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1
Viterbo, Francesca, Laura Read, Kenneth Nowak, Andrew W. Wood, David Gochis, Robert Cifelli e Mimi Hughes. "General Assessment of the Operational Utility of National Water Model Reservoir Inflows for the Bureau of Reclamation Facilities". Water 12, n. 10 (16 ottobre 2020): 2897. http://dx.doi.org/10.3390/w12102897.
Testo completoAbstract (sommario):
This work investigates the utility of the National Oceanic and Atmospheric Administration’s National Water Model (NWM) for water management operations by assessing the total inflow into a select number of reservoirs across the Central and Western U.S. Total inflow is generally an unmeasured quantity, though critically important for anticipating both floods and shortages in supply over a short-term (hourly) to sub-seasonal (monthly) time horizon. The NWM offers such information at over 5000 reservoirs across the U.S., however, its skill at representing inflow processes is largely unknown. The goal of this work is to understand the drivers for both well performing and poor performing NWM inflows such that managers can get a sense of the capability of NWM to capture natural hydrologic processes and in some cases, the effects of upstream management. We analyzed the inflows for a subset of Bureau of Reclamation (BoR) reservoirs within the NWM over the long-term simulations (retrospectively, seven years) and for short, medium and long-range operational forecast cycles over a one-year period. We utilize ancillary reservoir characteristics (e.g., physical and operational) to explain variation in inflow performance across the selected reservoirs. In general, we find that NWM inflows in snow-driven basins outperform those in rain-driven, and that assimilated basin area, upstream management, and calibrated basin area all influence the NWM’s ability to reproduce daily reservoir inflows. The final outcome of this work proposes a framework for how the NWM reservoir inflows can be useful for reservoir management, linking reservoir purposes with the forecast cycles and retrospective simulations.
2
Bennis, Saad, e Narut Kang. "Multivariate Technique for Validating Historical Hydrometric Data with Redundant Measurements". Hydrology Research 31, n. 2 (1 aprile 2000): 107–26. http://dx.doi.org/10.2166/nh.2000.0008.
Testo completoAbstract (sommario):
The aim of this research was to develop an automated methodology for validating chronological series of natural inflows to reservoirs. Theoretically, gauges located on the same reservoir should indicate the same reading. However, under the influence of meteorological and hydraulic factors, or simply because of failed measuring equipment, there may be large deviations between the various measurements. Since the calculation of historical natural inflows is directly linked to the measurement of reservoir level by the water balance equation, there will be as many series of natural inflows as there are of reservoir levels. A multivariate filtering technique is used to validate the historical natural inflow computed by each water level variation. The multi filter methodology has the advantage of balancing the water volume of natural inflows to the reservoir when applied over a relatively long period of time. As a result, the validated flood peaks are not systematically overestimated or underestimated and the validated natural inflows are nearly identical for all the gauges. The proposed technique has been incorporated into a software program called ValiDeb, which has been successfully tested on-site on the Gatineau River in Quebec.
3
Pieters, Roger, e Gregory A. Lawrence. "Plunging inflows and the summer photic zone in reservoirs". Water Quality Research Journal 47, n. 3-4 (1 agosto 2012): 268–75. http://dx.doi.org/10.2166/wqrjc.2012.143.
Testo completoAbstract (sommario):
Kinbasket and Revelstoke Reservoirs are part of the Columbia River system in eastern British Columbia, Canada. Hydroelectricity from these large reservoirs represents about 30% of the province's generation capacity. Of interest to water use planning is the effect of reservoir operation on pelagic productivity. We address one small part of this question, namely, the supply of nutrients carried by inflows that plunge below the photic zone during the summer. Using an idealized water balance for the photic zone, three cases are considered: (1) a shallow outlet, (2) a deep outlet, and (3) no outflow. For a shallow outlet, all inflow that plunges below the photic zone is upwelled into the photic zone on its way to the outlet. For a deep outlet, inflow that plunges below the photic zone will short circuit or pass directly to the outlet unless entrainment generates upwelling of the inflow into the photic zone. For a reservoir with no outflow, such as a reservoir that is filling, inflow that plunges below the photic zone remains at depth unless either entrainment or a bathymetric effect generates flow into the photic zone; nutrients are then released when the reservoir is drawn down, often in winter.
4
Sutlovic, Elis, Snjezana Cujic-Coko e Ivan Medic. "Characteristics of basin inflows a statistical analysis for long-term/mid-term hydrothermal scheduling". Thermal Science 18, n. 3 (2014): 799–809. http://dx.doi.org/10.2298/tsci1403799s.
Testo completoAbstract (sommario):
The presented paper focuses on the characteristics of reservoir inflows and the appropriate inflow model for long-term/mid-term hydrothermal scheduling. The goal was to find the type of distribution that best fits the observed series of monthly and weekly average inflows in most cases for a model which considers the inflows as independent random variables without time correlation. Also, the objective was to explore the correlation between the inflows during time periods (for weekly and monthly intervals, respectively), and to investigate whether the more complex model of reservoir inflow as a dependent random variable is advisable for optimal long-term/mid-term hydrothermal scheduling. Differences in the characteristics of monthly and weekly inflows, which have been noticed during the analysis, are discussed. Numerical results are presented.
5
Sriworamas, Krit, Anongrit Kangrang, Teerawat Thongwan e Haris Prasanchum. "Optimal Reservoir of Small Reservoirs by Optimization Techniques on Reservoir Simulation Model". Advances in Civil Engineering 2021 (15 giugno 2021): 1–14. http://dx.doi.org/10.1155/2021/6625743.
Testo completoAbstract (sommario):
Reservoir rule curves are essential rules for store activity. This investigation connected the Genetic Algorithm, Firefly Algorithm, Bat Algorithm, Flower Pollination Algorithm, and Tabu Search Algorithm associated with the store reproduction model to look through the ideal supply standard bends, utilizing the Huay Ling Jone and Huay Sabag supplies situated in Yasothorn Province, Thailand, as the contextual investigation. Memorable inflow information of the two repositories were utilized in this investigation, and 1,000 examples of engineered inflows of stores were utilized to recreate the repository activity framework for assessing the acquired principle bends as displayed as far as water circumstances. Circumstances of water lack and abundance water appeared as far as the recurrence extent and length. The outcomes demonstrated that GA, FA, BA, FPA, and TS associated with the reservoir simulation model could give the ideal principle bends which better moderate the drought and flood circumstances contrasted and current guideline bends.
6
Uang-Aree, Prawit, e Sununtha Kingpaiboon. "Possibility of GPS precipitable water vapour for reservoir inflow forecasting". Journal of Water and Land Development 36, n. 1 (1 marzo 2018): 161–71. http://dx.doi.org/10.2478/jwld-2018-0016.
Testo completoAbstract (sommario):
AbstractWe investigated the possibility of using GPS precipitable water vapour (GPS-PWV) for forecasting reservoir inflow. The correlations between monthly GPS-PWV and the inflow of two reservoirs were examined and the relationship tested, using a group method of data handling (GMDH) type neural network algorithm. The daily and monthly reservoir inflows were directly proportional to daily and monthly GPS-PWV trends. Peak reservoir inflow, however, shifted from the peak averages for GPS-PWV. A strong relationship between GPS-PWV and inflow was confirmed by high R2 values, high coefficients of correlation, and acceptable mean absolute errors (MAE) of both the daily and monthly models. The Ubon Ratana reservoir model had a monthly MAE of 54.19·106 m3 and a daily MAE of 5.40·106 m3. By comparison, the Lumpow reservoir model had a monthly MAE of 25.65·106 m3 and a daily MAE of 2.62·106 m3. The models using GPS-PWV as input data responded to extreme inflow better than traditional variables such that reservoir inflow could be predicted using GPS-PWV without using actual inflow and rainfall data. GPS-PWV, thus, represents a helpful tool for regional and national water management. Further research including more reservoirs is needed to confirm this preliminary finding.
