Gumbel Method Research Articles

Pemetaan Banjir Kawasan Sungai Gadjah Putih dan Evaluasi Kinerja Saluran Drainase RW 14, Sumber, Banjarsari, Surakarta

Floods often occur due to river water overflowing to the surface. Flooding can also be caused by land development which increases surface runoff and impacts the drainage system. This can cause a decrease in the performance of the drainage channel. This research aims to map floods caused by runoff from the Gadjah Putih River, and the performance of existing drainage channels in RW 14 Sumber, Banjarsari, Surakarta. The rain data used is rain data from the Pabelan, Mojolaban, and Baki rain stations from 2000 to 2019. The Gumbel method is used to analyze rain return periods, runoff discharge analyzed by using Rational Method. Runoff discharge is explained at return periods of 2, 5, and 10 years, producing discharges of 8.15 m3/s respectively; 9.76 m3/day; and 10.61 m3/day. Floods are mapped using HEC-RAS by conducting steady flow analysis. The results of the flood mapping of the Gadjah Putih River showed that the area that experienced flooding at the return period of 2, 5 and 10 years respectively was 50,326.77 m2; 56,865.37 m2; 60,756.82 m2. Drainage performance analysis compares hydrology and hydraulic calculations. The analysis resulted drainage performance in RW 14 Sumber show that at the 2 year discharge period, 34 types of channels are safe, and 11 types of channels require repair; in the 5 year discharge period, 30 types of channels are safe, and 15 types of channels require repair; at the 10 year discharge period, 25 types of channels are safe, and 20 types of channels require repair.

ANALISIS HUJAN MAKSIMUM PADA DAERAH ALIRAN SUNGAI BABAK KABUPATEN LOMBOK BARAT

Hydrological analysis is the most important measurement in determining runoff in order to find ways to overcome flooding. The flow rate that is the basis for calculating flood control and protection is the planned flood flow rate obtained from the sum of the volume of rain runoff and the flow rate of the water catchment area in question during a certain return period. This research is a case study using rainfall data for 10 years, namely 2014-2023. Rainfall prediction is an estimate of the amount of rain that will fall in a river basin. There are several methods for determining annual rainfall, the Gumbel distribution method, Pearson log type III, and the normal method. After analyzing the annual rainfall data obtained at the West Lombok Regency Meteorology, Climatology and Geophysics Agency office, using three methods, namely the EJ Gumbel method, the Log Person Type III method and the Normal method, where from the three methods the maximum rainfall difference was quite large, In the following table you can see the difference in the amount of maximum rainfall in the return period T years.

Short-term extreme value prediction for the structural responses of the IEA 15 MW offshore wind turbine under extreme environmental conditions

As offshore wind turbines enter deep seas, large-scale models ranging from 15 MW to 20 MW are becoming the mainstream choice for the future market. The dynamic responses of 15 MW wind turbines under extreme environmental conditions should be considered in the design process. With increasing structure sizes, the mooring systems and tower base structures play essential roles in maintaining position and supporting wind turbines under harsh environmental conditions. Accurate estimation of the extreme mooring loads and dynamic responses at the tower base is crucial, particularly for the ultimate limit state (ULS) analysis. The dynamic responses of the offshore wind turbine are calculated by Open Fast and validated with other numerical tools. For the safety of deep-sea structures, it is necessary to consider the extreme environmental conditions with a 100-year return period, which is beyond the current standards. An environmental contour-based approach is proposed to select the short-term extreme conditions, enabling approximate prediction of the extreme values of the dynamic responses during the preliminary design stage. The Gumbel method and the ACER method are used to predict the short-term extreme dynamic responses. Comparative evaluations against the relevant standards for floating wind turbines are conducted to assess structural safety.

