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This paper designs and builds a stormwater pipe-river/channel experimental system at the first attempt to observe hydraulic dynamics between pipe flow and downstream water levels under different steady state conditions. In addition, a three-dimensional (3D) model is developed to facilitate the understanding of this complex hydraulic interaction, and the reliability of a widely used one-dimensional (1D) model is first investigated. Experiment and simulation results show that (1) a high downstream water level can increase pipe flow capacity at the early stage, and the pipe flow is followed by a slightly downward trend and finally rapidly decreased, (2) pipe flows exhibit complex behaviors during the transition from nonfull to full pipe flow by altering flow area and velocity, and (3) the observed flows are significantly lower than those from the 1D model for the nonfull pipe flow scenario. This study offers insights to the underlying complex hydraulic properties between pipe flows and downstream water levels, and also shows that the 1D model is insufficient to reveal such an interaction process, which may underestimate the urban flooding risk. [ABSTRACT FROM AUTHOR]

In this paper, the EPA storm water management model (EPA-SWMM) was used for the simulation of intermittent water distribution systems (WDSs). The model was compared with field data collected during an experimental campaign carried out in the intermittent WDS of a small municipality in southern Italy. In a novel way compared to the literature, the whole cycle of operation of the WDS was simulated, including the filling, the distribution, and the emptying phases of the intermittent network. To improve the description of the hydraulics of the WDS during intermittent water supply, the modeling also included private tanks that are normally interposed between network pipes and end users. Comparison of model results and experimental observations concerned water levels at the reservoirs and pressures at specific nodes of the water distribution network (WDN) during some days of experiments characterized by different water supply modalities and water demand. Globally, the developed model proved capable of simulating correctly the whole cycle of intermittent operation of the WDN with an average RMSE between model and experiments of 0.1 m for water levels and 5.2 m for pressures. Simulations also made it possible to formulate preliminary considerations about equity in water resource distribution among users. The potential and limitations of the study are discussed and suggestions for future research steps made. [ABSTRACT FROM AUTHOR]

Methane and other gases released from soft sediments are among the main sources of greenhouse gases in the atmosphere. In this paper, a growth model for isolated bubbles in the sediments was established based on the theory of linear elastic fracture mechanics. Water level drop experiments were conducted using magnesium lithium philip silicate transparent soils, and the changes in bubble pressure and morphology during water level drop were analyzed. The experimental results show that there is a critical pressure for bubble growth caused by a drop in water level. Bubbles only start to grow by fracturing the overlying sediments when the water level drops to the critical value because the critical bubble pressure is lower than the actual bubble pressure. The strength of soil, depth of the bubble position, longitudinal length of bubble, and amount and rate of water level drop are key factors affecting isolated bubble growth. Bubbles in the soils with higher strength are more difficult to reach the critical state but have a faster growth rate once they do reach it. The depth of bubble position only affects the time reaching the critical state and does not impact the post-growth process. Deeper bubbles are more difficult for initiating growth. For bubbles at the same depth, larger bubbles begin growing earlier. As bubbles become larger, the growth rate of the bubble increases progressively faster. Faster water level drops result in shorter times to reach their critical state and accelerate their growth rate. [ABSTRACT FROM AUTHOR]

Among all factors affecting the stability of soil slopes, the effects of seepage, and especially drawdown, have long been a topic of study. This paper proposed a novel method for predicting the phreatic surface of three-dimensional (3D) slopes. Based on the solved phreatic surface, the normal stress expression of the slip surface under seepage force was deduced. A strict overall analysis method that combines the seepage force to analyze the stability of the bank slopes with reservoir drawdown was proposed. The credibility of the proposed method was verified by calculating different conditions set by a classic slope model. Finally, the change rules of the phreatic surface and the safety evolution with reservoir drawdown of a practical slope in the Three Gorges reservoir area were studied. The results demonstrated that the safety factor of the slope first decreases and then increases with reservoir drawdown and the most unfavorable water level is at the lower 1/3–1/4 of the total height of the slope. [ABSTRACT FROM AUTHOR]

This document discusses a paper by Alexaer F. Nielsen on the design scour levels for dune revetments and seawalls. The discussers praise the author's findings and suggest incorporating wave statistics into the empirical equations for future use. The document includes a graph and table comparing predicted and measured values of scour depth, as well as mentioning a unified wave-breaking probability parameterization provided by Filipot et al. and Thornton and Guza. The formula presented in the paper predicts scour depth below the still water level (SWL) for dune revetments and seawalls, taking into account wave statistics based on the Rayleigh probability density function (pdf) of wave heights in deep water. The predicted values are generally smaller than the measured values, with minimal differences when using different parameters. The authors recommend considering wave statistics in future design applications of the formula. [Extracted from the article]

