Integrating VGI and 2D hydraulic models into a data assimilation framework for real time flood forecasting and mapping

Crowdsourced data can effectively observe environmental and urban ecosystem processes.The use of data produced by untrained people into flood forecasting models may effectively allow Early Warning Systems(EWS)to better perform while support decision-making to reduce the fatalities and economic losses due to inundation hazard.In this work,we develop a Data Assimilation(DA)method integrating Volunteered Geographic Information(VGI)and a 2D hydraulic model and we test its performances.The proposed framework seeks to extend the capabilities and performances of standard DA works,based on the use of traditional in situ sensors,by assimilating VGI while managing and taking into account the uncertainties related to the quality,and the location and timing of the entire set of observational data.The November 2012 flood in the Italian Tiber River basin was selected as the case study.Results show improvements of the model in terms of uncertainty with a significant persistence of the model updating after the integration of the VGI,even in the case of use of few-selected observations gathered from social media.This will encourage further research in the use of VGI for EWS considering the exponential increase of quality and quantity of smartphone and social media user worldwide.

Hydraulic modeling and optimization of jet mill bit considering the characteristics of depressurization and cuttings cleaning

A jet mill bit(JMB)is proposed to increase the drilling efficiency and safety of horizontal wells,which has the hydraulic characteristics of depressurization and cuttings cleaning.This paper fills the gap in the hydraulic study of the JMB by focusing on the hydraulic modeling and optimization of the JMB and considering these two hydraulic characteristics.First,the hydraulic depressurization model and the hydraulic cuttings cleaning model of the JMB are developed respectively.In the models,the pressure ratio and efficiency are chosen as the evaluation parameters of the depressurization capacity of the JMB,and the jet hydraulic power and jet impact force are chosen as the evaluation parameters of cuttings cleaning capacity of the JMB.Second,based on the hydraulic models,the effects of model parameters[friction loss coefficient,target inclination angle,rate of penetration(ROP),flow ratio,and well depth]on the hydraulic performance of the JMB are investigated.The results show that an increase in the friction loss coefficient and target inclination angle cause a significant reduction in the hydraulic depressurization capacity,and the effect of ROP is negligible.The flow ratio is positively related to the hydraulic cuttings cleaning capacity,and the well depth determines the maximum hydraulic cuttings cleaning capacity.Finally,by combining the hydraulic depressurization model and hydraulic cuttings cleaning model,an optimization method of JMB hydraulics is proposed to simultaneously maximize the jet depressurization capacity and the cuttings cleaning capacity.According to the drilling parameters given,the optimal values of the drilling fluid flow rate,backward nozzle diameter,forward nozzle diameter,and throat diameter can be determined.Moreover,a case study is conducted to verify the effectiveness of the optimization method.

Hydraulic model with roughness coefficient updating method based on Kalman filter for channel flood forecast

A real-time channel flood forecast model was developed to simulate channel flow in plain rivers based on the dynamic wave theory. Taking into consideration channel shape differences along the channel, a roughness updating technique was developed using the Kalman filter method to update Manning＇s roughness coefficient at each time step of the calculation processes. Channel shapes were simplified as rectangles, triangles, and parabolas, and the relationships between hydraulic radius and water depth were developed for plain rivers. Based on the relationship between the Froude number and the inertia terms of the momentum equation in the Saint-Venant equations, the relationship between Manning＇s roughness coefficient and water depth was obtained. Using the channel of the Huaihe River from Wangjiaba to Lutaizi stations as a case, to test the performance and rationality of the present flood routing model, the original hydraulic model was compared with the developed model. Results show that the stage hydrographs calculated by the developed flood routing model with the updated Manning＇s roughness coefficient have a good agreement with the observed stage hydrographs. This model performs better than the original hydraulic model.

Fuzzy adaptive PID control on hydraulic servo system of quadruped robot

Quadruped robot driven by high power density hydraulic device works in unstructured en- vironment. With variable load and various external disturbance, the hydraulic servo system has fea- tures such as nonlinear, time-varying parameters. Traditional control method has some limitation. In order to help the hydraulic servo system of the quadruped robot to adapt to harsh environments, and to obtain high control quality and control precision, an incremental fuzzy adaptive PID controller based on position feedback is designed to solve the related technical problems. Matlab/Simulink sim- ulation and experimental results show that the incremental fuzzy adaptive PID controller improves the dynamic performance of the system, enhances the respond speed and precision of the hydraulic ser- vo system, and has some theory significance and practical value.

