Analysis of flooding potential with different return periods-A case study of Dianbao River in Kaohsiung City, Taiwan

2020 ◽  
Author(s):  
Tien-Hsiang Hsieh ◽  
Wen-Cheng Liu
Keyword(s):  
Error Analysis ◽  
Extreme Rainfall ◽  
Economic Losses ◽  
Return Periods ◽  
Rainfall Runoff ◽  
Time To Peak ◽  
Water Catchment ◽  
Typhoon Event ◽  
Kaohsiung City ◽  
2D Model

<p>　　In Taiwan, when the rainy season comes, the extreme rainfall and typhoon events cause floods and economic losses in the middle and lower reaches, which impacts on the safety of people's lives. In this study, we took Dianbao River in Kaohsiung City as an example and simulated the rainfall-runoff in the upstream water catchment area based on the HEC-HMS model and used its results as the flow input condition of the FLO-2D model. The two models were validated by the Kongrey typhoon event in 2013 and the Megi typhoon event in 2016. In terms of upstream watershed, the analysis results of the HEC-HMS rainfall-runoff errors for the Kongrey typhoon and the Megi typhoon were as follows: percent errors of peak discharge (EQ<sub>P</sub>) were 0.6% and 4.6%, respectively; errors of time to peak (ET<sub>P</sub>) were 0 hour and 2 hours, respectively; coefficients of efficiency (CE) were 0.89 and 0.91, respectively. In the Dianbao River, the FLO-2D model error analysis results of Kongrey typhoon and Megi typhoon events were as follows: percent errors of peak water level (EW<sub>P</sub>) were 13.51% and 4.71%, respectively; errors of time to peak (ET<sub>P</sub>) were 1 hour and 0 hour, respectively; coefficients of efficiency (CE) were 0.69 and 0.79, respectively. The simulation and validation of the two typhoon-inundated areas were reasonable and then the model was applied to explore the flood potential of the Dianbao River during different flood return periods.</p><p><strong>Keywords</strong><strong>：</strong><strong>HEC-HMS</strong><strong>、</strong><strong>FLO-2D</strong><strong>、</strong><strong>rainfall-runoff</strong><strong>、</strong><strong>error analysis</strong><strong>、</strong><strong>flooding potential</strong></p>

scholarly journals Numerical simulation of runoff from extreme rainfall events in a mountain water catchment

2002 ◽  
Vol 2 (1/2) ◽  
pp. 109-117 ◽  
Author(s):  
J. Burguete ◽  
P. García-Navarro ◽  
R. Aliod
Keyword(s):  
Extreme Rainfall ◽  
Flood Mitigation ◽  
Mitigation Measures ◽  
Rainfall Runoff ◽  
Shallow Water Flow ◽  
Extreme Rainfall Events ◽  
Small Reservoir ◽  
Rainfall Events ◽  
Water Catchment

Abstract. A numerical model for unsteady shallow water flow over initially dry areas is applied to a case study in a small drainage area at the Spanish Ebro River basin. Several flood mitigation measures (reforestation, construction of a small reservoir and channelization) are simulated in the model in order to compare different extreme rainfall-runoff scenarios.

scholarly journals Estimation of the effects of climate change on flood-triggered economic losses in Japan

2013 ◽  
Vol 1 (2) ◽  
pp. 1619-1649 ◽  
Author(s):  
S. Tezuka ◽  
H. Takiguchi ◽  
S. Kazama ◽  
R. Sarukkalige ◽  
A. Sato ◽  
...  
Keyword(s):  
Climate Change ◽  
Extreme Rainfall ◽  
Economic Loss ◽  
Flood Damage ◽  
Economic Losses ◽  
Return Periods ◽  
Climate Data ◽  
Rainfall Analysis ◽  
Kagoshima Prefecture ◽  
The Relationship