Real-time monitoring and forecasting are essential to ensure an on-time and on-demand supply of water diversion projects. However, water transfer systems currently lack spatiotemporal data in a dense resolution, failing to monitor real-time conditions and test plausible scenarios. To address the problem, this paper proposes a novel digital twin framework. It includes a real-time self-correcting model, which combines (1) a hydraulic solver using the one-dimensional Saint-Venant equations; and (2) a method updating hydraulic states driven by field observed data. This framework consists of four phases: preparation, warming up, tuning, and monitoring and predicting. Particularly in monitoring and predicting, an identification method for diagnosing abnormal events is also proposed as one of the functions of the twin model. The model shows beyond 98% similarity to reality based on the metric similarity (S) proposed in this paper on both of two real-world scenarios: a large flow scenario and a normal one. The deviation is generally lower than 5 cm for water level 2 m3/s for discharge. The abnormal situation diagnosis method also provides timely fault detection for daily scheduling. It is anticipated that this framework can be a powerful tool to estimate current canal states and predict change trends, further ensuring the security and efficiency of operations for large-scale water diversion projects. [ABSTRACT FROM AUTHOR]

A new method to determine design scour levels for dune revetments and seawalls is presented. The method is based on the thesis that toe scour is a function of the nearshore incident wave energy and was calibrated with results from several moveable bed model studies covering a large range of scales. The method determines scour levels to a still water level datum defined at the incident wave-breaking location. Therefore, the method incorporates many more parameters than those that pertain to existing methods including tidal stage, storm surge, wave setup, wave period, and seabed slope. However, application of the method is not difficult with a methodology being presented. The sensitivity of the method to variations in the values for the input parameters is examined and the limits of their applicability are presented. Recommendations for further research are given. Seawalls are prone to collapse during storms if their footings are undermined by breaking waves. When designing seawalls, it is important to determine the level to which such scour can occur. However, existing methods for determining scour are simplistic and do not provide a scour level. This paper presents a new equation to predict scour levels for the design of seawall footings. The equation includes many of the important factors relating to storm scour including storm tide level, wave, and beach conditions. The equation was developed on the results of several scale model studies carried out in various laboratories over several decades with some comparisons with real-world experiences. The paper comprises all of the information used with clear diagrams. A simple application method is presented, the various factors that need to be considered for design are discussed, and recommendations for further studies are made. [ABSTRACT FROM AUTHOR]

The dynamic compaction mechanism of high-groundwater-level (HGL) foundations is still unclear, which seriously affects the engineering application of dynamic compaction in the riverbed and land reclamation. In this study, a dynamic compaction model test was established to analyze the vibration acceleration of the tamper, the soil surface, and the soil interior under different depths of groundwater level. Meanwhile, the propagation of the vibration wave was also analyzed, and the energy dissipation of dynamic compaction under the HGL foundation was studied combined with the modal damping ratio (ζ). The results showed that HGL resulted in poor foundation improvement. The main effects were the energy consumption and the friction reduction between the particles when the tamper was in contact with the water, which resulted in vibration acceleration and a sharp decrease in crater depth. The crater will not maintain its cylindrical shape, and further tamping will negatively affect the reinforcement. Vibration analysis showed that dynamic compaction results in dense soil with an increased damping ratio, but when the soil is tamped at the HGL foundation, the soil tends to oscillate, and the damping ratio decreases. In terms of energy, more than 70% of energy was dissipated directly under the tamping point of the high-groundwater-level foundation. Dynamic compaction has been extended from land foundation reinforcement to artificial reclamation foundation as an economical and environmentally friendly foundation treatment technique. The groundwater level in the coastal area is usually higher than that on land, which plays a decisive role in the success of dynamic compaction. However, there are few theoretical and experimental studies on the dynamic compaction of high-groundwater-level foundations. This paper analyzed the energy transfer and consumption of the dynamic compaction method for high-groundwater-level foundations from the perspective of vibration waves. The results showed that compared with dry sand, dynamic compaction of high-groundwater-level foundations will obviously consume reinforcement energy. Dynamic compaction causes groundwater levels to rise around the tamping point. The higher the tamping energy level, the more obvious the groundwater level rise. The results can provide a reference for expanding the treatment range of the dynamic compaction method and applying the dynamic compaction method to high groundwater foundations. [ABSTRACT FROM AUTHOR]

Soil arching that is generated and develops within the ground behind the retaining wall in a multistrutted excavation is a soil stress transfer process related to the relative movement between the well-retained soil mass and the inward-moved soil mass. The lateral earth pressure behind the wall is redistributed induced by this soil arching, which has not been deeply investigated. In this paper, the wall deflection, lateral soil movement, ground surface settlement, strut forces, total lateral earth pressure, and the water level outside the excavation were monitored in a multistrutted excavation in soft soil. The measured results indicated that the lateral earth pressure redistribution was associated with the arching effect. A lateral earth pressure model considering the soil arching effect is proposed, and was verified using measurements obtained from this study and the literature. It was found that the coefficients of the proposed model are linearly related to the ratio of the soil volume loss to the gain (RLG), which can be used to characterize the soil arching process development. This study improves the understanding of the lateral earth pressure redistribution induced by soil arching, and the proposed model can be used to calculate more-realistic lateral earth pressure. [ABSTRACT FROM AUTHOR]

