scholarly journals Urban Flood Analysis in Ungauged Drainage Basin Using Short-Term and High-Resolution Remotely Sensed Rainfall Records

2021 ◽  
Vol 13 (11) ◽  
pp. 2204
Author(s):  
Zhihua Zhu ◽  
Yueying Yang ◽  
Yanpeng Cai ◽  
Zhifeng Yang
Keyword(s):  
Return Period ◽  
Urban Areas ◽  
Drainage Basin ◽  
Remotely Sensed ◽  
Return Periods ◽  
Modeling Framework ◽  
Urban Flood ◽  
Extreme Rainfall Events ◽  
Design Rainfall ◽  
Flood Analysis

Analyzing flooding in urban areas is a great challenge due to the lack of long-term rainfall records. This study hereby seeks to propose a modeling framework for urban flood analysis in ungauged drainage basins. A platform called “RainyDay” combined with a nine-year record of hourly, 0.1° remotely sensed rainfall data are used to generate extreme rainfall events. These events are used as inputs to a hydrological model. The comprehensive characteristics of urban flooding are reflected through the projection pursuit method. We simulate runoff for different return periods for a typical urban drainage basin. The combination of RainyDay and short-record remotely sensed rainfall can reproduce recent observed rainfall frequencies, which are relatively close to the design rainfall calculated by the intensity-duration-frequency formula. More specifically, the design rainfall is closer at high (higher than 20-yr) return period or long duration (longer than 6 h). Contrasting with the flood-simulated results under different return periods, RainyDay-based estimates may underestimate the flood characteristics under low return period or short duration scenarios, but they can reflect the characteristics with increasing duration or return period. The proposed modeling framework provides an alternative way to estimate the ensemble spread of rainfall and flood estimates rather than a single estimate value.

scholarly journals Modelling and assessment of urban flood hazards based on rainfall intensity-duration-frequency curves reformation

2016 ◽  
Author(s):  
Reza Ghazavi ◽  
Ali Moafi Rabori ◽  
Mohsen Ahadnejad Reveshty
Keyword(s):  
Return Period ◽  
Urban Areas ◽  
Rainfall Intensity ◽  
Flood Hazards ◽  
Return Periods ◽  
Urban Flood ◽  
Design Storm ◽  
Hourly Rainfall ◽  
Idf Curves ◽  
Intensity Duration Frequency

Abstract. Estimate design storm based on rainfall intensity–duration–frequency (IDF) curves is an important parameter for hydrologic planning of urban areas. The main aim of this study was to estimate rainfall intensities of Zanjan city watershed based on overall relationship of rainfall IDF curves and appropriate model of hourly rainfall estimation (Sherman method, Ghahreman and Abkhezr method). Hydrologic and hydraulic impacts of rainfall IDF curves change in flood properties was evaluated via Stormwater Management Model (SWMM). The accuracy of model simulations was confirmed based on the results of calibration. Design hyetographs in different return periods show that estimated rainfall depth via Sherman method are greater than other method except for 2-year return period. According to Ghahreman and Abkhezr method, decrease of runoff peak was 30, 39, 41 and 42 percent for 5-10-20 and 50-year return periods respectively, while runoff peak for 2-year return period was increased by 20 percent.

scholarly journals A paradigm of extreme rainfall pluvial floods in complex urban areas: the flood event of 15 July 2020 in Palermo (Italy)

2021 ◽  
Author(s):  
Antonio Francipane ◽  
Dario Pumo ◽  
Marco Sinagra ◽  
Goffredo La Loggia ◽  
Leonardo V. Noto
Keyword(s):  
Urban Areas ◽  
Extreme Rainfall ◽  
Mediterranean Area ◽  
Progressive Increase ◽  
Urban Context ◽  
Modeling Framework ◽  
Urban Flood ◽  
Extreme Rainfall Events ◽  
Natural Systems ◽  
The Mediterranean

