Hydraulic Model Research Articles

Rewinding the Tape: Documentary Heritage to (Re)discover “Lost” Natural Hazards—Evidence and Inferences from Southern Italy

The knowledge of natural hazards that occurred in the past is essential for implementing forecasting and prevention actions, for managing risk, and identifying proper land use. Floods do not escape this rule. This article sheds light on an unknown intense rainfall period, which affected the Campania region and the territory of the current Molise region (Southern Italy) on October–November 1961. The period culminated in floods, particularly involving the town of Benevento (Campania region), which had been affected by several inundations over centuries. The research made an extensive use of unpublished archival sources. The documents allowed us to both outline the pluviometric and hydrological picture of the period and catalogue seventeen physical and environmental effects suffered by over two hundred municipalities. Furthermore, we also disclosed the economic consequences in the wide territory involved. Special attention was paid to Benevento, for which we also drew up the scenario map related to the 19 October flood. For this town, historical data were effective for developing and testing the hydraulic model of the Sabato and Calore Rivers, which overflowed at the site. In this regard, we made some considerations on the current flood risk of the town. From a methodological point of view, we stress the importance of a historical approach in close relationship to other expertise for the knowledge of natural hazards, tracing also some future perspectives. The research complies with the 2030 Agenda for Sustainable Development and its Goal 11 concerned with making cities and human settlements inclusive, safe, resilient, and sustainable. The research findings will be useful for scholars and practitioners for both improving flood hazard models and arranging archival research path. Finally, local authorities in charge of risk mitigation can also benefit from the research results.

Optimization of LID Strategies for Urban CSO Reduction and Cost Efficiency: A Beijing Case Study

Combined sewer overflow (CSO) can lead to serious urban water environment pollution and health risks to residents. Low Impact Development (LID) facilities are one of the important measures to alleviate CSO and have been widely applied. The rational selection of LID facility types, locations, and scales is the most important task, which can effectively improve resource utilization efficiency. Based on the NSGA-II multi-objective optimization algorithm and coupled with the SWMM sewer network hydraulic model, this study takes the combined sewer overflows and the construction cost of LID facilities as optimization objectives and optimizes the types and scales of LID layout in the study area, including eight different return periods. By using the Pareto frontier and visualizing the results of the model, the effects of different rainfall return periods on the CSO control and investment cost of LID layout schemes are compared. The results show the following: (1) the optimization model can demonstrate the relationship between CSO control volume and LID construction cost under different LID layout schemes through the Pareto frontier, showing three different trends, indicating that the relationship between overflow volume and investment cost is nonlinear; (2) with the increase in rainfall intensity, higher requirements are proposed for LID schemes to meet CSO control targets, leading to a decrease in the number of Pareto frontier solution sets. Under larger rainfall intensities, it is difficult to achieve the same overflow control effect by increasing the scale of LID construction. Therefore, considering constraining the LID construction cost between RMB 5.3 and 5.38 million is helpful to determine the most suitable solution; (3) in the optimal layout schemes under different return periods, 87.3% of the locations where LID is deployed have similar scales. Based on these locations with a relatively large proportion of deployment, it can be determined that special attention should be paid to spatial positions in LID planning and construction. This study provides valuable insights for solving combined sewer overflow problems and optimizing urban drainage management and provides guidance for future planning and decision-making processes.

Efficiency Evaluation of Surface Water Collection Infrastructure during Floods: Information Analysis and Zoning Management

Objective: Flood events, occurring as natural and unexpected phenomena, have become increasingly prevalent in recent decades. Assessing the probability of flood risk and creating flood zoning maps in vulnerable areas, particularly urban regions, are crucial for mitigating flood damages and managing such events. This research aims to determine the flood-prone zones along the Darakeh River, located in Tehran, the capital city of Iran, by integrating the hydraulic model HEC-RAS with Geographic Information System (GIS). Methods: After establishing the physiographic characteristics of the watershed, including area, perimeter, elevation, slope, and time of concentration, influential factors on flood occurrences such as permeability, hydrological soil groups, runoff potential, curve number, land use, and vegetation cover were identified. This information, along with other hydraulic data and flow specifications such as boundary conditions, roughness coefficients, and design discharge, was incorporated into the HEC-RAS model. The model was executed for different return periods of 2, 5, 10, 25, 50, and 100 years. Subsequently, the hydraulic model outputs were transferred to the GIS model to obtain the flood-prone zones along the Darakeh River for the aforementioned return periods. Results: As observed, in the middle section of the Khoshke Channel, which has a lower gradient, the floodplain exhibits a wider extent. Furthermore, along the course of the river and after passing through a stretch of the Khoshke Channel with a reduced gradient, the floodplain's area increases up to the location of the western flood channel. Conclusion: It is concluded that areas with lower river slopes exhibited larger flood-prone zones, highlighting the necessity of increased attention to prevent significant damages in urban areas during flood events.