A double rubber dam with the upper dam inflated by air and lower dam inflated by water is proposed in this paper. Large-scale physical hydraulic model tests are carried out to investigate the influence of the inflated air and water pressures, external water levels, anchoring distances, and cross-sectional perimeter ratios on the static response of the proposed structure. This study reveals that the optimum inflated air pressure in the upper dam is 0.25γwL1 and that in the lower dam is 0.45γwL1 , where γw and L1 are the unit weight of water and perimeter of the upper dam. The optimum anchoring distance is 0.06L1 , and the optimum perimeter ratio of the lower to upper dams is 0.9. Under the same external water depth, the material requirements of the proposed rubber dam are 105.8%–126% of the traditional rubber dam, and the tensile strength is 29.6%–48.8%. Considering the perimeter and tensile strength requirements, the total material costs of the air- and water-inflated double rubber dams are only 11.5%–24.2% of the traditional rubber dam. [ABSTRACT FROM AUTHOR]

Influenced by climate warming and human disturbance, the contradiction between flood control and water supply of the rivers-connected lake is becoming more prominent, and the prevailing dispatch system mainly aimed at flood control is a serious challenge for storage allocation. This paper presents a lake impoundment in advance method during flood recession period, which preliminarily explores the traditional dispatch model and couples it with a high-precision hydrodynamic model. A one- and two-dimensional coupled hydrodynamic model was constructed for integrated flood regulation in the "river-lake-flood detention basin" system. Then a sample library of water storage strategies was developed, which combined impounding times and gate operation schemes based on previous engineering experience. Thus, by combining large-scale numerical simulations of flood scenarios and risk-benefit assessment, the dispatching schemes facilitating the combined use of gates during the post-flood period under different wet-dry conditions were determined. The results show that: (1) the hydrological-hydrodynamic model has high accuracy for realizing the elaborate simulation of flood evolution and inundation dynamic between lands and lakes, with the average error controlled from 0.03 to 0.14 m, (2) the strategy extraction method of post-flood impoundment in advance for the lake basin is proposed, which takes the impounding times, gate scheduling rules, and inflow scenarios into account comprehensively, and (3) under the optimal storage strategies, the water storage efficiency is significantly improved, with the water level overrun rate controlled at 19.24%, the terminal storage level raised by 0.96 m, and the storage capacity increased by 17.0×108 m3 on average. The outcomes will provide support for flood control and water storage improvement during the post-flood period, which is beneficial to the utilization and management of flood resources. [ABSTRACT FROM AUTHOR]

This paper will present stability analyses and charts to estimate the factor of safety (FS) for partially submerged undrained slopes with linearly increasing strength with depth and unlimited foundation depth. The problem has been tackled previously by ignoring the free standing water when the soil below and above the external water level, buoyant (γ′), and saturated unit weight (γsat), respectively, were assigned. This could then be combined with a simple unit weight averaging formula. In this paper, an analytical method that is based on optimization analyses will be proposed and charts will be presented that deliver an equivalent homogeneous unit weight as a function of slope angle (β), water depth (dw), and γsat. This equivalent unit weight (γequiv) will then be assigned to the entire slope and used in conjunction with the stability charts Hunter and Schuster proposed in 1968. The analyses will use an optimization approach that assumes circular failure mechanisms, which will be validated using finite-element (FE) strength reduction. In almost all cases, the charts that are presented in this paper led to a lower and more conservative FS than those obtained that used the simple weighted average approach. Some cases where the charts might lead to unconservative solutions when compared with FE solutions will be identified and discussed. [ABSTRACT FROM AUTHOR]

In the US federal system, state governments play important roles between the federal and local levels in water resources planning, coordination, and regulation. How they coordinate these functions can indicate the degree of integration of their agencies and programs. A database of state programs was used to compile indicators of integration among water quality and quantity and drinking water source quality, as well as the status of comprehensive water planning. In most prior appropriation states and in some states in riparian areas, the management of water withdrawals and water quality remains in separate agencies. Some 35 of 50 states have a version of a "state water plan." A scattered pattern of institutional arrangements shows that titles and functional coordination evolve in response to contextual situations, although state water management agencies have matured, and many have stable organizational forms. Water rights and regulatory controls for clean water and safe drinking water are firmly in place. Organizational structures are not likely to change much, but integration can be improved through management mechanisms and appropriate uses of planning, particularly at the watershed scale. State governments are pressed to be active in water resources management because they have authority in a geographic sphere closest to the scales of watersheds, river basins, and regional aquifers. This authority is important for states to respond to new threats like climate change, worsening floods, long-term drought, and public health challenges. Like in other levels of government, the workforce in state water management agencies is mobile and requires constant capacity building. Institutional memory is especially important, and state government executives require a rapid but comprehensive view of past experiences in organizational management in regulation, planning, and interactions with the federal and state governments. The paper provides a review of these experiences, along with suggested priorities for water management enhancements that may help in the future. [ABSTRACT FROM AUTHOR]