Abstract. In the last years, some regions of the Mediterranean area are witnessing a progressive increase in extreme events, such as urban and flash floods, as a response to the increasingly frequent and severe extreme rainfall events and their ground effects, which are often exacerbated by ever-growing urbanization. In such a context, the traditional defense of urban areas, which are usually based on urban drainage systems designed without regard to the impacts of urbanization and climate change on natural systems, may not be sufficient to deal with the risk deriving from the occurrence of such events. This study focuses on a very recent and particularly intense urban flood that occurred in Palermo on 15 July 2020 that represents a perfect example of extreme rainfall pluvial floods in a complex urban area that many cities, especially in the Mediterranean region, have been experiencing in recent years. A conceptual hydrological model and a 2D hydraulic model, particularly suitable for simulations in a very complex urban context, have been used to simulate the event. Results have been qualitatively validated by means of crowdsourced information and satellite images. The experience of Palermo, which has highlighted the urgent need for a shift in the way of managing stormwater in urban settlements, can be assumed as a paradigm of management of extreme rainfall pluvial floods in complex urban areas. Although the approaches and the related policies cannot be identical for all cities, the modeling framework here used to assess the impacts of the event under study and some conclusive remarks could be easily transferred to other and different urban contexts.

scholarly journals A paradigm of extreme rainfall pluvial floods in complex urban areas: the flood event of 15 July 2020 in Palermo (Italy)

2021 ◽  
Vol 21 (8) ◽  
pp. 2563-2580
Author(s):  
Antonio Francipane ◽  
Dario Pumo ◽  
Marco Sinagra ◽  
Goffredo La Loggia ◽  
Leonardo Valerio Noto
Keyword(s):  
Urban Areas ◽  
Extreme Rainfall ◽  
Mediterranean Area ◽  
Progressive Increase ◽  
Urban Context ◽  
Modeling Framework ◽  
Urban Flood ◽  
Extreme Rainfall Events ◽  
Urban Settlements ◽  
The Mediterranean

Abstract. In the last few years, some regions of the Mediterranean area have witnessed a progressive increase in extreme events, such as urban and flash floods, as a response to the increasingly frequent and severe extreme rainfall events, which are often exacerbated by the ever-growing urbanization. In such a context, the urban drainage systems may not be sufficient to convey the rainwater, thus increasing the risk deriving from the occurrence of such events. This study focuses on a particularly intense urban flood that occurred in Palermo (Italy) on 15 July 2020; it represents a typical pluvial flood due to extreme rainfall on a complex urban area that many cities have experienced in recent years, especially in the Mediterranean region. A conceptual hydrological model and a 2D hydraulic model, particularly suitable for simulations in a very complex urban context, have been used to simulate the event. Results have been qualitatively validated by means of crowdsourced information and satellite images. The experience of Palermo, which has highlighted the urgent need for a shift in the way stormwater in urban settlements is managed, can be assumed to be a paradigm for modeling pluvial floods in complex urban areas under extreme rainfall conditions. Although the approaches and the related policies cannot be identical for all cities, the modeling framework used here to assess the impacts of the event under study and some conclusive remarks could be easily transferred to other, different urban contexts.

Flood analysis in mixed-urban areas reflecting interactions with the complete water cycle through coupled hydrologic-hydraulic modelling

2010 ◽  
Vol 62 (6) ◽  
pp. 1386-1392 ◽  
Author(s):  
N. D. Sto. Domingo ◽  
A. Refsgaard ◽  
O. Mark ◽  
B. Paludan
Keyword(s):  
Urban Areas ◽  
Overland Flow ◽  
Computer Modelling ◽  
Water Cycle ◽  
New Method ◽  
Urban Flood ◽  
Flood Modelling ◽  
Essential Components ◽  
Flood Analysis ◽  
Urban Flood Modelling

