Artykuły w czasopismach: „Hershfield Method:”

1

Afzali-Gorouh, Zahra, Bahram Bakhtiari i Kourosh Qaderi. "Probable maximum precipitation estimation in a humid climate". Natural Hazards and Earth System Sciences 18, nr 11 (20.11.2018): 3109–19. http://dx.doi.org/10.5194/nhess-18-3109-2018.

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Abstract. Probable maximum precipitation (PMP) estimation is one of the most important components for designing hydraulic structures. The aim of this study was the estimation of 24 h PMP (PMP24) using statistical and hydro-meteorological (physical) approaches in the humid climate of the Qareh-Su basin, which is located in the northern part of Iran. Firstly, for the statistical estimate of PMP, the equations of empirical curves of the Hershfield method were extracted and the Hershfield standard and modified methods were written in Java programming language, as a user-friendly and multi-platform application called the PMP Calculator. Secondly, a hydro-meteorological approach, which is called the convergence model, was used to calculate PMP24. The results of both approaches were evaluated based on statistical criteria, such as the mean absolute error (MAE), mean squared error (MSE), root mean squared error (RMSE), mean absolute percentage error (MAPE), correlation coefficient (r), and coefficient of determination (R2). The maximum values of PMP24 for the Hershfield standard and modified methods were estimated to be 448 and 201 mm, respectively, while the PMP obtained by the physical approach was 143 mm. Comparison of PMP24 values with the maximum 24 h precipitation demonstrated that based on performance criteria including the MAE, MSE, RMSE, MAPE, r, and R2, the physical approach performed better than the statistical approach and it provided the most reliable estimates for PMP. Also, the accuracy of the Hershfield modified method was better than the standard method using modified Km values, and the standard method gives excessively large PMP for construction costs.

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Chavan, Sagar Rohidas, i V. V. Srinivas. "Regionalization based envelope curves for PMP estimation by Hershfield method". International Journal of Climatology 37, nr 10 (30.12.2016): 3767–79. http://dx.doi.org/10.1002/joc.4951.

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Elíasson, Jónas. "Statistical Estimates of PMP Values". Hydrology Research 25, nr 4 (1.08.1994): 301–12. http://dx.doi.org/10.2166/nh.1994.0010.

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The article discusses two statistical methods to estimate PMP values, the Hershfield and the NERC methods. Neither method offers any explanation why the PMP values can be calculated by the use of unbounded statistical distributions, but both methods include the use of envelope curves that are not independent of the region. Bounded data that fits an unbounded distribution must deviate from the distribution for high return periods and tend to a limiting value, and then there exists, a limiting reduced variate that can be used to find the PMP value. When the distribution is EV1, the limiting reduced variate can be defined by a mapping transformation, or by cutting off the distribution. It is shown that when Hershfield or NERC methods are used, the limiting reduced variate is included in the PMP values and can be separated from regional parameters. It is suggested that the limiting reduced variate, that depends solely on return period, may more easily be transferred between regions than the other parameters. This may be a great help in finding PMP values in regions where observations are not extensive enough to define limiting return periods with necessary certainty. A case study with data from Iceland demonstrates, that using the limiting reduced variate, similarities emerge in the Icelandic data and the NERC PMP that justify the acceptance of the NERC method.

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Elíasson, Jónas. "Probable Maximum Precipitation in Iceland – Station Values –". Hydrology Research 23, nr 1 (1.02.1992): 49–56. http://dx.doi.org/10.2166/nh.1992.0004.