Abstract. This study evaluates the effects of climate change on economic losses due to flood-related damage in Japan. Three selected GCM climate data were downscaled using an analytical method that uses observed precipitation data as the reference resolution. The downscaled climate data were used to estimate extreme rainfall for different return periods. The extreme rainfall estimates were then entered into a two-dimensional (2-D) non-uniform flow model to estimate flood inundation information. A novel technique based on the land use type of the flood area was employed to estimate economic losses due to flood damage. The results of the rainfall analysis shows that at present (in 2000), the Nankai region, the area from Wakayama Prefecture to Kagoshima Prefecture and the mountains of the Japan Alps receive very high extreme rainfall. By 2050, in addition to these areas, the rainfall in the Tokai and Koshinetsu regions will be 1.2 to 1.3 times greater than at present. The flood-related economic loss estimation shows that the relationship between increased extreme rainfall and increased potential economic loss due to flood damage has a nearly linear relationship. The overall variations show that the potential economic loss is greater for the SRES-B1, A2 and A1B scenarios for all return periods. These results clearly show that flood-related economic losses in Japan will increase significantly in the future as a result of climate change.

Extreme Rainfall Events in the Hawaiian Islands

2009 ◽  
Vol 48 (3) ◽  
pp. 502-516 ◽  
Author(s):  
Pao-Shin Chu ◽  
Xin Zhao ◽  
Ying Ruan ◽  
Melodie Grubbs
Keyword(s):  
Return Period ◽  
Heavy Rainfall ◽  
Hawaiian Islands ◽  
Daily Rainfall ◽  
Extreme Rainfall ◽  
Generalized Extreme Value Distribution ◽  
Economic Losses ◽  
Return Periods ◽  
Extreme Rainfall Events ◽  
Rainfall Events

Abstract Heavy rainfall and the associated floods occur frequently in the Hawaiian Islands and have caused huge economic losses as well as social problems. Extreme rainfall events in this study are defined by three different methods based on 1) the mean annual number of days on which 24-h accumulation exceeds a given daily rainfall amount, 2) the value associated with a specific daily rainfall percentile, and 3) the annual maximum daily rainfall values associated with a specific return period. For estimating the statistics of return periods, the three-parameter generalized extreme value distribution is fit using the method of L-moments. Spatial patterns of heavy and very heavy rainfall events across the islands are mapped separately based on the aforementioned three methods. Among all islands, the pattern on the island of Hawaii is most distinguishable, with a high frequency of events along the eastern slopes of Mauna Kea and a low frequency of events on the western portion so that a sharp gradient in extreme events from east to west is prominent. On other islands, extreme rainfall events tend to occur locally, mainly on the windward slopes. A case is presented for estimating return periods given different rainfall intensity for a station in Upper Manoa, Oahu. For the Halloween flood in 2004, the estimated return period is approximately 27 yr, and its true value should be no less than 13 yr with 95% confidence as determined from the adjusted bootstrap resampling technique.

scholarly journals Multi-Objective Model-Based Assessment of Green-Grey Infrastructures for Urban Flood Mitigation

Hydrology ◽  
2021 ◽  
Vol 8 (3) ◽  
pp. 110
Author(s):  
Carlos Martínez ◽  
Zoran Vojinovic ◽  
Arlex Sanchez
Keyword(s):  
Green Infrastructure ◽  
Overland Flow ◽  
Flood Damage ◽  
Optimal Number ◽  
Rainfall Runoff ◽  
Urban Catchment ◽  
Model Based ◽  
Model Domain ◽  
Infiltration Processes ◽  
2D Model

This paper presents the performance quantification of different green-grey infrastructures, including rainfall-runoff and infiltration processes, on the overland flow and its connection with a sewer system. The present study suggests three main components to form the structure of the proposed model-based assessment. The first two components provide the optimal number of green infrastructure (GI) practices allocated in an urban catchment and optimal grey infrastructures, such as pipe and storage tank sizing. The third component evaluates selected combined green-grey infrastructures based on rainfall-runoff and infiltration computation in a 2D model domain. This framework was applied in an urban catchment in Dhaka City (Bangladesh) where different green-grey infrastructures were evaluated in relation to flood damage and investment costs. These practices implemented separately have an impact on the reduction of damage and investment costs. However, their combination has been shown to be the best action to follow. Finally, it was proved that including rainfall-runoff and infiltration processes, along with the representation of GI within a 2D model domain, enhances the analysis of the optimal combination of infrastructures, which in turn allows the drainage system to be assessed holistically.