The potential devastating effects of urban flooding have given high importance to thorough understanding and management of water movement within catchments, and computer modelling tools have found widespread use for this purpose. The state-of-the-art in urban flood modelling is the use of a coupled 1D pipe and 2D overland flow model to simultaneously represent pipe and surface flows. This method has been found to be accurate for highly paved areas, but inappropriate when land hydrology is important. The objectives of this study are to introduce a new urban flood modelling procedure that is able to reflect system interactions with hydrology, verify that the new procedure operates well, and underline the importance of considering the complete water cycle in urban flood analysis. A physically-based and distributed hydrological model was linked to a drainage network model for urban flood analysis, and the essential components and concepts used were described in this study. The procedure was then applied to a catchment previously modelled with the traditional 1D-2D procedure to determine if the new method performs similarly well. Then, results from applying the new method in a mixed-urban area were analyzed to determine how important hydrologic contributions are to flooding in the area.

scholarly journals Risk Assessment of Urban Floods Based on a SWMM-MIKE21-Coupled Model Using GF-2 Data

2021 ◽  
Vol 13 (21) ◽  
pp. 4381
Author(s):  
Lidong Zhao ◽  
Ting Zhang ◽  
Jun Fu ◽  
Jianzhu Li ◽  
Zhengxiong Cao ◽  
...  
Keyword(s):  
Risk Assessment ◽  
Return Period ◽  
Flood Risk ◽  
Global Climate ◽  
Total Loss ◽  
Return Periods ◽  
Rapid Urbanization ◽  
Urban Floods ◽  
Urban Flood ◽  
Inundation Depth

Global climate change and rapid urbanization have caused increases in urban floods. Urban flood risk assessment is a vital method for preventing and controlling such disasters. This paper takes the central region of Cangzhou city in Hebei Province as an example. Detailed topographical information, such as the buildings and roads in the study area, was extracted from GF-2 data. By coupling the two models, the SWMM and MIKE21, the spatial distribution of the inundation region, and the water depth in the study area under different return periods, were simulated in detail. The results showed that, for the different return periods, the inundation region was generally consistent. However, there was a large increase in the mean inundation depth within a 10-to-30-year return period, and the increase in the maximum inundation depth and inundation area remained steady. The comprehensive runoff coefficient in all of the scenarios exceeded 0.8, indicating that the drainage system in the study area is insufficient and has a higher flood risk. The flood risk of the study area was evaluated based on the damage curve, which was obtained from field investigations. The results demonstrate that the loss per unit area was less than CNY 250/m2 in each return period in the majority of the damaged areas. Additionally, the total loss was mainly influenced by the damaged area, but, in commercial areas, the total loss was highly sensitive to the inundation depth.

scholarly journals Case Study of Urban Flood Inundation—Impact of Temporal Variability in Rainfall Events

Water ◽  
2021 ◽  
Vol 13 (23) ◽  
pp. 3438
Author(s):  
Ting Li ◽  
Gyuwon Lee ◽  
Gwangseob Kim
Keyword(s):  
Drainage Basin ◽  
Temporal Distribution ◽  
Extreme Rainfall ◽  
Exceedance Probability ◽  
Distribution Characteristics ◽  
Drainage Basins ◽  
Urban Flood ◽  
Extreme Rainfall Events ◽  
Rainfall Events ◽  
Storm Water Management Model

This study aimed to calculate and analyze total overflows that accumulate in urban manholes in the target drainage basin of Samsung-dong, Seoul in heavy rainfall events with different temporal distribution characteristics, using the EPA’s Storm Water Management Model (EPA-SWMM model). Inundation behaviors were analyzed using the two-dimensional flood model (FLO-2D). The extreme rainfall events were produced using different exceedance probability Huff distributions for different durations and return periods, such as from 1 to 3 h and 10 years, 50 years, 80 years, 100 years, respectively. The inundation model was validated using the actual flood observations on 21 September 2010 in the Samsung-dong drainage basin. The total overflow amount showed considerable differences according to the different time distribution characteristics, such as the temporal location of the storm peak and the concentration level of the storm. Furthermore, the inundation behaviors were also related to the temporal characteristics of storms. The results illustrated that the consideration of the temporal distribution characteristics of extreme rainfall events is essential for an accurate understanding of the rainfall–runoff response and inundation behavior in urban drainage basins.