Operation Risk Simulation and Interaction Impact of Stormwater and Sewage Systems Based on Storm Water Management Model

With the increasing urbanization rate, higher demand is placed on drainage systems, necessitating analysis of their risk profiles. While many studies focus on the individual hydraulic modeling of stormwater and wastewater systems when considering operational risks, they often overlook the exacerbating effects of combined stormwater and wastewater flows on each other’s risks. In this study, we constructed a model of the combined stormwater and wastewater drainage system in Lijiao, Guangdong Province. We analyzed the operational risks of both stormwater and sewage networks in different scenarios, focusing on full-load pipes, overload pipes, node overflows, and minimum flow velocities. Furthermore, we compared the exacerbating effects of sewage and stormwater on each other’s network operational risks. Simulation results indicated that, for sewage networks with combined sewer sections, the lengths of full-load pipes and overload pipes increased by an average of 27.4% and 16.3%, respectively, during rainy weather scenarios compared to dry weather. After considering the inflow of sewage into combined sewer sections, the average length of full-load pipes increased by 3.8 km, overload pipe length increased by 1.1 km, and overflow volume increased by 2.26 × 104 m3. As the return period of rainfall events increases, these inter-system impacts gradually diminish. Therefore, when modeling drainage systems and assessing operational risks, particularly during low return period rainfall events, the inclusion of both stormwater and sewage in combined sewer networks should be comprehensively considered.

A Multi-step Data Assimilation Framework to Investigate the Effect of Measurement Uncertainty in the Reduction of Water Distribution Network Model Errors

AbstractWater distribution network (WDN) models are a common decision support tool for understanding the behavior and performance of WDNs, aiding in the planning and management of WDN systems. The increasing availability of real-time data has recently promoted the exploration of Data Assimilation (DA) techniques to improve these models. However, flow, pressure and demand data are uncertain, particularly due to sensor characteristics such as precision and noise. An open question is to what extent DA can still improve hydraulic models when the data used to this end is uncertain. This paper proposes a three-step Ensemble Kalman Filter based DA approach for WDNs (3-EnKF-WDN), building on previous approaches, and advancing in two main fronts: the use of extended period simulation, and the use of pressure-dependent demand (PDD) analysis. Different scenarios considering uncertain sensor data, with varied precision and noise, are applied to two networks of different sizes, representative of real-world WDNs. The computational demand of the 3-EnKF-WDN method is also assessed. Results show that increasing sensor’s precision and decreasing the noise in state measurements reduce model error, as expected. However, we also found that model errors: 1) are reduced more effectively by using 3-EnKF-WDN than by increasing sensors’ precision; 2) are not reduced if certain noise thresholds are surpassed; 3) can be reduced without assimilating demand data if the WDNs are fully monitored with head sensors in all the nodes and flow sensors in all the links.

Modeling the flood protection services of levee setbacks, a nature-based solution

Levee setbacks are an intuitive nature-based solution that can improve the flood protection services provided by levees and help rehabilitate levee-stressed ecosystems. Their application in professional practice is in part limited by a lack of guidance on how to size setbacks to balance different interests in floodplain land use. To help address this application barrier, we demonstrate how flood hazard and levee failure risk reduction may be modeled with a numerical hydraulic model of a leveed river in the Midwestern USA, as well as how to calculate scaling relationships between levee failure risk reduction and setback size. Our results suggest setbacks can greatly reduce the severity of flood hazards, for example, by alleviating flow bottlenecks and lowering flood heights. Our results also suggest that improvements in levee reliability scale non-linearly with setback size and exhibit diminishing returns. We conclude with a discussion of design insights and cautions to support the application of setbacks in practice.

Detection and pre-localization of anomalous consumption events in water distribution networks through automated, pressure-based methodology

Anomalous water-consumption events (AEs) can significantly impact the functioning of water distribution networks, and their prompt identification can improve the service provided by water utilities. This study proposes a new methodology for AE detection and pre-localization in water distribution networks relying exclusively on pressure-data collected in the field, which are exploited to evaluate differential-pressure trends for all possible pressure-sensors couples located in the WDN. In greater detail, AEs are detected and pre-localized by analysing differential-pressure trends over time. The level of deviation of these trends from the standard is considered to provide information about (i) AE alert levels and (ii) the area of the network where the AE is most likely to occur. The application of the methodology to two real case studies featuring different characteristics in terms of residential and industrial users demonstrated method effectiveness in detecting and pre-localizing individual and simultaneous AEs of different magnitude and occurring at different times of the day, providing useful information about the presence of AEs without the need for hydraulic models, and allowing the evaluation of their effects in terms of piezometric head alteration in the different areas of the system.

