Dam Operation Research Articles

Lessons Learned from Flood Management in Iran

Iran has a longstanding challenge in supplying water during prolonged drought periods. This has drawn considerable attention towards the dam industry over the past four decades, leading to the study, construction and operation of several large dams. These dams played a critical role in controlling the massive floods of 2019 and 2020, among others. Nevertheless, due to the increased intensity and frequency of extreme events because of climate change, the downstream regions of these large storage dams still face significant damages. This is mainly attributed to the insufficient dredging of rivers and tributaries, lack of rule curve and operation guideline for some storage dams, inaccurate prediction of flood volume, violation of land-use and water management action plans, promotion of industries with high water need, and floodplain encroachment. In this study, we aim to evaluate the performance of several large dams in the Karkheh and Karoon river basin, located in southwestern Iran, in managing the floods took place in the aforementioned periods. We also discuss the challenges and the lessons learned, with suggestions for improving the flood management in the country.

Role of changing land use and land cover (LULC) on the 2018 megafloods over Kerala, India

The state of Kerala, India, experienced massive flooding in August 2018. Unprecedented extreme rainfall left the region with huge losses of infrastructure. Several studies reported the role of improper dam operations and climate change in this region. However, changing land use/land cover (LULC) is an important driver of flood modulation; we therefore studied regional LULC changes (over 4 decades) and their impacts on flooding during this event using the Weather Research Forecasting (WRF)-Hydro model. We downscaled the NCEP final operational global analysis data using WRF to provide meteorological inputs for the gridded WRF-Hydro model. WRF downscaled forcing, along with observed discharge, were used to calibrate WRF-Hydro, which was run with the meteorological forcing of the August 2018 floods using LULC corresponding to 1985, 1995, 2005, and 2018. Analysis of LULC change indicated a significant loss of evergreen forest and reductions in shrubland during 1995-2005 and considerable loss of mixed forest during 2005-2018. The most extensive changes in flooding attributes (discharge, inundation area, and flood surface height) were found for LULC changes from 1995 to 2005. Specifically, comparing 2005 to 1995, we found that high flows (estimated by Q10) increased by >10% at many stations (up to ~50% for several locations). The increase in surface water head was ~40% over some parts with increased inundation. During 2005-2018, afforestation measures reduced the steep decline in LC observed during 1995-2005. Thus, the contribution of LULC changes to the August 2018 flooding is mainly due to the deforestation-related changes during 1995-2005. This substantial role of LC in enhancing flood hazards highlights the need to better manage LC in watersheds.

Influence of catastrophic flood on microplastics organization in surface water of the Three Gorges Reservoir, China

The Three Gorges Dam (TGD) is the world's largest hydropower project. It could potentially influence the footprint and transport of microplastics (MPs) in Yangtze River, which is the largest riverine input of oceanic MPs worldwide. In addition to analyzing the MP particles of all size categories and polymer groups, we also evaluated the stability, pollution risk and source identification of MPs after the catastrophic flood of 2020 in the Three Gorges Reservoir (TGR) and downstream of the TGD. We found that the MP abundance (6214 ± 5394 particles/m3) in the TGR water increased by a 57.9% growth after this catastrophic flood. Interestingly, we observed the small-sized MPs (SMPs; < 300 μm) were dominant in the TGR (accounting for ∼65.4% of the total MP particles). After flooding, the main morphological types were fragment and fiber, while the major polymer was polyethylene (PE). Although the MP level was at a low pollution risk, 13.6% of the sampling sites in the TGR water faced potential ecological risks driven by SMPs. In particular, there was no significant difference in the abundances, morphological types, and polymer composition of MPs between upstream and downstream of the TGD (p > 0.05), indicating flooding control operation could weaken the barrier effect of the dam on MPs. Further, based on the conditional fragmentation model, the PE fragments in SMPs of the TGR remained at a stable state. MPs in the TGR mainly originated from anthropogenic activities (wastewater, containers, and agriculture films), with atmospheric deposition as a potential transport pathway for polymers. Our study demonstrates that dam operation during the flood period can influence the MP organization in TGR, providing new insights of the global land-sea transportation of MPs in the Yangtze River.

