Maximum Flood Discharge Research Articles

Selected Crater and Small Caldera Lakes in Alaska: Characteristics and Hazards

This study addresses the characteristics, potential hazards, and both eruptive and non-eruptive role of water at selected volcanic crater lakes in Alaska. Crater lakes are an important feature of some stratovolcanoes in Alaska. Of the volcanoes in the state with known Holocene eruptive activity, about one third have summit crater lakes. Also included are two volcanoes with small caldera lakes (Katmai, Kaguyak). The lakes play an important but not well studied role in influencing eruptive behavior and pose some significant hydrologic hazards. Floods from crater lakes in Alaska are evaluated by estimating maximum potential crater lake water volumes and peak outflow discharge with a dam-break model. Some recent eruptions and hydrologic events that involved crater lakes also are reviewed. The large volumes of water potentially hosted by crater lakes in Alaska indicate that significant flowage hazards resulting from catastrophic breaching of crater rims are possible. Estimates of maximum peak flood discharge associated with breaching of lake-filled craters derived from dam-break modeling indicate that flood magnitudes could be as large as 103–106 m3/s if summit crater lakes drain rapidly when at maximum volume. Many of the Alaska crater lakes discussed are situated in hydrothermally altered craters characterized by complex assemblages of stratified unconsolidated volcaniclastic deposits, in a region known for large magnitude (>M7) earthquakes. Although there are only a few historical examples of eruptions involving crater lakes in Alaska, these provide noteworthy examples of the role of external water in cooling pyroclastic deposits, acidic crater-lake drainage, and water-related hazards such as lahars and base surge.

Characteristics and process controls of statistical flood moments in Europe – a data-based analysis

Abstract. Many recent studies have sought to characterize variations of the annual maximum flood discharge series over time and across space in Europe, including some that have elucidated different process controls on different statistical properties of these series. To further support these studies, we conduct a pan-European assessment of process controls on key properties of this series, including the mean annual flood (MAF) and coefficients of variation (CV) and skewness (CS) of flood discharges. These annual maximum flood discharge series consist of instantaneous peaks and daily means observed in 2370 catchments in Europe without strong human modifications covering the period 1960–2010. We explore how the estimated moments MAF, CV and CS vary due to catchment size, climate and other controls across Europe, where their averages are 0.17 m3 s−1 km−2, 0.52 and 1.28, respectively. The results indicate that MAF is largest along the Atlantic coast, in the high-rainfall areas of the Mediterranean coast and in mountainous regions, while it is smallest in the sheltered parts of the East European Plain. The CV is largest in southern and eastern Europe, while it is smallest in the regions subject to strong Atlantic influence. The pattern of the CS is similar, albeit more erratic, in line with the greater sampling variability of CS. In the Mediterranean, MAF, CV and CS decrease strongly with catchment area, suggesting that floods in small catchments are relatively very large, while in eastern Europe this dependence is much weaker, mainly due to more synchronized timing of snowmelt over large areas. The process controls on the flood moments in five predetermined hydroclimatic regions are identified through correlation and multiple linear regression analyses with a range of covariates, and the interpretation is aided by a seasonality analysis. Precipitation-related covariates are found to be the main controls of the spatial patterns of MAF in most of Europe except for regions in which snowmelt contributes to MAF, where air temperature is more important. The Aridity Index is, by far, the most important control on the spatial pattern of CV in all of Europe. Overall, the findings suggest that, at the continental scale, climate variables dominate over land surface characteristics, such as land use and soil type, in controlling the spatial patterns of flood moments. Finally, to provide a performance baseline for more local studies, we assess the estimation accuracy of regional multiple linear regression models for estimating flood moments in ungauged basins.