Real time probabilistic inundation forecasts using a LSTM neural network

Probabilistic inundation forecasts that consider the uncertainty in rainfall predictions are crucial for flood early warning systems to effectively manage and reduce potential risks posed by pluvial flood events. Timely generation of such forecasts is challenging with physically-based numerical models due to computational demands. In contrast, data-driven models have a relatively low computational cost and can generate results quickly, making them a promising alternative to overcome this issue. This study proposes a long short-term memory (LSTM) neural network that can predict inundation progression over time at a high spatial resolution The network is trained on 1600 hydraulic simulations conducted using a 1D2D hydraulic model. With the trained network, probabilistic inundation forecasts are generated by combining the deterministic inundation predictions of 50 ensemble members of the rainfall forecast. The model is successfully tested for temporally varying rainfall events in a rural study area, and can generate accurate probabilistic inundation forecasts within seconds.

Temperature homogenization control of parabolic trough solar collector field based on hydraulic calculation and extended Kalman filter

Parabolic Trough Collector fields serve as the heat-absorbing components in large-scale commercial solar trough power plants. However, they frequently encounter challenges related to uneven spatial distribution of solar irradiation and heat transfer fluid flow. These disparities often lead to temperature inhomogeneity across the field, thereby jeopardizing both the safety and economic efficiency of the collector field. To address these issues, this study first introduces a proportional-integral and feedforward based flow control strategy designed to stabilize the fluid outlet temperature in the collector field. Subsequently, a flow allocation scheme aimed at achieving temperature uniformity across individual collector loops is presented. This scheme relies on the effective irradiation estimates for each collector loop, calculated using the extended Kalman filter algorithm and a suggested hydraulic model. Simulation results demonstrate that these control strategies not only stabilize the outlet temperature of the collector field at the desired set value but also significantly diminish temperature variances among individual collector loops, with reduced computational overhead. The maximum temperature difference between loops can be reduced from 126.3 °C to 12.7 °C under uneven radiation intensity, ranging from 563 W/m2 to 885 W/m2, by the proposed temperature homogenization control strategy.

Evaluation of pavement resilience to flooding with inverted pavement structure

Conventional pavement structures are vulnerable due to degradation of unbound materials after water inundation. Inverted pavement structure has been proven to be cost-effective and energy efficient, while its resilience has not been investigated. This study is aimed at assessing the resilience of inverted pavements to flooding events using an integrated hydraulic and mechanical modelling approach. Two-dimensional hydraulic models were established to analyse flooding-induced moisture variations in the pavements. Based on the moisture distribution results, three-dimensional mechanical models were developed to calculate critical pavement responses under moving load. The results show that the subgrade with higher groundwater table or larger hydraulic conductivity was more likely to be invaded by water. Compared with conventional pavement, the increases of critical pavement responses in inverted pavement were significantly smaller after long-period flooding, which indicates the potential benefits of inverted pavement in enhancing the resilience to flooding impact.

Inundation mapping using hydraulic modeling with high-resolution remote sensed data: a case study in the Acre River Basin, Brazil

Inundation mapping using hydraulic modeling with high-resolution remote sensed data: a case study in the Acre River Basin, Brazil

Flood hazard assessment in Chenab River basin using hydraulic simulation modeling and remote sensing

Flood hazard assessment in Chenab River basin using hydraulic simulation modeling and remote sensing