scholarly journals Return period assessment of urban pluvial floods through modelling of rainfall–flood response

2018 ◽  
Vol 20 (4) ◽  
pp. 829-845 ◽  
Author(s):  
Damian Murla Tuyls ◽  
Søren Thorndahl ◽  
Michael R. Rasmussen
Keyword(s):  
Return Period ◽  
Urban Areas ◽  
Urban Drainage ◽  
Return Periods ◽  
Drainage Systems ◽  
Flood Impacts ◽  
Urban Drainage Systems ◽  
Flood Estimation ◽  
Flood Response ◽  
The Impact

Abstract Intense rainfall in urban areas can often generate severe flood impacts. Consequently, it is crucial to design systems to minimize potential flood damages. Traditional, simple design of urban drainage systems assumes agreement between rainfall return period and its consequent flood return period; however, this does not always apply. Hydraulic infrastructures found in urban drainage systems can increase system heterogeneity and perturb the impact of severe rainfall response. In this study, a surface flood return period assessment was carried out at Lystrup (Denmark), which has received the impact of flooding in recent years. A 35 years' rainfall dataset together with a coupled 1D/2D surface and network model was used to analyse and assess flood return period response. Results show an ambiguous relation between rainfall and flood return periods indicating that linear rainfall–runoff relationships will, for the analysed case study, be insufficient for flood estimation. Simulation-based mapping of return periods for flood area and volume has been suggested, and moreover, a novel approach has been developed to map local flood response time and relate this to rainfall characteristics. This approach allows to carefully analyse rainfall impacts and flooding response for a correct flood return period assessment in urban areas.

scholarly journals Urban Flood Control in Sringin Catchment, Semarang City, Central Java Province, Indonesia

2018 ◽  
Vol 4 (2) ◽  
pp. 191
Author(s):  
Ngo Pheaktra ◽  
Istiarto Istiarto ◽  
Rachmad Jayadi
Keyword(s):  
Return Period ◽  
Flood Control ◽  
Flow Analysis ◽  
Drainage System ◽  
Urban Flood ◽  
Central Java ◽  
Design Rainfall ◽  
Prone Area ◽  
Lowland Area ◽  
Flood Prone Area

Sringin is the lowland area located in Semarang city which has been vulnerable to rob flooding from the Java Sea along with flood triggered by the intense amount of rainfall. The case study will further discuss the hydrological analysis, transformation of rational method into flow hydrograph with the design rainfall of 25-year return period, and unsteady flow analysis by HEC-RAS 5.0.3 under existing condition and design condition. The result shows that the design rainfall of 25-year return period measures 173 mm in vertical length and data collected from the office of public work, Semarang city can be used to implement the design scenario with normalization of drainage system and the increase of levee with the freeboard up to 0.75 m is proved to be the solution to the flood inundation in that flood-prone area while the flood under existing condition has caused excessive discharge at downstream up to 9 hours.

scholarly journals Impact of Extreme Rainfall on Flood Hydrographs

2021 ◽  
Vol 884 (1) ◽  
pp. 012018
Author(s):  
I G Tunas ◽  
H Azikin ◽  
G M Oka
Keyword(s):  
Return Period ◽  
Extreme Events ◽  
Daily Rainfall ◽  
Extreme Rainfall ◽  
Rainfall Data ◽  
Return Periods ◽  
Daily Rainfall Data ◽  
Design Rainfall ◽  
Flood Hydrograph ◽  
Maximum Daily Rainfall