Estimating Extreme Rainfall Equation Parameter in Southeast Brazil Using Machine Learning

Purpose: This article explores the use of advanced machine learning techniques, including Random Forests and Deep Learning, to predict parameters of the intense rainfall equation. Methods: The study applies deep neural networks and random forests to predict parameters of the intense rainfall equation. Random Forests method is employed to handle the heterogeneity of data, while Deep Learning captures non-linear relationships. The application takes place in the state of Rio de Janeiro, with a focus on predicting parameters for specific municipalities using available data from the ANA (Brazilian Water Agency). Results and Conclusion: The neural network demonstrates accuracy in learning these parameters, with discrepancies attributed to differences in historical data periods. Despite limitations, the neural network shows promise in predictions, while the Random Forest closely aligns with the results of the neural network and the Gumbel method. The algorithms perform less accurately in regions with limited training data, emphasizing the need for additional variables to enhance prediction accuracy. Research implications: The most significant implication of this research is the potential improvement in intense rainfall forecast, using advanced machine learning techniques such as Random Forests and Deep Learning. Society will benefit with it resulting in better systems, in specific municipalities within the state of Rio de Janeiro, for early warning, risk managements, and urban planning.

ANALISIS TINGKAT KERUSAKAN PANTAI AKIBAT BENCANA ABRASI DAN UPAYA PENANGANANNYA (PESISIR DESA STOWE BRANG)

Abrasion that occurs in Sumbawa Regency, Utan District, Stowe Brang Village is caused by wave factors, land characteristics which are generally in the form of peat, silt and sand are very vulnerable to erosion due to waves. In addition to natural factors, abrasion can also be blamed on human factors. The variables used in this study consist of 2 of them, namely: (1) Natural Factors, (2) Human Factors. The purpose of this study is to describe the coastal condition of Stowe Brang Village, Utan District, Sumbawa Regency. The analysis method used is Descriptive Analysis with a combination of Quantitative and Qualitative. To assess the condition of damage to coastal areas, it is necessary to survey the location of mangrove vegetation conditions, how far the coastline is to the pond, and the condition of the river estuary at the site. Furthermore, based on the value of the coastal damage index, the prioritization of handling refers to SE PU No. 11 of 2021. Based on the results of the analysis, there are several factors that affect the occurrence of abrasion at the study site, including factors still lack of vegetation on the beach, flat land slope factors, sandy beach type factors and the absence of coral reefs, sea wave factors that are large enough. To get wave plan data requires wind data for 10 years, tidal data, topographic data and bathymetry. Based on the results of data analysis, the wave height of the 10-year plan with the Gumbel method is 0.4 m. The form of handling efforts that can be done is the addition of mangrove vegetation and can also be done by building coastal protection constructions such as breakwater construction with plain concrete blocks

Floodplain mapping of an ungauged river: A case study on Seti River in Pokhara, Nepal

Settlements and infrastructures along the banks of Seti River in Pokhara, Nepal are at high risk of flood. Floodplain mapping for ungauged Seti River is not straightforward like the one for gauged rivers. Main goal of this study was to prepare floodplain maps along the ungauged Seti River in Pokhara, as a case study, using one-dimensional HEC-RAS model. First, catchment area ratio (CAR) method was applied to find annual flow in ungauged Seti River based on flow data of gauged Mardi station. Once the annual maximum flow was estimated for sufficient time length (i.e., 42 years), peak flood was predicted using Gumbel method for various reaches of Seti River within Pokhara. Thus, estimated peak floods were also compared with the peak floods predicted using Gumbel method based on the annual flow data of Tanahu station. As the specific discharge observed to be comparable with each other (difference ≤ 2.68%), CAR method found be a reliable one that is useful for ungauged river. Then, Cowan’s approach was applied to estimate Manning’s roughness coefficient (n) and used it for calibration of HEC-RAS model. Cowan approach found to be a best alternative for ungauged river as the comparison of modelled flow depth with measured flow depth yielded only 3.82% difference. Finally, 1D hydraulic modelling was performed using calibrated HEC-RAS model with available 12.5 m resolution DEM terrain data. Floodplain maps were prepared based on the HEC-RAS simulation results coupled with Google Earth map. The flood inundation area within Pokhara was found to be 2.76, 3.05, and 3.59 Km2 for the peak flood of 20, 50, and 100 years return periods, respectively. Moreover, Laltin Bazar and Gaighat areas were identified to be at high risk of flood such that these areas found to be inundated with 20 or greater years return period floods, compared to Ramghat area which was observed to be flooded with the peak flood of 50 or more years return period. Floodplain maps of this study could be used for preparing flood hazard maps, planning infrastructures, and flood management.