Flood risk assessment, a case study in an arid environment of Southeast Morocco

Abstract Since the early 1980s, several regions of Morocco have experienced alternating series of wet and dry periods related to climate change, with significant consequences for the country’s economy. This study aims to map flood hazards by using a hydraulic modeling approach, with a specific focus on the Oued (river) Zaouiat Sidi Hamza passing through Zaouiat Sidi Hamza township belonging to the High Ziz watershed (province of Midelt, region of Drâa-Tafilalet, Morocco). Hydraulic modeling and flood simulation were carried out followed by mapping of the flood hazard. The Oued Zaouiat Sidi Hamza River can cause torrential flooding issues, particularly during periods of heavy storms, impacting agricultural land and certain buildings on both river banks. All the cultivated areas developed alongside the river are at risk of flooding. Moreover, undermining and erosion of the river’s banks lead to rising high-water levels and flooding agricultural terraces. The use of geographic information systems and hydraulic modeling tools is essential to gain a deeper understanding of this situation. Also, the mapping of lineaments and fractures in the study area, carried out by satellite image processing, helped to quantify the directional influence of these lineaments on the flow of the hydrographic network, on the orientation of the circulation of surface water, and on the storage of groundwater. According to this study, the most vulnerable areas to flooding and erosion are those that receive the most water in the basin and have steep slopes. Decision-makers can use the results to produce development plans tailored to combat these risks and raise awareness among the population concerned, improving water resource evaluation and forecasting, as well as improving agricultural production.

Adoption of a fast dynamic model to simulate transient operations of MNSR

After developing a thermal–hydraulic model, it should be coupled to a point kinetic model to completely simulate transient behavior of a miniature neutron research reactor (MNSR). In this study introduction and validation of such a dynamic model which could be used as computing source of a micro-simulator, is presented. A time dependent point kinetic model in association to a simple control algorithm and reactivity feedbacks calculation (poisons and temperature) is adopted. In order to validate the model, it is compared against MNSR operational data in different scenarios such as normal fixed power operations, and reactivity insertion operations, and post shutdown scenarios. Result indicates that the coupled model could estimate the critical rod position for different power levels with an error less than 5%. Although the control algorithm is simple, it could predict the actual trend of control rod position accordance to the actual data. The coupled model simulates different reactivity insertion accident similar to the reactor operations in such a way that the error between estimated power peak, peak time, and long-term power is less than 5%.

Modeling hydraulic conductivity function of frozen soil

Hydraulic conductivity function for frozen soils (HCFF) is crucial for accurately simulating the water transfer process in cold regions, impacting hydrological states and frost heave diseases. However, the HCFF model capturing the relation between hydraulic conductivity and unfrozen water content (θ) or temperature (T) remains an open question. This study delves into HCFF encompassing both empirical and prediction models. This study begins with introducing θ-form and innovative T-form empirical HCFF models, showcasing their solid performance in fitting measured hydraulic conductivity data. Furthermore, the extension of the T-form empirical model to incorporate vapor flow and bimodal soils, through the introduction of maximum vapor conductivity and weighting factors, demonstrates a closer alignment with physical mechanisms and observed trends. In terms of predicting HCFF, the study provides a theoretical foundation through statistical hydraulic conductivity models and thermodynamic equilibrium in frozen soils. Additionally, it clarifies three routes for HCFF prediction—single Soil Freeze Characteristic Curve (SFCC), single Soil Water Characteristic Curve (SWCC), and a combination of the two—and validates their effectiveness through test results and comparison of HCFF prediction outcomes using SWCC and SFCC data from specific soil samples. In practice, the empirical and prediction models are recommended for available hydraulic conductivity data and available SFCC or SWCC data, respectively. Overall, this study not only lays the theoretical groundwork for most prediction models but also presents a valid empirical equation for modeling hydraulic conductivity function tailored specifically for frozen soils.

Enhancing nutrient absorption through the influence of mangrove ecosystem on flow rate and retention time in salt marshes

This study investigates the impact of pneumatophores (the aerial roots of Avicenna marina) on water flow rate, retention time, contact time, and consequently on nutrient absorption through the sediment in sub-tropical salt marshes. The goal is to realize how the density of mangroves in salt marshes influences the kinematic factors of streamflow at estuaries. To this end, a field experiment was carried out to assess nutrient and organic compound levels in the sediment and water samples, spanning six sampling stations along the Chabahar River discharging to the Chabahar Bay, Iran. Then, we delved into the influence of altering environmental parameters, such as density and geometry, on the kinematic features of the flow through statistical analysis and hydraulic modeling. The results showed that the aerial roots reduce the flow rate and increase both retention and contact times. The longest retention time was observed at station #5 due to increased vegetation density and decreased instream velocity. In addition, measurements of total organic matter, total organic carbon, and total nitrogen indicated that an extended contact time resulted in increased absorption flux to the stream by sediments. As a result, pneumatophores can serve as an effective sink for organic matter in ecotones in salt marshes.