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The meteorological stations in Iceland are rather few compared to the size of the country, and their service time is short compared to other developed countries. Investigations of individual 24-hour station PMP values computed by the Hershfield and NERC methods show trends that are important for the application of PMP values in engineering design. The results fall into two series, one with high PMP values and the other with lower values. The low values originate from station groups situated in areas with mildly sloping terrain and here the results compare fully with what should be expected from experience from other countries. The other series shows results that do not compare as well with previously published results. Their general characteristics is that PMP values calculated hy the Hershfield method are of the order 80% higher than the corresponding results obtained by the NERC method. The results of this high series do not check against results obtained from meteorological models. It is noteworthy, that all the stations of the low series belong to station groups where the terrain is gently sloping, i.e. average terrain slopes less than 1.4%, while in the high series all the stations belong to station groups where the terrain slopes steeply from a highland plateau down to sea level. It is concluded that the generalized estimates of PMP values needed in engineering design could be obtained.

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Sutopo, Yeri, Karuniadi Satrio Utomo i Naufal Tinov. "The Effects of Spillway Width on Outflow Discharge and Flow Elevation for the Probable Maximum Flood (PMF)". Civil Engineering Journal 8, nr 4 (1.04.2022): 723–33. http://dx.doi.org/10.28991/cej-2022-08-04-08.

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The purpose of this study was to analyze the effect of spillway width on flow elevation at the weir crest based on the flood discharge design for the Probable Maximum Flood (PMF) return period using flood routing hydrologically at the Cacaban Dam (Indonesia). The rainfall Probable Maximum Precipitation (PMP) design uses the Hershfield Equation. The design of the flood discharge analysis of QPMF used the Nakayasu Synthetic Unit Hydrograph (HSS). Flood routing uses the hydrologic routing method. The Cacaban Dam is located in Jati Village, Kedung Banteng District, Tegal Regency, Central Java Province, Indonesia. The results of the research data analysis showed that increased spillway crest widths led to decreased flow evaluation at the spillway crest, and increased outflow discharge. Thus, if a large storage volume of the reservoir is intended, then the width of the spillway crest must be reduced. Otherwise, the width of the spillway crest must be increased. In terms of flood control in the Tegal Regency, it's better to make the crest of the spillway smaller. Doi: 10.28991/CEJ-2022-08-04-08 Full Text: PDF

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Sibuea, Puji R. A., Dewi R. Agriamah, Edi Riawan, Rusmawan Suwarman i Atika Lubis. "Estimation of Probable Maximum Precipitation (PMP) and Probable Maximum Flood (PMF) Using GSSHA Model (Case Study Area Upper Citarum Watershed)". IOP Conference Series: Earth and Environmental Science 893, nr 1 (1.11.2021): 012023. http://dx.doi.org/10.1088/1755-1315/893/1/012023.

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Abstract Probable Maximum Flood (PMF) used in the design of hydrological structures reliabilities and safety which its value is obtained from the Probable Maximum Precipitation (PMP). The objectives of this study are to estimate PMP and PMF value in Upper Citarum Watershed and understand the impact from different PMP value to PMF value with two scenarios those are Scenario A and B. Scenario A will calculate the PMP value from each Global Satellite Mapping of Precipitation (GSMaP) rainfall data grid and Scenario B calculate the PMP value from the mean area rainfall. PMP value will be obtained by the statistical Hershfield method, and the PMF will be obtained by employed the PMP value as the input data in Gridded Surface Subsurface Hydrologic Analysis (GSSHA) hydrologic model. Model simulation results for PMF hydrographs from both scenarios show that spatial distribution of rainfall in the Upper Citarum watershed will affect the calculated discharge and whether Scenario A or B can be applied in the study area for PMP duration equal or higher than 72 hours. PMF peak discharge for Scenario A is averagely 13,12% larger than Scenario B.

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Walega, A., i B. Michalec. "Characteristics of extreme heavy precipitation events occurring in the area of Cracow (Poland)". Soil and Water Research 9, No. 4 (10.11.2014): 182–91. http://dx.doi.org/10.17221/99/2013-swr.