scholarly journals A Spatial Improved-kNN-Based Flood Inundation Risk Framework for Urban Tourism under Two Rainfall Scenarios

2021 ◽  
Vol 13 (5) ◽  
pp. 2859
Author(s):  
Shuang Liu ◽  
Rui Liu ◽  
Nengzhi Tan
Keyword(s):  
Nearest Neighbor ◽  
Scientific Information ◽  
Climate Extremes ◽  
Extreme Rainfall ◽  
Tourism Industry ◽  
Urban Tourism ◽  
Evaluation Framework ◽  
Economic Losses ◽  
Flood Inundation ◽  
K Nearest Neighbor

Urban tourism has been suffering socio-economic challenges from flood inundation risk (FIR) triggered by extraordinary rainfall under climate extremes. The evaluation of FIR is essential for mitigating economic losses, and even casualties. This study proposes an innovative spatial framework integrating improved k-nearest neighbor (kNN), remote sensing (RS), and geographic information system (GIS) to analyze FIR for tourism sites. Shanghai, China, was selected as a case study. Tempo-spatial factors, including climate, topography, drainage, vegetation, and soil, were selected to generate several flood-related gridded indicators as inputs into the evaluation framework. A likelihood of FIR was mapped to represent possible inundation for tourist sites under a moderate-heavy rainfall scenario and extreme rainfall scenario. The resultant map was verified by the maximum inundation extent merged by RS images and water bodies. The evaluation outcomes deliver the baseline and scientific information for urban planners and policymakers to take cost-effective measures for decreasing and evading the pressure of FIR on the sustainable development of urban tourism. The spatial improved-kNN-based framework provides an innovative, effective, and easy-to-use approach to evaluate the risk for the tourism industry under climate change.

scholarly journals Derivation of S-Curve from Oscillatory Hydrograph Using Digital Filter

Water ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1456
Author(s):  
Kee-Won Seong ◽  
Jang Hyun Sung
Keyword(s):  
Digital Filter ◽  
Model Performance ◽  
Performance Criteria ◽  
Rainfall Runoff ◽  
Small Watershed ◽  
Unit Hydrograph ◽  
Time To Peak ◽  
S Curve ◽  
And Performance ◽  
Smooth Data

An oscillatory S-curve causes unexpected fluctuations in a unit hydrograph (UH) of desired duration or an instantaneous UH (IUH) that may affect the constraints for hydrologic stability. On the other hand, the Savitzky–Golay smoothing and differentiation filter (SG filter) is a digital filter known to smooth data without distorting the signal tendency. The present study proposes a method based on the SG filter to cope with oscillatory S-curves. Compared to previous conventional methods, the application of the SG filter to an S-curve was shown to drastically reduce the oscillation problems on the UH and IUH. In this method, the SG filter parameters are selected to give the minimum influence on smoothing and differentiation. Based on runoff reproduction results and performance criteria, it appears that the SG filter performed both smoothing and differentiation without the remarkable variation of hydrograph properties such as peak or time-to peak. The IUH, UH, and S-curve were estimated using storm data from two watersheds. The reproduced runoffs showed high levels of model performance criteria. In addition, the analyses of two other watersheds revealed that small watershed areas may experience scale problems. The proposed method is believed to be valuable when error-prone data are involved in analyzing the linear rainfall–runoff relationship.

scholarly journals A comparative survey of the impacts of extreme rainfall in two international case studies

