Hasil untuk "River, lake, and water-supply engineering (General)"

Laís Mariana Wosniack, Daniel Henrique Marco Detzel

ABSTRACT Nonstationarity presents a challenge for hydrological design, particularly for large structures that require high return period floods. This paper assesses the statistical properties of annual maximum daily streamflows from 152 hydropower plants (HPPs) operating in Brazil. For series exhibiting temporal trends, we propose the Empirical Quantile Mapping method for correcting nonstationarity. For comparison, we employed the Flow Accumulative Curve technique as a benchmark. These approaches are employed prior to a revisited flood frequency analysis to estimate the 10,000-year design flood. Results indicate that 70 HPPs show evidence of nonstationarity. These series were further examined using a risk index, and we discuss in further detail the cases of the Iguaçu and São Francisco basins. The findings highlight the importance of developing methodologies that account for nonstationarity in the definition of high-recurrence flows.

Aline Guidolin da Luz, Bruna Arcie Polli, Tobias Bernward Bleninger et al.

ABSTRACT In the face of climate change, water scarcity, and changes in land use, efficient management of energy generation is essential to ensure national energy security. In the context of Joint Resolution ANA/ANEEL n° 127/2022, this study aimed to compare four methods for estimating reservoir sedimentation: comparison of Depth-Area-Volume curves (DAV), sedimentometric analysis, use of computer programs with simplified methods, and comparison of cross-sections, with DAV method as the reference. The results showed that all methods indicated a reduction in reservoir volume due to sedimentation, however the cross-section method presented closest values to the reference method.

GUO Li-jin, WU Hao-tian

[Objectives] To enhance water quality prediction accuracy, this study aims to address the following challenges: (1) traditional prediction methods often rely on simple, elementary decomposition techniques, limiting their ability to extract meaningful data features. (2) Single models and basic optimization algorithms result in low prediction accuracy. (3) Most approaches fail to leverage the advantages of different networks to analyze components of varying complexity, leading to inefficient model utilization. (4) Few studies incorporate error correction after prediction. This study proposes a novel hybrid model for water quality prediction. [Methods] First, the original water quality sequence was decomposed using Complete Ensemble Empirical Mode Decomposition with Adaptive Noise (CEEMDAN). Next, Fuzzy Dispersion Entropy (FuzzDE) categorized the components into high-, medium-, and low-complexity subsequences. Then, an Improved Mantis Search Algorithm (IMSA) optimized three distinct models: Bidirectional Long Short-Term Memory (BiLSTM) for high-complexity components, Least Squares Support Vector Regression (LSSVR) for medium-complexity components, and Extreme Learning Machine (ELM) for low-complexity components. The predictions were combined and reconstructed, and a BiLSTM-based error correction model further corrected the errors, yielding the final prediction results. [Results] The study introduced four key innovations to the original Mantis Search Algorithm (MSA): (1) combining Logistic-Tent chaotic mapping for population initialization, ensuring uniform and random distribution of initial solutions to enhance global search capability and convergence speed; (2) nonlinear acceleration factor, refining MSA’s core update formula to transition from global exploration to local exploitation, mitigating local optima entrapment; (3) elite-guided adaptive update strategy, addressing the excessive randomness in the position update strategy when Mantis attacks fail, improving late-stage search efficiency while preserving some randomness; (4) opposition-based learning, generating individuals opposite to the current individual to enhance global optimization. IMSA’s performance was validated using benchmark functions (Rosenbrock for unimodal, Michalewicz for multimodal), confirming improved global search and convergence precision. After determining the network hyperparameters, ablation experiments were conducted to analyze the contribution of each strategy to the network model, providing a clear understanding of how each strategy impacts prediction performance. Finally, the sequence of model usage was validated by using FuzzDE to calculate the complexity of each component, creating high-, medium-, and low-complexity subsequences. The learning capabilities of different networks for these subsequences were verified, with BiLSTM used to predict high-complexity components, LSSVR for medium-complexity components, and ELM for low-complexity components. [Conclusions] This study performed a simulation verification using dissolved oxygen (DO) concentrations from two sections of Youshui River (a tributary of the Yuanjiang River) and pH values from one station in the Xiangjiang River Basin. Missing values were addressed via linear interpolation. For outlier treatment, the study considered that outliers in the data might be caused by sudden pollution events and discontinuous non-point source pollution. Directly removing them could lead to information loss, so outliers were retained. After integrating decomposition, use of entropy, algorithm optimization, and error correction models, eleven comparative experiments were established to evaluate the effectiveness of each optimization method. The hybrid model’s effectiveness was validated using RMSE, R2, and MAPE metrics. Ultimately, the R2 reached over 90%, demonstrating that the prediction accuracy of the hybrid model outperformed other comparative models.