Analisis Hidrograf DAS Poso dengan Metode Hidrograf Satuan Sintetis Snyder dan Hidrograf Satuan Sintetis Soil Conversation Service (SCS)

The Poso River is a river located in Poso Regency, Central Sulawesi Province, which has a length of 74.58 km, and watershed area of 1092.810 km2. Energy in the Poso River is used for hydroelectric power plant (PLTA). With the construction of the Poso hydropower plant, maximum flood discharge data is needed for the prevention of Poso hydro power plant safety. In calculating the flood discharge, the method used is a synthetic unit hydrograph. Synthetic unit hydrograph is a graph of the relationship between flow rate (Q) and time (t). In this study, the method used to calculate the designed flood discharge is the Snyder synthetic unit hydrograph method and the Soil Conversation Service (SCS) synthetic unit hydrograph. The aims of this study are to determine the largest flood discharge value and to determine the hydrograph shapes of the two methods. The parameters that will be obtained from both methods are peak time (Tp), base time (Tb) and peak discharge (Qp). From the analysis it can be found that in the Snyder SUH method, the peak time (Tp) is 12.616 hours, the base time (Tb) is 67.276 hours with a peak discharge (Qp) of 21.672 m3sec. Whereas in the SCS SUH method, the peak time (Tp) is 10.954 hours, the base time (Tb) is 57.268 hours with a peak discharge (Qp) of 20.751 m3/sec. The result demonstrates the result that the largest flood discharge has occurred in the Snyder SUH method.

Influence of post-pyrogenic successions of the forests of the Urals on the formation of maximum rainfall flood discharges

The issues of losses on the crowns of forest stands in the conditions of forest successions after fires and associated changes in the maximum discharge of rainfall floods are considered. The results of complex field, experimental work, deterministic modelling are presented. It has been established that with the complete burnout of forests in the catchment, the maximum flow rates can increase by 40% compared to the initial state of the forests, and with the restoration of forests, the maximum flow rates of floods again decrease by 15-20% over a 20-year period.

FLOOD INUNDATION AND DAM BREAK ANALYSIS FOR DISASTER RISK MITIGATION (A CASE STUDY OF WAY APU DAM )

This paper presents a numerical modeling to simulate flood inundation and dam break analysis of Way Apu dam for an emergency action plan (EAP), by considering EAP guidelines for ICOLD (International Committee on Large Dam). The Way Apu dam, located in Way Apu River, Maluku, Indonesia is a multi-purpose dam constructed mainly for irrigation, hydropower, water supply, and flood control. Therefore, the dam’s outflow discharge needs to be analyzed, due to the large amount of rainfall in eastern Indonesia. Thus, there is a need to analyze flood inundation mapping and dam break simulation in a bid to identify the flood mitigation risk zone and early warning system, within the downstream area of Way Apu dam. In this study, the flood inundation mapping and dam break simulation were analyzed using HEC-RAS 5.0.7. The analysis results of flood routing generate the outflow peak discharge reduction over spillway were 7.36 % (Ten years return period discharge, Q10) and just 2.14% (Probable maximum flood discharge, QPMF), indicating the simulation results of Hec-Ras 5.0.7 model for conditions with or without dam break did not show significant difference in dam’s downstream area. According to these results, 6 sub-districts are affected by the flood (Grandeng, Waeleman, Wanakarta, Waenetat, Debowae, Mako) with a maximum flood height range between 1-2.5 m (Q10) and 2.9-4.2 m (QPMF). The simulation results of arrival time also showed the estimation of evacuation time for QPMF ranges from 6 - 12 hours.

The Influence of Weathering, Water Sources, and Hydrological Cycles on Lithium Isotopic Compositions in River Water and Groundwater of the Ganges–Brahmaputra–Meghna River System in Bangladesh