Thermal-hydraulic modeling and analysis of hydraulic system by pseudo-bond graph

To increase the efficiency and reliability of the thermodynamics analysis of the hydraulic system, the method based on pseudo-bond graph is introduced. According to the working mechanism of hydraulic components, they can be separated into two categories: capacitive components and resistive components. Then, the thermal-hydraulic pseudo-bond graphs of capacitive C element and resistance R element were developed, based on the conservation of mass and energy. Subsequently, the connection rule for the pseudo-bond graph elements and the method to construct the complete thermal-hydraulic system model were proposed. On the basis of heat transfer analysis of a typical hydraulic circuit containing a piston pump, the lumped parameter mathematical model of the system was given. The good agreement between the simulation results and experimental data demonstrates the validity of the modeling method.

Hydraulic metal structure health diagnosis based on data mining technology

In conjunction with association rules for data mining, the connections between testing indices and strong and weak association rules were determined, and new derivative rules were obtained by further reasoning. Association rules were used to analyze correlation and check consistency between indices. This study shows that the judgment obtained by weak association rules or non-association rules is more accurate and more credible than that obtained by strong association rules. When the testing grades of two indices in the weak association rules are inconsistent, the testing grades of indices are more likely to be erroneous, and the mistakes are often caused by human factors. Clustering data mining technology was used to analyze the reliability of a diagnosis, or to perform health diagnosis directly. Analysis showed that the clustering results are related to the indices selected, and that if the indices selected are more significant, the characteristics of clustering results are also more significant, and the analysis or diagnosis is more credible. The indices and diagnosis analysis function produced by this study provide a necessary theoretical foundation and new ideas for the development of hydraulic metal structure health diagnosis technology.

Floodplain Mapping of Nashwaak River,Canada:An Assessment Based on High-Resolution Hydraulic Simulation

Recent advances in hydraulic modeling create improved methodology to accurately predict the extent of floodplain map in order to assist policy makers to develop flood hazard mitigation measures and timely inform the local communities with the flood risk alerts.However,accurate prediction of the inundation map also depends on the spatial resolution of the topographic data.In this study,we developed a novel high-resolution modeling framework for Nashwaak River watershed,New Brunswick,Canada to capture significant flooding along the banks of the river for the two historic flood events and accurately map the floodplains for both the gauged and ungauged areas of the watershed.The model is based on HEC-RAS(US Army Corps of Engineers Hydrologic Engineering Center River Analysis System)hydraulic model and the topographic data were generated from high-resolution LiDAR data of~0.5 m.The model runs were driven by observed flow conditions applied at the boundary and the framework is based on different spatial resolution to determine the effect of spatial resolution on the predicted inundation.We validated the model simulated water surface elevation with the observed data and the model reproduces reasonably good skill score.Results from the numerical simulation suggest that apart from the strength of the stream velocity,design of the modeling framework plays an important role in determining the inundation depth as well as the maximum flooding extent.

HYDRAULIC MODEL OF A NEW BIPOLAR CELL FOR ALUMINUM PRODUCTION

The electrolyte circulations in monopolar cell and two-compartment bipolar cell with submerged electrodes were described by a hydraulic model.The influence of current density,electrode tilt,anode-cathode distance(ACD)and immersion depth of electrodes on the electrolyte circulation velocities between electrodes had been studied.Results demonstrated that the flow rates in the two compartments of bipolar cell were very different,which provided important information for the structure design of bipolar cell.

Hydraulics Management Model of Response Function Solved by Laplace Transform Boundary Element Method

In solving a response function by the boundary element method, the use of the singular valued method and the Laplace transform in a time domain makes the solving process be simplified and the result be accurate. The restricted condition matrix formed by the response matrix method is much smaller than that by embedding method. In addition, the response function may realize directly the management decision making. So it is efficient for establishing and solving hydraulics management models.

1D-2D Hydraulic Modeling of a Diversion Channel on the Cavally River in Zouan-Hounien,Cote d’Ivoire

On the Cavally River, located on the border between C?te d’Ivoire and Liberia, several hydraulic structures such as bridges and diversion channels are planned to be made in recent years in the operating perimeter of the Ity mining company. A 1D-2D hydraulic model was developed to design a diversion channel to cut a meander of the Cavally River in order to ensure hydraulic operation similar to the initial conditions of the river (water levels, flow and velocities). This model was designed with a flow rate of 240 m3/s and a Manning coefficient of 0.052 m1/3·s-1 for the minor bed and 0.06 m1/3·s-1 for the major bed. The results from the hydraulic model show that the hydraulic conditions (water levels, velocities) in the channel before and after the diversion remain almost like those of the Cavally River.