7
Wu, Binbin, Guoqiang Wang, Changming Liu e Zongxue Xu. "Modeling impacts of highly regulated inflow on thermal regime and water age in a shallow reservoir". Journal of Hydroinformatics 15, n. 4 (26 marzo 2013): 1312–25. http://dx.doi.org/10.2166/hydro.2013.178.
Testo completoAbstract (sommario):
Thermal regime and transport of dissolved pollutants, strongly related to water quality and algae bloom in reservoirs, may be quantized by indicators of water temperature and water age, respectively, and these indicators are more spatially and temporally variant in shallow reservoirs. Here, a two-dimensional model was used for studying characteristics of the indicators in Douhe Reservoir, based on data of the year 2008. Douhe Reservoir is a typical shallow reservoir in Northern China, characterized by highly regulated inflow and thermal effluent. The impacts of the regulated inflow on reservoir thermal regime and water age were then analyzed through numerical experiments. The results show that the effects of inflow are associated with the flow circulations induced by inflow, thermal effluent, and wind. The most efficient inflows for alleviating thermal pollution and improving water exchange are 32.5 and 19.5 m3/s, respectively. A positive logarithmic correlation is found between water temperature and water age under the impact of inflow, while thermal effluent and wind have a slightly negative effect on the correlation. These findings provide useful information for better understanding the complex hydrodynamic and mass transport processes in a shallow reservoir.
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Coerver, Hubertus M., Martine M. Rutten e Nick C. van de Giesen. "Deduction of reservoir operating rules for application in global hydrological models". Hydrology and Earth System Sciences 22, n. 1 (31 gennaio 2018): 831–51. http://dx.doi.org/10.5194/hess-22-831-2018.
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Abstract. A big challenge in constructing global hydrological models is the inclusion of anthropogenic impacts on the water cycle, such as caused by dams. Dam operators make decisions based on experience and often uncertain information. In this study information generally available to dam operators, like inflow into the reservoir and storage levels, was used to derive fuzzy rules describing the way a reservoir is operated. Using an artificial neural network capable of mimicking fuzzy logic, called the ANFIS adaptive-network-based fuzzy inference system, fuzzy rules linking inflow and storage with reservoir release were determined for 11 reservoirs in central Asia, the US and Vietnam. By varying the input variables of the neural network, different configurations of fuzzy rules were created and tested. It was found that the release from relatively large reservoirs was significantly dependent on information concerning recent storage levels, while release from smaller reservoirs was more dependent on reservoir inflows. Subsequently, the derived rules were used to simulate reservoir release with an average Nash–Sutcliffe coefficient of 0.81.
9
Yang, Sheng-Chi, e Tsun-Hua Yang. "Uncertainty Assessment: Reservoir Inflow Forecasting with Ensemble Precipitation Forecasts and HEC-HMS". Advances in Meteorology 2014 (2014): 1–11. http://dx.doi.org/10.1155/2014/581756.
Testo completoAbstract (sommario):
During an extreme event, having accurate inflow forecasting with enough lead time helps reservoir operators decrease the impact of floods downstream. Furthermore, being able to efficiently operate reservoirs could help maximize flood protection while saving water for drier times of the year. This study combines ensemble quantitative precipitation forecasts and a hydrological model to provide a 3-day reservoir inflow in the Shihmen Reservoir, Taiwan. A total of six historical typhoons were used for model calibration, validation, and application. An understanding of cascaded uncertainties from the numerical weather model through the hydrological model is necessary for a better use for forecasting. This study thus conducted an assessment of forecast uncertainty on magnitude and timing of peak and cumulative inflows. It found that using the ensemble-mean had less uncertainty than randomly selecting individual member. The inflow forecasts with shorter length of cumulative time had a higher uncertainty. The results showed that using the ensemble precipitation forecasts with the hydrological model would have the advantage of extra lead time and serve as a valuable reference for operating reservoirs.
10
Byun, Do-Seong, Yang-Ki Cho, In-Ae Huh e Deirdre E. Hart. "Runoff-induced vertical thermal dynamics in a canyon-shaped reservoir during the summer monsoon". Marine and Freshwater Research 56, n. 7 (2005): 959. http://dx.doi.org/10.1071/mf04285.
Testo completoAbstract (sommario):
During the summer rainy season, double thermoclines were observed in a small canyon-shaped reservoir. The physical processes leading to thermocline evolution are examined from the vertical temperature profile observed along the reservoir before and after rain. Observations show that their evolution is related to the inflow of runoff, which is colder than the reservoir surface water and post-rain fair-weather conditions. Tongue-like distributions of turbidity, conductivity and nutrient concentrations downstream from the headwater clearly reveal the presence of runoff-induced intermediate inflows. In addition to supplying nutrients, the inflow provides the oxygen-deficient intermediate layer with a rich supply of dissolved oxygen. Concurrently, in the upper part of the reservoir runoff-induced inflows may drive the oxygen-deficient bottom water to shift downstream along the layer beneath the runoff-induced inflow. The water mass between the two thermoclines may operate as a source of nutrients for algal development in early autumn when the upper thermocline is destroyed by the convective overturn owing to the surface cooling.
11
Latif, Sarmad Dashti, Suzlyana Marhain, Md Shabbir Hossain, Ali Najah Ahmed, Mohsen Sherif, Ahmed Sefelnasr e Ahmed El-Shafie. "Optimizing the Operation Release Policy Using Charged System Search Algorithm: A Case Study of Klang Gates Dam, Malaysia". Sustainability 13, n. 11 (24 maggio 2021): 5900. http://dx.doi.org/10.3390/su13115900.
Testo completoAbstract (sommario):
In planning and managing water resources, the implementation of optimization techniques in the operation of reservoirs has become an important focus. An optimal reservoir operating policy should take into consideration the uncertainty associated with uncontrolled reservoir inflows. The charged system search (CSS) algorithm model is developed in the present study to achieve optimum operating policy for the current reservoir. The aim of the model is to minimize the cost of system performance, which is the sum of square deviations from the distinction between the release of the target and the actual demand. The decision variable is the release of a reservoir with an initial volume of storage, reservoir inflow, and final volume of storage for a given period. Historical rainfall data is used to approximate the inflow volume. The charged system search (CSS) is developed by utilizing a spreadsheet model to simulate and perform optimization. The model gives the steady-state probabilities of reservoir storage as output. The model is applied to the reservoir of Klang Gates for the development of an optimal reservoir operating policy. The steady-state optimal operating system is used in this model.
12
Mhiribidi, Delight, Joel Nobert, Webster Gumindoga e Donald T. Rwasoka. "Optimal water resource allocation modelling in the Lowveld of Zimbabwe". Proceedings of the International Association of Hydrological Sciences 378 (29 maggio 2018): 67–72. http://dx.doi.org/10.5194/piahs-378-67-2018.
Testo completoAbstract (sommario):
Abstract. The management and allocation of water from multi-reservoir systems is complex and thus requires dynamic modelling systems to achieve optimality. A multi-reservoir system in the Southern Lowveld of Zimbabwe is used for irrigation of sugarcane estates that produce sugar for both local and export consumption. The system is burdened with water allocation problems, made worse by decommissioning of dams. Thus the aim of this research was to develop an operating policy model for the Lowveld multi-reservoir system.The Mann Kendall Trend and Wilcoxon Signed-Rank tests were used to assess the variability of historic monthly rainfall and dam inflows for the period 1899–2015. The WEAP model was set up to evaluate the water allocation system of the catchment and come-up with a reference scenario for the 2015/2016 hydrologic year. Stochastic Dynamic Programming approach was used for optimisation of the multi-reservoirs releases.Results showed no significant trend in the rainfall but a significantly decreasing trend in inflows (p < 0.05). The water allocation model (WEAP) showed significant deficits ( ∼ 40 %) in irrigation water allocation in the reference scenario. The optimal rule curves for all the twelve months for each reservoir were obtained and considered to be a proper guideline for solving multi- reservoir management problems within the catchment. The rule curves are effective tools in guiding decision makers in the release of water without emptying the reservoirs but at the same time satisfying the demands based on the inflow, initial storage and end of month storage.
