentation management. This study investigated the potential of an alternating sequence of engineered topographic nozzles and oversized landforms, utilizing flow convergence routing theory, to redistribute sediment erosion foci in a dam's backwater zone for remote mountain reservoirs with a sediment storage capacity of ~105 m3. To test scientific ideas and engineering alternatives, the current topography of the backwater zone upstream from Our House Dam on the confined, mountainous Middle Yuba River, California, was virtually re-contoured into different scenarios for numerical experimentation. As most of the dam's backwater zone is filled with sediment (a common global problem) in a narrow, confined canyon, two-dimensional hydrodynamic modeling was useful for evaluating erosion patterns resulting from different manipulations. The results found that high velocity concentrates through nozzles and dissipates through oversized landforms, resulting in the latter exhibiting hydraulics indicative of functioning as sediment settling basins. These basins can be located away from the dam where key infrastructure needs clearance from sedimentation. As flow increases through the sequence of nozzles and oversized landforms, each nozzle's hydraulic jet will persist farther into the oversized area. Moderate in-channel flow (daily recurrence of ~5–30 %) was best for creating conditions to force deposition of sediment in oversized landforms. At high enough discharge (recurrence of <1–5 %) significant sediment erosion can occur throughout the constructed terrain in the backwater zone, so the whole topographic scheme can become overwhelmed and ineffective. Thus, the performance of re-contouring as an aid in reservoir sedimentation management is location and flow-dependent, necessitating careful design refinement for local conditions and assessment of financial benefits and costs. Overall, this study opens a new realm of sediment management for dam operators and regulators hard-pressed to know what to do when a moderate-sized mountain reservoir with poor accessibility has a sediment storage capacity of ~105 m3.

Spatial and wavelet analysis of precipitation and river discharge during operation of the Three Gorges Dam, China

The Three Gorges Dam and Reservoir on the Yangtze River is one of the world's largest dams. After the dam's construction in 1997, the reservoir started filling up, expanding to a size of over 600 km2. Therefore, its possible influence on maintaining the size and water level of this waterbody is significant and concerning. This research utilized wavelet coherence analysis to examine the temporal correlation and phase coherence among various datasets, including dam injection (1998–2018) and discharge (2003–2018) data, ground station precipitation data along the Yangtze River (1998–2020), and river discharge raster maps 1998–2018. The analysis revealed a strong coherence between dam operation and river discharge rates, as well as a minor seasonal coherence between dam operation and precipitation. The periodic properties of the datasets indicate that, in addition to the general seasonal changes observed in the wavelet coherence analysis, other periodic signals in the datasets are also coherent over time. This coherence may be attributed to the simultaneous impacts of dam operation on precipitation and river discharge. The reasons for this coherence are still unknown, and further studies are required, incorporating information on soil moisture, groundwater levels, air humidity, and the monsoon, to understand how the dam affects them.

Cairn Burial of the historical period around Khansaar dam, Toujerdi district of Fars province, Iran

In the historical period, the Fars region in Iran was one of the most important cultural areas in the world, and it is considered the origin of the ancient Achaemenid and Sasanian empires. Although some areas of Sarchahan county have been studied well, no archaeological survey has been conducted there until the construction of Khansaar Dam and rescue operations in its area. As part of an archaeological survey in the Toujerdi district of Sarchahan county, 92 cairn burials were found. According to the survey conducted in five areas around Khansaar Dam, the distribution of cairn burials, commonly known as Khereftkhaneh, has been identified. From Pakistan to the west of Iran, this type of burial method can be observed, and the burials of Toujerdi region can be considered associated with burials from the Parthian and Sasanian periods.

