The Effect of Storm-Induced Precipitation on Flooding in Macau City

2020 ◽  
Author(s):  
Jie Yang ◽  
Jiandong Liu ◽  
Dong-Eon Kim ◽  
Linlin Li ◽  
Kai Meng Mok ◽  
...  
Keyword(s):  
Overland Flow ◽  
Surface Wind ◽  
Mass Conservation ◽  
Wave Model ◽  
Heavy Precipitation ◽  
Ocean Waves ◽  
Reanalysis Data ◽  
Water Levels ◽  
Inundation Extent ◽  
Typhoon Event

Abstract The extent and depth of coastal flooding caused by tropical cyclone can be underestimated without considering the contribution by storm-induced precipitation. In this study, the dynamic flooding processes in Macau are simulated accounting for the combined effect of storm surge and precipitation during Typhoon Mangkhut in 2018. The surface wind and atmospheric pressure during this typhoon event are generated by a parametric vortex model and are used to drive a surge–tide–wave model for producing storm-induced water levels. The precipitation rate from ERA5 reanalysis data is utilized in this modelling suite as an additional source of water mass. The numerical model is first thoroughly validated by comparing the numerical results against the measured water levels and significant wave heights at tidal gauge and wave buoy stations. By switching on/off the rainfall function in the mass conservation and momentum equations, we compare and analyze the differences of inundation depths and inundation extent induced by precipitation. The differences in the maximum inundation depths vary spatially and the increments owing to precipitation are less than 50 mm in most flooded regions, the associated contribution is less than 10% in areas with moderate and severe flooding. The effect of precipitation as additional rainfall-induced forces in the momentum equations plays a more important role than that in the mass conservation. The inundation depths induced by tide and surge are approximately two times of that induced by precipitation. Moreover, the compound effects by ocean waves and precipitation tend to decrease the increment of precipitation-induced inundation depths by precipitation alone. Finally, we also assess the performance of the overland flow model Itzï on Macau Peninsula for the same typhoon event. The present study helps identifying vulnerable areas subject to heavy precipitation in Macau and gaining more understanding of flooding mechanisms by different physical drivers.

scholarly journals Storm surge and wave simulations in the Gulf of Mexico using a consistent drag relation for atmospheric and storm surge models

2012 ◽  
Vol 12 (7) ◽  
pp. 2399-2410 ◽  
Author(s):  
D. Vatvani ◽  
N. C. Zweers ◽  
M. van Ormondt ◽  
A. J. Smale ◽  
H. de Vries ◽  
...  
Keyword(s):  
Wind Speed ◽  
Gulf Of Mexico ◽  
Drag Coefficient ◽  
Storm Surge ◽  
Weather Prediction ◽  
Surface Wind ◽  
Wave Model ◽  
Water Levels ◽  
Observation Data ◽  
Wave Effects

Abstract. To simulate winds and water levels, numerical weather prediction (NWP) and storm surge models generally use the traditional bulk relation for wind stress, which is characterized by a wind drag coefficient. A still commonly used drag coefficient in those models, some of them were developed in the past, is based on a relation, according to which the magnitude of the coefficient is either constant or increases monotonically with increasing surface wind speed (Bender, 2007; Kim et al., 2008; Kohno and Higaki, 2006). The NWP and surge models are often tuned independently from each other in order to obtain good results. Observations have indicated that the magnitude of the drag coefficient levels off at a wind speed of about 30 m s−1, and then decreases with further increase of the wind speed. Above a wind speed of approximately 30 m s−1, the stress above the air-sea interface starts to saturate. To represent the reducing and levelling off of the drag coefficient, the original Charnock drag formulation has been extended with a correction term. In line with the above, the Delft3D storm surge model is tested using both Charnock's and improved Makin's wind drag parameterization to evaluate the improvements on the storm surge model results, with and without inclusion of the wave effects. The effect of waves on storm surge is included by simultaneously simulating waves with the SWAN model on identical model grids in a coupled mode. However, the results presented here will focus on the storm surge results that include the wave effects. The runs were carried out in the Gulf of Mexico for Katrina and Ivan hurricane events. The storm surge model was initially forced with H*wind data (Powell et al., 2010) to test the effect of the Makin's wind drag parameterization on the storm surge model separately. The computed wind, water levels and waves are subsequently compared with observation data. Based on the good results obtained, we conclude that, for a good reproduction of the storm surges under hurricane conditions, Makin's new drag parameterization is favourable above the traditional Charnock relation. Furthermore, we are encouraged by these results to continue the studies and establish the effect of improved Makin's wind drag parameterization in the wave model. The results from this study will be used to evaluate the relevance of extending the present towards implementation of a similar wind drag parameterization in the SWAN wave model, in line with our aim to apply a consistent wind drag formulation throughout the entire storm surge modelling approach.