SHI Linping, LIAO Zhiying, XIE Zhigao et al.

The spillway of Dongchong Reservoir adopts an engineering scheme of spillway step energy dissipation and downstream stilling basin underflow. However, due to the limitations of terrain and geological conditions, the width of the stilling basin is small, and the angle between it and the river is 145°; meanwhile, the current downstream traffic bridge hinders flood discharge, resulting in many unfavorable factors. For the original scheme, the discharge entering the stilling basin makes the water surface fluctuate greatly, and the water flow out of the basin accelerates significantly. The main flow in the river is concentrated, and a large-scale backflow area is formed on the left of the upstream traffic bridge. This paper optimizes the layout scheme of the stilling basin through hydraulic model tests. The results show that through measures such as deepening the stilling basin, installing T-shaped piers in the front section of the basin, shifting the left side wall of the stilling basin to the left, and lowering the tail-weir and creating a reverse slope towards the river, etc., the water flow pattern is significantly improved. After the discharge enters the basin, the fluctuation amplitude of the water surface decreases, and the water flow out of the basin no longer accelerates. The water flow in the river is dispersed and the flow velocity falls. The research results can provide a reference for similar projects.

Renata Sayuri Muranaka, Jonas Soares Rangel, Marcelo Antonio Marotta et al.

ABSTRACT The pursuit of efficient water distribution network (WDN) projects that reflect the complexities of real systems has spurred the development and application of various optimization techniques. Among these, multi and many-objective optimization hold particular significance due to the intrinsic interplay between variables within water distribution networks. Within this domain, evolutionary algorithms have emerged as a promising optimization option, offering a range of methodologies documented in the literature. To systematically evaluate these approaches, a methodology was devised to compare six evolutionary algorithms in the context of water distribution networks optimization: NSGA-II, NSGA-III, U-NSGA-III, R-NSGA-III, MOEA/D, and RVEA, using two distinct objective functions. The comparative analysis utilized as key metrics the efficiency criteria (E), cumulative distribution function (CDF), error statistics and algorithm complexity. The findings revealed that while most algorithms successfully converged to the known global optimum of the employed case study, NSGA-II and NSGA-III exhibited superior performance, notably in minimizing costs. These results demonstrate the efficacy of these algorithms in tackling the complexities inherent in water distribution networks optimization, positioning them as leading contenders in this field.

CAO Yangyang

T. Mazakov, Sholpan Jomartova, G. Ziyatbekova et al.

The article is devoted to the development of a river flow modeling technique. The paper considers possible approaches to modeling the flow of fluids, as well as an analysis of existing solution methods and the formulation of research problems. The task is analyzed and the main problems that may arise in the course of its solution are identified. A general description of the problem and the formulation of research objectives are given. The advantages and disadvantages of the described methods are highlighted. A comparative analysis of known methods for complex analysis, forecasting the consequences of natural and man-made emergencies using modern technologies of mathematical modeling and a computational experiment with displaying the results in a geographic information system and a study of a mathematical model of a dam breakthrough was carried out. A description of the flood and flood monitoring technology developed in Kazakhstan is given, the results of its practical use in certain regions are discussed, and directions for further development are outlined. Thus, based on the analysis of various existing methods, the goal and main objectives of research aimed at developing a methodology for predicting a hydrodynamic accident as an emergency were formulated. The continuous wave method or ultrasonic pulse echo method is used. Based on microprocessor technology and sensors, an autonomous microcomputer system for transmitting climate data has been developed. A program for monitoring the factors of breakthrough waves in real time has been developed. An autonomous microcomputer system for transmitting climate data has been developed. The autonomous power supply subsystem for satellite data transmission systems includes a set of equipment, the functions of which are to generate and store energy for its subsequent use in order to provide power supply to the equipment. Water level measurement equipment can be different. To ensure the functioning of the system, the measuring equipment will be interfaced with the data transmission subsystem and the power supply subsystem. The pairing of these systems will make it possible to monitor the water level in moraine lakes, the location of which is extremely inaccessible. Technical means measuring the water level must be able to receive data from sensors with different periodicity. The accumulated data is used to predict possible floods and floods, calculate water consumption, and for other purposes. The characteristics of dams and the capabilities of modern control systems based on the use of microprocessor technology are analyzed.

Qiaofeng Tan, Yunze Mao, Xin Wen et al.