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The variability of extremely heavy precipitation events with duration of 120 min occurring in the area of Cracow, southern Poland was assessed. The analysis was performed using time series of maximum annual precipitation events with durations t = 5, 10, 15, 30, 60, and 120 min, recorded at the Botanical Garden station at the Jagiellonian University in the period of 1906–1990. The periodicity of precipitation was analyzed using the autocorrelation function and Fourier spectral density analysis. The Probable Maximum Precipitation (PMP) was calculated by Hershfield’s statistical method. The analysis of the autocorrelation function of sequences and the Fourier spectral density revealed a clear periodicity of the maximum precipitation. For precipitation with t = 60 min, the maximum values occur every 9 years, but also shorter periods (3-year) may be observed. The PMP values calculated for Cracow differ significantly from the values calculated using the probability distribution, as well as from the ones observed and they increase with increasing precipitation duration. The differences between the PMP and probable as well as observed precipitation tend to decrease with increasing duration of precipitation.

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Allias Omar, Siti Mariam, Wan Noorul Hafilah Wan Ariffin, Lariyah Mohd Sidek, Hidayah Basri, Mohd Hazri Moh Khambali i Ali Najah Ahmed. "Hydrological Analysis of Batu Dam, Malaysia in the Urban Area: Flood and Failure Analysis Preparing for Climate Change". International Journal of Environmental Research and Public Health 19, nr 24 (9.12.2022): 16530. http://dx.doi.org/10.3390/ijerph192416530.

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Extensive hydrological analysis is carried out to estimate floods for the Batu Dam, a hydropower dam located in the urban area upstream of Kuala Lumpur, Malaysia. The study demonstrates the operational state and reliability of the dam structure based on hydrologic assessment of the dam. The surrounding area is affected by heavy rainfall and climate change every year, which increases the probability of flooding and threatens a dense population downstream of the dam. This study evaluates the adequacy of dam spillways by considering the latest Probable Maximum Precipitation (PMP) and Probable Maximum Flood (PMF) values of the concerned dams. In this study, the PMP estimations are applied using comparison of both statistical method by Hershfield and National Hydraulic Research Institute of Malaysia (NAHRIM) Envelope Curve as input for PMF establishments. Since the PMF is derived from the PMP values, the highest design flood standard can be applied to any dam, ensuring inflow into the reservoirs and limiting the risk of dam structural failure. Hydrologic modeling using HEC-HMS provides PMF values for the Batu dam. Based on the results, Batu Dam is found to have 200.6 m3/s spillway discharge capacities. Under PMF conditions, the Batu dam will not face overtopping since the peak outflow of the reservoir level is still below the crest level of the dam.

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Hussain, M., S. Nadya i F. J. Chia. "Estimating Probable Maximum Precipitation for Linau River Basin in Sarawak". Journal of Civil Engineering, Science and Technology 5, nr 3 (1.12.2014): 1–5. http://dx.doi.org/10.33736/jcest.138.2014.

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The probable maximum precipitation (PMP) is the greatest depth of precipitation for a given duration that is physically possible over a given size storm area at a particular geographical location at a certain time of the year. PMP is very important to be considered for the design of river regulating structures i.e Dams and Barrages to overcome any possible chance of overtopping failure as well as for public safety and hazards downstream of any of these structures. Especially if these structures located in the upstream of the of the populated town or city than the failure could damage severely such areas. As such the PMP convention is always a requirement as primary design dam/reservoir criteria when public safety is of concern. The PMP is used to derive Probable Maximum Flood (PMF), which further used in hydraulic modeling to check the impact assessments for such occasions. This paper focuses on estimation of PMP for Linau River Basin in Sarawak using statistical method proposed by World Meteorological Organization (WMO), which is described in its operational manual. Long Lidam and Long Laku are located in Linau River Basin but Long Laku has long discontinuity in the data set thus the rainfall series at Long Lidam is further used for PMP estimation. The missing data was in-filled using Belaga rain gauge station as Long Lidam rainfall has good correlation with Belaga rainfall data. Hershfield statistical method has been adopted to estimate the 24-hour duration PMP. The Probable Maximum Precipitation for 24-hour duration storm is estimated as 691 mm for the Linau River Basin.