Dynamic Flow Alteration Index for Complex River Networks With Cascading Reservoir Systems

AbstractLarge dams degrade the river’s health by heavily regulating the natural flows. Despite a long history of research on flow regulation due to dams, most studies focused only on the impact of a single dam and ignored the combined impact of flow regulation on a river network. We propose a new Dynamic Flow Alteration Index (DFAI) to quantify the local and cumulative degree of regulation by comparing the observed controlled flows with the naturalized flows based on a moving time horizon for the highly regulated Colorado River Basin. The proposed DFAI matches closely to dam’s localized regulation for headwater gages and starts to diverge as we move downstream due to increase in cumulative impact of the dams. DFAI considers the impact of dam operations on flow characteristics such as shifting of peak flow occurrence and dampening of peak flows. DFAI estimates the degree of regulation to be small for upstream dams and finds the maximum network regulation to be 2.52 years at Glen Canyon reservoir. DFAI also successfully captures the reduction in cumulative regulation when dam operations (e.g., Hoover Dam) bring the altered flow in synchronization with natural regime due to downstream flow requirements. The impact of San Juan River Basin Recovery Implementation Program is also captured by DFAI as the reduction in network regulation drops by 1.5 years for Navajo Dam. Our findings using DFAI suggest the need to develop naturalized flows for major river basins to quantify the flow alteration under continually changing climate and human influences.

Monitoring Water Quality of the Haihe River Based on Ground-Based Hyperspectral Remote Sensing

The Haihe River is a typical sluice-controlled river in the north of China. The construction and operation of sluice dams change the flow and other hydrological factors of rivers, which have adverse effects on water, making it difficult to study the characteristics of water quality change and water environment control in northern rivers. In recent years, remote sensing has been widely used in water quality monitoring. However, due to the low signal-to-noise ratio (SNR) and the limitation of instrument resolution, satellite remote sensing is still a challenge to inland water quality monitoring. Ground-based hyperspectral remote sensing has a high temporal-spatial resolution and can be simply fixed in the water edge to achieve real-time continuous detection. A combination of hyperspectral remote sensing devices and BP neural networks is used in the current research to invert water quality parameters. The measured values and remote sensing reflectance of eight water quality parameters (chlorophyll-a (Chl-a), phycocyanin (PC), total suspended sediments (TSS), total nitrogen (TN), total phosphorus (TP), ammonia nitrogen (NH4-N), nitrate-nitrogen (NO3-N), and pH) were modeled and verified. The results show that the performance R2 of the training model is above 80%, and the performance R2 of the verification model is above 70%. In the training model, the highest fitting degree is TN (R2 = 1, RMSE = 0.0012 mg/L), and the lowest fitting degree is PC (R2 = 0.87, RMSE = 0.0011 mg/L). Therefore, the application of hyperspectral remote sensing technology to water quality detection in the Haihe River is a feasible method. The model built in the hyperspectral remote sensing equipment can help decision-makers to easily understand the real-time changes of water quality parameters.

Willingness to Pay for Public Benefit Functions of Daecheong Dam Operation: Moderating Effects of Climate Change Perceptions

This study estimates the economic value of the Daecheong Dam for the public function of responding to climate change. It examines the moderating effect of climate change perceptions on value estimates by applying choice experiments (CE). The study specifies three dam function attributes—drought management (DM), flood control (FC), and water quality monitoring (WM)—subdivided into three levels to improve the existing conditions. Survey data from 603 households living in Daejeon, Chungbuk, and Chungnam have been collected to perform the CE. Subsequently, two clusters—high-involvement and low-involvement groups—have been extracted, based on the climate change perception index. The main results of comparing the marginal willingness-to-pay between the two clusters are as follows. The attributes and price variable significantly affected the choice probability to benefit from improvements in the rational signs of the coefficients. This does not violate the independence of the irrelevant alternatives assumption. The improvement values of high-involvement and low-involvement groups are estimated as KRW 21,570 and KRW 14,572 a year per household, respectively. Both show the same value intensities in the order of WM, DM, and FC.

Improving Flow Discharge-Suspended Sediment Relations: Intelligent Algorithms versus Data Separation