scholarly journals The Effect of the Difference in Intensity and Track of Tropical Cyclone on Significant Wave Height and Wave Direction in the Southeast Indian Ocean

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Yosafat Donni Haryanto ◽  
Nelly Florida Riama ◽  
Dendi Rona Purnama ◽  
Aurel Dwiyana Sigalingging
Keyword(s):  
Tropical Cyclone ◽  
Indian Ocean ◽  
Tropical Cyclones ◽  
Wave Height ◽  
Significant Wave Height ◽  
Surface Wind ◽  
Ocean Waves ◽  
Reanalysis Data ◽  
Wave Direction ◽  
Significant Wave

This study aims to analyze the effect of the differences in intensity and track of tropical cyclones upon significant wave heights and direction of ocean waves in the southeast Indian Ocean. We used the tropical cyclone data from Japan Aerospace Exploration Agency (JAXA) starting from December 1997 to November 2017. The significant wave height and wave direction data are reanalysis data from Copernicus Marine Environment Monitoring Service (CMEMS), and the mean sea level pressure, surface wind speed, and wind direction data are reanalysis data from European Center for Medium-Range Weather Forecasts (ECMWF) from December 1997 to November 2017. The results show that the significant wave height increases with the increasing intensity of tropical cyclones. Meanwhile, the direction of the waves is influenced by the presence of tropical cyclones when tropical cyclones enter the categories of 3, 4, and 5. Tropical cyclones that move far from land tend to have higher significant wave height and wider affected areas compared to tropical cyclones that move near the mainland following the coastline

scholarly journals Analysis of the development of a hydrological balance for future decades in the Senianska depression in the Eastern Slovak lowland

2010 ◽  
Vol 18 (4) ◽  
pp. 30-40 ◽  
Author(s):  
M. Tegelhoffová
Keyword(s):  
River Basin ◽  
Overland Flow ◽  
Water Levels ◽  
Water Control ◽  
Mike She ◽  
Hydrological Balance ◽  
Small Water ◽  
Model Domain ◽  
Physically Based ◽  
Set Up

Analysis of the development of a hydrological balance for future decades in the Senianska depression in the Eastern Slovak lowlandThe goal of the article was to analyze the hydrological balance for future decades in a pilot area in the Eastern Slovak lowland. The aim was to set up the physically-based Mike SHE hydrological model for the modeling hydrological balance in the selected wetland ecosystem in the Eastern Slovak Lowland. The pilot area - the Senianska depression is located near the village of Senne, between the Laborec and Uh Rivers. Specifically, it is a traditional landscape of meadows, marshes, cultivated soil, small water control structures and forests. To get a complete model set up for simulating elements of the hydrologic balance in the pilot area, it was necessary to devise a model for a larger area, which includes the pilot area - the Senianska depression. Therefore, both the Mike SHE model was set up for the Laborec River basin (a model domain of 500 × 500 m) and the Čierna voda River basin (a model domain of 100 × 100 m), for the simulation period of 1981-2007, is order to get the boundary conditions (overland flow depth, water levels, discharges and groundwater table) for the model of the pilot area. The Mike SHE model constructed for the pilot area - the Senianska depression (a model domain of 1 × 1 m) -was used to simulate the elements of the hydrological balance for the existing conditions during the simulation period of 1983-2007 and for climate scenarios for the simulation period of 1983-2100. The results of the simulated elements of the hydrological balance for the existing conditions were used for a comparison of the evolution of the hydrologic conditions in the past, for identifying wet and flooded areas and for identifying the spatial distribution of the actual evapotranspiration in the pilot area. The built-up model with setting values was used for modeling the hydrological balance in changed conditions - climate change.

scholarly journals Evaluating skill of BMKG wave model forecast (Wavewatch-3) with observation data in Indian Ocean (5 – 31 December 2017).