This paper investigates the failure mechanism of nonuniform large geotextile-reinforced cofferdam under seepage and excavation effects on soft sediments. A numerical model is established and validated with available testing results. Then, parametric studies are carried out to investigate the potential influence factors. This study found that the difference between the upstream and downstream water levels and the excavation depth both have significant influences on the stability of cofferdams, where excavation is the key influence factor affecting the stability of the cofferdam. Numerical results revealed that the safety factor could reduce by about 20% with excavation of about 1.5 m. An empirical equation is proposed for quantitative prediction of the stability of geotextile-reinforced cofferdams. A thorough understanding about the failure mechanisms of cofferdams as well as an empirical formula for predicting the stability is concluded in this study, which could provide engineering guide for flexible foundations reinforced by geotextiles. [ABSTRACT FROM AUTHOR]

Sewage systems are built to carry contaminated wastewater from domestic discharge points to collection points for treatment. However, their capacity can be reduced by obstructions, displaced pipe joints, or broken pipes, creating abnormal hydraulic conditions. Wastewater overflows are a potential consequence of these abnormal conditions, which pose a direct threat to the environment and human health. This paper describes a permanent continuous monitoring system of a real sewage network using ultrasonic water level sensors for the purpose of blockage/choke detection, as installed in the suburb of Stonyfell, South Australia. From 62 available data sets collected over 1 year, two distinctive features of growing chokes were identified, including irregular peaks and durations that the water level remains irregularly high in the sewer maintenance holes. An early choke detection method was formulated based on the later feature, which continuously scans the near-real-time data to find time periods containing these abnormal water levels. Application of the methodology showed that the proposed method is effective in detecting possible chokes and overflow events before they occur. In most cases, the warning from the first detection is early enough to allow proactive maintenance attendance to be scheduled by the water utility. [ABSTRACT FROM AUTHOR]

Cascade reservoirs have interrupted the distribution and transportation of nutrients, which brings environmental and ecological problems. However, the current ecological operation methods focusing on the hydrologic regime cannot solve these problems. This paper presents an ecological optimal operation method that aims at restoring the transport pattern of biogenic substances. First, this paper establishes an optimization model that combines multiobjective reservoir operations with a dynamic mass balance calculation of total phosphorus (TP), taking the maximum TP export as the ecological objective, and a traditional model taking hydrologic regime as the ecological objective for further comparison. Then, the upper Mekong River Basin (i.e., the Lancang River Basin) is taken as a case study to investigate the competitive relationship between power generation and TP export under varying minimum outputs. The mechanism of TP export is then analyzed and the concept of optimum period for TP export is proposed. The results and analyses show that a competitive relationship between the power generation originates from the differences between the optimal operation processes for maximum TP export and maximum power generation. Lower water level, lower flow in nonflood season, and higher flow in flood season, especially in the optimum period for TP export are conducive to TP export. This method is then compared to the traditional method, which considers hydrologic regimes as the ecological objective under different conditions. The results show that reservoirs with higher sedimentation coefficient and larger capacity should consider more about the biogenic substances; otherwise, the hydrologic regime and biogenic substances can be substituted for each other to some extent. [ABSTRACT FROM AUTHOR]

The devastating impacts of frequent coastal storms, such as Hurricane Katrina in New Orleans in 2005 or Superstorm Sandy in New York City in 2012, in major low-lying metropolitan areas have had repercussions far beyond previously experienced disasters. Two key findings that describe these repercussions related to these events were stated as follows: in the case of Katrina, there was a lack of holistic or system-based thinking, and in the case of Sandy, there was an insufficient integration of critical infrastructure. Among different remediation actions, inland placement of best management practices (BMPs) in order to protect coastal cities from storm surges has received a lot of attention. However, nearshore BMPs as a way of source (wave height) reduction have not yet been thoroughly investigated. Nearshore practices are especially attractive in coastal areas that experience significant wave heights as a total water level component. In this paper, the effects of bathymetric shallowing through an apron on reducing the wave height and water level during storms are investigated in coastal areas. Southern Brooklyn in New York City is selected as the case study. A hydrodynamic model is utilized to generate wave height and storm tide. A water-level hydrograph in ungauged areas of the case study is constructed, which has not been realized before in similar coastal flood studies. Water level variations are investigated to include generated storm surge and wave characteristics. The results show that shallowing can reduce the peak of wave height and water level by 47% and 10%, respectively, in open coastal areas. In a more contained bay area, the reduction of a water level was more than 13%. These figures show the potential of nearshore BMP applications that could significantly improve our flood preparedness plans. The proposed methodology can be applied to other coastal geographical settings. [ABSTRACT FROM AUTHOR]