Information on the transport of fluvial suspended sediment loads (SSL) is crucial due to its effects on water quality, pollutant transport and transformation, dam operations, and reservoir capacity. As such, adopting a reliable method to accurately estimate SSL is a key topic for watershed managers, hydrologists, river engineers, and hydraulic engineers. One of the most common methods for estimating SSL or suspended sediment concentrations (SSC) is sediment rating curve (SRC), which has several weaknesses. Here, we optimize the SRC equation using two main approaches. Firstly, three well recognized metaheuristic algorithms (genetic algorithm (GA), particle swarm optimization (PSO), and imperialist competitive algorithm (ICA)) were used together with two classical approaches (food and agriculture organization (FAO) and non-parametric smearing estimator (CF2)) to optimize the coefficients of the SRC regression model. The second approach uses separation of data based on season and flow discharge (Qw) characteristics. A support vector regression (SVR) model using only Qw as an input was employed for SSC estimation and the results were compared with the SRC and its optimized versions. Metaheuristic algorithms improved the performance of the SRC model and the PSO model outperformed the other algorithms. These results also indicate that the model performance was directly related to the temporal separation of data. Based on these findings, if data are more homogenous and related to the limited climatic conditions used in the estimation of SSC, the estimations are improved. Moreover, it was observed that optimizing SRC through metaheuristic models was much more effective than separating data in the SCR model. The results also indicated that with the same input data, SVR was superior to the SRC model and its optimized version.

LOCAL STUDIES OF ICE COVER EFFECTS ON DAM GATES

The experience of operation of surface emergency gates in ice-breaking conditions at a number of hydroelectric power plants has shown the insuffi cient eff ectiveness of the methods used to combat freezing of structures. The rules for technical operation of spillway dam gates in winter provide for heating of structures by slots, threshold and skin in conjunction with measures to maintain mines before construction. However, measures to heat gates and build mines are not always suffi ciently justifi ed and justifi ed. In order to obtain full-scale data and scientifi c information for the development of recommendations on operating and accounting modes during design, full-scale studies of stresses and defl ections in the load-bearing elements of the watershed gate of the hydroelectric power station were carried out. This article presents the results of fi eld studies in comparison with calculated values. As a result of the studies, information on the static operation of fl at gates in winter conditions is obtained, which is of theoretical and practical interest. The materials can be used to clarify technical operation rules and to clarify regulatory documents for the design of hydromechanical equipment at hydroelectric power stations.

Coupled Continuous-Time Markov Chain–Bayesian Network Model for Dam Failure Risk Prediction

Hydropower dams are critical infrastructure systems characterized by their complex, dynamic, and stochastic behaviors. The frequent variation in the hydrological and meteorological variables poses a higher probability of dam failure, highlighting the need to improve pertinent risk assessment approaches to predict failure risks, considering the uncertain states of such variables. Bayesian networks (BN) analysis has been a key risk assessment tool for decades; however, BN’s static acyclic nature is a recognized drawback. In this paper, a continuous-time Markov chain (CTMC) is coupled with a BN model to enable the dynamic assessment of dam failure risk. In this respect, BN is used to represent the interrelation among the system variables and simulate the propagation of uncertainties throughout the system, whereas the CTMC is adopted to describe the continuous transition of the system variables over their respective states. To demonstrate its applicability, the developed coupled BN-CTMC model was employed to predict the probability of failure of the Daisy Lake Dam in the province of British Columbia, Canada, under the uncertainty of reservoir water level, inflow, and wind speed states. The developed BN-CTMC modeling approach can aid in the development of reliable dam operation schemes and risk mitigation strategies through (1) adequately representing the propagation of the hydrological (e.g., inflow and reservoir water level) and meteorological (e.g., wind speed) variable uncertainties through dam system dynamical processes; (2) effectively quantifying dam failure risk under different operational conditions and failure scenarios; (3) accurately specifying the critical periods of dam system operational safety; and (4) providing in-depth understanding of the relationships between the dam system’s failure and associated variables over time.

Prioritization of hydroelectric power plant earth dam safety procedures: a multi-criteria approach

The number of procedures focused on dam safety is very large, mainly due to the rules established by different regulatory bodies, the guidelines that are part of the recommended best practices for engineering works, and the common sense and conservatism present in dam operation and maintenance because of the large socioeconomic and environmental impacts that any incident with a dam can cause. In practice, the vulnerability of a dam is inversely proportional to the improvement of safety procedures, such as monitoring and sensing, and the staff’s capacity to interpret the information in timely fashion. Therefore, establishing priorities for these procedures is essential for the plant management to define the scheduling and detailing of inspections and monitoring, as well as training needs. The MCDA model described here was specified based on regulations and practical public domain guidelines. The subjective estimation of preferences was done by the staff of a hydroelectric plant located in central Brazil. It employed the Simos method combined with a procedure adopted to convert the scores to the format of paired comparisons. The weights for dam safety procedures were obtained using the fuzzy AHP method. The method allowed obtaining the classification of safety procedures according to their priorities, and thus provided the plant management with elements to better schedule monitoring and staff training.