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Seo, Miru, Sunghun Kim, Heechul Kim, Hanbeen Kim, Ju-Young Shin i Jun-Haeng Heo. "Evaluation of Statistical PMP Considering RCP Climate Change Scenarios in Republic of Korea". Water 15, nr 9 (2.05.2023): 1756. http://dx.doi.org/10.3390/w15091756.

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Extreme rainfall and floods have increased in frequency and severity in recent years, due to climate change and urbanization. Consequently, interest in estimating the probable maximum precipitation (PMP) has been burgeoning. The World Meteorological Organization (WMO) recommends two types of methods for calculating the PMP: hydrometeorological and statistical methods. This study proposes a modified Hershfield’s nomograph method and assesses the changes in PMP values based on the two representative concentration pathway (RCP4.5 and RCP8.5) scenarios in South Korea. To achieve the intended objective, five techniques were employed to compute statistical PMPs (SPMPs). Moreover, the most suitable statistical method was selected by comparing the calculated SPMP with the hydrometeorological PMP (HPMP), by applying statistical criteria. Accordingly, SPMPs from the five methods were compared with the HPMPs for the historical period of 2020 and the future period of 2100 for RCP 4.5 and 8.5 scenarios, respectively. The results confirmed that the SPMPs from the modified Hershfield’s nomograph showed the smallest MAE (mean absolute error), MAPE (mean absolute percentage error), and RMSE (root mean square error), which are the best results compared with the HPMP with an average SPMP/HPMP ratio of 0.988 for the 2020 historical period. In addition, Hershfield’s method with varying KM exhibits the worst results for both RCP scenarios, with SPMP/HPMP ratios of 0.377 for RCP4.5 and 0.304 for RCP8.5, respectively. On the contrary, the modified Hershfield’s nomograph was the most appropriate method for estimating the future SPMPs: the average ratios were 0.878 and 0.726 for the 2100 future period under the RCP 4.5 and 8.5 scenarios, respectively, in South Korea.

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Koutsoyiannis, Demetris. "A probabilistic view of hershfield's method for estimating probable maximum precipitation". Water Resources Research 35, nr 4 (kwiecień 1999): 1313–22. http://dx.doi.org/10.1029/1999wr900002.

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Fernando, W. C. D. K., i S. S. Wickramasuriya. "Concept of Threshold in the Estimation of Probable Maximum Precipitation: Hershfield’s Method Revisited". Journal of Hydrologic Engineering 26, nr 3 (marzec 2021): 04020069. http://dx.doi.org/10.1061/(asce)he.1943-5584.0002045.

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J, Razali, Sidek L.M, Rashid M.A, Hussein A i M. Marufuzzaman. "Probable Maximum Precipitation Comparison using Hershfield’s Statistical Method and Hydro-Meteorological Method for Sungai Perak Hydroelectric Scheme". International Journal of Engineering & Technology 7, nr 4.35 (30.11.2018): 603. http://dx.doi.org/10.14419/ijet.v7i4.35.22922.

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One of the potential risks attributed to the occurrence of dam overtopping and dam wall failure due to the inadequacy of the spillway capacities is the loss of life and property damages in the downstream area. The current practices in most countries in minimizing these risks are by analyzing the extreme precipitation that leads to extreme flood. Extreme precipitation is best known as Probable Maximum Precipitation (PMP) and this estimation is useful in determining Probable Maximum Flood (PMF) in reviewing the spillway adequacy of dam structures. This paper presented PMP estimations using two approaches; physical method (Hydro-meteorological Method) and statistical approach (Hershfield’s Method) at the Sungai Perak Hydroelectric Scheme that consists of four cascading dams namely Temengor dam, Bersia dam, Kenering dam and Chenderoh dam. The highest PMP estimates from these two methods will be chosen as the rainfall input to establish PMF hydrographs. Estimations using Hydro-meteorological generalized map produces 40-50% higher estimates compared to Hersfield’s method with the PMP values of 550mm (1hours), 600mm (3hours), 800mm (6hours), 820mm (12hours), 1300mm (24hour) and 1600mm (72 hours). Accepting the Hydro-meteorological Method to determine PMF values for this hydroelectric scheme may be the best course since the estimations of the extreme precipitations using this method are the highest.