2017 ◽  
Author(s):  
Matthieu Spekkers ◽  
Viktor Rözer ◽  
Annegret Thieken ◽  
Marie-Claire ten Veldhuis ◽  
Heidi Kreibich
Keyword(s):  
Case Studies ◽  
Online Survey ◽  
Residential Buildings ◽  
Age Groups ◽  
Extreme Rainfall ◽  
Water Levels ◽  
Economic Losses ◽  
Biased Sampling ◽  
Wide Range ◽  
Damage Data

Abstract. Flooding is assessed as the most important natural hazard in Europe, causing thousands of deaths, affecting millions of people and accounting for large economic losses in the past decade. Little is known about the damage processes associated with extreme rainfall in cities, due to a lack of accurate, comparable and consistent damage data. The objective of this study is to investigate the impacts of extreme rainfall on residential buildings and how affected households coped with these impacts in terms of precautionary and emergency actions. Analyses are based on a unique dataset of damage characteristics and a wide range of potential damage explaining variables at the household level, collected through computer-aided telephone interviews (CATI) and an online survey. Exploratory data analyses based on a total of 859 completed questionnaires in the cities of Münster (Germany) and Amsterdam (the Netherlands) revealed that the uptake of emergency measures is related to characteristics of the hazardous event. In case of high water levels, more efforts are made to reduce damage, while emergency response that aims to prevent damage is less likely to be effective. The difference in magnitude of the events in Münster and Amsterdam in terms of rainfall intensity and water depth, is probably also the most important cause for the differences between the cities in terms of the suffered financial losses. Factors that significantly contributed to damage in at least one of the case studies are water contamination, the presence of a basement in the building and people's awareness of the upcoming event. Moreover, this study confirms conclusions by previous studies that people's experience with damaging events positively correlates with precautionary behaviour. For improving future damage data acquisition, we recommend to include cell-phones in a CATI survey to avoid biased sampling towards certain age groups.

scholarly journals Rainfall-runoff relationships at event scale in western Mediterranean ephemeral streams

2021 ◽  
Author(s):  
Roberto Serrano-Notivoli ◽  
Alberto Martínez-Salvador ◽  
Rafael García-Lorenzo ◽  
David Espín-Sánchez ◽  
Carmelo Conesa-García
Keyword(s):  
Western Mediterranean ◽  
Additive Models ◽  
Future Climate Change ◽  
Ephemeral Streams ◽  
Return Periods ◽  
Rainfall Runoff ◽  
Event Scale ◽  
Rainfall Events ◽  
Flow Generation ◽  
Terrain Characteristics

Abstract. Ephemeral streams are highly dependent on rainfall and terrain characteristics and, therefore, very sensitive to minor changes in these environments. Western Mediterranean area exhibits a highly irregular precipitation regime with a great variety of rainfall events driving the flow generation on intermittent watercourses, and future climate change scenarios depict a lower magnitude and higher intensity of precipitation in this area, potentially leading to severe changes in flows. We explored the rainfall-runoff relationships in two semiarid watersheds in southern Spain (Algeciras and Upper Mula) to model the different types of rainfall events required to generate new flow in both intermittent streams. We used a nonlinear approach through Generalized Additive Models at event scale in terms of magnitude, duration, and intensity, contextualizing resulting thresholds in a long-term perspective through the calculation of return periods. Results showed that the average ~ 1.2-day and <1.5 mm event was not enough to create new flows. At least a 4-day event ranging from 4 to 20 mm, depending on the watershed was needed to ensure new flow at a high probability (95 %). While these thresholds represented low return periods (from 4 to 10 years), the great irregularity of annual precipitation and rainfall characteristics, makes prediction highly uncertain. Almost a third part of the rainfall events resulted in similar or lower flow than previous day, emphasizing the importance of lithological and terrain characteristics that lead to differences in flow generation between the watersheds.

scholarly journals Climate and hydrological variability: the catchment filtering role