The silicate weathering of continental rocks plays a vital role in determining ocean chemistry and global climate. Spatiotemporal variations in the Li isotope ratio (δ7Li) of terrestrial waters can be used to identify regimes of current and past weathering processes. Here we examine: 1) monthly dissolved δ7Li variation in the Ganges River’s lower reaches; and 2) the spatiotemporal variation of river water of the Brahmaputra, Meghna rivers, and groundwater in Bangladesh. From the beginning to maximum flood discharges of the rainy season (i.e., from June to September), Li concentrations and δ7Li in the Ganges River show remarkable changes, with a large influence from Himalayan sources. However, most Li discharge across the rainy season is at steady-state and strongly influenced by the secondary mineral formation in the low-altitude floodplain. Secondary mineral formation strongly influences the Meghna River’s Li isotopic composition along with fractionation lines similar to the Ganges River. A geothermal input is an additional Li source for the Brahmaputra River. For groundwater samples shallower than ∼60 m depth, both δ7Li and Li/Na are highly scattered regardless of the sampling region, suggesting the variable extent of fractionation. For deep groundwater (70–310 m) with a longer residence time (3,000 to 20,000 years), the lower δ7Li values indicate more congruent weathering. These results suggest that Li isotope fractionation in rivers and groundwater depends on the timescale of water-mineral interaction, which plays an essential role in determining the isotopic signature of terrestrial Li inputs to the ocean.

Comparison of different estimation methods for extreme value distribution

The extreme value distribution was developed for modeling extreme-order statistics or extreme events. In this study, we discuss the distribution of the largest extreme. The main objective of this paper is to determine the best estimators of the unknown parameters of the extreme value distribution. Thus, both classical and Bayesian methods are used. The classical estimation methods under consideration are maximum likelihood estimators, moment’s estimators, least squares estimators, and weighted least squares estimators, percentile estimators, the ordinary least squares estimators, best linear unbiased estimators, L-moments estimators, trimmed L-moments estimators, and Bain and Engelhardt estimators. We also propose new estimators for the unknown parameters. Bayesian estimators of the parameters are derived by using Lindley’s approximation and Markov Chain Monte Carlo methods. The asymptotic confidence intervals are considered by using maximum likelihood estimators. The Bayesian credible intervals are also obtained by using Gibbs sampling. The performances of these estimation methods are compared with respect to their biases and mean square errors through a simulation study. The maximum daily flood discharge (annual) data sets of the Meriç River and Feather River are analyzed at the end of the study for a better understanding of the methods presented in this paper.

Desain Embung Berbantu Komputer Di Kali Sabi Kota Tangerang Banten

The problem of flooding in the city of Tangerang is a problem that requires further treatment. Improper management of water resources is one of the factors that cause flooding which results in losses for the community.The activity carried out as an effort to prevent floods is the creation of water retention. The purpose of this research is to know the flood discharge in Kali Sabi, know volume that must be accommodate, determine the capacity for water retention, produce an effective technical water retention design, and obtain an estimated cost of making the water retention. This research was conducted in April-July 2020 in Uwung Jaya Village, Tangerang City using topographic and rainfall data for 12 years. Rain distribution using the Log Pearson III . The results of the analysis revealed that the effective rainfall of the 5-year return period was 66.314 mm with a maximum flood discharge of 83.69 m³. Volume runoff that had to be overcome was 1084.64 m³. The effective storage capacity of the water retention is ± 1975 m³ with an area of ± 525 m², with construction materials, reinforced concrete with K-225 quality and 10 mm diameter reinforcement. Water retention has two steel sliding gates at the inlet and outlet. Construction of the water retention is estimated to cost Rp. 813,839,000.00.

Pengendalian Banjir di Daerah Aliran Sungai (DAS) Ampal Kota Balikpapan: Analisa Kapasitas Sungai

Ampal acts as the main channel in ampal drainage system. This river is located in urban areas that serves to drain the water from the upstream to the sea (Makassar Strait). Channel reduction, occurred in the middle to downstream channel, caused by sedimentation leads to capacity reduction, further its unability to drain the flood. The purpose of this study is to determine the river capacity as an alternative flood prevention. Hydrology and hydraulics data are used in the analysis process. In flood discharge calculation, the SCS-CN (Soil Conservation Service - curve number) runoff calculation method is used. Based on the data and analysis, the maximum flood discharge values flowing in the Ampal catchment are 100.20 m3/s for the middle section and 170.40 m3/s at the downstream. The central part of the Ampal River capacity is 60.69 m3/sec. and 168.50 m3/sec. at the downstream. Using three additional bozem, the problem at Section 3 Ampal River can be solved, with 7.70 m3/s flood discharge reduction.