2021 ◽  
Vol 893 (1) ◽  
pp. 012058
Author(s):  
R Kurniawan ◽  
H Harsa ◽  
A Ramdhani ◽  
W Fitria ◽  
D Rahmawati ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Wave Height ◽  
Model Performance ◽  
Forecast Accuracy ◽  
Wave Model ◽  
Ocean Waves ◽  
Observation Data ◽  
Operating Characteristics ◽  
Wave Forecast ◽  
Good For

Abstract Providing Maritime meteorological forecasts (including ocean wave information) is one of BMKG duties. Currently, BMKG employs Wavewatch-3 (WW3) model to forecast ocean waves in Indonesia. Evaluating the wave forecasts is very important to improve the forecasts skill. This paper presents the evaluation of 7-days ahead BMKG’s wave forecast. The evaluation was performed by comparing wave data observation and BMKG wave forecast. The observation data were obtained from RV Mirai 1708 cruise on December 5th to 31st 2017 at the Indian Ocean around 04°14'S and 101°31'E. Some statistical properties and Relative Operating Characteristics (ROC) curve were utilized to assess the model performance. The evaluation processes were carried out on model’s parameters: Significant Wave Height (Hs) and Wind surface for each 7-days forecast started from 00 UTC. The comparation results show that, in average, WW3 forecasts are over-estimate the wave height than that of the observation. The forecast skills determined from the correlation and ROC curves are good for the first- and second-day forecast, while the third until seventh day decrease to fair. This phenomenon is suspected to be caused by the wind data characteristics provided by the Global Forecasts System (GFS) as the input of the model. Nevertheless, although statistical correlation is good for up to 2 days forecast, the average value of Root Mean Square Error (RMSE), absolute bias, and relative error are high. In general, this verifies the overestimate results of the model output and should be taken into consideration to improve BMKG’s wave model performance and forecast accuracy.

Effect of Uni- and Bi-Directional Coupling of Ocean-Met Interaction on Significant Wave Height and Local Wind

2017 ◽  
Author(s):  
Adil Rasheed ◽  
Jakob Kristoffer Süld ◽  
Mandar Tabib
Keyword(s):  
Wave Height ◽  
Significant Wave Height ◽  
Surface Wind ◽  
Wave Model ◽  
Ocean Surface ◽  
Observation Data ◽  
Local Wind ◽  
Near Surface ◽  
Significant Wave ◽  
Bidirectional Coupling

Accurate prediction of near surface wind and wave height are important for many offshore activities like fishing, boating, surfing, installation and maintenance of marine structures. The current work investigates the use of different methodologies to make accurate predictions of significant wave height and local wind. The methodology consists of coupling an atmospheric code HARMONIE and a wave model WAM. Two different kinds of coupling methodologies: unidirectional and bidirectional coupling are tested. While in Unidirectional coupling only the effects of atmosphere on ocean surface are taken into account, in bidirectional coupling the effects of ocean surface on the atmosphere are also accounted for. The predicted values of wave height and local wind at 10m above the ocean surface using both the methodologies are compared against observation data. The results show that during windy conditions, a bidirectional coupling methodology has better prediction capability.

scholarly journals Spatially Tracking Wave Events in Partitioned Numerical Wave Model Outputs

2019 ◽  
Vol 36 (10) ◽  
pp. 1933-1944 ◽  
Author(s):  
Haoyu Jiang
Keyword(s):  
Grid Point ◽  
Wave Model ◽  
Ocean Waves ◽  
Model Verification ◽  
Analysis Model ◽  
Wave Parameters ◽  
Numerical Wave ◽  
Wave Models ◽  
Spectral Partitioning ◽  
The Impact