Rainfall Intensity-Duration-Frequency Relationships: A Robust Foundation for Urban Decision-Making and Flood Management: A Case Study

Ahmedabad, a city in India, experiences varying climatic patterns and is prone to extreme rainfall and relies on established intensity-duration-frequency (IDF) relationships for critical infrastructure planning and flood management. While the city has existing IDF relationships, these curves were established some time ago and still lack well-established IDF Curves. To fill this research gap this study is dedicated to the development of IDF curves for Ahmedabad City, utilizing 45 years of rainfall data (1978 to 2022) sourced from the Indian Meteorological Department (IMD) making our study a pioneering effort in this direction. Employing frequency analysis methodologies, the relationships between rainfall intensity, storm duration, and return periods were established. IDF curves were generated for durations of 5, 10, 15, 30 minutes, and 1, 2, 6, 12 and 24 hours for Ahmedabad City. Short-term rainfall intensities were derived from daily rainfall values using the IMD formula. The empirical approach, Gumbel distribution, and Log Pearson Type-III distribution were applied. The Gumbel method tends to produce slightly higher rainfall intensities for shorter return periods, while the LPT III method exhibits the opposite pattern for longer return periods, such as 25, 50, and 100 years. In general, both approaches yield closely matching results across most return periods. The IDF curves produced in this study offer a versatile set of rainfall scenarios for diverse applications, including the design and modification of hydraulic structures, stormwater management infrastructure, and flood mitigation systems in Ahmedabad City. The outcomes of this research contribute not only to filling a crucial research gap but also empower decision-makers and urban planners with updated and reliable data crucial for enhancing the city’s resilience against extreme rainfall events.

Artifact Assessment in the Skull Base Region of Head CT Images with Various Tilt Angles Relative to the Orbitomeatal Line

The aim of this study was to evaluate artifacts in the skull base region of head computed tomography (CT) images with various tilt angles relative to the orbitomeatal line. CT images of a head phantom acquired by helical and non-helical scanning with the tilt angles set from 0 to 20 degrees in 5-degree increments were evaluated in this study. Regions of interest (ROIs) were set at the cerebellum, temporal lobe, frontal lobe, and basal ganglia in the phantom images. Artifacts were evaluated by the coefficient of variation (CV) of the mean CT value between ROIs and the location parameter (β) of the Gumbel method. The CV and β values increased with increasing tilt angle for both helical and nonhelical images in the frontal lobes, but both decreased in the cerebellar region. In the temporal lobe and basal ganglia, there was no trend of change with tilt angle. Increasing the tilt angle relative to the OM line increased artifacts at the frontal lobes and decreased artifacts at the cerebellar region.

Analisis Kapasitas Sistem Saluran Drainase (Studi Kasus Drainase Jalan Siliwangi Kota Batam)