Although there is extensive work related to design and implementation of model-driven optimal groundwater management, evaluation of the performance of those models is less reported. This hinders transferability of lessons learned and wide adoption of specific policies. This paper reports a study designed to evaluate the effectiveness of a real-time optimal groundwater management tool, optimized regional operations plan (OROP), used in the Tampa Bay region (located on the west coast of Florida in the United States) since 1998. The overarching question in this study is how different groundwater levels would have been at monitoring sites if such an operational decision-supporting tool was not implemented. The proposed framework is comprised of multiple steps, including generating a non-OROP groundwater pumping scenario that would have happened without the decision support tool in place, running a modified optimization model in retrospective mode, and comparing water level between OROP-based and non-OROP–based pumpage scenarios. The framework is applied to historical data in the past decade (2010–2019). In generating an alternative pumpage scenario, realistic model constraints (e.g., pump capacity, pipeline hydraulics, and network) were used to generate wellfield pumpage to meet demands. Wellfield pumpage is then disaggregated at individual wells. Differences in resulting water levels at monitoring wells, at multiple timescales, between the OROP and non-OROP pumpage scenarios were calculated. Results reveal that although at a weekly timescale the effectiveness of OROP seems minimal over the region, the cumulative effectiveness at the monthly and annual timescales is remarkable. It is also found that benefit of using OROP is even higher during dry seasons when groundwater levels are more critical in maintaining wetland health. The proposed framework presented in this study can be applied to other areas in evaluating groundwater management strategies. [ABSTRACT FROM AUTHOR]

Pump energy consumption is the major operational cost of water distribution systems (WDS). Defining better pump operation policies can reduce the cost and the enhance service provided. The nonlinear hydraulic behavior of WDS makes the pump scheduling problem complex, especially in large WDS in which several tanks and pumping stations coexist. The nonlinear hydraulic behavior of WDS is captured using numerical simulation. However, the required energy calculations were computed from the flow rate and head increase after the pumping stations. There are many optimization algorithms for the reduction of the operational cost. The majority of these algorithms are applied to hypothetical case studies with reduced feasible solution spaces. When the search space becomes large and many alternatives (pumps combinations) are possible, most of the proposed algorithms fail. Thus, the application of these algorithms in real case studies is very limited, and water utility managers still rely on human expertise to schedule pump operation rather than on automatic scheduling. This paper proposes the use of a genetic algorithm for large WDS with a many tanks and pumps. Offline hydraulic simulations allow the definition of water level bounds in the tanks. The combination of the pumps is determined a priori and the optimization algorithm is run in a reduced search space. These preparations allow the genetic algorithm to identify quickly the optimal policy and reduce the cost of energy consumption. The proposed framework was applied to the WDS of the city of Asmara, Eritrea, with 12 tanks and 9 pumping stations. The results showed that the tanks controlled by pumps worked perfectly and the water level was kept within the defined ranges. However, the constraints were not fulfilled for uncontrolled tanks. This application showed the limitations of methodologies proposed in the literature, and it is suggested that further techniques be found to schedule the pump working policies of large WDS while reducing the violations of constraints. [ABSTRACT FROM AUTHOR]

Optimal operation of hydropower reservoir systems is a classical optimization problem of high dimensionality and stochastic nature. A key challenge lies in improving the interpretability of operation strategies, i.e., the cause–effect relationship between system outputs (or actions) and contributing variables such as states and inputs. This paper reports for the first time a new deep reinforcement learning (DRL) framework for optimal operation of reservoir systems based on deep Q-networks (DQNs), which provides a significant advance in understanding the performance of optimal operations. DQN combines Q-learning and two deep artificial neural networks (ANNs), and acts as the agent to interact with the reservoir system through learning its states and providing actions. Three knowledge forms of learning considering the states, actions, and rewards were constructed to improve the interpretability of operation strategies. The impacts of these knowledge forms and DRL learning parameters on operation performance were analyzed. The DRL framework was tested on the Huanren hydropower system in China, using 400-year synthetic flow data for training and 30-year observed flow data for verification. The discretization levels of reservoir water level and energy output yield contrasting effects: finer discretization of water level improved performance in terms of annual hydropower generated and hydropower production reliability; however, finer discretization of hydropower production can reduce search efficiency, and thus the resulting DRL performance. Compared with benchmark algorithms including dynamic programming, stochastic dynamic programming, and decision tree, the proposed DRL approach can effectively factor in future inflow uncertainties when determining optimal operations and can generate markedly higher hydropower. This study provides new knowledge of the performance of DRL in the context of hydropower system characteristics and data input features, and shows promise for potentially being implemented in practice to derive operation policies that can be updated automatically by learning from new data. [ABSTRACT FROM AUTHOR]

