Development and Application of an Urban Flood Forecasting and Warning Process to Reduce Urban Flood Damage: A Case Study of Dorim River Basin, Seoul

Early and accurate flood forecasting and warning for urban flood risk areas is an essential factor to reduce flood damage. This paper presents the urban flood forecasting and warning process to reduce damage in the main flood risk area of South Korea. This process is developed based on the rainfall-runoff model and deep learning model. A model-driven method was devised to construct the accurate physical model with combined inland-river and flood control facilities, such as pump stations and underground storages. To calibrate the rainfall-runoff model, data of gauging stations and pump stations of an urban stream in August 2020 were used, and the model result was presented as an R2 value of 0.63~0.79. Accurate flood warning criteria of the urban stream were analyzed according to the various rainfall scenarios from the model-driven method. As flood forecasting and warning in the urban stream, deep learning models, vanilla ANN, Long Short-Term Memory (LSTM), Stack-LSTM, and Bidirectional LSTM were constructed. Deep learning models using 10-min hydrological time-series data from gauging stations were trained to warn of expected flood risks based on the water level in the urban stream. A forecasting and warning method that applied the bidirectional LSTM showed an R2 value of 0.9 for the water level forecast with 30 min lead time, indicating the possibility of effective flood forecasting and warning. This case study aims to contribute to the reduction of casualties and flood damage in urban streams and accurate flood warnings in typical urban flood risk areas of South Korea. The developed urban flood forecasting and warning process can be applied effectively as a non-structural measure to mitigate urban flood damage and can be extended considering watershed characteristics.

Runoff Prediction Based on the Discharge of Pump Stations in an Urban Stream Using a Modified Multi-Layer Perceptron Combined with Meta-Heuristic Optimization

Runoff in urban streams is the most important factor influencing urban inundation. It also affects inundation in other areas as various urban streams and rivers are connected. Current runoff predictions obtained using a multi-layer perceptron (MLP) exhibit limited accuracy. In this study, the runoff of urban streams was predicted by applying an MLP using a harmony search (MLPHS) to overcome the shortcomings of MLPs using existing optimizers and compared with the observed runoff and the runoff predicted by an MLP using a real-coded genetic algorithm (RCGA). Furthermore, the results of the MLPHS were compared with the results of the MLP with existing optimizers such as the stochastic gradient descent, adaptive gradient, and root mean squared propagation. The runoff of urban steams was predicted based on the discharge of each pump station and rainfall information. The results obtained with the MLPHS exhibited the smallest error of 39.804 m3/s when compared to the peak value of the observed runoff. The MLPHS gave more accurate runoff prediction results than the MLP using the RCGA and that using existing optimizers. The accurate prediction of the runoff in an urban stream using an MLPHS based on the discharge of each pump station is possible.

Distributed Fault Detection and Isolation Approach for Oil Pipelines

Fault detection and isolation (FDI) in oil pipeline systems (OPS) is a very critical issue because faults in these systems such as leaks or equipment malfunctions may cause significant safety accidents and economic losses. These are the challenging factors, along with the environmental regulations for developing efficient FDI approaches for OPS. This paper proposes a model-based distributed FDI approach, which uses a structural model of the system in conjunction with algorithms to generate diagnostic tests that may be implemented in local diagnosers along the OPS. The proposed approach allows detection and isolation of faults in pipeline sections (pipeline segments), pump stations, as well as process control equipment. In this way, simulation of the obtained diagnostic tests in a benchmark application shows that all faults of interest (pipeline segment faults and sensor faults) are detected and isolated.

Simulation and Optimization of Airport Rainwater Drainage System at Different Control Measures

The impervious area of the airport is high, which leads to the deterioration of the water environment and frequent waterlogging disasters. The construction of sponge airport has become an important and arduous task in the new era of civil aviation design industry in China. In order to compare the effects of different control measures at different scenarios, take the airport along China's southeast coast as an example, three scenarios were designed in this study (Scenario 1: no LID facilities and other measures; Scenario 2: two pump stations were setting; Scenario 3: both LID facilities and pump stations). Three simulation models under LID facilities and other measures were developed using SWMM with return period of 5a. The simulation results at different scenarios were compared, the number and the best opening scheme of pumps for each reservoir are finally obtained. The results of Scenario 3 show that the full-flow duration of nodes in the study area is greatly shortened. The decrease of full-flow duration of J1, J2 and J3 was 1.2, 0.8 and 0.5 hours respectively, with reduction rates of 40%, 53.3% and 28.6% respectively. The rainfall peak flows both the first and the second were reduced in this scenario, and the reduction rates were 10.68% and 12.78% respectively. However, the reduction effect of the third peak is poor with the further increase of rainfall intensity. The reduction rate of the total inflow and peak flow of rainwater buckets and permeable pavement is better than that of vegetative swale. The results of this study can provide the reference for the design of sponge airport and the airport flood control management.