AbstractNumerical wave models can output partitioned wave parameters at each grid point using a spectral partitioning technique. Because these wave partitions are usually organized according to the magnitude of their wave energy without considering the coherence of wave parameters in space, it can be difficult to observe the spatial distributions of wave field features from these outputs. In this study, an approach for spatially tracking coherent wave events (which means a cluster of partitions originating from the same meteorological event) from partitioned numerical wave model outputs is presented to solve this problem. First, an efficient traverse algorithm applicable for different types of grids, termed breadth-first search, is employed to track wave events using the continuity of wave parameters. Second, to reduce the impact of the garden sprinkler effect on tracking, tracked wave events are merged if their boundary outlines and wave parameters on these boundaries are both in good agreement. Partitioned wave information from the Integrated Ocean Waves for Geophysical and other Applications dataset is used to test the performance of this spatial tracking approach. The test results indicate that this approach is able to capture the primary features of partitioned wave fields, demonstrating its potential for wave data analysis, model verification, and data assimilation.

scholarly journals Assessment of the importance of the current-wave coupling in the shelf ocean forecasts

Ocean Science ◽  
2007 ◽  
Vol 3 (3) ◽  
pp. 345-362 ◽  
Author(s):  
G. Jordà ◽  
R. Bolaños ◽  
M. Espino ◽  
A. Sánchez-Arcilla
Keyword(s):  
Surface Wind ◽  
Circulation Model ◽  
Wave Model ◽  
Western Mediterranean ◽  
Stokes Drift ◽  
Coupled Modelling ◽  
Wave Refraction ◽  
Waves And Currents ◽  
Nw Mediterranean ◽  
Sequential Coupling

Abstract. The effects of wave-current interactions on shelf ocean forecasts is investigated in the framework of the MFSTEP (Mediterranean Forecasting System Project Towards Enviromental Predictions) project. A one way sequential coupling approach is adopted to link the wave model (WAM) to the circulation model (SYMPHONIE). The coupling of waves and currents has been done considering four main processes: wave refraction due to currents, surface wind drag and bottom drag modifications due to waves, and the wave induced mass flux. The coupled modelling system is implemented in the southern Catalan shelf (NW Mediterranean), a region with characteristics similar to most of the Mediterranean shelves. The sensitivity experiments are run in a typical operational configuration. The wave refraction by currents seems to be not very relevant in a microtidal context such as the western Mediterranean. The main effect of waves on current forecasts is through the modification of the wind drag. The Stokes drift also plays a significant role due to its spatial and temporal characteristics. Finally, the enhanced bottom friction is just noticeable in the inner shelf.

Numerical Simulation and Practical Sand Silting in Waterways of Langya Bay

2008 ◽  
Author(s):  
Lin Zhao ◽  
Bingchen Liang ◽  
Hongda Shi ◽  
Xiangzhu Liu
Keyword(s):  
Wave Model ◽  
Water Levels ◽  
Open Boundary ◽  
Observation Data ◽  
Surface Drag ◽  
Time And Space ◽  
Sediment Distribution ◽  
Waves And Currents ◽  
Basin Water ◽  
Sediment Model