Batam City is one of the cities in the Riau Archipelago Province with the largest population growth. Along with the development of the city and the increase in population, the need for public facilities and infrastructures also need to be developed, such as on Jalan Siliwangi. Jalan Siliwangi is one of the roads in the Batu Besar area, Nongsa sub-district in Batam city which is experiencing problems with the drainage system. Drainage is a technical measure to prevent excess water due to high rainfall intensity and drain it to a collection point. Rainfall intensity is a condition where rain is highly concentrated and occurs at a certain time. This research was conducted to know whether the Siliwangi Road drainage channel is working optimally so that it can accommodate water during high rainfall. This analysis uses the Gumbel method using extreme values. The extreme values of rain intensity that will be taken into account are several return periods, namely 2, 5, 10, 25, 50, and 100 years. The calculated channel discharge using location data is Q = 0.5637 m3/second, while the planned discharge calculated using rainfall data is Q = 2.064 m3/second. From the results of the analysis of the dimensions of the planned canal found in the field, it does not meet the design capacity so waterlogging occurs, where the height and width of the planning canal are larger. By using the frequency distribution formula of the Gumbel and Log Person Type III methods for the calculation and application of parameters related to the analysis of average data, standard deviation, and determining the frequency of rainfall for the T-year return period in the discussion above, it can be concluded that the drainage channel on Jalan Siliwangi Batam unable to prevent inundation or flooding during high rainfall.

Comparison of Extreme Wind and Waves Using Different Statistical Methods in 40 Offshore Wind Energy Lease Areas Worldwide

With the ongoing global drive towards renewable energy, several potential offshore wind energy lease areas worldwide have come into focus. This study aims to estimate the extreme wind and wave conditions across several newly designated offshore wind lease sites spanning six continents that are crucial for risk assessment and the design of offshore wind turbines. Firstly, the raw data of wind speeds and wave heights prevailing in these different lease areas were obtained. Following this, an in-depth extreme value analysis was performed over different return periods. Two principal methodologies were applied for this comparative study: the block-maxima and the peaks-over-threshold (POT) approaches. Various statistical techniques, including the Gumbel method of moments, Gumbel maximum likelihood, Gumbel least-squares, and the three-parameter GEV, were employed under the block-maxima approach to obtain the distribution parameters. The threshold for the POT approach was defined using the mean residual life method, and the distribution parameters were obtained using the maximum likelihood method. The Gumbel least-squares method emerged as the most conservative estimator of extreme values in the majority of cases, while the POT approach generally yielded lower extreme values compared to the block-maxima approach. However, the results from the POT approach showed large variations based on the selected threshold. This comprehensive study’s findings will provide valuable input for the efficient planning, design, and construction of future offshore wind farms.

PERENCANAAN DRAINASE PERUMAHAN POGOH RESIDENCE 2 KELURAHAN TANJUNG PAKU, KOTA SOLOK

Abstract: Drainage has the meaning of draining, draining, dumping, or diverting water. In general, drainage is defined as a series of water structures that function to reduce or remove excess water from an area or land, so that the land can be used optimally. Drainage is also defined as an attempt to control groundwater quality in relation to salinity. The purpose of this study is to plan the drainage of Pogoh Residence 2 Housing, Tanjung Paku Village, Solok City. The data or information used is secondary data obtained from Tanjung Paku Village and primary data obtained from direct surveys in the field. So it is necessary to plan an economical drainage dimension that can drain water more optimally with a smaller cross-sectional pressure or drainage wall for the Pogoh Residence 2 Housing area with a trapezoidal channel type. After analyzing the calculation, it is found that the flow rate Q = 0.60 m³/sec with the top width b1 = 0.30 m, height h = 0,40 m, bottom width b2 = 0.25 m and flood water discharge for a 10 year return period. is Qmax = 0.54 m³/s. The data processing method uses manual calculations in accordance with the Gumbel Method, Rational Method and Haspers Method. to calculate the rain discharge, and the Manning formula for channel discharge.Keywords: Gumbel, Rational, Haspers, Trapezoidal Drainage Methods.