Regional Hydrologic Classification for Sustainable Dam Operations in China: Exploratory Applications in the Yangtze River Basin

AbstractRegulated rivers worldwide are managed to meet human demands and reduce flood hazards but the resulting flow regime often fails to support ecological and hydrogeomorphic processes. Designing environmental flows (e‐flows) for regulated rivers has been the focus of recent studies, but in the absence of site‐specific monitoring data, it can be difficult to assign flow regimes. Given the recent development of dams throughout China, and the desire to minimize adverse downstream ecological effects, we classified river basins to identify characteristics for improved basin management. The purpose of the classification is to minimize the need for localized data when developing initial evaluations for planning e‐flow prioritization plans. Building on the functional flow framework of managing rivers to deliver environmental water in the right place, time, and amount, we use k‐means consensus clustering to group 185 subbasins of China’s Yangtze River into seven hydroclasses (consensus = 0.80). Similar hydrogeomorphic and ecological characteristics are used for the purposes of identifying flow regime components indexed against threatened aquatic species and anthropogenic pressures. This case study can inform water resource management and e‐flow requirements broadly. As hydropower dams are expected to more than double over the next 15 years globally, flexible management strategies that balance ecosystem needs with human demands can support efforts for sustainable development.

Riverbed deformation and its response to human intervention on the lower reaches of the Yangtze River

AbstractThe operation of the world's largest hydropower dam, the Three Gorges Dam (TGD), has significantly influenced the middle and lower reaches of the Yangtze River (YR). However, research has not been conducted on the impact of local engineering projects on the evolution of the tidal channel of the YR. This study used historical water depth and level data to analyze the factors influencing riverbed deformation in the Nanjing reach of the tidal channel of the YR. Moreover, the effect of local engineering projects on riverbed deformation in the study area was quantitatively analyzed. Our results indicated that between 1998 and 2013, ~78.26 × 106 m3 of sediment accumulated in the study area. The goose‐head bifurcated section of this reach exhibited the most significant change in riverbed deformation during this period. Between 1998 and 2013, 46.97 × 106 m3 of sediment accumulated in this section, the riverbed elevation increased by 1.01 m, and the thalweg increased by 2.78 m. Quantitative analysis of the volume of sediment accumulated in the near‐bank area indicated that revetment engineering accounted for &gt;40% of the accumulation. The results of this study provide a more accurate understanding of channel deformation in the lower reaches of the YR. Moreover, the results will improve the prediction accuracy of river channel evolution and assist in channel regulation and future local engineering construction projects.

Numerical Analysis of Concrete Gravity Dam Seepage Characteristics Evolution considering the Calcium Leaching Effect

During the long-term service life of hydraulic structures, the calcium compounds in cement-based materials decompose in the aqueous environment, leading to the continuous change of seepage characteristics. To study the influence of calcium leaching on the concrete dam seepage characteristics, we proposed a new mathematic model of the cement-based material calcium leaching model under advection-diffusion-driven leaching. A solid-liquid nonequilibrium model is adopted to model the decomposition of calcium hydroxide (CH) and calcium silicate hydrate gel (C-S-H). To calculate the porosity more accurately, the proposed model takes the effect of different calcium compound decomposition on the porosity increase in consideration, respectively. Shimantan dam is selected for the three-dimensional (3D) calcium leaching analyses. The 3D finite element model of this dam is analyzed using COMSOL Multiphysics software that is based on the finite element method. Based on the proposed model, seepage characteristics evolutions of the Shimantan dam are studied. Good agreement between the numerical results and the monitored data indicates the accuracy of this simulation. The result shows that after 100 a leaching duration, the uplift pressure increases by 40.8%, and the leakage quantities of the dam body and foundation increase by 48 and 17 times. The rise of uplift pressure and leakage changes caused by curtain deterioration are the main influences of calcium leaching on the dam seepage. The parameter sensitivity results show that it is necessary to reduce CH content in cement-based materials to obtain better calcium leaching durability. This model and simulation results can guide the operation of concrete dams under advection-diffusion-driven leaching.

