Sewer System for Improving Flood Control in Tokyo: A Step towards a Return Period of 70 Years

1994 ◽  
Vol 29 (1-2) ◽  
pp. 303-310 ◽  
Author(s):  
Kazuyuki Higuchi ◽  
Masahiro Maeda ◽  
Yasuyuki Shintani
Keyword(s):  
Return Period ◽  
Flood Control ◽  
Rainfall Intensity ◽  
Runoff Coefficient ◽  
Large Drop ◽  
Construction Costs ◽  
Sewer System ◽  
Construction Period ◽  
Metropolitan Government ◽  
Under Construction

The Tokyo Metropolitan Government has planned future flood control for a rainfall intensity of 100 mm/hr, which corresponds to a return period of 70 years, and a runoff coefficient of 0.8. Considering that the realization of this plan requires a long construction period and high construction costs, the decision was made to proceed by stages. In the first stage, the improvement of the facilities will be based on a rainfall intensity of 75 mm/hr (presently 50 mm/hr), corresponding to a return period of 17 years, and a runoff coefficient of 0.8. In the next stage the facilities will be improved to accommodate a rainfall intensity of 100 mm/hr. In the Nakano and Suginami regions, which suffer frequently from flooding, the plan of improvement based on a rainfall intensity of 75 mm/hr is being implemented before other areas. This facility will be used as a storage sewer for the time being. The Wada-Yayoi Trunk Sewer, as a project of this plan, will have a diameter of 8 m and a 50 m earth cover. This trunk sewer will be constructed considering several constraints. To resolve these problems, hydraulic experiments as well as an inventory study have been carried out. A large drop shaft for the trunk sewer is under construction.

scholarly journals Predictive Performance Analysis of PDF – IDF Model Types Using Rainfall Observations from Fourteen Gauged Stations

2021 ◽  
pp. 125-143
Author(s):  
Ify L. Nwaogazie ◽  
M. G. Sam ◽  
A. O. David
Keyword(s):  
Return Period ◽  
Flood Control ◽  
Goodness Of Fit ◽  
Rainfall Intensity ◽  
Model Development ◽  
Predictive Performance ◽  
Specific Model ◽  
Data Set ◽  
Pearson Type ◽  
Significant Difference

The design of structures for flood mitigation depends on the adequate estimation of rainfall intensity over a given catchment which is achieved by the rainfall intensity duration frequency modelling. In this study, an extensive comparative analyses were carried out on the predictive performance of three PDF – IDF model types, namely: Gumbel Extreme Value Type 1 (GEVT – 1), Log-Pearson Type 3 (LPT – 3) and Normal Distribution (ND) in 14 selected cities in Southern Nigeria. This is to rank the order of best performance. The principle of general model development was adopted in which rainfall intensities at different durations and specified return periods were used as input data set. This is not same as return period specific model that involves rainfall intensities for various durations and a given return period. The predicted rainfall intensity values with the PDF – IDF model types indicate high goodness of fit (R2) and Mean Squared Errors (MSE) ranging from: (a) R2 = 0.875 – 0.992; MSE = 33.17 – 224.6 for GEVT – 1; (b) R2 = 0.849 – 0.990; MSE = 65.34 – 405.5 for LPT – 3 and (c) R2 = 0.839 – 0.992; MSE = 29.23 – 200.2 for ND. The comparative analysis of all the 42 general models (14 locations versus 3 model types) considered showed that the order of best performance is LPT – 3 1st, GEVT - 1 2nd and ND 3rd for each return period (10, 50 and 100 years). The Kruskal Wallis test of significance indicates that no significant difference exists in the predictive performance of the three General models across the board. This may be due to the fact that the fourteen locations of the study area are bordering with the Atlantic Ocean and seems to have similar climatology. These developed General models are recommended for the computation of intensities in the fourteen locations for the design of flood control structures; and the order of preference should be LPT – 3 > GEVT – 1 > ND.

scholarly journals PEMODELAN HIDROLOGI DENGAN MENGGUNAKAN WMS (WATERSHED MODELING SYSTEM), DAERAH KAJIAN DI DAS CILIWUNG HULU

2015 ◽  
Vol 16 (1) ◽  
pp. 1
Author(s):  
Destianingrum Ratna P ◽  
M. Bayu Rizky Prayoga ◽  
Ardila Yananto
Keyword(s):  
Water Resources ◽  
Return Period ◽  
Rainfall Intensity ◽  
Hydrological Cycle ◽  
Watershed Modeling ◽  
Peak Discharge ◽  
Main Stream ◽  
Runoff Coefficient ◽  
Hydrological Models ◽  
Stream Length