Multivariate flood frequency analysis has been widely used in the design and risk assessment of hydraulic structures. However, analytical solutions are often obtained based on an idealized linear reservoir model in which a linear routing process is assumed, and consequently, the flood risk is likely to be over- or underestimated. The present study proposes a nonlinear reservoir model in which the relationships of reservoir water level with reservoir volume and discharge are assumed to be nonlinear in order to more accurately describe the routing process as it takes into consideration the interactions between hydrological loading and different discharge structures. The structure return period is calculated based on the copula function and compared with that based on the linear reservoir model and the bivariate return period based on the Kendall distribution function. The results show that the structure return period based on the linear model leads to an underestimation of the flood risk under the conditions of high reservoir water level. For the same reservoir, linear and nonlinear reservoir models give quite different reservoir volume-water level and discharge-water level curves; therefore, they differ substantially in the sensitivity to flood events with different combinations of flood peak and volume. We also analyze the effects of the parameters involved in the reservoir volume-water level and discharge-water level relationships on the maximum water level at different return periods in order to better understand the applicability and effectiveness of the proposed method for different hydraulic projects. HIGHLIGHTS The structure return period is calculated based on the nonlinear reservoir model.; Nonlinear relationships of water level with volume and discharge are assumed.; Interactions between hydrological loading and different structures are analyzed.; Effects of different storage and discharge capacity parameters are discussed.;

Carlo Lucca Coutinho Ungaretti Rossi, Marcelo Giulian Marques, Eder Daniel Teixeira et al.

ABSTRACT Simplified methods are useful alternatives for prior analysis of the effects of dam rupture and can guide the decision-making process for carrying out more complete studies. In this context, a new simplified approach is presented, which enables the analysis of aspects from dam rupture of earthen dams that failed due to overtopping, considering dam height and reservoir volume as input data. Hypothetical cases were analyzed applying dam-break hydrodynamic simulations, which results allowed the development of equations capable of estimating peak flow attenuation and peak discharge arrival time along the downstream valley. The proposed approach was applied in a hypothetical case study (15 m high dam and 17 hm3 reservoir volume), obtaining results close to those achieved through other methods, especially in case of estimating the maximum discharges throughout the downstream valley, where the average differences between the results of the methods were of the order of 15%.

DA Mingchang, JIAO Jie, SU Zhengyang

There are many problems in safety management and risk assessment of underground reservoir project in karst area because of the special structure and environment.Taking a typical karst underground reservoir project in southwest China as the research object,this paper establishes the three-dimensional finite element model of its cave block to analyze the variation law of its temperature field,stress field and displacement field under different working conditions.The results show that:the overall deformation of the cave block was small,and the stress level of the cave block was generally within the safe range under various working conditions.There was stress concentration at the local position between the cave block and bedrock,but the overall stress distribution met the requirements of the code.The research results serve as a reference for safety evaluation and risk analysis of underground reservoir projects in karst areas.

Andri Warsa, Joni Haryadi, Endi Setiadi Kartamihardja

The Tilong Reservoir located in Kupang District, has 154.97 ha surface area with an average depth of 12.5 m, water volume is 19 million m3 and water discharge around 86.4-106.3 m3/day. The main function of this reservoir is for irrigation. Capture fisheries activity has not been optimally developed. The development of capture fisheries can be done through culture-based fisheries (CBF), namely milkfish (Channos channos) or tilapia (Oreochromis niloticus) stocking. The aims of this study is to determine the potential of fisheries production and the seed needs for CBF development in the Tilong reservoir. The study was conducted in March and September 2016 at three observation stations. Water sample was taken at 0.5 and 2.0 m from the surface which is the euphotic depth. The results showed that CBF activities in the Tilong Reservoir could successful because supported by the limnology conditions was suitable for fish life, the availability of seeds produced from hatchery was sufficient for stocking and support of local communities through local wisdom. Fish seeds are produced by 13 hatchery which are capable of producing milkfish and tilapia seeds of 7,040,770 and 7,023,400 per year. Based on these aspects, capture fisheries through CBF are feasible to be developed in the Tilong Reservoir. The fisheries production potential in the Tilong Reservoir ranges from 75.9 to 77.5 kg/ha/year or 11.9-12.0 tons/year. The optimal number of milkfish and tilapia seeds that can be stocked ranges from 71,000-73,500 individuals/year and 72,000-75,000 individuals/year respectively. The fish production estimated from stocking was about 40% of the potential production with economic value of Rp 20,500,000 and Rp 21,500,000.