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Tajbakhsh, Mohammad, i Nadhir Al-Ansari. "Comparative study of multi-station method and Hershfield’s approaches for PMP determination (case study: Northeast of Iran)". Sustainable Water Resources Management 5, nr 3 (8.10.2018): 1133–41. http://dx.doi.org/10.1007/s40899-018-0291-z.

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Lee, Kwan Tun, Yu Han Hsu i Jing Zong Yang. "Estimating Typhoon-Induced Maximum Flood for Spillway Safety Assessment—Case Studies in Taiwan". Water 15, nr 17 (24.08.2023): 3040. http://dx.doi.org/10.3390/w15173040.

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Dam safety assessment is usually conducted regularly to investigate the risks associated with the dam and propose remedies to ensure effective reservoir operations. One crucial aspect of the evaluation involves performing hydrological analyses to determine if the existing spillway can successfully deliver the probable maximum flood (PMF) downstream. This study applied storm transposition and typhoon rainstorm methods for PMP estimations. The resulting PMP values were then used as input for runoff models to generate flood hydrographs for PMF determination. A modification for the storm transposition method was proposed to determine the barrier height considering the moisture inflow direction. In estimating the orographic rainfall in the typhoon rainstorm model, an effective terrain slope was suggested according to different windward directions based on DEM analysis. Shihmen Reservoir and Feitsui Reservoir, located in northern Taiwan, were used as examples to conduct the PMP and PMF analysis. The obtained PMPs were further compared with the results generated by Hershfield’s method to assess the reasonability of the estimation. The results show that the maximum deviation of the 24-h PMP values estimated by the three methods is within 30% in the Shihmen watershed and 16% in the Feitsui watershed. The PMF estimations in the two reservoir watersheds are larger than the design discharges of the existing spillways. Hence, extending the capacity of the existing spillways or constructing upstream bypasses to avoid catastrophic flooding downstream is required.

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Fattahi, Ebrahim, i Maral Habibi. "Estimation of probable maximum precipitation 24-h (PMP 24-h) through statistical methods over Iran". Water Supply, 29.07.2022. http://dx.doi.org/10.2166/ws.2022.281.

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Abstract Estimating the probable maximum precipitation (PMP) is necessary to calculate the probable maximum flood (PMF). It is of high importance in checking the adequacy of dam overflow capacity and other development and water transfer plans of a given area. In this research, using the annual 24-hour maximum rainfall data set of 45 synoptic stations throughout the country, the PMP values were calculated through the original Hershfield method and then the Hershfield-Desa method. By comparing the obtained results of 24-hour PMP estimation through the two mentioned methods, it is found that the estimation of PMP values in the original/first Hershfield method is well higher than the expected value (2.54 to 4.03). While in the modified method (Desa method), PMP values are significantly reduced and seem more reasonable (1.02 to 1.3). Meanwhile, the calculated variability and skewness coefficients also indicated more variability of PMP values in the southern stations of the country compared to rainy regions, which makes the estimation of PMP in the southern regions of the country considerably unreliable.

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Daba, Nigatu Nura, Tamene Adugna Demissie i Chala Hailu Sime. "Probable maximum precipitation estimation using Hershfield’s statistical method: a case of Dedessa sub-basin, Ethiopia". Modeling Earth Systems and Environment, 10.07.2021. http://dx.doi.org/10.1007/s40808-021-01228-y.

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