Intisari  Permasalahan sumberdaya air dari hari ke hari semakin memburuk, baik kualitas maupun kuantitas air. DAS sebagai wadah dari berbagai komponen biosfer yang saling berinteraksi memegang peranan yang penting dalam siklus hidrologi dan fungsi penyediaan air. Berbagai macam model hidrologi telah dikembangkan, Model-model tersebut bisa digunakan untuk memecahkan permasalahan sumberdaya air tersebut. Salah satu model yang bisa digunakan adalah model rasional yang terdapat dalam Waterhsed Modeling System (WMS). Tujuan dari penelitian ini adalah untuk melakukan ekstraksi karakteristik DAS dan mengestimasi nilai debit puncak DAS Ciliwung Hulu berdasarkan nilai curah hujan beberapa kala ulang dengan menggunakan Watershed Modelling System. Dari hasil penelitian didapatkan bahwa karakteristik DAS yang dapat diekstraksi dengan menggunakan WMS adalah luas DAS, panjang sungai utama, kemiringan DAS, dan kemiringan aliran  sungai. Nilai koefisien aliran permukaan DAS Ciliwung Hulu adalah sebesar  0,72. Nilai intensitas hujan untuk kala ulang 2 tahun sebesar 117 mm/jam, kala ulang 5 tahun sebesar 135 mm/jam, kala ulang 10 tahun sebesar 143 mm/jam, kala ulang 25 tahun sebesar 152 mm/jam, kala ulang 50 tahun sebesar 157 mm/jam, dan kala ulang 100 tahun sebesar 162 mm/jam. Untuk nilai estimasi debit puncak di DAS Ciliwung Hulu, untuk kala ulang 2 tahun sebesar 735, 588 m3/detik, untuk kala ulang 5 tahun sebesar 852,713 m3/detik, untuk kala ulang 10 tahun sebesar 904,363 m3/detik, untuk kala ulang 25 tahun sebesar 959,448 m3/detik, untuk kala ulang 50 tahun sebesar 992,448 m3/detik dan untuk kala ulang 100 tahun sebesar 1.023,313 m3/detik.Abstract  Water resources problems are getting worse from by the day, both the quality and quantity of water. Watershed as a container of various components of the interacting biosphere is playing an important role in the hydrological cycle and water supply functions. Various kinds of hydrological models have been developed. The models can be used to help solving the water resources problems. One of models that can be used are contained in Watershed Modeling System (WMS) is Rational Method. The purpose of this study was to perform the extraction of watershed characteristics and estimate the peak discharge in Ciliwung Hulu Watershed based on the value of rainfall in some return period by using the Watershed Modeling System. The results of study show that the characteristics of the watershed that can be extracted by using WMS are watershed area, main stream length, the slope of the watershed, and the slope of the river. Runoff coefficient value of Ciliwung Hulu Watershed is 0,72. Rainfall intensity value for 2-year return period is 117 mm/h, when the 5-year return period is 135 mm/h, when the 10-year return period is 143 mm/h, when the 25-year return period is 152 mm/h, when the 50-year return periods 157 mm/h, and when 100-year return period is 162 mm/hour. For the estimated value of the peak discharge in Ciliwung Hulu watershed for 2-year return period amounted to 735,588 m3/sec, for 5-year return period amounted to 852,713 m3/sec, for a 10-year return period amounted to 904,363 m3/sec, for a 25 year return period amounted to 959,448 m3/sec, for 50-year return period amounted to 992,448 m3/sec and for 100 years return period amounted to 1023,313 m3/sec.

scholarly journals Study on the Classification of Urban Waterlogging Rainstorms and Rainfall Thresholds in Cities Lacking Actual Data

Water ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 3328
Author(s):  
Bingyan Ma ◽  
Zening Wu ◽  
Huiliang Wang ◽  
Yuan Guo
Keyword(s):  
Return Period ◽  
Flood Control ◽  
Rainfall Intensity ◽  
Influencing Factor ◽  
Extreme Rainfall ◽  
Observation Data ◽  
Urban Flood ◽  
Storm Water Management Model ◽  
Different Characteristics