Abstract Extreme rainfall is the main factor triggering flooding in various regions of the world including Indonesia. The increase in intensity and duration of current extreme rainfall is predicted as a result of global climate change. This paper aims to analyze the impact of extreme rainfall to the peak discharge of flood hydrographs at a watershed outlet in Palu, Sulawesi, Indonesia. Maximum daily rainfall data for the period 1990-1999 recorded at the Palu Meteorological Station, Central Sulawesi were selected using the Annual Maximum Series Method, and grouped into two types. Type I is the maximum daily rainfall data with extreme events and Type II is the maximum daily rainfall data without extreme events. Frequency analysis was applied to the two data groups using the best distribution method of: Normal, Normal Log, Pearson III Log, and Gumbel to obtain the design rainfall of each data group. In the next stage, the design rainfall transformation into a flood hydrograph is performed using the Nakayasu Synthetic Unit Hydrograph based on a number of return periods in one of the rivers flowing into Palu Bay, namely the Poboya River. The analysis results show that the design rainfall graphs with both extreme rainfall and without extreme rainfall are identical at the low return period and divergent at the high return period with a difference of up to 21.6% at the 1000-year return period. Correspondingly, extreme rainfall has a greater impact at the peak of the flood hydrograph with increasing return periods ranging from -1.28% to 26.81% over the entire return period.

Estimation of Extreme Rainfall in South Africa and Development of Methods to Account for Non-stationary Climate Data

2020 ◽  
Author(s):  
Katelyn Johnson ◽  
Jeff Smithers
Keyword(s):  
South Africa ◽  
Frequency Analysis ◽  
Return Period ◽  
Extreme Rainfall ◽  
Climate Data ◽  
Extreme Rainfall Events ◽  
Rainfall Events ◽  
New Approach ◽  
Design Rainfall ◽  
High Return

<p>The estimation of design rainfalls and design floods are required by engineers and hydrologists to design and quantify the risk of failure of hydraulic structures. Extreme design rainfall quantities such as high-return period rainfalls and the probable maximum precipitation (PMP) are needed to design high-hazard hydraulic structures. In South Africa, previous design rainfall estimates have been produced up to the 200 year return period. PMP estimates were last determined nearly 50 years ago based on only 30 years of data. Most studies on extreme rainfall reported are based on frequency analysis assuming stationary conditions. Previous studies in South Africa have assumed a stationary climate. However, the assumption of a stationary climate in rainfall and flood frequency analysis has been challenged owing to evidence of climate change. Recent literature indicates that the magnitude and frequency of extreme rainfall events has been changing and this is likely to continue in future. Hence, methods to account for trends in extreme rainfall events in a changing environment need to be developed. In addition, the concept of PMP, particularly as used for the design and safety evaluation of large dams in South Africa, is being challenged with the recommendation that high-return period design rainfalls be used in these assessments. The aims of this study are: (i) to estimate extreme design rainfall values, with a focus on return periods greater than 200 years, (ii) to update PMP estimates using updated data and modernised methods, and (iii) to account for non-stationary climate data in the estimation of these extreme rainfall events in South Africa. Frequency analysis using LH-moments, which more accurately fit the upper tail of distributions, have been used to estimate high-return period design rainfalls. Regular L-moments are shown to overestimate the extreme rainfall quantities when compared to LH-moments by giving undue favour to outliers. PMP estimates have been determined using a storm maximisation and transposition approach. Radial Basis Functions (RFBs) have been used to transpose PMP estimates to ungauged locations, producing PMPs for the entire country. Approximately 80 % of the new PMPs are greater than the previous estimates. This is probably due to the many limitations of the old approach and differences used in the new approach, indicating that the new approach undertaken in this study may provide improved estimates. The PMP represents the upper limit of extreme rainfall, however, comparisons of high-return period rainfalls to the PMP show that the PMP is sometimes exceeded by the high-return period rainfalls. To develop methods to estimate extreme design rainfall events in a non-stationary climate, this study explores the impacts of climate drivers, such as the Southern Oscillation Index (SOI), and changes in atmospheric variables, such as dew point temperature, on high-return period rainfalls and the PMP.</p>

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