Study on a horizontal axial flow pump during runaway process with bidirectional operating conditions

The ultra-low head pump stations often have bidirectional demand of water delivery, so there is a risk of runaway accident occurring in both conditions. To analyze the difference of the runaway process under forward runaway condition (FRC) and backward runaway condition (BRC), the whole flow system of a horizontal axial flow pump is considered. The Shear-Stress Transport (SST) k–ω model is adopted and the volume of fluid (VOF) model is applied to simulate the water surface in the reservoirs. Meanwhile, the torque balance equation is introduced to obtain the real time rotational speed, then the bidirectional runaway process of the pump with the same head is simulated. In addition, the vortex transport equation and swirl number are proposed to reveal the flow characteristics during the runaway process. The results show that the runaway process can be divided into five stages: the drop, braking, rising, convergence and runaway stages, according to the changing law of torque curve. In the rising stage, the pressure difference on the blade surface continues to increase, which contributes to the abnormal torque increase. In this stage, the flow hits the pressure surface (PS) at a faster speed enlarging the pressure on PS, and the flow separation takes place on the suction surface (SS) weakening the pressure on SS. During the convergence and runaway stage, the pulsation amplitude of torque and axial force under FRC is obviously larger than those under BRC. This is because the rotation frequency of the vortex rope is the same as main pressure fluctuation frequency in impeller under FRC, which enhances the pulsation amplitude. Whereas the vortices are broken due to the inhibitive effect from guide vanes under BRC.

Simulation and Optimization of Airport Rainwater Drainage System At Different Control Strategies

The impervious area of the airport is high, which leads to the deterioration of the water environment and frequent waterlogging disasters. The construction of sponge airport has become an important and arduous task in the new era of civil aviation design industry in China. In order to compare the effects of different control strategies at different scenarios, take the airport along China's southeast coast as an example, three scenarios were designed in this study (Scenario 1: no LID facilities and other measures; Scenario 2: two pump stations were setting; Scenario 3: both LID facilities and pump stations). Three simulation models under LID facilities and other measures were developed using SWMM with return period of 5a. The simulation results at different scenarios were compared, the number and the best opening scheme of pumps for each reservoir are finally obtained. The results of Scenario 3 show that the full-flow duration of nodes in the study area is greatly shortened. The decrease of full-flow duration of J1, J2 and J3 was 1.2, 0.8 and 0.5 hours respectively, with reduction rates of 40%, 53.3% and 28.6% respectively. The rainfall peak flows both the first and the second were reduced in this scenario, and the reduction rates were 10.68% and 12.78% respectively. However, the reduction effect of the third peak is poor with the further increase of rainfall intensity. The reduction rate of the total inflow and peak flow of rainwater buckets and permeable pavement is better than that of vegetative swale. The results of this study can provide the reference for the design of sponge airport and the airport flood control management.

Method for Operating Drainage Pump Stations Considering Downstream Water Level and Reduction in Urban River Flooding

Korea experiences increasing annual torrential rains owing to climate change and river flooding. The government is expanding a new drainage pump station to minimize flood damage, but the river level has not been adjusted because of torrential rains. Therefore, the river level must be adjusted to operate the drainage pump station, and it can be adjusted through the reservoir of the drainage pump station. In this study, we developed a method for operating drainage pump stations to control the river level and verify the effectiveness of the proposed method. A stormwater management model (SWMM) was used to simulate the Suyeong River and Oncheon River in Busan, Korea. The rainfall data from 2011 to 2021 were investigated. The data were sorted into ten big floods that occurred in Busan. The model was calibrated with actual rainfall data. The water level of the Suyeong River and the Oncheon River was the highest in most simulations. The simulation results showed an average decrease of 3018.2 m3 in Suyeong River flooding, and the Oncheon River needed to be supplemented due to structural problems. As a result of the recombination by simply supplementing the structural problems of the Oncheon River, the average flooding of 194.5 m3 was reduced. The proposed method is economical and efficient for reducing urban stream flooding in areas susceptible to severe damage caused by climate change.

Smart Pump Station for Cross Country Pipelines

Cross-country pipelines are the safest mode of transportation for petroleum products. A typical hydrocarbon multi-product cross-country pipeline network consists of Dispatch station, cross-country Pipeline, Intermediate Pump Stations, Sectionalizing Valve Stations, intermediate pigging stations and Receipt Stations. Dispatch station, Intermediate Pump Stations and Receipt stations are manned stations to meet the operational and maintenance requirements in the pipeline network. Since pipelines operate round the clock, operations work force are required on 24 × 7 basis at these control rooms. Typically, work force expenses account for more than 25% of total operating cost. Cross-country pipelines are often laid in areas away from Urban and Industrialized areas. Intermediate Booster stations are also mostly located in remote areas. The work force operating these stations have to stay in hardship locations to ensure pipeline operations are unhindered. In order to optimize the work force requirements at Intermediate Pump stations and to ensure seamless and safe operations, it is proposed to construct Smart pump stations. The smart pump stations are intelligent enough with state of the art instrumentation to be monitored / controlled / operated from a remote controlling station which is a non-hardship location. The smart pump stations are designed such that it will have self-sufficient systems which will require minimum human interface from remote controlling stations. HPCL has implemented the smart pump station design philosophy in its ongoing Vijayawada Dharmapuri Pipeline project wherein two Intermediate Pump (IP) stations viz. Donakonda & Kalakada are designed and are being constructed as smart pump stations which are being completely automated and will be remotely monitored / controlled from remote controlling stations at Vijayawada & Kadapa respectively. Design philosophy of Smart Stations entails developing a completely new and a tailor made design philosophy for Process, mechanical, Electrical, Instrumentation, cathodic protection system, SCADA, Telecom & allied systems, fire & safety and accordingly getting all the equipment selected / manufactured / installed / commissioned.