Sediment Yield Analysis in Tahtaköprü Dam Basin

The determination of the volume of water to be stored is one of the most important criteria for dam and pond planning and operation. This amount is calculated locally prior to planning studies, and a bathymetric map is created following water storage in the reservoir. Because of sedimentation during the operation period, the volume of the reservoir decreases over time, and this situation appears as a problem in the operation of the water structure. In this study, the reservoir storage volume changes and reservoir sediment accumulation rates between the locally produced map before the construction of Tahtaköprü Dam and the hydrographic survey maps prepared during operation period were investigated by using GIS modules. It was determined that the decrease in the storage volume of the dam reservoir at the maximum water level by 9.15% and at the minimum water level by 51.90% was due to sediment accumulation. The effect of the changes in the land cover and forest area in the basin on reservoir sedimentation was examined and it was found that land cover and forest area in the basin have reduced sediment accumulation in the reservoir. Furthermore, sediment thickness change was mapped to compare the decrease in the storage volume capacity of the reservoir at the maximum water level and at the minimum water level by comparing the digital elevation models of 1962, 1980 and 2014 to support the decision-makers on determining reservoir operation rules in order to benefit water resources effectively within the scope of sustainable management of water resources.

Environmental Flow Requirements of Estuaries: Providing Resilience to Current and Future Climate and Direct Anthropogenic Changes

Estuaries host unique biodiversity and deliver a range of ecosystem services at the interface between catchment and the ocean. They are also among the most degraded ecosystems on Earth. Freshwater flow regimes drive ecological processes contributing to their biodiversity and economic value, but have been modified extensively in many systems by upstream water use. Knowledge of freshwater flow requirements for estuaries (environmental flows or E-flows) lags behind that of rivers and their floodplains. Generalising estuarine E-flows is further complicated by responses that appear to be specific to each system. Here we critically review the E-flow requirements of estuaries to 1) identify the key ecosystem processes (hydrodynamics, salinity regulation, sediment dynamics, nutrient cycling and trophic transfer, and connectivity) modulated by freshwater flow regimes, 2) identify key drivers (rainfall, runoff, temperature, sea level rise and direct anthropogenic) that generate changes to the magnitude, quality and timing of flows, and 3) propose mitigation strategies (e.g., modification of dam operations and habitat restoration) to buffer against the risks of altered freshwater flows and build resilience to direct and indirect anthropogenic disturbances. These strategies support re-establishment of the natural characteristics of freshwater flow regimes which are foundational to healthy estuarine ecosystems.

Reflections on almost a century of hydrological studies on Africa's largest lake

Abstract. Lake Victoria is the largest lake in Africa and its outflows strongly influence flows in the White Nile, including the availability of water for hydropower generation, irrigation and water supply. Understanding the water balance is a major challenge since the lake is large enough to influence the local climate and its catchment spans several countries. Hydrometeorological monitoring networks are also sparse in some parts of the basin. In this paper, we consider the history of water balance estimates for the lake and how the science has developed as new information and techniques have become available, including in areas such as seasonal flow forecasting and estimating the potential impacts of dam operations and climate change. These findings are placed into a wider context including the challenges arising from a changing climate and evolving ideas from international research programmes, which lead to some suggestions for future research priorities for Lake Victoria and other sub-Saharan/Rift Valley lakes.

The anatomy of two species of emergent macrophytes of the genus Polygonum differentially changes in response to water‐level fluctuations

AbstractTemporal fluctuations in water levels are important ecological driving forces in shallow aquatic ecosystems. Alterations to fluviometric levels are even more conspicuous after the construction of dams, and aquatic macrophytes respond with anatomical and morphological adaptations to such changes. We performed an experiment to analyse the anatomical responses of two common Neotropical species of emergent macrophytes (Polygonum ferrugineum and P. acuminatum) to water‐level fluctuations. The experiment simulated three water‐level variations: constant low water, constant deep water and fluctuating water levels (0.8‐m oscillation/6 days; commonly caused by dam operation). We measured anatomical responses of roots (perimeter and number of the intercellular spaces), stems (perimeter and number of the intercellular spaces and cortical thickness) and leaves (palisade and lacunous parenchyma thickness). Water level affected all anatomical traits we measured and all increased when plants remained submerged (high‐depth treatment). Compared with P. ferrugineum, P. acuminatum had higher values of both perimeter of the intercellular space in the roots and number of intercellular spaces in the stems. These results indicate that water‐level fluctuations influence the anatomy of both species and that, compared with P. ferrugineum, P. acuminatum has greater plasticity and better tolerates submersion. These responses may be explained by the different survival strategies of each species when growing under submersion. Thus, our results reflect the different selective pressures from water levels experienced by these two species during their evolution.