13
Haché, Mario, Marc Durocher e Bernard Bobée. "Modélisation non paramétrique de la relation entre les caractéristiques du vent et la différence de niveaux sur un grand réservoir". Canadian Journal of Civil Engineering 30, n. 4 (1 agosto 2003): 684–95. http://dx.doi.org/10.1139/l03-049.
Testo completoAbstract (sommario):
The natural inflow at a site is a key variable for optimal management of water resources, particularly for hydroelectric production. For sites with dams and hydroelectric powerplants, this variable cannot be measured directly, and the water balance equation is used to determine the quantity of water a site receives on its surface during a certain period of time. However, several errors affect the natural inflows computed this way. One of the principal sources of uncertainty for large reservoirs is the nonrepresentativeness of water level because of the wind effect. To quantify the effect of wind on the reservoir surface, a nonparametric regression model was used to relate the water level differences between several stations located on the same reservoir and the characteristics of the wind (direction and intensity). The study showed that the nonparametric regression model substantially improves the knowledge of the water level differences between several stations when there is presence of wind. With this model, it is possible to characterize the types of wind affecting the reservoir and to establish validation strategies for the data. The studied reservoirs are Outardes-4 and Gouin, two large reservoirs located in the north of the province of Québec, Canada.Key words: wind, reservoir, water level, nonparametric regression, natural inflow, performance criteria.
14
Salami, Adebayo Wahab, Bolaji Fatai Sule, Tope Lacroix Adunkpe, Ayanniyi Mufutau Ayanshola e Solomon Olakunle Bilewu. "Evaluation of the Hydropower Generation Potential of a Dam Using Optimization Techniques: Application to Doma Dam, Nassarawa, in North Central Nigeria". Slovak Journal of Civil Engineering 25, n. 1 (1 marzo 2017): 1–9. http://dx.doi.org/10.1515/sjce-2017-0001.
Testo completoAbstract (sommario):
Abstract Optimization models have been developed to maximize annual energy generation from the Doma dam, subject to the constraint of releases for irrigation, ecological purposes, the water supply, the maximum yield from the reservoir and reservoir storage. The model was solved with LINGO software for various mean annual inflow exceedence probabilities. Two scenarios of hydropower retrofitting were considered. Scenario 1, with the reservoir inflows at 50%, 75%, and 90% probabilities of exceedence, gives the total annual hydropower as 0.531 MW, 0.450 MW and 0.291 MW, respectively. The corresponding values for scenario 2 were 0.615 MW, 0.507 MW, and 0.346 MW respectively. The study also considered increasing the reservoir’s live storage to 32.63Mm3 by taking part of the flood storage so that the maximum draft increases to 7 Mm3. With this upper limit of storage and draft with reservoir inflows of 50%, 75% and 90% probabilities of exceedence, the hydropower generated increased to 0.609 MW, 0.540 MW, and 0.347 MW respectively for the scenario 1 arrangement, while those of scenario 2 increased to 0.699 MW, 0.579MW and 0.406 MW respectively. The results indicate that the Doma Dam is suitable for the production of hydroelectric power and that its generation potential is between 0.61 MW and 0.70 MW.
15
Phien, Huynh Ngoc. "Reservoir storage capacity with gamma inflows". Journal of Hydrology 146 (giugno 1993): 383–89. http://dx.doi.org/10.1016/0022-1694(93)90285-h.
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Yu, Chunxue, Xinan Yin, Zhifeng Yang e Zhi Dang. "Sustainable Water Resource Management of Regulated Rivers under Uncertain Inflow Conditions Using a Noisy Genetic Algorithm". International Journal of Environmental Research and Public Health 16, n. 5 (9 marzo 2019): 868. http://dx.doi.org/10.3390/ijerph16050868.
Testo completoAbstract (sommario):
Ecofriendly reservoir operation is an important tool for sustainable water resource management in regulated rivers. Optimization of reservoir operation is potentially affected by the stochastic characteristics of inflows. However, inflow stochastics are not widely incorporated in ecofriendly reservoir operation optimization. The reasons might be that computational cost and unsatisfactory performance are two key issues for reservoir operation under uncertainty inflows, since traditional simulation methods are usually needed to evaluate over many realizations and the results vary between different realizations. To solve this problem, a noisy genetic algorithm (NGA) is adopted in this study. The NGA uses an improved type of fitness function called sampling fitness function to reduce the noise of fitness assessment. Meanwhile, the Monte Carlo method, which is a commonly used approach to handle the stochastic problem, is also adopted here to compare the effectiveness of the NGA. Degree of hydrologic alteration and water supply reliability, are used to indicate satisfaction of environmental flow requirements and human needs. Using the Tanghe Reservoir in China as an example, the results of this study showed that the NGA can be a useful tool for ecofriendly reservoir operation under stochastic inflow conditions. Compared with the Monte Carlo method, the NGA reduces ~90% of the computational time and obtains higher water supply reliability in the optimization.
17
Zabalza-Martínez, J., S. Vicente-Serrano, J. López-Moreno, G. Borràs Calvo, R. Savé, D. Pascual, E. Pla, E. Morán-Tejeda, F. Domínguez-Castro e C. Tague. "The Influence of Climate and Land-Cover Scenarios on Dam Management Strategies in a High Water Pressure Catchment in Northeast Spain". Water 10, n. 11 (16 novembre 2018): 1668. http://dx.doi.org/10.3390/w10111668.
Testo completoAbstract (sommario):
This paper evaluates the response of streamflow in a Mediterranean medium-scaled basin under land-use and climate change scenarios and its plausible implication on the management of Boadella–Darnius reservoir (NE Spain). Land cover and climate change scenarios supposed over the next several decades were used to simulate reservoir inflow using the Regional Hydro-Ecologic Simulation System (RHESsys) and to analyze the future impacts on water management (2021–2050). Results reveal a clear decrease in dam inflow (−34%) since the dam was operational from 1971 to 2013. The simulations obtained with RHESsys show a similar decrease (−31%) from 2021 to 2050. Considering the ecological minimum flow outlined by water authorities and the projected decrease in reservoir’s inflows, different water management strategies are needed to mitigate the effects of the expected climate change.
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Chiamsathit, Chuthamat, Adebayo J. Adeloye e Soundharajan Bankaru-Swamy. "Inflow forecasting using Artificial Neural Networks for reservoir operation". Proceedings of the International Association of Hydrological Sciences 373 (12 maggio 2016): 209–14. http://dx.doi.org/10.5194/piahs-373-209-2016.
Testo completoAbstract (sommario):
Abstract. In this study, multi-layer perceptron (MLP) artificial neural networks have been applied to forecast one-month-ahead inflow for the Ubonratana reservoir, Thailand. To assess how well the forecast inflows have performed in the operation of the reservoir, simulations were carried out guided by the systems rule curves. As basis of comparison, four inflow situations were considered: (1) inflow known and assumed to be the historic (Type A); (2) inflow known and assumed to be the forecast (Type F); (3) inflow known and assumed to be the historic mean for month (Type M); and (4) inflow is unknown with release decision only conditioned on the starting reservoir storage (Type N). Reservoir performance was summarised in terms of reliability, resilience, vulnerability and sustainability. It was found that Type F inflow situation produced the best performance while Type N was the worst performing. This clearly demonstrates the importance of good inflow information for effective reservoir operation.
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Ehteram, Mohammad, Vijay P. Singh, Hojat Karami, Khosrow Hosseini, Mojgan Dianatikhah, Md Hossain, Chow Ming Fai e Ahmed El-Shafie. "Irrigation Management Based on Reservoir Operation with an Improved Weed Algorithm". Water 10, n. 9 (17 settembre 2018): 1267. http://dx.doi.org/10.3390/w10091267.