Assessing hydrological alterations in Malibamatso River using River Flow Health Index

ABSTRACT Hydrological regimes substantially influence the biodiversity of river ecosystems, and hydrological alteration is considered the primary driving force within these ecosystems. The River Flow Health Index method is used to investigate the hydrological alterations of the Katse Dam on the Malibamatso River. The method utilizes river discharges for 1986–2021 at a downstream gauge station in the basin. 171 hydrological parameters evaluated from the river flows are used to estimate the River Flow Health Index, which measures the conditions before and after the dam operation. The departure of the river flows from the natural state is provided on a 0–1 scale. Under the prevailing reservoir operation, substantial hydrological alterations are observed, especially for the rate of change component. In general, the Katse Dam impoundment alters the hydrological regimes, with the River Flow Health Index of 0.515 suggesting major alterations in different flow regime components. The study provides major insights for river scientists and managers to re-operate the dam and re-implement environmental flows to restore natural flow conditions.

Effects of Hydrological Drought Periods on Thermal Stability of Brazilian Reservoirs

Droughts can impact ecosystem services provided by reservoirs. Quantifying the intensity of droughts and evaluating their potential effects on the thermal stability of reservoirs are subjects that demand greater attention, due to both the importance of temperature on aquatic metabolism and the climate change scenarios that predict an increase in the frequency of extreme weather events. This study aimed to investigate drought periods in ten Brazilian reservoirs and to discuss their effects on each reservoir’s thermal stability. The Standardized Precipitation Index at a twelve month timescale (SPI-12) was applied to identify the hydrological drought periods. One-dimensional vertical hydrodynamic modeling was used to simulate the water balance and the thermal dynamics in the reservoirs. Schmidt Stability Index (St) was calculated to assess the thermal stability of the reservoirs. The drought periods identified by the SPI-12 are related to decreasing water levels of the reservoirs, but the dam operating strategies and the upstream influence of cascading reservoirs are important drivers of fluctuations. A significant difference in St between wet and dry conditions was found only during summer for all reservoirs. Thus, this study identified alterations in thermal regime during drought periods according to the seasons and the reservoirs characteristics.

Scientific Research Support for the Construction and Operation of Inwashed Tailing Dumps at Operating Sites

Accidents at mining enterprises, including tailing dumps, pose significant threats to human lives, structures, and the environment. This study focuses on designing, constructing, and operating tailing dumps in Siberia’s northern region. To ensure safety and minimize environmental impacts, comprehensive scientific monitoring and research were conducted at all stages, including design, construction, operation, and disposal. The aim was to create a uniform mass within the dam body, requiring understanding of the tailing structure and technological characteristics during placement. Parameters like particle size, distribution, density, and moisture content were considered to assess the physical and geometric properties of the tailings. Estimated monitoring was introduced as a permanent model to quickly assess the stability of hydrotechnical constructions. This involved monitoring changes in exploitation properties, structure height, beach length, and water levels. A controlled inwashing technology for subsequent dam layers was developed. Complex research facilitated the formulation of an estimated monitoring methodology and an algorithm for tailing dam formation. Practical application demonstrated high reliability and confirmed load-bearing capacity, allowing for the forecast of dam stability and safe execution. Findings led to alterations in work techniques, ensuring safe and efficient operation of tailing dams.

Guide curves in stochastic dynamic programming to optimize operation policies in sequential hydropower dams

The guide curves are tools that specify rules for dam operation that allow reducing the chances of unwanted spill or deficit events. In this research, we analyzed the importance of using guide curves and penalizing the deviation of such curves by the occurrence of surplus volume, or deficit, using optimization tools on an objective function that apply stochastic dynamic programming (SDP), guide curves and reservoir operation simulation all together, to obtain and evaluate biweekly operation policies for hydropower generation purposes. The main dams of the Grijalva River were taken as a case study. The optimization tool is based on sequential decision stages (time intervals) to operate a dam system that considers the restrictions on storage volumes, defined by high and low guide curves. An objective function was considered which maximizes energy generation, it uses coefficients to penalize unwanted events of spills, deficits, and operation conditions outside the limits of the guide curves. In conjunction with the agencies that manage the system, three tests with different guide curves were defined. To analyze their sensitivity in the results (mainly events of spillage) one more test was defined for an operation rule without considering guide curves. The system behavior was simulated with the historical record, where five variables were analyzed: total spills and deficit, minimum and maximum storage, as well as the average energy generated. By using the guide curves, the occurrence of spills and deficits was avoided.