Influence of Swimming Pool Design on Hydraulic Behavior: A Numerical and Experimental Study

A swimming pool can be considered as a chemical reactor with specific hydraulic and macro-mixing characteristics. The nature of flow into the pool depends on various characteristics, such as water inlets and outlets (number and position), pool geometry, and flow rate. This study investigates how swimming pool design affects hydraulic behavior based on experimental and computational fluid dynamics studies (CFD). This paper does not describe the hydraulic behavior of all existing swimming pools, however the cases studied here are representative of pool designs widely used in Europe and the United States. The model developed, based on the principle of a stirred reactor, could be used as a first approach in describing the hydraulic behavior of regular pools. This model is suitable for the study of physical and chemical phenomena with long characteristic times. Other, more advanced, models were shown to be more suitable to the case of fast chemical processes.

Using Hydraulic Engineering Model Experiment to Study the Sediment Trapping Efficiency of Adjustable Check Dam

The construction of fully closed check dam (CD) is a conventional flood prevention mechanism implemented on rivers. Fully closed CDs trap large amounts of sediments in rivers to stabilize the river slopes and control erosion. However, fully closed CDs cannot selectively trap sediment and may easily overflow, causing them to losing their ability to mediate and hold sediments. Previous studies proposed the concept of “breathable CDs”. The researcher introduced metal slit dam (SD) that could be assembled and disassembled quickly and conveniently. Once a CD reaches maximum capacity, operators must ensure that the water channels of the dam are free from blockage. Moreover, they must inspect the internal accumulation conditions of the dam periodically or immediately following heavy typhoon rains. When necessary, either the sediment buildup in the upriver blockage must be cleared, or the transverse structure of the dam must be removed to allow fine particles to be discharged along with a moderate amount of water. These actions can free up the sediment-storing capacity of the dam for the next heavy typhoon rains. In addition, operators should also inspect the damages inflicted on the dam, such as erosion, wear and tear, and deformation conditions. Damaged components should be disassembled and repaired if possible, or recycled and reused. The present study performed channel tests to simulate closed CDs, SDs, steel pipe dam (SPDs), and steel pipe plus slit dam (SPSDs) for 50-year and 100-year frequency floods. Results were then analyzed to determine the sediment trapping (ST) effects of various CDs, the effects of “adjustable CDs”, and the changes of moderated riverbeds.

Development, assessment and implementation of integrated stormwater management plan: a case study in Shanghai

An innovative stormwater master plan based on low impact development LID is proposed.Unlike the traditional urban drainage plan this plan employs a sustainable stormwater management approach in communities utilizing LID practices to reduce runoff and pollution load. An integrated hydraulic model which combines the traditional drainage sewer system with LID practices is adopted to assess the master plan.Through a long-term continuous simulation for 20 years the results reveal that the runoff volume will be reduced by over 80% following full implementation of this plan. Combining with the local conditions technical guidelines are established to provide assistance in implementing the stormwater master plan. Bioretention facilities for three main roads are constructed and other areas of development are being implemented sequentially under the guidance of the plan. This project provides an alternative method of stormwater management through the implementation of LID and it acts as a good example for other developing districts in China.

Uniformity evaluation and optimization of fluid flow characteristics in a seven-strand tundish

The effect of flow control devices（FCDs） on the uniformity of flow characteristics in a seven-strand symmetrical trapezoidal tundish was studied using both an experimental 1：2.5 hydraulic model and a numerical simulation of a 1：1 geometric model.The variation coefficient（CV） was defined to evaluate the flow uniformity of the seven-strand tundish.An optimized FCD configuration was proposed on the basis of the evaluation of experimental results.It is concluded that a turbulence inhibitor（TI） and U-type dam are essential to improve the uniformity of fluid flow in the seven-strand tundish.In addition,the configuration of inclination T-type dams with a height of 200 mm between the second and third strands and with a height of 300 mm between the third and fourth strands can minimize the proportion of dead zone.After optimizing the configuration of FCDs,the variation coefficient reduces below 20%of the mean value,and the average proportion of dead zone is just 14.6%;in addition,the temperature fluctuation between the strands could be controlled within 0.6 K.In summary,the uniformity of flow and temperature in the seven-strand tundish is greatly improved.