A Framework of Dam-Break Hazard Risk Mapping for a Data-Sparse Region in Indonesia

This paper introduces a new simple approach for dam-break hazard mapping in a data-sparse region. A hypothetical breaching case of an earthen dam, i.e., the Ketro Dam in Central Java, (Indonesia) was considered. Open-access hydrological databases, i.e., TRMM and CHIRPS, were collected and compared with the rainfall ground station data to ensure data quality. Additionally, the 3-h rainfall distribution of the TRMM database was employed and validated with the measured data to establish the 24-h rainfall distribution of the probable maximum precipitation. The probable maximum flood discharge was computed with the SCS method, and the reservoir routing computation was conducted to determine the possible breaching mechanisms. The result shows that the Ketro Dam proves safe against overtopping, and thus only the piping mechanism has been taken into consideration. Using the breaching hydrograph, the open-access Digital Elevation Model MERIT Hydro, and the high-performance shallow water model NUFSAW2D, the flood propagation to the downstream part of the dam was simulated, enabling fast computations for different scenarios. The quantification of the susceptibility rate of urban areas was eased with overlay analysis utilizing InaSAFE, a plugin for the QGIS model. This study shows that even for a data-sparse region, the recent open-access databases in terms of hydrological and hydraulic aspects may be used to generate a dam-break hazard map. This will benefit the related stakeholders to take proper action to reduce the loss of life.

Debit Banjir Rancangan DAS Tojo Metode HSS ITB 1

Floods often occur in several regions in Indonesia. The problem is the flooding with its uncertain characteristics is one of the environmental problems that has not been handled optimally. The method of converting rain data into discharge data for flood analysis has been widely presented in previous studies. The methods used to analyze flood discharge also vary, starting from rational, empirical, statistical models to the unit hydrograph model. This research aims to determine the flood discharge design for return periods 2, 5, 10, 20, 25, 50, and 100 years in Tojo watershed, Tojo Una-una Regency using the synthetic unit hydrograph method of ITB-1. Research methods are data collection and data analysis. Data collection was carried out at several agencies and collecting from online sources. Results of this research design flood discharge that was analyzed by synthetic unit hydrograph of ITB-1 method. The maximum design flood discharge at Tojo watershed are 82.375m3/s for a 2-year, 98.21 m3/s for a 5-year, 104.77 m3/s for a 10-year, 111.83 m3/s for a 20-year, 113.3 m3/s for a 25-year, 118.87 m3/s for a 50-year, 123.86 m3/s for a 100-year return period

Application Research of Mathematical Model in Tallo River Flood Analysis

Rivers are natural elements, and rivers play an important role in shaping the style of the community. The Tallo River in Makassar has advantages in economy, entertainment and transportation. But almost every year, the area along the river is always flood. this probelm can be solved by examine the phenomena and conditions of the level of flood watersheds vulnerability using hydrological approach through Muskingum kinematic methods, which is a common flood routing methods. By approaching the hydrological conditions of the Tallo river watershed, the results of this study are expected to provide the best alternative treatment options. The flood discharge value is executed based on the rainfall data that collected from three stations along the river namely Hasanuddin, Malino and Senre. After that, the flood discharge plan is conducted to obtaing the outflow value by using the inflow value through Muskingum method. The length of the river considered in this study is about 20 km, and it is divided into 5 segments every 4 km. The x value is between 0.1 and 0.3, and the K value is between 0.16-0.57. The obtained maximum flood discharge from the Muskingum calculation for the 2-year return period occurred at 801,330 m3/sec with an X value = 0.1 and K = 0.58.