Testo completoAbstract (sommario):
Water scarcity is a serious problem throughout the world. One critical part of this problem is supplying sufficient water to meet irrigation demands for agricultural production. The present study introduced an improved weed algorithm for reservoir operation with the aim of decreasing irrigation deficits. The Aswan High Dam, one of the most important dams in Egypt, was selected for this study to supply irrigation demands. The improved weed algorithm (IWA) had developed local search ability so that the exploration ability for the IWA increased and it could escape from local optima. Three inflows (low, medium and high) to the reservoir were considered for the downstream demands. For example, the average solution for the IWA at high inflow was 0.985 while it was 1.037, 1.040, 1.115 and 1.121 for the weed algorithm (WA), bat algorithm (BA), improved particle swarm optimization algorithm (IPSOA) and genetic algorithm (GA). This meant that the IWA decreased the objective function for high inflow by 5.01%, 5.20%, 11.65% and 12% compared to the WA, BA, IPSOA and GA, respectively. The computational time for the IWA at high inflow was 22 s, which was 12%, 18%, 24% and 29% lower than the WA, BA, IPSOA and GA, respectively. Results indicated that the IWA could meet the demands at all three inflows. The reliability index for the IWA for the three inflows was greater than the WA, BA, IPSOA and GA, meaning that the released water based on IWA could well supply the downstream demands. Thus, the improved weed algorithm is suggested for solving complex problems in water resources management.
20
Thongwan, Teerawat, Anongrit Kangrang, Rapeepat Techarungreungsakul e Ratsuda Ngamsert. "Future Inflow under Land Use and Climate Changes and Participation Process into the Medium-Sized Reservoirs in Thailand". Advances in Civil Engineering 2020 (20 gennaio 2020): 1–17. http://dx.doi.org/10.1155/2020/5812530.
Testo completoAbstract (sommario):
The rainfall and runoff within a watershed area upper reservoir are necessary data for reservoir operation. In this manner, climate and land use changes are legitimately affected to inflow trademark into the reservoir storage. This investigation expects to appraise future inflow under the effect of atmosphere and land use changes of the Huay Sabag and Huay Ling Jone reservoirs, Thailand, during the period 2018–2067. The future inflow was evaluated by utilizing the SWAT model with the PRECIS territorial atmosphere model of B2 emanation situation, and considering land use information from the CA Markov model, both the balanced land use by support procedure type, and then unbalanced sort. Land use from CA Markov was adjusted by participation decides based on Taro Yamane table at the 90% of confidence. The outcome found that the normal precipitation and temperature were expanded in both upper store regions. The biggest land use change demonstrated the extension of the sugarcane and Para rubber tree, while paddy field and forest regions were diminished. The normal future inflows into the store under the two cases were expanded in examination with the watched information during the pattern year. However, the future inflow from the case of using CA Markov adjusting by participation process was higher than the future inflow from another case of using CA Markov without participation adjusting insignificantly for both reservoirs.
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Shan, He, Yin Xin’an e Zhifeng Yang. "Identifying effective reservoir capacity, water supply, inflow for tradeoff between human and ecological demand". MATEC Web of Conferences 246 (2018): 01034. http://dx.doi.org/10.1051/matecconf/201824601034.
Testo completoAbstract (sommario):
To protect the river ecosystem and sustain ecological flow regime, it’s vital to consider environmental flow management in reservoir operation. Many researches try to use more detailed environmental flow management strategies to improve ecological flow regime. However, ecological flow regime not only is influenced by environmental flow management strategy, but also by three kinds of parameters, including reservoir capacity, reservoir inflow and water supply yield. The aim of this paper is to illustrate how ecological flow regime is affected by different reservoir capacities, reservoir inflows and water supply yields and to find a proper reservoir capacity, reservoir inflow or water supply yield under which the optimal ecological flow regime is the best and could not be improved. In this paper, an environmental flow management strategy, which is Four-period release approach (FP), is developed. Besides, social benefit and ecosystem needs are satisfied simultaneously. The results show that changing reservoir capacity, reservoir inflow or water supply yield could improve ecological flow regime.
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Westra, Seth, e Ashish Sharma. "Probabilistic Estimation of Multivariate Streamflow Using Independent Component Analysis and Climate Information". Journal of Hydrometeorology 10, n. 6 (1 dicembre 2009): 1479–92. http://dx.doi.org/10.1175/2009jhm1121.1.
Testo completoAbstract (sommario):
Abstract A statistical estimation approach is presented and applied to multiple reservoir inflow series that form part of Sydney’s water supply system. The approach involves first identifying sources of interannual and interdecadal climate variability using a combination of correlation- and wavelet-based methods, then using this information to construct probabilistic, multivariate seasonal estimates using a method based on independent component analysis (ICA). The attraction of the ICA-based approach is that, by transforming the multivariate dataset into a set of independent time series, it is possible to maintain the parsimony of univariate statistical methods while ensuring that both the spatial and temporal dependencies are accurately captured. Based on a correlation analysis of the reservoir inflows with the original sea surface temperature anomaly data, the principal sources of variability in Sydney’s reservoir inflows appears to be a combination of the El Niño–Southern Oscillation (ENSO) phenomenon and the Pacific decadal oscillation (PDO). A multivariate ICA-based estimation model was then used to capture this variability, and it was shown that this approach performed well in maintaining the temporal dependence while also accurately maintaining the spatial dependencies that exist in the 11-dimensional historical reservoir inflow dataset.
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Shi, Lu, Bing Bai, Haiqing Wu e Xiaochun Li. "Evaluating Reservoir Risks and Their Influencing Factors during CO2 Injection into Multilayered Reservoirs". Geofluids 2017 (2017): 1–14. http://dx.doi.org/10.1155/2017/6059142.
Testo completoAbstract (sommario):
Wellbore and site safety must be ensured during CO2 injection into multiple reservoirs during carbon capture and storage projects. This study focuses on multireservoir injection and investigates the characteristics of the flow-rate distribution and reservoir-risk evaluation as well as their unique influences on multireservoir injection. The results show that more CO2 enters the upper layers than the lower layers. With the increase in injection pressure, the risks of the upper reservoirs increase more dramatically than those of the low reservoirs, which can cause the critical reservoir (CR) to shift. The CO2 injection temperature has a similar effect on the injection flow rate but no effect on the CR’s location. Despite having no effect on the flow-rate distribution, the formation-fracturing pressures in the reservoirs determine which layer becomes the CR. As the thickness or permeability of a layer increases, the inflows exhibit upward and downward trends in this layer and the lower layers, respectively, whereas the inflows of the upper layers remain unchanged; meanwhile, the risks of the lower layer and those of the others decrease and remain constant, respectively. Compared to other parameters, the reservoir porosities have a negligible effect on the reservoir risks and flow-rate distributions.
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Nair, Sukanya J., e K. Sasikumar. "Fuzzy reliability-based optimization of a hydropower reservoir". Journal of Hydroinformatics 21, n. 2 (1 febbraio 2019): 308–17. http://dx.doi.org/10.2166/hydro.2019.078.
Testo completoAbstract (sommario):
Abstract Reservoir operation modeling and optimization are inevitable components of water resources planning and management. Determination of reservoir operating policy is a multi-stage decision-making problem characterized by uncertainty. Uncertainty in inflows and power demands lead to varying degrees of the working of a reservoir from one period to another. This transition, being ambiguous in nature, can be addressed in a fuzzy framework. The different working states of the reservoir are described as fuzzy states. Based on the degree of success in meeting the power demand and randomness associated with inflows, hydropower production is considered as a random fuzzy event. This paper examines the scope of profust reliability theory, a theory used in the reliability analysis of manufactured systems, in the performance optimization of a hydropower reservoir system. The operating policy derived from a profust reliability-based optimization model is compared with a simulation model. The model is then used to derive the optimal operation policy for a hypothetical reservoir fed by normally distributed inflow, for a period of five years. The results show that the model is useful in deriving optimal operating policies with improved reliabilities in hydropower production.