Simulation of Flood Propagation from the Niandouba Dam Outlet(Kayanga River,Senegal)to the Waïma Lake Inlet Using HEC RAS for Water Resource Management in the AnambéIrrigated Perimeters

Dams are designed for water storage intended to compensate downstream fluctuations that are stabilizing water supply and hydropower production.Hydraulic modelling tools and schemes allow understanding the hydraulic characteristics of the irrigation systems and mitigating uncertainty inherent to dam removals.The construction of the Niandouba dam at the confluence of the Kayanga and Anambérivers(Senegal)has perturbed the natural flow of the AnambéRiver to feed the Waïma Lake and irrigated perimeters.The flow gauges at the Kayanga and AnambéRivers are no longer operational.In this study,the HEC-RAS(Hydrological Engineering Centre River Analysis System)and the RAS Mapper is used to simulate the flow propagation of the Kayanga-Anambéhydraulic system ranging from the Niandouba dam to the entry of Waïma lake.The HEC-RAS modelling enables the estimating of,among other variables,water levels,depths and flow velocities for the different flow configurations and different cross-sectional zones.This study presents a flood mapping of the Kayanga-Anambéhydro system using the RAS Mapper and HEC-RAS hydraulic modelling tools.The study has exhibited the depths at the inlet of the supply channels where the pumping stations are located.

Experiment and numerical simulation of two-phase flow in oxygen enriched side-blown furnace

Taking an oxygen enriched side-blown furnace as the prototype,a hydraulic model was established according to the similarity principle.The influence of three factors on the gas-liquid two-phase flow was analyzed,i.e.the airflow speed,the submerged depth and the downward angle of the nozzle.A numerical simulation of the hydraulic model was carried out trying to find the suitable turbulence model which can describe the side-blown two-phase flow correctly by comparing the simulation results with the experimental data.The experiment shows that the airflow speed has a great influence on the flow of the water.The submerged depth of the nozzle has a relatively smaller influence on the penetration depth and the surface fluctuation height in the liquid phase.When the nozzle is at a downward angle of 15°,the penetration depth and the surface fluctuation height are reduced.It is concluded that the numerical results with the realizable k-εturbulence model are the closest to the experiment for the penetration depth,the surface fluctuation height and the bubble scale.

Direct shear tests on cemented paste backfill-rock wall and cemented paste backfill-backfill interfaces

Even though a large number of large-scale arch dams with height larger than 200 m have been built in the world, the transient groundwater flow behaviors and the seepage control effects in the dam foundations under difficult geological conditions are rarely reported. This paper presents a case study on the transient groundwater flow behaviors in the rock foundation of Jinping I double-curvature arch dam, the world＇s highest dam of this type to date that has been completed. Taking into account the geological settings at the site, an inverse modeling technique utilizing the time series measurements of both hydraulic head and discharge was adopted to back-calculate the permeability of the foundation rocks,which effectively improves the uniqueness and reliability of the inverse modeling results. The transient seepage flow in the dam foundation during the reservoir impounding was then modeled with a parabolic variational inequality（PVI） method. The distribution of pore water pressure, the amount of leakage, and the performance of the seepage control system in the dam foundation during the entire impounding process were finally illustrated with the numerical results.

Simulation algorithm for spiral case structure in hydropower station

In this study, the damage-plasticity model for concrete that was verified by the model experiment was used to calculate the damage to a spiral case structure based on the damage mechanics theory. The concrete structure surrounding the spiral case was simulated with a three-dimensional finite element model. Then, the distribution and evolution of the structural damage were studied. Based on investigation of the change of gap openings between the steel liner and concrete structure, the impact of the non-uniform variation of gaps on the load-beating ratio between the steel liner and concrete structure was analyzed. The comparison of calculated results of the simplified and simulation algorithms shows that the simulation algorithm is a feasible option for the calculation of spiral case structures. In addition, the shell-spring model was introduced for optimization analysis, and the results were reasonable.

Modeling the effects of rainfall on vehicular traffic

Traffic management and drainage system are two vital issues for any metropolitan city. Like other big cities, Karachi is also facing problems due to lack of traffic management and poor drainage system. The main objective of the study is to model the interdisciplinary issues of storm water and its effect on the traffic of Karachi. The specific objectives are （1） to calibrate and validate urban hydraulic and traffic micro-simulation models and （2） to model storm water and traffic for future conditions. This study is carried out on a 3-km section of arterial road. In this study, loose coupling of two models is done. For urban drainage, PCSWMM, and for traffic, VISSIM is used. Both models are calibrated for an existing situation on rainfall event of August 3, 2013, and then used for prediction of future scenario based on 50-year and 100-year return periods of rainfall. Sensitivity analysis of VISSIM is performed. Locations and lengths of road sections, where ponding happens for the future scenario, are identified using PCSWMM. These lengths axe then marked in VISSIM as low-speed areas, and delays are measured. Analysis of PCSWMM shows that for 100-year return period, there is maximum 0.318 ha-m （3180 cubic meters） water stored in the depressions of the road after 10 h of rainfall. Analysis of VISSIM shows that for a 100-year return period, there is a maximum delay of 35 min on NIPA to Hasan Square section of University Road.