Extreme rainfall is the main influencing factor of urban waterlogging. Different types of rainfall often have different characteristics of waterlogging. In order to establish a more accurate urban flood control system, it is necessary to classify waterlogging rainstorms and divide their thresholds. This study proposes a method for applying web crawlers to identify waterlogging rainfall in cities lacking waterlogging observation data and classifying them using the rainfall intensity–duration curves. By selecting appropriate duration thresholds and return period, waterlogging rainstorms are divided into rainfall intensity waterlogging (IW), rainfall amount of waterlogging (AW), combined waterlogging (CW) and no waterlogging (NW). In the application of Zhengzhou City, China, the urban flood control standard and the rainfall time distribution characteristics are used as the basis for the selection of the return period and duration thresholds, and the storm water management model (SWMM) is constructed to simulate the 4 kinds of rainfall characteristics of waterlogging, which is similar to actual situations. It proves that the method is suitable for the classification and thresholds division of different waterlogging rainfall in cities. The results show that the best duration thresholds in Zhengzhou are 20 min (M20) and 60 min (M60), and the best return period standard is 2 a. The thresholds for the 4 types of waterlogging rainstorm are: M20 ≥ 26.47 mm, M60 ≥ 43.80 mm, CW; M20 ≥ 26.47 mm, M60 < 43.80 mm, IW; M20 < 26.47 mm, M60 ≥ 43.80 mm, AW; M20 < 26.47 mm and M60 < 43.80 mm, No waterlogging.

scholarly journals Evaluation Of Sediment Management Strategies For Large Reservoirs

2021 ◽  
Author(s):  
Muhammad Usman Rashid ◽  
Haris Miqdad ◽  
Muhammad Saad ul Hassan ◽  
Abdul Haseeb
Keyword(s):  
Flood Control ◽  
Net Present Value ◽  
Management Strategies ◽  
Vital Role ◽  
Cost Ratio ◽  
Benefit Cost Ratio ◽  
Sediment Flushing ◽  
Under Construction ◽  
Benefit Cost ◽  
Tarbela Reservoir

Abstract Multipurpose large dams play a key role in the development of world by providing water for irrigation, flood control and hydropower. Tarbela is one of the world's largest earth and rock fill dam. Being multipurpose dam, it provides vital role for economic stability and social development of Pakistan. Tarbela Reservoir has lost its significant capacity due to sediment deposition. The objective of the study was to evaluate different options for evacuation of deposited sediments and reducing sediment inflows to Tarbela Reservoir through sediment modeling by HEC-RAS. Sediment flushing from existing power tunnels was evaluated in first option and found not feasible due to the downstream constraints and loss of 7848 MW hydropower from Tarbela and Ghazi Barotha. New sediment bypass tunnels were proposed on right bank of the dam to overcome the constraints in second option. Sediment modeling was performed by HEC-RAS to evaluate each scenario of sediment flushing with different parameters. The sediment balance ratio and long term capacity ratio was also checked for each scenario for technical evaluation and also economic analysis was performed. Most technical viable scenario was flushing for 90 days at reservoir drawdown level of 390 m with discharge of 5000m 3 /s. However, this scenario was not economically feasible as net present value was negative, internal rate of return was 3-4 %, and benefit cost ratio was found less than one. The 3 rd option, with under construction multipurpose Diamer Basha Dam on upstream of Tarbela Reservoir, was also evaluated on HEC-RAS. Results depicted that large amount of sediments were trapped in the upstream reservoir which ultimately reduced significantly the inflow of sediments and delta movement in Tarbela Reservoir. This option is recommended because it will enhance the life of Tarbela Reservoir and it will keep on providing multiple benefits for longer time.

scholarly journals Evaluation of flood risk as a step in determining the “Acceptable Risk” criteria. Case study: Dengkeng River, Klaten, Central Java

2021 ◽  
Vol 894 (1) ◽  
pp. 012045
Author(s):  
A Sarminingsih ◽  
M Hadiwidodo
Keyword(s):  
Control System ◽  
Return Period ◽  
Flood Risk ◽  
Flood Control ◽  
Public Works ◽  
Acceptable Risk ◽  
Performance Function ◽  
Central Java ◽  
Flood Discharge ◽  
Potential Risks