Dongjiakou Harbor is located at the Langya Bay in the city of Qingdao, Shandong Province. It is a multi-functional harbor of heavy passing capacity under planning in China. The sediment distribution and dispersion in the waterways and harbor basin water areas is of great importance to the construction and operation of the harbor. This article is based on the measurement of waves and currents as well as sediment suspension characteristics on site, and using numerical methods to predict the dispersion and deposition rules in this area. A combined wave-current-sediment model of COHERENS-SED is created through the combination of hydrodynamic model COHERENS and wave model SWAN as well as a sedimentation model SED developed by the authors. Inside COHERENS-SED, SWAN is regarded as a subroutine and it gets time and space varying current velocity and surface elevation from COHERENS. COHERENS gets time and space varying wave relevant parameters calculated by SWAN. Wave-enhanced bottom stress, wave dependent surface drag coefficient and radiation stress are introduced to COHERENS. Then a fully coupled hydrodynamic–sediment model COHERENS-SED accounting for interaction between the waves and currents is obtained and adopted to simulate these hydrodynamic conditions and the sedimentation processes in Langya Bay area. The open boundary of waves and currents is obtained through nesting from running a wider model which includes the Bohai Sea and the North Yellow Sea with coarser solution and contains coastal regions of Shandong Peninsula which includes the whole area of Langya Bay. Generally, the values of time series of current velocities, current directions and water levels as well as sediment concentrations have good agreements with observation data. The study shows the currents in the waterways and harbor basin water areas are relatively weak due to the narrow water width at the port mouth and the current directions parallel to the wharf directions. Also, sediment dispersion scales and strength are predicted according to the computation. The study also estimates the average sediment deposition amount and seabed erosion in this area. Besides, significant wave height and wave period obtained by COHERENS-SWAN shows that simulation result with wave-current interaction is better agreed with the measurement than the case without current.

Modeling the Effect of Groundwater Abstraction on Wei River Riverine Ecological Flow Using the Coupled Model of Groundwater and Surfacewater

2012 ◽  
Vol 433-440 ◽  
pp. 1453-1457 ◽  
Author(s):  
Bo Zhang ◽  
Mei Hong ◽  
Zu Hao Zhou ◽  
Yang Wen Jia ◽  
Hui Li ◽  
...  
Keyword(s):  
Overland Flow ◽  
River Flow ◽  
Shallow Groundwater ◽  
Coupled Model ◽  
Wave Model ◽  
Coupling Model ◽  
Analysis Tool ◽  
Groundwater Abstraction ◽  
Coupled Calculation ◽  
Balance Analysis

In this study, the latest version of river boundary modular in MODFLOW, was employed in this watershed for the case study of coupled calculation between river and aquifer. Because of the complex interaction of groundwater and surface water in this area, the coupling model of SFR modular for river diffusive wave model and isochronal cell method for overland flow confluence model and numerical calculation of groundwater is coupled to simulate the runoff process of Weihe river. The model validation was aiming at river flow rate and groundwater field. The results show that 65% of the abstracted shallow groundwater comes from the river water and the reduced amount of river baseflow by the groundwater abstraction is 122 million m3 per year, which is also validated by a water balance analysis of river links. The 50% reduction of shallow groundwater abstraction may lead to a recover of 3 m of the lowest groundwater level. The study provides a sound analysis tool to the integrated water resources and ecology management in the region.

scholarly journals Observational Evidence of Frontal-Scale Atmospheric Responses to Kuroshio Extension Variability

2015 ◽  
Vol 28 (23) ◽  
pp. 9459-9472 ◽  
Author(s):  
Yi-Hui Wang ◽  
W. Timothy Liu
Keyword(s):  
Kuroshio Extension ◽  
Linear Regression Analysis ◽  
Surface Wind ◽  
Reanalysis Data ◽  
Satellite Observations ◽  
Climate Index ◽  
Boreal Winter ◽  
Atmospheric Response ◽  
Free Atmosphere ◽  
Low Frequencies

Abstract This study investigates the regional atmospheric response to the Kuroshio Extension (KE) using a combination of multiple satellite observations and reanalysis data from boreal winter over a period of at least a decade. The goal is to understand the relationship between KE variations and atmospheric responses at low frequencies. A climate index is used to measure the interannual to decadal KE variability, which leaves remarkable imprints on the mesoscale sea surface temperature (SST). Clear spatial coherence between the SST signals and frontal-scale atmospheric variables, including surface wind convergence, vertical velocity, precipitation, and clouds, is identified by linear regression analysis. Consistent with previous studies, the penetrating effect of the KE variability on the free atmosphere is found. The westward tilt of the atmospheric response above the KE near 500 hPa is revealed. The difference in the associations of frontal-scale air temperature and geopotential height with the KE variability between the satellite observations and the reanalysis data suggests an imperfect interpretation of frontal-scale oceanic forcing on the overlying atmosphere in the reanalysis assimilation system.

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