25
Glynn, John E., e Peter W. Glynn. "On the behaviour of a long cascade of linear reservoirs". Journal of Applied Probability 37, n. 02 (giugno 2000): 417–28. http://dx.doi.org/10.1017/s002190020001562x.
Testo completoAbstract (sommario):
This paper describes the limiting asymptotic behaviour of a long cascade of linear reservoirs fed by stationary inflows into the first reservoir. We show that the storage in the nth reservoir becomes asymptotically deterministic as n → ∞, and establish a central limit theorem for the random fluctuations about the deterministic approximation. In addition, we prove a large deviations theorem that provides precise logarithmic asymptotics for the tail probabilities associated with the storage in the nth reservoir when n is large.
26
Glynn, John E., e Peter W. Glynn. "On the behaviour of a long cascade of linear reservoirs". Journal of Applied Probability 37, n. 2 (giugno 2000): 417–28. http://dx.doi.org/10.1239/jap/1014842547.
Testo completoAbstract (sommario):
This paper describes the limiting asymptotic behaviour of a long cascade of linear reservoirs fed by stationary inflows into the first reservoir. We show that the storage in the nth reservoir becomes asymptotically deterministic as n → ∞, and establish a central limit theorem for the random fluctuations about the deterministic approximation. In addition, we prove a large deviations theorem that provides precise logarithmic asymptotics for the tail probabilities associated with the storage in the nth reservoir when n is large.
27
Marti, Clelia Luisa, Rianda Mills e Jörg Imberger. "Pathways of multiple inflows into a stratified reservoir: Thomson Reservoir, Australia". Advances in Water Resources 34, n. 5 (maggio 2011): 551–61. http://dx.doi.org/10.1016/j.advwatres.2011.01.003.
Testo completo
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Celeste, Alcigeimes B., Wilson F. Curi e Rosires C. Curi. "Implicit Stochastic Optimization for deriving reservoir operating rules in semiarid Brazil". Pesquisa Operacional 29, n. 1 (aprile 2009): 223–34. http://dx.doi.org/10.1590/s0101-74382009000100011.
Testo completoAbstract (sommario):
This paper deals with the application of Implicit Stochastic Optimization (ISO) to determine monthly operating rules for a reservoir system located in the semiarid Northeast of Brazil. ISO employs a deterministic optimization model to find optimal reservoir allocations under several possible inflow scenarios and later constructs the rules by analyzing the ensemble of these optimal releases. The operating policies provide the monthly reservoir release conditioned on the storage at the beginning of the month and the inflow predicted for the month. In addition to the classical regression analysis, this study establishes the rules by a two-dimensional interpolation strategy. After the rules are identified, they are applied to operate the system under new inflow realizations and show ability to produce policies similar to those obtained by deterministic optimization taking the same inflows as perfect forecasts.
29
Lu, Liyu, Chunhua Tao e Weibin Huang. "Study on Flood and Sediment Joint Operation of Dadu River Downstream Cascade Reservoirs". MATEC Web of Conferences 246 (2018): 01082. http://dx.doi.org/10.1051/matecconf/201824601082.
Testo completoAbstract (sommario):
There is large amount of high hardness sand in the water flow in Dadu river. The problem of sediment deposition is very prominent in the two early reservoirs, Gongzui reservoir and Tongjiezi reservoir. In order to decrease sediment deposition effectively and extend the service life of them, the sediment characteristics of Dadu river cascade hydropower stations are analysed, as well as changes of sediment deposition in Gongzui reservoir and Tongjiezi reservoir after Pubugou reservoir puts into operation. Flood forecast and pre-discharge operation theory are studied for utilizing the discarding water to improve sediment-flushing effect, and flood and sediment joint dispatching schemes of cascade reservoirs are proposed. In order to evaluate effects of joint dispatching schemes, SBED extended one-dimensional flushing sediment mathematical model of deposited reservoir is built, and the mathematical model is used for simulative computation of coming 20-years sediment-flushing effect. After that, the effects of different schemes are analyzed comparatively. Three conclusions can be drawn from the studying. Firstly, the sediment in Gongzui reservoir and Tongjiezi reservoir is obviously reduced after Pubugou reservoir puts into operation. Secondly, flood forecast, pre-discharge operation theory and creating sand-flushing conditions can obviously improve sediment-flushing effects and avoid wasting power generation water when the water levels and outflows of Pubugou reservoir, Gongzui reservoir and Tongjiezi reservoir are rationally controlled. Finally, the larger the inflows and the lower the water level of Gongzui reservoir and Tongjiezi reservoir is, the more obvious the sediment-flushing effects are. According to situations of power plant at the time, such as rules of flood controlling and operation requirements of flood discharge facilities, it is recommended that the inflow of Gongzui reservoir is controlled at about 4500m3/s, and timely lower the water levels of Gongzui reservoir and Tongjiezi reservoir to their dead water levels, when carrying out joint dispatching schemes.
30
Nikitin, V. M., e E. N. Malinovskaya. "Hydro Power Plants in the Interconnected Power System of Siberia: Trends and Problems". E3S Web of Conferences 209 (2020): 05019. http://dx.doi.org/10.1051/e3sconf/202020905019.
Testo completoAbstract (sommario):
The paper discusses the trends, features, and current problems of the operation of hydro power plants in the interconnected power system (IPS) of Siberia. The main feature of the IPS of Siberia is a high proportion of hydro power plants and, as a result, a strong dependence of power generation on the natural fluctuations of water inflows into reservoirs. The problems affecting the power system efficiency arise when the inflows deviate from normal and close-to-normal values. The study indicates the need to improve the current system of managing and planning the operation of hydro power plants. The important factor that can increase the efficiency and reliability of the power system operation is bringing the permissible ranges of variations in reservoir levels in compliance with the design values. Planning the long-term power balances and increasing their validity should involve predictive scenarios of water inflows into reservoirs.
31
Li, Yuanya, Junhua Zhang e Huaibao Ma. "Analytical Froude number solution for reservoir density inflows". Journal of Hydraulic Research 49, n. 5 (26 settembre 2011): 693–96. http://dx.doi.org/10.1080/00221686.2011.593905.
Testo completo
32
Mimikou, V., e Nalbandis Grad. "Influence Of Reservoir Inflows’ Persistence On Storage Capacity". International Journal of Modelling and Simulation 7, n. 4 (gennaio 1987): 164–67. http://dx.doi.org/10.1080/02286203.1987.11760019.
Testo completo
33
Changchit, Chaweng, e M. P. Terrell. "A multiobjective reservoir operation model with stochatic inflows". Computers & Industrial Engineering 24, n. 2 (aprile 1993): 303–13. http://dx.doi.org/10.1016/0360-8352(93)90016-q.
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34
Turner, Sean W. D., Wenwei Xu e Nathalie Voisin. "Inferred inflow forecast horizons guiding reservoir release decisions across the United States". Hydrology and Earth System Sciences 24, n. 3 (19 marzo 2020): 1275–91. http://dx.doi.org/10.5194/hess-24-1275-2020.