2015 ◽  
Vol 19 (1) ◽  
pp. 379-387 ◽  
Author(s):  
I. Andrés-Doménech ◽  
R. García-Bartual ◽  
A. Montanari ◽  
J. B. Marco
Keyword(s):  
Climate Change ◽  
Climate Variability ◽  
Peak Flow ◽  
Flood Frequency ◽  
Annual Maximum ◽  
Return Periods ◽  
Rainfall Runoff ◽  
Maximum Peak ◽  
Hydrological Variability ◽  
The Impact

Abstract. Measuring the impact of climate change on flood frequency is a complex and controversial task. Identifying hydrological changes is difficult given the factors, other than climate variability, which lead to significant variations in runoff series. The catchment filtering role is often overlooked and thus may hinder the correct identification of climate variability signatures on hydrological processes. Does climate variability necessarily imply hydrological variability? This research aims to analytically derive the flood frequency distribution based on realistic hypotheses about the rainfall process and the rainfall–runoff transformation. The annual maximum peak flow probability distribution is analytically derived to quantify the filtering effect of the rainfall–runoff process on climate change. A sensitivity analysis is performed according to typical semi-arid Mediterranean climatic and hydrological conditions, assuming a simple but common scheme for the rainfall–runoff transformation in small-size ungauged catchments, i.e. the CN-SCS model. Variability in annual maximum peak flows and its statistical significance are analysed when changes in the climatic input are introduced. Results show that depending on changes in the annual number of rainfall events, the catchment filtering role is particularly significant, especially when the event rainfall volume distribution is not strongly skewed. Results largely depend on the return period: for large return periods, peak flow variability is significantly affected by the climatic input, while for lower return periods, infiltration processes smooth out the impact of climate change.

Testing the impacts of wildfire on hydrological and sediment response using the OpenLISEM model

2021 ◽  
Author(s):  
Jinfeng Wu ◽  
João Pedro Nunes ◽  
Jantiene E. M. Baartman
Keyword(s):  
Water Discharge ◽  
Extreme Rainfall ◽  
Fire Occurrence ◽  
Return Periods ◽  
Extreme Rainfall Events ◽  
Rainfall Events ◽  
Erosion Risk ◽  
Sediment Yields ◽  
Splash Erosion ◽  
Event Based

&lt;p&gt;Wildfires have become a major concern to society in recent decades because increases in the number and severity of wildfires have negative effects on soil and water resources, especially in headwater areas. Models are typically applied to estimate the potential adverse effects of fire. However, few modeling studies have been conducted for meso-scale catchments, and only a fraction of these studies include transport and deposition of eroded material within the catchment or represent spatial erosion patterns. In this study, we firstly designed the procedure of event-based automatic calibration using PEST, parameters ensemble, and jack-knife cross-validation that is suitable for event-based OpenLISEM calibration and validation, especially in data-scarce burned areas. The calibrated and validated OpenLISEM proved capable of providing reasonable accurate predictions of hydrological responses and sediment yields in this burned catchment. Then the model was applied with design storms of six different return periods (0.2, 0.5, 1, 2, 5, and 10 years) to simulate and evaluate pre- and post-wildfire hydrological and erosion responses at the catchment scale. Our results show rainfall amount and intensity play a more important role than fire occurrence in the catchment water discharge and sediment yields, while fire occurrence is regarded as an important factor for peak water discharge, indicating that high post-fire hydro-sedimentary responses are frequently related to extreme rainfall events. The results also suggest a partial shift from flow to splash erosion after fire, especially for higher return periods, explained by a combination of higher splash erosion in burnt upstream areas with a limited sediment transport capacity of surface runoff, preventing flow erosion in downstream areas. In consequence, the pre-fire erosion risk in the croplands of this catchment is partly shifted to a post-fire erosion risk in upper slope forest and natural areas, especially for storms with lower return periods, although erosion risks in croplands are important both before and after fires. This is relevant, as a shift of sediment sources to burnt areas might lead to downstream contamination even if sediment yields remain small. These findings have significant implications to identify areas for post-wildfire stabilization and rehabilitation, which is particularly important given the predicted increase in the occurrence of fires and extreme rainfall events with climate change.&lt;/p&gt;

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