PERENCANAAN SALURAN SEKUNDER D.I MANINJAU KECAMATAN PANTI KABUPATEN PASAMAN

Pasaman Regency is one of the regencies in West Sumatra Province, the capital of Pasaman Regency is located in Lubuk Attitude. This district has an area of 3,947.63 km2 and a population of 253,299 according to the 2010 population census and 301,444 people in 2021 with a government covering 12 sub-districts and 37 Nagari. Geographically, Pasaman Regency is crossed by the equator and is located at 0°55' North Latitude to 0°6' South Latitude and 99°45' to 100°21' East Longitude. The Maninjau area of Panti sub-district has an agricultural area of 200 ha. Regency by using primary and secondary data collection and using rainfall data for the last 10 years. data processing using the harsper and gumbel methods. From the results of the calculation of the channel planning dimensions, the calculation results where the Q value is 4.44 m³/sec is greater than the Qmax value 3.90 m³/s from the calculation results using the Gumbel method for R 5TH is 334 mm and The results of calculations using the Haspers method with a Q value of 3.90 m³/sec. The results of the study can be used as input and reference for planning irrigation needs in the future. the results of this research on irrigation can provide the greatest benefit to the community, and the purpose of this irrigation itself can be achieved and beneficial as optimally as possible.Keywords: Channel Dimensions, Water discharge rainfall, HaspersMethood, Gumbel Method, Secondary Channel

PERENCANAAN JARINGAN IRIGASI D.I TANJUANG BALIK KECAMATAN SUNGAI PUA KABUPATEN AGAM

The Tanjuang Balik Irrigation Area irrigates an area of 110 hectares of rice fields. The water source for the Tanjuang Balik Irrigation Area comes from Dam Ampuah River which irrigates from Ampuah to Koto Panjang. The Tanjuang Balik Irrigation Area is ± 7 km from the center of Bukittinggi City. In the Irrigation Network Planning, design analysis must be carried out which includes analysis of rainfall, calculation of discharge, and channel dimensions. So that the irrigation system can be interpreted as an effort to provide optimal and efficient water supply in order to get maximum crop production results. The main objective of the Tanjuang Balik Irrigation Network Planning is to maintain food self-sufficiency, with an area of 110 hectares of rice fields, from the area of the rice fields it is expected to harvest 8 tons / ha each time harvest. By repairing the network and providing adequate water as needed. In planning the dimensions of the channel obtained through the rainfall process using the harpes method and the gumbel method. Discharge data is needed to determine the calculation of water availability at the intake building. To get a good discharge calculation, it is necessary to record long-term river discharge data, this is needed to reduce the occurrence of too large calculation data storage. the calculation results the gumbel analysis of 1.028 mm and the calculation result from the HASPERT analysis of 0,04 m/dt the result of the planned discharge is 1,62 m/dt for the Tertiary channel planning in D.I Tanjuang Balik , it is planned to be able to accommodate water when the discharge is maximum.Keywords:discharge, Dimension of GUMBEL and HASPERT, and Tertiary rain fall channels.

Analysis of extreme wind wave based on weibull and fisher tippett I (gumbel) distribution

Extreme waves are an important factor in coastal structures both offshore structures and onshore structure design. However, due to the difficulty of measuring ocean waves, many areas still do not have measured wave height data. Data processing is required to transform the measured wind data into wind-wave value in order to solve this issue. This study aims to analyze extreme waves based on wind data from BMKG Panjang and BMKG Radin Inten II stations. For analysis of determination of extreme waves can be done by using Fisher Tippet Type I (Gumbel) and Weibull methods. The result show that Weibull method gives the higher value than Gumbel method, with the maximum percentage of 43.04% at the 2-year return period.

Rainfall-driven machine learning models for accurate flood inundation mapping in Karachi, Pakistan

Urban pluvial flooding (UPF) has emerged as a serious natural hazard, especially in recent years. Previous research on UPF prediction has mainly focused on hydrological models, which required a large amount of data. However, a data-driven method can significantly reduce the computational cost by using rainfall amounts to predict pluvial flooding. Intensity-duration-frequency (IDF) curves using the Gumbel method can provide a better interpretation of the correlation between rainfall intensity, duration, and probability of occurrence of a given rainfall amount. In this study, machine learning models (ML) for rainfall amounts were used to identify flood points in a case study conducted in Karachi, Pakistan. Thirteen inundation factors were used for the ML models, including a new factor, curve number. Ten ML models were applied first on training and then on validation data, yielding the inundation points. The training and validation process of the model included 384 flood points. Several statistics were used to verify the performance and accuracy of the model. We found that the Light Gradient Boost Machine and Random Forest Classifier models were the most accurate in training and validating the model, while the Decision Tree and K-Nearest Neighbor models were the least accurate in training and validating the model. The study provides valuable information for decision makers to protect communities from flood hazards by incorporating the likely intensity and duration of rainfall events and carefully selecting influencing factors into flood event prediction models.