Testo completoAbstract (sommario):
Abstract. Medium- to long-range forecasts often guide reservoir release decisions to support water management objectives, including mitigating flood and drought risks. While there is a burgeoning field of science targeted at improving forecast products and associated decision support models, data describing how and when forecasts are applied in practice remain undeveloped. This lack of knowledge may prevent hydrological modelers from developing accurate reservoir release schemes for large-scale, distributed hydrology models that are increasingly used to assess the vulnerabilities of large regions to hydrological stress. We address this issue by estimating seasonally varying, regulated inflow forecast horizons used in the operations of more than 300 dams throughout the conterminous United States (CONUS). For each dam, we take actual forward observed inflows (perfect foresight) as a proxy for forecasted flows available to the operator and then identify for each week of the year the forward horizon that best explains the release decisions taken. Resulting “horizon curves” specify for each dam the inferred inflow forecast horizon as a function of the week of the water year. These curves are analyzed for strength of evidence for contribution of medium- to long-range forecasts in decision making. We use random forest classification to estimate that approximately 80 % of large dams and reservoirs in the US (1553±50 out of 1927 dams with at least 10 Mm3 storage capacity) adopt medium- to long-range inflow forecasts to inform release decisions during at least part of the water year. Long-range forecast horizons (more than 6 weeks ahead) are detected in the operations of reservoirs located in high-elevation regions of the western US, where snowpack information likely guides the release. A simulation exercise conducted on four key western US reservoirs indicates that forecast-informed models of reservoir operations may outperform models that neglect the horizon curve – including during flood and drought conditions.
35
Schlein, G. A., I. I. Kleshchenko, A. A. Baluev e A. F. Semenenko. "Development potential of jet pumps and technology in the oil and gas industry". Oil and Gas Studies, n. 3 (8 luglio 2020): 75–88. http://dx.doi.org/10.31660/0445-0108-2020-3-75-88.
Testo completoAbstract (sommario):
The article deals with innovative technologies for the development and research of oil and gas wells by jet devices in various conditions of occurrence of productive formations. Data are given about the results of work with jet pumps for intensifying the inflows in fields of Western Siberia and about their efficiency to change well productivity. We show development potential of jet pumps and technology in the oil and gas industry to improve the quality of well construction and well operation. Attention is drawn to new technologies and designs of jet pumps, which have been developed for well development, research of two or more reservoirs with the aim of combining them into one production facility. The article gives valuable information on effective technical and technological solutions for well development and stimulation of inflows from reservoirs with abnormally high reservoir pressure. The use of this technique and technology in well development processes allows you to obtain enhanced information about the reservoir properties of productive formations, as well as to increase their productivity.
36
Arsenault, Richard, e Pascal Côté. "Analysis of the effects of biases in ensemble streamflow prediction (ESP) forecasts on electricity production in hydropower reservoir management". Hydrology and Earth System Sciences 23, n. 6 (28 giugno 2019): 2735–50. http://dx.doi.org/10.5194/hess-23-2735-2019.
Testo completoAbstract (sommario):
Abstract. This paper presents an analysis of the effects of biased extended streamflow prediction (ESP) forecasts on three deterministic optimization techniques implemented in a simulated operational context with a rolling horizon test bed for managing a cascade of hydroelectric reservoirs and generating stations in Québec, Canada. The observed weather data were fed to the hydrological model, and the synthetic streamflow subsequently generated was considered to be a proxy for the observed inflow. A traditional, climatology-based ESP forecast approach was used to generate ensemble streamflow scenarios, which were used by three reservoir management optimization approaches. Both positive and negative biases were then forced into the ensembles by multiplying the streamflow values by constant factors. The optimization method's response to those biases was measured through the evaluation of the average annual energy generation in a forward-rolling simulation test bed in which the entire system is precisely and accurately modelled. The ensemble climate data forecasts, the hydrological modelling and ESP forecast generation, optimization model, and decision-making process are all integrated, as is the simulation model that updates reservoir levels and computes generation at each time step. The study focussed on one hydropower system both with and without minimum baseload constraints. This study finds that the tested deterministic optimization algorithms lack the capacity to compensate for uncertainty in future inflows and therefore place the reservoir levels at greater risk to maximize short-term profit. It is shown that for this particular system, an increase in ESP forecast inflows of approximately 5 % allows managing the reservoirs at optimal levels and producing the most energy on average, effectively negating the deterministic model's tendency to underestimate the risk of spilling. Finally, it is shown that implementing minimum load constraints serves as a de facto control on deterministic bias by forcing the system to draw more water from the reservoirs than what the models consider to be optimal trajectories.
37
Pacheco, F. S., M. C. S. Soares, A. T. Assireu, M. P. Curtarelli, F. Roland, G. Abril, J. L. Stech, P. C. Alvalá e J. P. Ometto. "The effects of river inflow and retention time on the spatial heterogeneity of chlorophyll and water–air CO<sub>2</sub> fluxes in a tropical hydropower reservoir". Biogeosciences 12, n. 1 (9 gennaio 2015): 147–62. http://dx.doi.org/10.5194/bg-12-147-2015.
Testo completoAbstract (sommario):
Abstract. Abundant research has been devoted to understanding the complexity of the biogeochemical and physical processes that are responsible for greenhouse gas (GHG) emissions from hydropower reservoirs. These systems may have spatially complex and heterogeneous GHG emissions due to flooded biomass, river inflows, primary production and dam operation. In this study, we investigated the relationships between the water–air CO2 fluxes and the phytoplanktonic biomass in the Funil Reservoir, which is an old, stratified tropical reservoir that exhibits intense phytoplankton blooms and a low partial pressure of CO2 (pCO2). Our results indicated that the seasonal and spatial variability of chlorophyll concentrations (Chl) and pCO2 in the Funil Reservoir are related more to changes in the river inflow over the year than to environmental factors such as air temperature and solar radiation. Field data and hydro\\-dynamic simulations revealed that river inflow contributes to increased heterogeneity during the dry season due to variations in the reservoir retention time and river temperature. Contradictory conclusions could be drawn if only temporal data collected near the dam were considered without spatial data to represent CO2 fluxes throughout the reservoir. During periods of high retention, the average CO2 fluxes were 10.3 mmol m−2 d−1 based on temporal data near the dam versus −7.2 mmol m−2 d−1 with spatial data from along the reservoir surface. In this case, the use of solely temporal data to calculate CO2 fluxes results in the reservoir acting as a CO2 source rather than a sink. This finding suggests that the lack of spatial data in reservoir C budget calculations can affect regional and global estimates. Our results support the idea that the Funil Reservoir is a dynamic system where the hydrodynamics represented by changes in the river inflow and retention time are potentially a more important force driving both the Chl and pCO2 spatial variability than the in-system ecological factors.
38
Seidou, O., B. Robert, C. Marche, J. Rousselle e M. Lefebvre. "Construction probabiliste de scénarios d'apports à un réservoir". Canadian Journal of Civil Engineering 31, n. 1 (1 gennaio 2004): 146–54. http://dx.doi.org/10.1139/l03-108.
Testo completoAbstract (sommario):
The behaviour of a hydric system depends on three factors : (i) the state of the installation, (ii) the operating rules, and (iii) the inflows. While the first two factors are (in theory) known to the manager, the third can only be estimated by means of more or less precise forecasts. A significant part of the risk, to which is subjected the system at a given time, is induced by the uncertainty in the future inflows. The evaluation of this uncertainty is therefore a first step in the incorporation of risk into management. Its evaluation is then a stage preliminary to the integration of the risk in management. A method of construction of inflow scenarios starting from an arbitrary date t of the year is developed in this paper. It uses a Markovian process formerly developed by the authors to model short-term uncertainty in stream flow. These scenarios, which are not equiprobable, are built to reproduce the statistical behaviour of the river or reservoir and have the shape of an event tree whose structure is defined by the user before application of the method. Two examples of application on two rivers located in Quebec, Canada, are presented.Key words: reservoir operation, previsions, inflows, risk, uncertainty.
39
Mamman, Mohammed J., Otache Y. Martins, Jibril Ibrahim e Mohammed I. Shaba. "Evaluation of Best-Fit Probability Distribution Models for the Prediction of Inflows of Kainji Reservoir, Niger State, Nigeria". Air, Soil and Water Research 10 (1 gennaio 2017): 117862211769103. http://dx.doi.org/10.1177/1178622117691034.