Analysis of water surface profile and flood discharge of Cijangkelok river

The downstream of Cisanggarung River Basin is often affected by floods with an increasing degree of intensity every year. For instance, the 2017 severe floods caused economic losses and fatalities, especially along the border of Cirebon and Brebes Regency. The flood was attributed to high rainfall intensity and the meeting point between Cisanggarung River and the Cijangkelok River. Therefore, a study on the flood in this area is highly vital to reduce the affected area in the future. This study aims to analyze the maximum flood discharge capacity in the Cijangkelok River and analyze cross-sectional river capacity using numerical model simulations. Based on the hydrological calculations and analysis, it is known that the planned flood discharge in the Cijangkelok River in the 5-year return period is 256,25 m3/s, the 10-year return period is 310,35 m3/s, the 25-year return period is 392,91 m3/s, and the 50-year return period is 465,93 m3/s. The analysis of the water surface profile of each flood discharge return period shows that overflow occurs in the cross-section 4090, 8254, 9166, 9753, and 11970. It is also revealed that the existing cross-section of the Cijangkelok River is unable to accommodate hydrological discharge. Field visit results show that the river has siltation or sedimentation, the river embankments are irregular, and land-use changes around the Cijangkelok River that affects the river.

Technical Evaluation and Boezem Bratang Operation Patterns In Surabaya

Surabaya is the second largest and most populous city in Indonesia and is inseparable from the problem of flooding which is still flooded the area of East Surabaya.Flooding is caused by Bratang boezem unable to accommodate rainwater discharge. Boeang Surabaya has an area of 19,900 m2, has two systems namely flood gates and flood pumps. The floodgate system will work to drain the boezem bratang water to wonokromo river if the water elevation at Wonokromo River is at under the elevation of Bratang boezem water and flow Gravitatively while the pump system will work if the floodgate system is no longer functioning. To overcome the problem of flooding in the region, it is necessary to conduct hydrological and hydraulics analysis by performing boezem routing to determine the Boezem capacity whether it can accept the planned rain discharge. a depth of 3 m is unable to accommodate a maximum flood discharge period of 2.5 and 10 years. so it is planned to increase the boezem depth which was originally 3 m to 4.6 m, and increase the pump capacity which was originally from 10.5 m3 / s to 14 m3 / s.From the plan, after the hydrologic and hydraulics analysis using Boezem routing, Boezem has been able to accommodate the planned rain discharge.

Occasional Floods On The Rivers Of Russian Plain In The 20<sup>Th</sup> –21<sup>St</sup> Centuries

The article focuses on the study of flood flow changes on the rivers of the European Territory of Russia (ETR) in the last thirty years. This is an extremely important problem, as with floods, whose contribution to the structure of the annual flow of European rivers in recent decades has been increasing, the most destructive floods are associated. On the example of 55 representative hydrological gauge stations located on the ETR in regions with different conditions of runoff formation, the features of both summer and winter floods formation are considered. It has been established that over the past thirty years on the most rivers there has been an intensive reduction in the ratio of volumes and maximum flood discharges in relation to the similar characteristics of the basic runoff. Increased groundwater supply is observed, and the absence of significant freezing of the soil leads to an increase in infiltration. The volumes of flood runoff and the basic runoff become comparable or the proportion of the latter begins to prevail. The main reason for the increase in minimum water discharge is associated with an increase in flood flow under the influence of more intense and prolonged thaws. A distinctive feature of the water regime of recent decades has been the flood peaks in almost any season of the hydrological year. In the middle and southern part of the ETR – in the basins of the Volga, Oka, Vyatka, Don Rivers – there is an increase in low-water flow and in the quota of flood in annual flow. On some rivers of the ETR, the spring flood runoff currently accounts for less than 50% of the annual runoff.

The Integration of Retention Pond And Composite Sluice in Flood Prevention in Makassar City

in 2018, Badan Pengkajian dan Penerapan Teknologi (BPPT) has developed composite sluice for controlling flood goals. The integration of retention pond and composite sluice deemed necessary to be analyzed as the integrated system as a flood disaster mitigation effort. This study aims to give a brief overview of the suitable retention pond capacity, which is integrating with composite sluice as a flood prevention effort. The retention pond designed in this study requires rainfall data, land use data and topography map. This study method uses empirical formulation based on statistical parametric on hydrology analyze and hydraulic analyze as a basis of retention pond capacity calculation and composite sluice as flood controller. The result of this study are; the maximum flood discharge in 10 years return period is 103,28 m3/s, while the riverbed discharge capacity with 8 meters width is 68,29 m3/s. To prevent flooding the retention pond volume with capacity volume in 1.117.214,24 m3 has required. In sluice practical width calculation for the retention pond, the resulting amount is 28,70 meters. It takes 32 units of composite sluice if the current needs to be maintained. The side composite sluice width has obtained 1 meter while the total composite sluice building width with four units for the retention pond is 6,4 meters.