Influence of reactivity and dosage of MgO expansive agent on shrinkage and crack resistance of face slab concrete

Enhancing cracking resistance of face slab concrete is essential for the structural integrity and normal operation of concrete-faced rockfill dams (CFRDs). In this study, the effects of MgO with three reactivities and three dosages on the shrinkage and crack resistance of face slab concrete were systematically investigated by slab test, restrained drying shrinkage test and temperature stress test machine (TSTM). The results indicate that: (1) 7 %–25% of the total drying shrinkage and all (or most of) the autogenous shrinkage can be compensated by adding 5 %–10% MgO. The reactive MgO (M60) starts to compensate the drying and autogenous shrinkage at 1 day and compensates more shrinkage at early age than the moderate reactive MgO (M150) and the weak reactive MgO (M300), while M300 begins to compensate the shrinkage at about 50 days and produces larger compensation than M60 and M150 at late age. (2) M60 performs better than M150 in improving the crack resistance of face slab concrete to constraint and thermal stress. The increase in dosage of M60 and M150 from 0 to 10% prolongs the initial cracking time of face slab concrete by 10.0–27.5 h, increases the cracking strain by 9.2 %–25.7%, enhances the cracking tensile stress (σ) by 4.7 %–18.8% and lowers the cracking temperature (Tc) by 2.6–7.4 °C. Conversely, M300 weakens the cracking resistance. (3) The reactive MgO with relatively high dosage is suggested to eliminate the early shrinkage and to improve the cracking resistance of face slab concrete.

Do the Volume-of-Fluid and the Two-Phase Euler Compete for Modeling a Spillway Aerator?

Spillway design is key to the effective and safe operation of dams. Typically, the flow is characterized by high velocity, high levels of turbulence, and aeration. In the last two decades, advances in computational fluid dynamics (CFD) made available several numerical tools to aid hydraulic structures engineers. The most frequent approach is to solve the Reynolds-averaged Navier–Stokes equations using an Euler type model combined with the volume-of-fluid (VoF) method. Regardless of a few applications, the complete two-phase Euler is still considered to demand exorbitant computational resources. An assessment is performed in a spillway offset aerator, comparing the two-phase volume-of-fluid (TPVoF) with the complete two-phase Euler (CTPE). Both models are included in the OpenFOAM® toolbox. As expected, the TPVoF results depend highly on the mesh, not showing convergence in the maximum chute bottom pressure and the lower-nappe aeration, tending to null aeration as resolution increases. The CTPE combined with the k–ω SST Sato turbulence model exhibits the most accurate results and mesh convergence in the lower-nappe aeration. Surprisingly, intermediate mesh resolutions are sufficient to surpass the TPVoF performance with reasonable calculation efforts. Moreover, compressibility, flow bulking, and several entrained air effects in the flow are comprehended. Despite not reproducing all aspects of the flow with acceptable accuracy, the complete two-phase Euler demonstrated an efficient cost-benefit performance and high value in spillway aerated flows. Nonetheless, further developments are expected to enhance the efficiency and stability of this model.

The thermal stress state arising in the contact area of mass concreteduring construction

Introduction. The contact area of concrete gravity dams is of vital importance. Substantial temperature gradients and tensile stresses can arise in the process of concrete casting and thermal regime creation; they can cause thermal cracking. The practice of monitoring the construction and operation of concrete gravity dams has identified frequent vertical cracking along and across the dam axis, which can have an adverse impact on structural behaviour. Despite the large number of research works, some of which are mentioned in the work, the extent of influence of the modulus of elasticity in the bed on the thermally stressed state of mass concrete has yet to be fully resolved. The purpose of the research is to enhance the insight into the stress-strain state arising in the contact area of mass concrete and the bed, depending on its rigidity.&#x0D; Materials and methods. The research was conducted using the numerical finite element method and the MIDAS software package.&#x0D; Results. The influence of bed rigidity on the thermally stressed state arising in the contact area of mass concrete in the process of construction has been analyzed. Several options featuring different ratios between the modulus elasticity of the bed and mass concrete were considered in respect of a mass concrete structure made of vibrated and rolled concretes. Emerging stresses are compared. Mathematical expressions are obtained to project maximum tensile stresses occurring in the contact area.&#x0D; Conclusions. A more rigid bed rises maximum tensile temperature stresses, which increase the risk of thermal cracking. Research results can be used to predict maximum tensile stresses near the contact section of the mass concrete, whose dimensions are close to those of the structure under research.