Testo completoAbstract (sommario):
The analysis of time series is essential for building mathematical models to generate synthetic hydrologic records, to forecast hydrologic events, to detect intrinsic stochastic characteristics of hydrologic variables, as well as to fill missing and extend records. To this end, various probability distribution models were fitted to river inflows of Kainji Reservoir in New Bussa, Niger State, Nigeria. This is to evaluate the probability function that is best suitable for the prediction of their values and subsequently using the best model to predict for both the expected maximum and minimum monthly inflows at some specific return periods. Three models, ie, Gumbel extreme value type I (EVI), log-normal (LN), and normal (N), were evaluated for the inflows and the best model was selected based on the statistical goodness-of-fit test. The values of goodness-of-fit test for Kainji hydropower dam are as follows: r = 0.96, R2 = 0.99, SEE = 0.0087, χ2 = 0.0054, for Gumbel (EVI); r = 0.79, R2 = 0.85, SEE = 0.02, χ2 = 0.31 for LN; and r = 0.0.75, R2 = 0.0.68, SEE = 0.056, χ2 = 1376.39 for N. For the Kainji hydropower dams, the Gumbel (EVI) model gave the best fit. These probability distribution models can be used to predict the near-future reservoir inflow at the Kainji hydropower dams.
40
Nandalal, K. D. W., e Janos J. Bogardi. "Optimal operation of a reservoir for quality control using inflows and outflows". Water Science and Technology 31, n. 8 (1 aprile 1995): 273–80. http://dx.doi.org/10.2166/wst.1995.0319.
Testo completoAbstract (sommario):
This paper presents two optimization models developed for the derivation of operation policies for a reservoir when the quality considerations are important besides satisfying the quantity requirement. In one model only the releases are controlled. In the other model both inflows and releases are controlled. Reservoir operational policy is based on the Incremental Dynamic Programming technique. Complete mixing is assumed to be occurring in the reservoir throughout the year. The models are applied to a reservoir on the Shapur river in Southern Iran. The results obtained from the models show their potential in improving the quality of water supplied from a reservoir. The improvements obtained by manipulating both inflows and releases are observed to be higher than the ones achieved by simple release control.
41
Hoseinzadeh, Toktam, Mojtaba Shourian e Jafar Yazdi. "Optimum design and operation of a hydropower reservoir considering uncertainty of inflow". Journal of Hydroinformatics 22, n. 6 (4 settembre 2020): 1452–67. http://dx.doi.org/10.2166/hydro.2020.044.
Testo completoAbstract (sommario):
Abstract Due to the large number of variables and nonlinear relations, hydropower plant design and operation optimization problems belong to the Non-polynomial hard class of problems. In this study, optimum design and operation of a hydropower reservoir is compared in two cases using deterministic and stochastic inflows by two meta-heuristic algorithms. Particle swarm optimization (PSO) and cuckoo optimization algorithm (COA) are applied under two conditions of using the historical inflow time series as a deterministic approach and the eigenvector-based synthetic generations as a stochastic approach for optimum design and operation of the Bakhtiari hydropower plant in Iran. The problem is solved in two states of finding the optimum values for the reservoir and power plant capacities (as the design decision variables) with known standard operation policy (SOP) and optimum values for the capacities and the reservoir releases variables (as the design and operating variables). Results obtained by the models indicate that the role of operation optimization is negligible as the SOP used in the design models led to near optimum solutions. Considering uncertainty in the reservoir inflows resulted in an increase of the installation capacity and consequently the energy production. In addition, PSO demonstrated more efficiency compared to COA in dealing with the proposed optimization problem that has a complex feasible search space.
42
Straškrabová, V., J. Komárková e V. Vyhnálek. "Degradation of Organic Substances in Reservoirs". Water Science and Technology 28, n. 6 (1 settembre 1993): 95–104. http://dx.doi.org/10.2166/wst.1993.0133.
Testo completoAbstract (sommario):
Due to the retention of water in an impoundment, the degradation of easily decomposable organic substances expressed as BOD (“self- purification”) is higher in a reservoir compared to a similar stretch of flowing river. For the same reason, the production of new organic matter by phytoplankton (PP) is also enhanced after impoundment. Data on reservoirs with theoretical retention time (RT) in the range of 1 - 535 days showed that PP reached 9 - 99% of the total input (TI) expressed as BOD (TI = PP + BOD load by inflows). The share of PP increases with increasing RT, decreases with increasing mean depth and depends on the quality of inflows. During 10 years' period, the relation of BOD and PP to bacterial and algal respiration has been examined in a temperate, dimictic, canyon-shaped reservoir. Total budget showed that BOD decrease fluctuated between 70 to 88% of TI, irrespective of the increasing PP during the whole period.
43
Nguyen, Anh, Thomas Cochrane e Markus Pahlow. "A Framework to Assess the Reliability of a Multipurpose Reservoir under Uncertainty in Land Use". Water 13, n. 3 (25 gennaio 2021): 287. http://dx.doi.org/10.3390/w13030287.
Testo completoAbstract (sommario):
Socioeconomic development in watersheds lead to land-use changes, which can alter water and sediment inflows into reservoirs, leading to uncertainty in water supply reliability. A modelling framework coupling the Soil and Water Assessments Tool (SWAT) and the @RISK genetic algorithm optimisation tool was developed to optimise water allocation and estimate water supply reliability under uncertainty in future land-use. The multi-purpose Nuicoc reservoir in Vietnam was used as a case study. Modelling results showed that an expansion of the urban areas by 10% and conversion of 5% of the forest to agricultural areas produced the highest water releases for downstream demands of all simulated scenarios, with 5 Mcm/year greater water releases than the baseline for the case where sedimentation was not considered. However, when sedimentation was considered, it generated the greatest decrease in water releases, with 6.25 Mcm/year less than the baseline. Additionally, it was determined that spatial distribution of land-use significantly affect sediment inflows into the reservoir, highlighting the importance of targeted sediment management. This demonstrates the usefulness of the proposed framework for decision-makers in assessing the impact of possible land-use changes on the reservoir operation.
44
Pacina, Jan, Zuzana Lenďáková, Jiří Štojdl, Tomáš Matys Grygar e Martin Dolejš. "Dynamics of Sediments in Reservoir Inflows: A Case Study of the Skalka and Nechranice Reservoirs, Czech Republic". ISPRS International Journal of Geo-Information 9, n. 4 (18 aprile 2020): 258. http://dx.doi.org/10.3390/ijgi9040258.
Testo completoAbstract (sommario):
A wide variety of geographic information system tools and methods was used for pre-dam topography reconstruction and reservoir bottom surveying in two dam reservoirs in the Ohře River, Czech Republic. The pre-dam topography was reconstructed based on archival aerial imagery and old maps. The benefits and drawbacks of these methods were tested and explained with emphasis on the fact that not all processed archival data are suitable for pre-dam topography modeling. Bathymetric surveying of a reservoir bottom is presently routine, but in this study, we used a wide combination of bathymetric mapping methods (sonar, ground penetration radar, and sub-bottom profiler) and topographic survey tools (LiDAR and photogrammetry), bringing great benefits for bottom dynamic analysis and data cross-validation. The data that we gathered made it possible to evaluate the formation of the inflow deltas in the reservoirs studied and assess the sediment reworking during recent seasonal drawdowns. A typical inflow delta was formed in the deeper of the two studied reservoirs, while the summer 2019 drawdown caused the formation and incision of a temporary drawdown channel and erosive downstream transport of approximately 1/10 of the delta body thickness in approximately 1/10 of the delta transverse size. No inflow delta was formed in the shallower of the studied reservoirs, but unexpectedly extensive sediment reworking was observed in the inflow part of the reservoir. Both the studied reservoirs and the pre-dam river floodplain have accumulated historical contamination by risk elements such as As, Hg, Pb; thus, the enhanced erosion of existing sediment bodies expected in the future, owing to more frequent droughts and global climate change, will endanger the ecological quality of the water and solids outflowing from the reservoirs.