Abstract The planning of a flood control system in Indonesia is based on the planning criteria issued by the Ministry of Public Works. Flood control planning is based on flood discharge with a specific return period depending on the order of the river and the number of protected populations. Flood events in areas where the flood control system has been planned continue to occur almost every year, meaning that the probability of being exceeded is not as planned. This study is intended to evaluate the criteria for the magnitude of the designed flood discharge in flood control planning that considers the acceptable risk. Potential risks are evaluated against system reliability. The probability of failure of the flood control system occurs if the resistance is smaller than the load expressed as a performance function. By knowing the performance function associated with the level of flood risk, then the flood discharge can be selected with the appropriate return period according to the acceptable risk.

scholarly journals Evaluation of Dimensions and Drainage Performance Office in the Aceh Tamiang Area Kuala Simpang

2021 ◽  
Vol 3 (1) ◽  
pp. 20-32
Author(s):  
Kamaluddin Lubis
Keyword(s):  
Channel Capacity ◽  
Discharge Capacity ◽  
Return Period ◽  
Rainfall Intensity ◽  
Drainage Channel ◽  
Flood Discharge ◽  
Discharge Plan ◽  
Runoff Discharge ◽  
High Degree

The Aceh Tamiang office area is one of the office areas in Kuala Simpang which consists of various offices in the Aceh Tamiang area. The purpose of this research is to identify the drainage condition of the existing primary drainage channel which accommodates runoff discharge, the shape and direction of the flow in the inundation channel in the Aceh Tamiang Kuala Simpang office area, which is expected to help solve the problem of flooding in the 832 m3 / second. And for the channel capacity in this primary drainage drainage of 0.829 m3 / sec, the value is smaller than the planned flood discharge (Qr). Rainfall intensity (I) of 126,432 mm / hour. The plan flood discharge (Qr) for a 5-year return period yields 2,551 m3 / second and the value for channel discharge capacity (Qs) is obtained from the calculation of 2,216 m3 / second. This value is smaller than the value of the planned flood discharge.area. From the results of research conducted by the Aceh Tamiang Kuala Simpang office area is a location with a fairly high degree of rainfall, with a rainfall intensity (I) of 126,432 mm / hour and a flood discharge plan for a 5-year return period obtained a result of 0.

scholarly journals On the role of the runoff coefficient in the mapping of rainfall to flood return periods

2009 ◽  
Vol 13 (5) ◽  
pp. 577-593 ◽  
Author(s):  
A. Viglione ◽  
R. Merz ◽  
G. Blöschl
Keyword(s):  
Monte Carlo ◽  
Return Period ◽  
Threshold Effect ◽  
Flood Frequency ◽  
Runoff Coefficient ◽  
Return Periods ◽  
Runoff Generation ◽  
Design Storm ◽  
Shed Light

Abstract. While the correspondence of rainfall return period TP and flood return period TQ is at the heart of the design storm procedure, their relationship is still poorly understood. The purpose of this paper is to shed light on the controls on this relationship examining in particular the effect of the variability of event runoff coefficients. A simplified world with block rainfall and linear catchment response is assumed and a derived flood frequency approach, both in analytical and Monte-Carlo modes, is used. The results indicate that TQ can be much higher than TP of the associated storm. The ratio TQ /TP depends on the average wetness of the system. In a dry system, TQ can be of the order of hundreds of times of TP. In contrast, in a wet system, the maximum flood return period is never more than a few times that of the corresponding storm. This is because a wet system cannot be much worse than it normally is. The presence of a threshold effect in runoff generation related to storm volume reduces the maximum ratio of TQ /TP since it decreases the randomness of the runoff coefficients and increases the probability to be in a wet situation. We also examine the relation between the return periods of the input and the output of the design storm procedure when using a pre-selected runoff coefficient and the question which runoff coefficients produce a flood return period equal to the rainfall return period. For the systems analysed here, this runoff coefficient is always larger than the median of the runoff coefficients that cause the maximum annual floods. It depends on the average wetness of the system and on the return period considered, and its variability is particularly high when a threshold effect in runoff generation is present.

scholarly journals Impact of Wheat Residue on Soil Erosion Processes

2018 ◽  
Vol 46 (2) ◽  
pp. 553-562 ◽  
Author(s):  
Ataollah KAVIAN ◽  
Leila GHOLAMI ◽  
Maziar MOHAMMADI ◽  
Velibor SPALEVIC ◽  
Moghadeseh FALAH SORAKI
Keyword(s):  
Soil Erosion ◽  
Water Conservation ◽  
Soil Conservation ◽  
Rainfall Intensity ◽  
Sandy Loam ◽  
Sediment Concentration ◽  
Runoff Coefficient ◽  
Northern Iran ◽  
Erosion Processes ◽  
Loam Soil