From the preceding literature review and an understanding of how flood inundation extents are extracted from SAR images, it is evident that extracting water levels from SAR data would result in less vertical error for flat areas with wide floodplains. 2 illustrates the potential wide flood inundation extent of the 500-year flood event in Melville. Discussion of "Hydraulic Model Calibration Using Water Levels Derived from Time Series High-Resolution SAR Images" by Nicolas M. Desrochers, Mélanie Trudel, Daniel L. Peters, Gabriela Siles, and Robert Leconte The discussers suggest that further studies on flood water level estimation using the SAR images for plain areas similar to the Canadian Prairies with flat floodplains will be beneficial for evaluating whether vertical error could be reduced compared to the best result obtained in the original paper (i.e., RMSE of 0.28 m between the SAR-derived and simulated water levels). [Extracted from the article]

This paper proposes a methodology to increase the level of water distribution equity in intermittent water distribution networks (WDNs) with users equipped with private tanks. The methodology makes it possible to identify optimal valve locations and settings to improve the distribution of water among users by rearranging the flow circulation in the network. Two optimization schemes based on the use of NSGA II were developed. The first scheme aims at maximizing the global distribution equity of a WDN through installation of valves fully closed. The second scheme looks also at the levels of supply of the individual nodes of a WDN and includes optimization of both locations and settings of control valves. The two optimization schemes are applied to the case study of a WDN in northern Italy considering a scenario of water shortage. The EPA's Storm Water Management Model software was used for the pressure-driven simulation of an intermittent WDN. Results of the application of the two optimization schemes highlight the potential for an increase in the global equity of the WDN by installation of a few valves. However, some nodes of the WDN were penalized by the new flow circulation as obtained by solutions provided by the first scheme. In fact, these nodes unacceptably worsen their condition compared to the no-valve scenario. Conversely, solutions obtained with the second scheme allowed demand satisfaction levels to not worsen compared to the no-valve scenario for all nodes. [ABSTRACT FROM AUTHOR]

In many applications, the adjustment of a gate opening to a specific value is crucial for the passage of a defined outflow or to maintain an upstream water level that serves upstream turnouts. Previous work used trial-and-error and interpolation methods to calculate the opening of sluice gates. This study concentrates on the development of a way to estimate the opening of sluice and radial gates to achieve the desired discharge or upstream water level. In addition to energy and momentum (E-M) principles, this paper develops relationships to determine the openings of sluice and radial gates under free- and submerged-flow conditions. Based on experimental data, the mean absolute relative errors for calculating the opening of sluice and radial gates under different flow conditions using the previously proposed methods, as well as dimensional analysis, were 4.3% and 7.1%, respectively. In this study, the calculated relative errors in employing E-M principles were reduced from 3.6% to 2.9%, in which the effects of energy loss were overlooked, and the gate's energy coefficient was introduced. [ABSTRACT FROM AUTHOR]

Large wood debris can cause critical damage to bridges and other riverine structures, and increase flood risk. Although their effects on hydrodynamic actions and flood levels have been investigated in recent research, little effort has been devoted to reducing the amount of debris that can accumulate at structures. This paper proposes and experimentally tested a new type of large wood debris retention system in which a series of alternating porous and rack-type modules is placed in-line with the current. Laboratory tests showed that the proposed retention system can offer high levels of efficiency in trapping large wood in rivers. The geometrical features of the structure play a major role and can be chosen carefully to optimize trapping efficiency. Results showed that large wood debris trapped by these structures have limited effects on the increase of the upstream water levels. Further development of the solution proposed in this work can pave the way for use of low-cost, highly effective debris retention systems for effective river management and large wood debris removal in practice. [ABSTRACT FROM AUTHOR]

With the increased emphasis on developing integrated models capable of simulating runoff through hydrologic systems that include hillslopes and wetlands, analytical solutions have become useful in analyzing and testing numerical models applied to both. An analytical solution in algebraic form is developed in this paper to describe a sinusoidal moisture profile migrating through a wetland or a hillslope, the magnitude of the peak runoff, and the phase lag. The solution is obtained for an instantaneous sinusoidal recharge signal, and results are expressed in terms of the basin geometry and flow resistance parameters. The analytical solution is used to verify the accuracy of a numerical model based on the implicit total variation diminishing Lax-Friedrichs (TVDLF) method. This method is used in the Regional Simulation Model (RSM) developed at the South Florida Water Management District (SFWMD) to simulate the complex hydrologic system of south Florida. The runoff peak, phase lag, propagation speed, and decay rate over a range of Péclet numbers are used in the comparison of analytical and numerical solutions. The numerical model using the TVDLF method is tested by applying to the Boggy Creek watershed in central Florida, and the wetland stormwater treatment area (STA)-3/4 in south Florida to simulate storm runoffs and water levels. Results show that the model using a general power-law equation to represent flow resistance, and a conceptual model consisting of a canallike drainage feature to represent rapid drainage can be used to simulate the hydrology in both the watershed and the wetland. [ABSTRACT FROM AUTHOR]

