scholarly journals Estimation of Design Flood for Rivers of Saurashtra Region Contributing into the Gulf of Khambhat

2016 ◽  
Vol 11 (3) ◽  
pp. 869-882
Author(s):  
Priyanka Kumari ◽  
Sushil Kumar
Keyword(s):  
Frequency Analysis ◽  
Return Period ◽  
Statistical Approach ◽  
River Basins ◽  
Hydraulic Structures ◽  
Deterministic Approach ◽  
Design Flood ◽  
Rainfall Frequency ◽  
Rainfall Frequency Analysis ◽  
Design Floods

Design flood has been estimated for rivers of Saurashtra region contributing into the Gulf of Khambhat using deterministic as well as statistical approach for planning, design and management of hydraulic structures. By comparing the results obtained by these approaches, one can easily estimate the flow rate or peak discharge to a given design return period and can establish the suitability of approach for this study area. Nine river basins with 20 dams of Saurashtra region were analyzed in this study. Though Saurashtra is one of the most water scarce regions of India yet it suffers from the flooding problem, as the numbers of rainy days are very less and the rainfall intensity is very high. Due to being a regulated basin, dam wise study was preferred. Deterministic approach was carried out using synthetic unit hydrograph (SUH) and regional flood formulae (RFF) methods for subzone-3a provided in Central Water Commission (CWC) report, 2001. Statistical approach was carried out using Rainfall frequency analysis employingGumbel’s EV1distribution. As there is no spill by these hydraulic structures and the annual flood data for the nine river sites are heavily affected by the storage dams in the upstream. Hence these data violate the basic principle of virgin flow. Hence the analysis of these data was not attempted further. The main objective of study was to carry out the rainfall frequency analysis for these river basins to get 24 hour rainfall for a return period of 25, 50 and 100 years for an individual basin instead of using the value obtained by iso-pluvial map to estimate the design flood. The overall results reveals that due to construction of number of dams in 9 river basins, design flood estimation on each dam by using deterministic approach is more feasible.Revised design floods using SUH and RFF method on the basis of estimated rainfall indicates over-estimated and under-estimated design floods. Since the percentage difference is very less between revised SUH and revised RFF method. So, for safety purpose one with higher value should be used.

scholarly journals Proposed Swedish Spillway Design Guidelines Compared with Historical Flood Marks at Lake Siljan

1989 ◽  
Vol 20 (4-5) ◽  
pp. 293-304 ◽  
Author(s):  
Joakim Harlin
Keyword(s):  
Sensitivity Analysis ◽  
Water Level ◽  
Frequency Analysis ◽  
Return Period ◽  
Design Guidelines ◽  
Water Levels ◽  
Spring Flood ◽  
Design Flood ◽  
Design Floods ◽  
Modelling Assumptions

A comparison between the proposed Swedish spillway design floods and historic flood marks made at lake Siljan in central Sweden, is shown. Frequency analysis is performed incorporating pregauge information on water levels together with a sensitivity analysis of modelling assumptions. A water level of 0.42 to 0.75 metres above the highest historic flood mark (166.10 m.a.sl., 1659) was obtained when routing the design spring flood through lake Siljan. The design autumn flood lifted the lake to 1.56 to 1.52 metres below the highest flood mark. Return period for the design spring and autumn flood was estimated to about 1,000 years. The uncertainty in frequency analysis proved to have larger impact than modelling assumptions on estimating the risk of the design flood.

scholarly journals Best-Fit Probability Distribution Model for Rainfall Frequency Analysis of Three Cities in South Eastern Nigeria

2017 ◽  
Vol 1 (1) ◽  
pp. 34-42 ◽  
Author(s):  
A. I. Agbonaye ◽  
O. C. Izinyon
Keyword(s):  
Probability Distribution ◽  
Frequency Analysis ◽  
Distribution Model ◽  
Hydraulic Structures ◽  
Annual Maximum ◽  
Rainfall Frequency ◽  
Pearson Type ◽  
Rainfall Frequency Analysis ◽  
Best Fit ◽  
Annual Maximum Series

Rainfall frequency analysis is the estimation of how often rainfall of specified magnitude will occur. Such analyses are helpful in defining policies relating to water resources management. It serves as the source of data for flood hazard mitigation and the design of hydraulic structures aimed at reducing losses due to floods action. In this study rainfall frequency analysis for three (3) cities in South Eastern Nigeria were carried out using annual maximum series of daily rainfall data for the stations. The objective of the study was to select the probability distribution model from among six commonly used probability distribution models namely: Generalized Extreme value distribution (GEV), Extreme value type I distribution (EVI), Generalized Pareto distribution (GPA), Pearson Type III (PIII), log Normal (LN) and Log Pearson Type III (LP111) distributions. These distributions were applied to annual maximum series of daily precipitation data at each station using the parameters of the distributions estimated by the method of moments. The best fit probability distribution model at each location was selected based on the results of seven goodness of fit tests entry: root mean square error (RMSE), relative root mean square error (RRMSE), mean absolute deviation index (MADI) and probability plot correlation coefficient (PPCC), Maximum Absolute Error (MAE), Chi square test and D- Index and a scoring and ranking scheme. Our results indicate that the best fit probability distribution model at all study locations is GEV and this was used to forecast rainfall return values for the stations for return periods of between 5years and 500years. The values obtained are useful for planning, design and management of hydraulic structures for flood mitigation and prevention of flood damage at the location.