Soil erosion is one of the key challenges in soil and water conservation. Vegetation that covers soil and organic and inorganic mulch is very useful for the control of erosion processes. This study examined treatment with wheat residual (as agriculture mulch) on infiltration, time to runoff, runoff coefficient, sediment concentration and soil erosion processes. The study has been conducted for sandy-loam soil taken from summer rangeland (Northern Iran) with simulated rainfall intensities of 50 and 100 mm h-1. The experiment was conducted in slopes of 30% in three replications with two amounts of wheat residual of 50 and 90 %. The results showed that conservation percent of soil erosion for wheat residual 50 and 90% was 61.68 and 73.25%, respectively (in rainfall intensity of 50 mm h-1). Also, the conservation percent of soil erosion for wheat residual of 50 and 90% cover was 70.68 and 90.55, respectively (in rainfall intensity of 100 mm h-1). It was concluded that the conservation treatments could reduce runoff coefficient, sediment concentration and soil erosion and increase the time to runoff and infiltration coefficient. This effect was significant on time for infiltration, sediment concentration and soil erosion variables (R2=0.99), time to runoff and runoff coefficient variables (R2=0.95). The interaction effects of rainfall intensity and soil conservation was significant for sediment concentration and soil erosion variables (R2=0.99).

scholarly journals Spatial and statistical analysis on the cause of flooding in Northwest Jakarta floodplain (Kapuk and Penjaringan Districts)

2018 ◽  
Vol 229 ◽  
pp. 04008
Author(s):  
Imam Priambodo ◽  
Mangapul P. Tambunan ◽  
Eko Kusratmoko
Keyword(s):  
Statistical Analysis ◽  
Rainfall Intensity ◽  
Capital City ◽  
Runoff Coefficient ◽  
Key Factors ◽  
Rain Intensity ◽  
Height Elevation ◽  
Paper Address ◽  
Water Inundation ◽  
Flooded Areas

Jakarta, as the capital city of Indonesia, is one of the most flooded areas in Indonesia. The floods occurred annually and heavy floods usually occurred once in a few years. This paper address the geographic distribution of floods and statistical analysis of the floods causes by using rain intensity, tidal height, elevation, and floods occurrence as the parameters. This research was conducted in Angke (Kapuk) and Penjaringan Districts, located in Northern Jakarta where the floods usually occur. The result shows that rainfall intensity, remaining water inundation from the previous flood, and land runoff coefficient as the key factors of flooding in these areas.

scholarly journals Study on Variation of Surface Runoff and Soil Moisture Content in the Subgrade of Permeable Pavement Structure

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Lijun Hou ◽  
Yuan Wang ◽  
Fengchun Shen ◽  
Ming Lei ◽  
Xiang Wang ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Soil Water ◽  
Surface Runoff ◽  
Rainfall Intensity ◽  
Soil Moisture Content ◽  
Asphalt Pavement ◽  
Infiltration Rate ◽  
Runoff Coefficient ◽  
Flood Peak

The self-designed indoor simulated rainfall device was used to rain on five types of pavement structures with 4 types of rainfall intensity (2.5 mm/min, 3.4 mm/min, 4.6 mm/min, and 5.5 mm/min). The effect of rainfall intensity on the surface runoff, the relation between the subgrade soil moisture content changes, and the influence of initial soil water content on rain infiltration rate are studied. The test results show that the surface runoff coefficient of densely asphalted pavement is greater than 90% in drainage pavements and it has little influence on the reducing and hysteresis of the flood peak. The surface runoff coefficient of large-void asphalt pavement (permeable) is less than 40%. Although the large-void asphalt pavement (permeable) can reduce a small amount of surface runoff, it has no obvious effect on the reduction and hysteresis of the flood peak. In semipermeable pavement, with the increasing of the thickness of base (graded gravel), the surface runoff coefficient decreases at different rainfall intensities, parts of the surface runoff are reduced, and the arrival of flood peaks is delayed. In permeable roads, almost no surface runoff occurred. As time continued, the soil moisture content quickly reached a saturated state and presented a stable infiltration situation under the action of gravity and the gradient of soil water suction. As the initial moisture content increases, the initial infiltration rate decreases and the time to reach a stable infiltration rate becomes shorter. The drier the soil, the greater the initial infiltration rate and the higher the soil moisture content after infiltration stabilization. Permeable roads can greatly alleviate the pressure of urban drainage and reduce the risk of storms and floods.

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