A comparison study of power performance and extreme load effects of large 10‐MW offshore wind turbines

AbstractThe utilisation of offshore wind turbines has rapidly increased in the last decade, which has resulted in a steady increase in wind turbine sizes. The global average offshore wind turbine size has increased from 1.5 MW to 6 MW in the last two decades. The research community has started to investigate huge 10 to 15 MW offshore wind turbines in recent years, resulting in the study of very innovative floating wind turbines using various substructure technologies. With this backdrop, this paper will investigate and thoroughly compare the power performance of extreme load effects of a large offshore 10 MW turbine installed on the monopile, spar, and semisubmersible substructures. This is performed by using the average conditional exceedance rate (ACER) and Gumbel methods to predict the extreme responses under the operating conditions of 8, 12, and 16 m/s mean wind speed, representing the below‐rated, rated, and above‐rated regions, respectively. The results show that the power performance and extreme loads experienced depends significantly on the operating regions. The mean power generation between the three different types of offshore wind turbines (OWTs) are closely in the whole operating range, which standard deviations differ significantly. Large standard deviations of power generation appear in the spar turbine under the below‐rated condition. Further, it was observed that the spar wind turbine generally experiences larger extreme loads due to larger platform pitch motion. In addition, the ACER method shows a better prediction for the 1, 2 and 5‐year extreme responses than the Gumbel method, which is due to the relatively poor data fitting of the Gumbel method at the upper tail. The study is believed to consolidate and close the knowledge gap in understanding wind turbine responses across the most common offshore substructure technologies and provide a basis for design and deployment of OWTs.

Perencanaan Kebutuhan Pompa Untuk Sistem Dewatering Tambang Emas Desa Bakan Kabupaten Bolaang Mongondow

One of the most frequent problems in open pit mining methods is the presence of water puddles in the lowest elevation of the pit. This often causesthe delay of production activities.Therefore, it is a need to design a good drainage system planning to deal with it. In this regard, pumps were needed. The aim of this research was to determine the of needed pumps and the best type of pumps to remove water in the pit effectively. This research used maps of mining sequence planningwhich would be then analysed with software Surpac 6.5.1.This was to identifythe width of catchment area. Furthermore, the rainfall data wasanalysed using polygon Thiessen method. The next process is to determine the rainfall plan with Gumbel method. Next was to determine the rainfall intensity plan by using Mononobe equations. Following this was determine the total discharge using rational method. Finally, the process was ended with the determining of the pumps type and pumps spesification to dry the water puddles in the pit. the result indicated that in the sump of the 3rd quarter 2020 with 100 l / sec pumping flow, pumping time 14 hours, total head 76.26 m, recommended pump type is a Multiflo MFC 385 with a rotation speed of recommendation per minute of 1400-1500, and an efficiency of 60% -65%. For 4th quarter sump 2020 with 105l / sec pumping discharge, 20 hour pumping time, total head 105,91 m, recommended type of pump is Multiflo MFC 385 with rotation speed recommendation permenit 1600-1700, with efficiency 60%. For the 1st quarter sump 2021 with a pumping rate of 102 l/sec, the pumping time is 20 hours, total head is 122.26 m, the recommended type of pump is Multiflo MFC 385 with a rotation speed of recommendation per minute 1700-1800, with 50% -60% efficiency. It can be suggested that it is necessary to add one more pump, Multiflo MFC 385, for the dewatering pit process.