45
Cuevas-Velásquez, Víctor, Alvaro Sordo-Ward, Jaime H. García-Palacios, Paola Bianucci e Luis Garrote. "Probabilistic Model for Real-Time Flood Operation of a Dam Based on a Deterministic Optimization Model". Water 12, n. 11 (16 novembre 2020): 3206. http://dx.doi.org/10.3390/w12113206.
Testo completoAbstract (sommario):
This paper presents a real-time flood control model for dams with gate-controlled spillways that brings together the advantages of an optimization model based on mixed integer linear programming (MILP) and a case-based learning scheme using Bayesian Networks (BNets). A BNet model was designed to reproduce the causal relationship between inflows, outflows and reservoir storage. The model was trained with synthetic events generated with the use of the MILP model. The BNet model produces a probabilistic description of recommended dam outflows over a time horizon of 1 to 5 h for the Talave reservoir in Spain. The results of implementing the BNet recommendation were compared against the results obtained while applying two conventional models: the MILP model, which assumes full knowledge of the inflow hydrograph, and the Volumetric Evaluation Method (VEM), a method widely used in Spain that works in real-time, but without any knowledge of future inflows. In order to compare the results of the three methods, the global risk index (Ir) was computed for each method, based on the simulated behavior for an ensemble of hydrograph inflows. The Ir values associated to the 2 h-forecast BNet model are lower than those obtained for VEM, which suggests improvement over standard practice. In conclusion, the BNet arises as a suitable and efficient model to support dam operators for the decision making process during flood events.
46
Xu, Wei, Xiaoying Fu, Xia Li e Ming Wang. "Data transformation models utilized in Bayesian probabilistic forecast considering inflow forecasts". Hydrology Research 50, n. 5 (10 luglio 2019): 1267–80. http://dx.doi.org/10.2166/nh.2019.028.
Testo completoAbstract (sommario):
Abstract This paper presents a new Bayesian probabilistic forecast (BPF) model to improve the efficiency and reliability of normal distribution transformation and to describe the uncertainties of medium-range forecasting inflows with 10 days forecast horizons. In this model, the inflow data will be transformed twice to a standard normal distribution. The Box–Cox (BC) model is first used to quickly transform the inflow data with a normal distribution, and then, the transformed data are converted to a standard normal distribution by the meta-Gaussian (MG) model. Based on the transformed inflows in the standard normal distribution, the prior and likelihood density functions of the BPF are established, respectively. In this study, the newly developed model is tested on China's Huanren hydropower reservoir and is compared with BPFs using MG and BC, separately. Comparative results show that the new BPF model exhibits significantly improved data transformation efficiency and forecast accuracy.
47
Zhong, Yixuan, Shenglian Guo, Huanhuan Ba, Feng Xiong, Fi-John Chang e Kairong Lin. "Evaluation of the BMA probabilistic inflow forecasts using TIGGE numeric precipitation predictions based on artificial neural network". Hydrology Research 49, n. 5 (21 febbraio 2018): 1417–33. http://dx.doi.org/10.2166/nh.2018.177.
Testo completoAbstract (sommario):
Abstract Reservoir inflow forecasting is a crucial task for reservoir management. Without considering precipitation predictions, the lead time for inflow is subject to the concentration time of precipitation in the basin. With the development of numeric weather prediction (NWP) techniques, it is possible to forecast inflows with long lead times. Since larger uncertainty usually occurs during the forecasting process, much attention has been paid to probabilistic forecasts, which uses a probabilistic distribution function instead of a deterministic value to predict the future status. In this study, we aim at establishing a probabilistic inflow forecasting scheme in the Danjiangkou reservoir basin based on NWP data retrieved from the Interactive Grand Global Ensemble (TIGGE) database by using the Bayesian model averaging (BMA) method, and evaluating the skills of the probabilistic inflow forecasts. An artificial neural network (ANN) is used to implement hydrologic modelling. Results show that the corrected TIGGE NWP data can be applied sufficiently to inflow forecasting at 1–3 d lead times. Despite the fact that the raw ensemble inflow forecasts are unreliable, the BMA probabilistic inflow forecasts perform much better than the raw ensemble forecasts in terms of probabilistic style and deterministic style, indicating the established scheme can offer a useful approach to probabilistic inflow forecasting.
48
Seifi, Abbas, e Keith W. Hipel. "Interior-Point Method for Reservoir Operation with Stochastic Inflows". Journal of Water Resources Planning and Management 127, n. 1 (febbraio 2001): 48–57. http://dx.doi.org/10.1061/(asce)0733-9496(2001)127:1(48).
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49
Sankarasubramanian, A., Upmanu Lall, Naresh Devineni e Susan Espinueva. "The Role of Monthly Updated Climate Forecasts in Improving Intraseasonal Water Allocation". Journal of Applied Meteorology and Climatology 48, n. 7 (1 luglio 2009): 1464–82. http://dx.doi.org/10.1175/2009jamc2122.1.
Testo completoAbstract (sommario):
Abstract Seasonal streamflow forecasts contingent on climate information are essential for short-term planning (e.g., water allocation) and for setting up contingency measures during extreme years. However, the water allocated based on the climate forecasts issued at the beginning of the season needs to be revised using the updated climate forecasts throughout the season. In this study, reservoir inflow forecasts downscaled from monthly updated precipitation forecasts from ECHAM4.5 forced with “persisted” SSTs were used to improve both seasonal and intraseasonal water allocation during the October–February season for the Angat reservoir, a multipurpose system, in the Philippines. Monthly updated reservoir inflow forecasts are ingested into a reservoir simulation model to allocate water for multiple uses by ensuring a high probability of meeting the end-of-season target storage that is required to meet the summer (March–May) demand. The forecast-based allocation is combined with the observed inflows during the season to estimate storages, spill, and generated hydropower from the system. The performance of the reservoir is compared under three scenarios: forecasts issued at the beginning of the season, monthly updated forecasts during the season, and use of climatological values. Retrospective reservoir analysis shows that the operation of a reservoir by using monthly updated inflow forecasts reduces the spill considerably by increasing the allocation for hydropower during above-normal-inflow years. During below-normal-inflow years, monthly updated streamflow forecasts could be effectively used for ensuring enough water for the summer season by meeting the end-of-season target storage. These analyses suggest the importance of performing experimental reservoir analyses to understand the potential challenges and opportunities in improving seasonal and intraseasonal water allocation by using real-time climate forecasts.
50
Yannopoulos, Panayotis, e Alexander Demetracopoulos. "A Novel Methodology for Multiple-Year Regulation of Reservoir Active Storage Capacity". Water 10, n. 9 (14 settembre 2018): 1254. http://dx.doi.org/10.3390/w10091254.
Testo completoAbstract (sommario):
Reservoir design entails the determination of the required storage capacity over multiple years of low flow conditions to ensure the coverage of multiple-purpose water demands. Dam operation depends on many factors that may result in the decrease of required safe yields, leading to inadequate outflow supplies in the design period. This study addresses two issues: (a) the computation of reservoir active storage capacity performed with the aid of the new concept of a zero-height dam, a procedure easy to interpret physically and implement computationally; and (b) the generation of appropriate inflow data, provided that a substantial record of monthly inflows is available. The treatment of the inflow data for the generation of inflow sequences for any desired regulation period is performed by two original methods (First and Second), which are entirely different from other available methods and allow for the selection of a reservoir capacity with the desired level of exceedance probability. The two methods proposed give practically the same results. However, the Second Method, which generates inflow data consisting of hydrologic years with inflow values for each month randomly selected from the observed values for that month, is superior in terms of the ease with which inflow sequences are generated. Also, due to the large size of the random sample that can be generated, the exceedance probability curves are very smooth and allow for the easy selection of reservoir storage capacity with any level of desired exceedance probability. The proposed methodology may be useful for consultants and reservoir managers.