From point to areal rainfall: linking the different approaches for the frequency characterisation of rainfalls in urban areas

2006 ◽  
Vol 54 (6-7) ◽  
pp. 33-40 ◽  
Author(s):  
M.H. Ramos ◽  
E. Leblois ◽  
J.-D. Creutin
Keyword(s):  
Frequency Analysis ◽  
Return Period ◽  
Urban Areas ◽  
Urban Water ◽  
Storm Events ◽  
Unified Approach ◽  
Rainfall Frequency ◽  
Rainfall Frequency Analysis ◽  
Areal Rainfall ◽  
The City

In urban water design and management, many hydrologic problems involve the frequency characterisation of rainfalls. Hydrologists are commonly asked to evaluate rainfall intensities for given recurrence frequencies or to indicate how rare an observed event is by estimating its return period. This study aims to improve the characterisation of rainfall hazard over a city by linking point to areal rainfall frequency analysis. We use a stochastic rainfall field generator based on the turning-bands method directly to assess areal rainfall distributions and to illustrate the link between different approaches. The simulating algorithm is applied to rainfall data from the city of Marseilles. The frequency analysis of simulated fields provides the elements to deal with the notions of return period and severity of observed storm events. The study concludes on the importance of a unified approach to assess rainfall better.

scholarly journals IDENTIFIKASI KEKERINGAN HIDROLOGI DI DAS CITARUM HULU

2015 ◽  
Vol 16 (1) ◽  
pp. 21
Author(s):  
Nyayu Fatimah Zahroh ◽  
Sara Aisyah Syafira
Keyword(s):  
Frequency Analysis ◽  
Return Period ◽  
Power Plants ◽  
Hydrological Drought ◽  
Average Period ◽  
Rainfall Frequency ◽  
Rainfall Frequency Analysis ◽  
Drought Occurrence

Intisari  DAS Citarum Hulu merupakan salah satu subdas yang paling berpengaruh di DAS Citarum dengan Waduk Sagulingnya. Besarnya debit yang masuk ke waduk menjadi sangat penting demi keberlangsungan kinerja waduk tersebut, misalnya untuk pembangkit listrik. Penelitian ini bertujuan untuk mengetahui karakteristik kekeringan hidrologi, relasinya dengan curah hujan, dan analisis frekuensi kejadian kekeringan hidrologi di DAS Citarum Hulu. Data dari pos duga air Nanjung digunakan dalam menentukan ambang batas kekeringan hidrologi yang kemudian diperoleh karakteristik kekeringan hidrologi. Hasil menunjukan bahwa rata-rata periode kekeringan di DAS Citarum Hulu terjadi mulai dari bulan Juni hingga Oktober. Terdapat keterlambatan antara waktu curah hujan turun dan waktu ketika debit naik akibat input dari curah hujan. Hasil analisis frekuensi menunjukan bahwa kekeringan maksimum yang terjadi pada tahun 1994 memiliki periode ulang 52 tahun dan kekeringan sering terjadi dengan durasi kurang dari 20 hari.  Abstract  Citarum Hulu is one of the most influential Citarum sub-basin with the Saguling Reservoir. The amount of discharge into the reservoir is very important for the sustainability of the reservoir's performance for power plants in example. This study aims to determine the characteristics of hydrological drought, its relationship with precipitation, and frequency analysis of hydrological drought occurrence in Citarum Hulu. Data from Nanjung post are used in determining the threshold of hydrological drought which then acquired the characteristics of hydrological drought. The results showed that the average period of drought in Citarum Hulu occurred from June to October. There is a lag between the time when rainfall drops and the time when the discharge rise due to the input of rainfall. Frequency analysis results showed that the maximum drought that occurred in 1994 had a 52-year return period and drought often occurs with a duration of less than 20 days.

Regional Rainfall Frequency Analysis for the State of Michigan

2005 ◽  
Vol 10 (6) ◽  
pp. 437-449 ◽  
Author(s):  
Christopher M. Trefry ◽  
David W. Watkins ◽  
Dennis Johnson
Keyword(s):  
Frequency Analysis ◽  
The State ◽  
Rainfall Frequency ◽  
Rainfall Frequency Analysis ◽  
Regional Rainfall

scholarly journals The Effect of Sample Size on Bivariate Rainfall Frequency Analysis of Extreme Precipitation

Proceedings ◽  
2018 ◽  
Vol 7 (1) ◽  
pp. 19 ◽  
Author(s):  
Nikoletta Stamatatou ◽  
Lampros Vasiliades ◽  
Athanasios Loukas
Keyword(s):  
Sample Size ◽  
Frequency Analysis ◽  
Extreme Precipitation ◽  
Goodness Of Fit ◽  
Return Periods ◽  
Goodness Of Fit Test ◽  
Maximum Rainfall ◽  
Rainfall Frequency ◽  
Rainfall Frequency Analysis ◽  
Pseudo Likelihood Estimation

The objective of this study is to compare univariate and joint bivariate return periods of extreme precipitation that all rely on different probability concepts in selected meteorological stations in Cyprus. Pairs of maximum rainfall depths with corresponding durations are estimated and compared using annual maximum series (AMS) for the complete period of the analysis and 30-year subsets for selected data periods. Marginal distributions of extreme precipitation are examined and used for the estimation of typical design periods. The dependence between extreme rainfall and duration is then assessed by an exploratory data analysis using K-plots and Chi-plots and the consistency of their relationship is quantified by Kendall’s correlation coefficient. Copulas from Archimedean, Elliptical, and Extreme Value families are fitted using a pseudo-likelihood estimation method, evaluated according to the corrected Akaike Information Criterion and verified using both graphical approaches and a goodness-of-fit test based on the Cramér-von Mises statistic. The selected copula functions and the corresponding conditional and joint return periods are calculated and the results are compared with the marginal univariate estimations of each variable. Results highlight the effect of sample size on univariate and bivariate rainfall frequency analysis for hydraulic engineering design practices.

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