Extreme response analysis of a floating vertical axis wind turbine based on modified environmental contour method

Floating vertical axis wind turbine (FVAWT) is a potential concept that could compete with the floating horizontal axis wind turbine (FHAWT) in the offshore wind industry. For a reliable FVAWT design, accurate prediction of extreme structural responses is crucial for ultimate limit state (ULS) design evaluation. Extreme structural responses of offshore wind turbines depend on operational modes and could present non-monotonic behavior with respect to environmental parameters. In this study, the extreme responses of a 3-bladed H-rotor semi-submersible FVAWT are evaluated using a simplified engineering approach, i.e., the modified environmental contour method (MECM). Judging from the response characteristics of the FVAWT with respect to increasing wind speed, the environmental contour with a return period of the cut-out wind speed is used. Along the selected environmental contour, the cut-out wind speed and the corresponding most probable sea state is chosen as the environmental design point. To generate statistical samples of structural responses, the Monte Carlo (MC) method is applied by carrying out fully-coupled time domain simulations under the selected environmental loadings. The Gumbel method, the Weibull tail method and the mean upcrossing rate (MUR) method are used to extrapolate the 50-yr long-term extreme responses. With a sufficiently large sample size, e.g. 100 MC simulations, the estimated extremes using different extrapolation methods are in close agreement with each other. However, the Weibull tail and MUR methods reduce the statistical uncertainty of the estimates due to higher data utilization. For practical engineering applications, massive amount of MC simulations is often not desirable. Therefore, the accuracy and statistical uncertainty of the estimated extreme responses associated with a reduced sample size is also investigated. For a sample of 10 simulations, the Weibull tail and MUR methods are able to predict extreme responses that are closer to the estimates using 100 simulations. The MUR method results in the lowest statistical uncertainty of the estimates.

Probable maximum precipitation analysis of high rainfall regions in India

Uttarakhand, Maharashtra, Assam & Meghalaya are the potential areas to study the precipitation, perform trend analysis and calculate the probable maximum precipitation. Probable Maximum Precipitation (PMP) has virtually zero risk of being exceeded for a given catchment area over a certain duration of time. The present work applies Hershfield Method to determine the PMP for rainfall data for the high rainfall regions of Uttarakhand, Maharashtra, Assam & Meghalaya (Assam and Meghalaya are considered as one region). Gumbel method, which is an extreme value distribution function is used to obtain the extreme value (EV) of precipitation. Further, the obtained PMP and EV values are compared with high rainfall months of La Niña years. Observation of the results showed that the obtained values from Hershfield Method are greater than the La Niña years precipitation values that have been observed till 2017, thus validating the obtained results. The outcomes from Probable Maximum Precipitation (PMP) works give insights into the extreme rainfall that can ever happen in a given catchment. The result obtained serves as indispensable input data for designing structures like dams, reservoirs, spillways, flood protection walls, sluice gates, weirs, etc. The design life of hydraulic structures is worked out using Probable Maximum Precipitation (PMF). The adopted technique and results of this study can be directly used as a design parameter for design as well as for water resources management.

Flood Frequency Analysis of Lower Krishna Basin using Gumbel Method at Prakasam Barrage, Vijayawada, Andhra Pradesh

The Gumbel Distribution approach is used in this study for analyzing the flood frequency in the lower Krishna basin. It is a probability distribution method that was used to predict river annual peak discharges from 2007 through 2021 (14 years). The probability distribution function was used to calculate the return period for 2, 5, 10, 15 and 20 years and estimated discharges were produced. The flood for the next 10 years will be 1239523 Cusecs and the predicted flood discharge for the next 25 years will be 1586634 Cusecs. The expected flood from 2 to 25 years has also indicated a consistent growing tendency in selected Prakasam barrage station. This type of information would be useful in the planning of engineering projects such as reservoirs, bridges, flood mitigation structures etc. Flood hazard maps can also be created using these methodologies.