R. Sujithkumar, G. Sivakumar

Chunhong Hu, Chunming Fang

F. Bryukhan

Pre-project geoecological studies were carried out in autumn 2015 along the entire length of the Tikhomandritsa river, in Navolok lake waters near the river source and Udomlya lake near its mouth, as well as on the territory adjacent to the river, as part of the Comprehensive Engineering Surveys. The aim of the studies was to obtain initial data to assess the current ambient conditions of the study area, as well as to develop the project of cleaning the upper stretch of the Tikhomandritsa riverbed and spillway structure construction. Water, bottom sediments and soil contamination levels were identified. It is found that the water quality in the studied water bodies belongs to the contaminated category. Bottom sediments at the upper stretch of the river up to a distance of 2.5 km from its source are pure and can be used in agriculture without restrictions. Bottom sediments samples taken at a distance of 5.5 km from the river source and its mouth contain dangerous level of coliform bacteria. Basing on the territory survey a tree and shurberry felling plan was drawn up and the volume of works of the river purification was determined. The project implementation will help to increase the river flow in dry water years, increase its self-cleaning velocity and environmental improvement of the area. In addition, the increase of water flow into Udomlya lake will provide Kalinin NPP with additional water resources for its process water supply. The conceptual scheme of this study is largely applicable for the basins of other small rivers.

Letícia Teixeira Palla Braga, Leila Nunes Menegasse Velásquez, Peter Marshall Fleming et al.

Localized recharge from sinkholes is very important in karst environment and especially in arid and semiarid regions, where it contributes to the recharge on karst fissured aquifers because these geomorphic structures favor the concentration of water runoff in areas with shortage of water. The study area is located in sub-basins of the Rio Verde Grande, in the Verdelândia and Varzelândia cities and it is part of the semi-arid climate (average regional rainfall = 790 mm), and is strongly marked by the presence of sinkholes in Neoproterozoic pelitic-carbonate of karst Bambuí Group. To understand the processes of this kind of recharge and quantify it in the study area, we used the automated identification in ArcGIS to select two sinkholes and the following methodological procedure was adopted: soil texture characterization; soil infiltration tests; permeability tests of aquitard/aquiclude from the bottom of the sinkhole; automated monitoring of rainfall and underground water level; hydric balance, estimated with the hydric balance and water level variation methods. The results showed local recharge values between 7,8% and 19,5% of the precipitation, demonstrating the importance of preserving these features in the region.

K. W. Johnson

M. Karamouz, A. Zeynolabedin, M. Olyaei

Drought is among the natural disaster that causes damages and affects many people’s life in many part of the world including in Iran. Recently, some factors such as climate variability and the impact of climate change have influenced drought frequency and intensity in many parts of the world. Drought can be divided into four categories of meteorological, hydrological, agricultural and social-economic. In meteorological the important feature is lack of rainfall. In hydrological drought river flows and dam storage are considered. Lack of soil moisture is the key factor in agricultural droughts while in social-economic type of drought the relation between supply and demand and social-economic damages due to water deficiency is studied. While the first three types relates to the lack of some hydrological characteristics, social-economic type of drought is actually the consequence of other types expressed in monetary values. Many indices are used in assessing drought; each has its own advantages and disadvantages and can be used for specific types of drought. Therefore knowing the types of drought can provide a better understanding of shortages and their characteristics. Drought vulnerability is a concept which shows the likelihood of damages from hazard in a particular place by focusing on the system status prior to the disaster. Drought vulnerability has been viewed as a potential for losses in the region due to water deficiency at the time of drought. In this study the application of vulnerability concept in drought management in East Azarbaijan province in Iran is investigated by providing vulnerability maps which demonstrates spatial characteristics of drought vulnerability. In the first step, certain governing parameters in drought analysis such as precipitation, temperature, land use, topography, solar radiation and ground water elevation have been investigated in the region. They are described in details and calculated in suitable time series. Vulnerabilities are ranked in 5 intervals and for each parameter vulnerability maps are prepared in GIS environment. Selection of theses parameters are based on factors such as regional features and availability of data. Considering the fact that the aforementioned parameters have different level of importance in vulnerability maps, different weights are assigned to the parameters considering how critical each parameter is in the overall drought analysis. Expert's opinion is selected in assigning weights. A multi-criteria decision making (MCDM) framework is used to check the consistency of the provided information. Then the weighted maps are overlaid to find the overall vulnerability map. The map shows very low, low, medium, intense and very intense regional vulnerabilities. According to the results, the west part of East Azarbaijan province is the most vulnerable region to drought which is expected due to the vicinity of this part to Urumia Lake that has been lost most of its water during the last decades. The least vulnerable part seems to be the Eastern part of the province with longer lasting resources. Taking into consideration that Caspian Sea is near this part with high precipitation record, the outcome of this study is in line with the general expectations. The result of this study can be used for preparedness planning and for allocating resources for facing droughts in this region.