The fluctuation of reservoir water levels has significant impact on bank slope stability near a reservoir. Therefore, it is necessary to analyze the stability of bank slopes with reservoir drawdown. In this paper, a novel method combining the seepage force with rigorous limit equilibrium method is proposed to analyze the stability of bank slopes near the reservoir. First, the calculation method of the phreatic surface and the seepage force is developed. Then, six equilibrium equations are established based on the equilibrium conditions of three forces along the coordinate axis and the equilibrium conditions of three moments around the coordinate axes. Finally, a trust–region–reflective iterative algorithm is used to determine the safety factor of bank slopes from these six equations. Moreover, the effects of drawdown speed, the height of the drawdown, permeability coefficient, and the aquifer thickness on bank slope stability are investigated using the proposed method. Two engineering cases of Ataden I landslide and Guanyinping landslide are used to verify the correctness and practicability of the proposed method. [ABSTRACT FROM AUTHOR]

This paper develops an optimal, multistage operation of gated spillways for the Karkheh Reservoir, Iran. In each stage of the proposed method, the opening of the gates is proportional to the water level of the reservoir. Two novelties are introduced in this work. The first one is consideration of the absence of a spillway or the existence of blocked spillway gates as two operation scenarios. The second novelty is attributed to using improvement of dam safety as an objective function rather than a constraint of the optimization problem. A genetic algorithm (GA) was implemented for determining the optimal opening of gates to minimize downstream damages. The nondominated sorting genetic algorithm-II (NSGA-II) was applied to optimize the two objectives of minimizing downstream damages and reducing the probability of dam overtopping. This paper's results reveal that increasing the number of stages of gate opening improved the value of the objective functions. On the other hand, the lack of spillways or blocked spillways increases the risk of dam overtopping for long return periods. [ABSTRACT FROM AUTHOR]

This paper explores the particle-scale origin of the additional shear strength of unsaturated granular materials in pendular states induced by the capillary effect by applying the stress–force–fabric (SFF) relationship theory to unsaturated granular material stress analysis. The work is based on discrete element simulations with the particle interaction model modified to incorporate the capillary effect. By decomposing the total stress tensor into a contact stress tensor originating from contact forces and a capillary stress tensor due to the capillary effect, the directional statistics of particle-scale information are examined. The observations are used to support the choice of the appropriate analytical approximations for the directional distributions associated with the solid skeleton and water bridges. The SFF relationship for unsaturated granular materials is formulated, and is shown to match the material stress state with good accuracy and is used to interpret the material strength in terms of the relevant microparameters. Macro and micro observations are carried out on both relatively dense and loose samples in triaxial shearing path to the critical state. The capillary force remains nearly isotropic during triaxial shearing. Anisotropy in the water bridge probability density, however, develops alongside the anisotropy in contact normal density, which decreases when the suction level decreases and the water content increases. The anisotropy effect in the water phase is much smaller than the solid skeleton, and a coupling effect with the solid phase makes the fabric anisotropy in wet materials smaller than that in dry materials. Combined with the SFF function, the increased solid coordination numbers and mean contact forces by the water bridge effect are more important factors for the suction-induced shear strength. [ABSTRACT FROM AUTHOR]

Model predictive control (MPC) is one of the most popular control techniques that has been widely used in many fields of water resources management, such as canal control for drainage, irrigation, and navigation. MPC uses an internal mathematical model to describe system dynamics over a given prediction horizon and then minimizes a hard-constrained optimization problem based on actual objectives. Due to the use of hard constraints, the optimization problem may occasionally be infeasible. A compromise is sometimes made to look for a feasible solution by softening the hard constraints, which means that the limit on water levels or flows is allowed to be violated to a certain extent. For example, water in a canal may go above the top of a dike during a high-discharge event, resulting in a spill. This amount of spilling water leaves the water system and does not flow back, which therefore should be deducted in the mathematical model of the water system. To deal with this spill, past studies often utilized a hybrid model and an integer optimization. However, the system in the hybrid model is usually nonlinear and nonsmooth, especially when it transits from one discrete state to another. In this paper, an alternative way is proposed to link the spill with the softened constraint, still maintaining the linearity of the water system. Results show that the proposed way to tackle the spilling water is easy to implement and the water level is more accurately regulated around the setpoint in a canal control problem. [ABSTRACT FROM AUTHOR]