Predviđanje maksimalnih godišnjih poplavnih protoka primjenom umjetnih neuronskih mreža

Predviđanje maksimalnih godišnjih poplavnih protoka primjenom umjetnih neuronskih mreža

Numerical evaluation of the general flow hydraulics and estimation of the river plain by solving the Saint–Venant equation

Continuity and momentum equations govern the movement of unsteady flows in open channels, known as Saint–Venant equations. Numerical models of flood routing are classified according to the simplifications made in these equations. Among the flood routing methods, one can refer to dynamic wave and kinematic models and the Att-Kin and Muskingum hydrological models. The kinematic-wave model solves the Saint–Venant equations approximately by considering the gravity and the frictional force terms. This method assumes that the slopes of the energy gradient and the bed slope are equal. The full dynamic wave model uses all the terms in the Saint–Venant equation to simulate unsteady flows. Besides, given the historical records of the past floods and based on the flow continuity equation, the Att-Kin and Muskingum hydrological models deal with flood routing operations. This study describes the principles of Saint–Venant equations and numerical models of dynamic and kinematic-waves, as well as Att-Kin and Muskingum models, the results of which are compared. For this purpose, the Mehrian River range was used. The maximum flood discharge, the maximum area of the river flood plain, and the maximum flood flow width were estimated by presenting a new mathematical relation. The results showed that the MIKE 11 dynamic wave model yields better results than other models by solving partial differential equations. Moreover, among the hydrological methods, the mathematical flood routing and zoning indicate the closeness of Muskingum hydrological results using the least-squares model and the least error with the numerical values of the software for the observed flood.

Hydrodynamic simulation of a dam breach of Cipanas Dam using HEC-RAS 5.0.5

Dams have many benefits for living creatures. On the other hand, dam breaks may also become disasters that cause potential losses of life and property. The Cipanas Dam has been planned for construction in Sumedang, West Java, and will have a storage capacity of up to 210 million m3. The area downstream of the Cipanas Dam contains many major infrastructures such as the Cikopo-Palimanan Toll Road and Kertajati International Airport that can be impacted by dam breach floods. This study analysed Cipanas Dam breach flow using HEC-RAS 5.0.5. The simulation assumed that a dam breach occurred through piping with 5 scenarios of breach time formation. The simulation resulted in flood hydrographs and flood inundation maps of the area downstream of the dam. The findings revealed that a breach formation time of 1 hour had the greatest flood effect. The maximum flood discharge was 38, 823.3 m3s-1 with a released water volume from the reservoir of 178, 814, 590 m3. The arrival time of the flood at the Cikopo-Palimanan Toll Road Bridge was 3 hours 45 minutes after the breach occurred, and the maximum flood depth was 15.78 m. Kertajati International Airport was not affected by the flood discharge.

Regional flood frequency analysis for flood index estimation in hydrologic regions with limited flood data

The objective of this study is to establish a regional relationship between mean annual peak flood and the catchment area based on the annual peak flood frequency analysis. Annual peak flood time series for various gauging sites of six basins in north part of Iraq are used in analysis. The procedure of analysis is approached by scaling a regional flood frequency distribution (index-flood of catchment) which is defined here as the mean annual maximum flood discharge and estimated by linear regression using physiographic and climatic catchment properties. The index-flood method was found to have slightly better prediction accuracies over the direct-regression method. The coefficient of determination R2 between reference and estimated index-floods is relatively high in most cases for all the gauging stations. All regions give very high R 2 correlation and the best model is the model (2), which is also associated with minimum value of RMSE.