Integrating FMI and ML/AI models on the open‐source digital twin framework OpenTwins

AbstractThe realm of digital twins is experiencing rapid growth and presents a wealth of opportunities for Industry 4.0. In conjunction with traditional simulation methods, digital twins offer a diverse range of possibilities. However, many existing tools in the domain of open‐source digital twins concentrate on specific use cases and do not provide a versatile framework. In contrast, the open‐source digital twin framework, OpenTwins, aims to provide a versatile framework that can be applied to a wide range of digital twin applications. In this article, we introduce a re‐definition of the original OpenTwins platform that enables the management of custom simulation services and the management of FMI simulation services, which is one of the most widely used simulation standards in the industry and its coexistence with machine learning models, which enables the definition of the next‐gen digital twins. Thanks to this integration, digital twins that reflect reality better can be developed, through hybrid models, where simulation data can feed the scarcity of machine learning data and so forth. As part of this project, a simulation model developed through the hydraulic software Epanet was validated in OpenTwins, in addition to an FMI simulation service. The hydraulic model was implemented and tested in an agricultural use case in collaboration with the University of Córdoba, Spain. A machine learning model has been developed to assess the behavior of an FMI simulation through machine learning.

Flood hazard comparison based on geomorphic flood index and hydraulic HEC-RAS (Case study in Ciliwung Watershed, Jakarta)

The Jakarta Special Capital Region is a highly vulnerable area to floods due to its location on wetlands laced by 13 major rivers and borders the Java Sea, with more than 40% of its land below sea level and groundwater extraction leading to the ground sinking. The city has experienced several major flood disasters, and climate change has increased the risk, frequency, and severity of flooding in Jakarta. The present study aims to identify areas with flood potential in the Jakarta Special Capital Region (Provinsi DKI Jakarta) using the Geospatial Flood Index (GFI) method recommended by the National Disaster Management Agency (BNPB). The GFI method is an alternative rapid assessment that utilizes the Digital Elevation Model for National Spatial (DEMNAS) data with an 8-meter spatial resolution and employs ARCGIS and QGIS software to identify areas with high potential for flooding and the extent of inundation. To assess the effectiveness of this method, a comparison is made with the Hydraulic HECRAS model for the section from the Automatic Water Level Recorder (AWLR) MT. Hartono to the Manggarai Flood Gate, considering flood return periods Q50 and Q100. The modeling results indicate that the inundation area estimated by the conventional GFI modeling is 150% larger than that the HECRAS Hydraulic model predicted.

Delayed pipe replacement halves environmental impacts but quadruples water loss

AbstractScheduling pipe replacement is critical for water distribution systems (WDSs) when managing finances and water loss. WDS replacements are often delayed due to high immediate costs without considering long‐term environmental consequences. This study is the first to examine a real‐world WDS using a novel workflow transferrable to other WDSs that integrates GIS, hydraulic modeling, breakage prediction, and life cycle analysis to evaluate environmental impacts and water loss of five replacement schedules (25‐, 50‐, 75‐, 100‐, 150‐year intervals). Environmental impacts were reduced by half when replacement interval changed from 25 year to 150 years, yet volume of water leaked from the system quadrupled. Benefits plateaued beyond 50–75‐year replacement while water loss steadily increased. Lowering water loss through break management enabled one‐sixth pipe replacement without exceeding original leakage at 25‐year replacement. Results were robust to uncertainty parameters and assert the importance of equilibrating environmental impacts and water loss when designing pipe replacement frequency.

Research on the influence of rock fracture toughness of layered formations on the hydraulic fracture propagation at the initial stage

Deep underground rocks exhibit significant layered heterogeneity due to geological evolution and sedimentation. Rock fracture toughness, as one of the important indicators of hydraulic crack propagation, also exhibits heterogeneous distribution. In order to investigate the influence of non-uniform fracture toughness of layered rocks on hydraulic crack propagation, this paper establishes a planar three-dimensional hydraulic crack propagation model. The model is numerically solved using the 3D displacement discontinuity method (3D-DDM) and the finite difference method. The calculation results indicate that when the distribution of the fracture toughness of layered rocks changes from uniform to non-uniform, the fracture morphology develops from a standard circular crack to an elliptical crack. When the difference of the rock fracture toughness between adjacent rock layers and the middle rock layer (pay zone) is large enough, the fracture morphology will develop towards a rectangular shape. In addition, when the fracture toughness of rock layers is non-uniformly distributed, the hydraulic crack not only rapidly expand in the softening layer (rock layer with lower fracture toughness), but also slowly propagate in the strong layer (rock layer with higher fracture toughness). However, the propagation speed in the softening layer is much faster than that in the strong layer. The results indicate that the heterogeneity of rock fracture toughness has an important impact on the morphology, propagation speed, and direction of hydraulic fractures.