A variety of methods are in use for the design of controllers for adjusting canal gate positions to maintain a constant water level immediately upstream from check gates. These methods generally rely on a series of tests on the water level's response to changes in canal gate position or flow, either by simulation or on the canal itself. This paper presents a method for tuning these controllers based on wave celerity through use of the integrator delay zero (IDZ) model. These equations can be used to determine the resonance peak height and resonance frequency. Unsteady-flow canal simulation models are used to show the response of controller design using these theoretical equations with a test case for ASCE Test Canal 1. A novel method is presented for avoiding disturbance amplification by considering the delay times in all canal pools downstream. [ABSTRACT FROM AUTHOR]

This paper investigates the source of the spurious numerical oscillations often observed in simulations using the well-known Preissmann slot method and proposes a nonoscillatory numerical fix that can efficiently suppress the numerical oscillations. The root of these oscillations is identified by comparing the orbits calculated by a first-order Godunov type model with an ideal numerical orbit in the phase plane. It is found that in the very thin layer in the vicinity of the conduit roof the numerical model has insufficient numerical viscosity to avoid the often-observed oscillations. In order to remove these spurious oscillations, an approximate Riemann solution is proposed that automatically enhances the numerical viscosity whenever the water level is in the vicinity of the conduit roof and the pressurization of the conduit is proximate. A comparison of results from the proposed model with both experimental data and analytical solutions show that it can provide nonoscillatory solutions over a wide range of the wave velocities ranging from 10 to 1,000 m=s. Furthermore, the proposed model effectively controls data smearing. [ABSTRACT FROM AUTHOR]

The research presented in this paper is focused on the effect of various parameters on the deformation response of embankment dams and the corresponding performance limit states. The parameters considered include the geometry of the embankment and hydraulic loading in terms of intensity, duration, and cycles of loading and unloading as a result of the rise and fall of the water level in the reservoir. The analysis of a model embankment dam is conducted using the finite-element approach and the results are incorporated into simplified deformation-based probabilistic analyses. The effect of the change in geometry on shear strains and horizontal deformations and the corresponding probabilities of exceeding three predefined limit states are presented. The analyses are also used to demonstrate the importance of taking into account the storm loading history when assessing the stability of the flood protection earth structures under future flood events. In a larger embankment model, the shear zone propagates deeper for failure to occur. The time to exceed Limit States I, II, and III increases as the size of an embankment model becomes longer. For example, failure occurs after 4.6 days in a model with a size factor of 0.1 compared with 12 days for a model with a size factor of 0.2. This is mainly because the advancement of the saturation front to a critical level occurs in less time in the smaller embankment. [ABSTRACT FROM AUTHOR]

External water level variations, such as rapid drawdown or flood loading, change the internal pore pressures in an embankment as a result of changes in the boundary conditions. Three different effects result: (1) changes in water pressure on the slope change the seepage boundary conditions, (2) changes in the total stress applied by the weight of the water on the slope change the confining pressure on the soil, and (3) changes in the stabilizing load from the reservoir cause changes in shear stress. Uncoupled transient seepage analyses, which consider only the first effect, are increasingly being advocated as an appropriate means to calculate pore pressures for effective stress stability analyses following water level changes. This paper discusses the limitations of uncoupled transient seepage analyses for calculating pore pressures during drawdown, explains the requirements for more appropriate analyses, and gives examples that show the errors incumbent on the use of uncoupled analyses. [ABSTRACT FROM AUTHOR]

Weirs or bed sills are low-head hydraulic structures used for bed stabilization, raising upstream water level, and reducing flow velocity. During high-flow events, the weir is fully submerged in the river and scouring occurs both upstream and downstream of the weir. For a fully submerged weir, the scour mechanism around the weir is dependent on approach flow intensity (clear-water scour conditions or live-bed scour conditions) and flow regimes (surface-flow regime or impinging-jet regime) over the weir. The fast evolution of underwater mobile topographies and propagating bedforms increase the complexities of the scour process and the difficulties for scour measurement at the submerged weir under live-bed scour conditions. This paper develops a measurement and data-processing technique for the study of scour at submerged weirs under extreme measurement environments and investigates the scour process both upstream and downstream of submerged weirs under live-bed scour conditions. The experiments are carried out with uniform sediment in a tilting sediment recirculating flume. Different flow rates and weir heights are used. For all the tests, the flow upstream of the weir is subcritical. Bed elevation changes are measured in the approach flow reach and in the scour zones both upstream and downstream of the weir using a Seatek multiple transducers array (MTA) (SeaTek Instrumentation, Florida). The highly contaminated raw bed-elevation data are filtered. Scour depths and bedform characteristics are extracted in data postprocessing. During live-bed conditions, a scour-and-fill process occurs immediately upstream from the weir in response to periodic approaching bedforms. The influence of the flow regimes on the scour mechanism downstream of the weir is discussed. Based on dimensionless analysis and experimental data, equations for prediction of the scour depth at the weir are proposed. [ABSTRACT FROM AUTHOR]