Maximum Flood Level Research Articles

Reservoir optimal operation to adapt the non-stationary hydrological series<sup>*</sup>

为完善变化环境下水库防洪调度方案，建立了集水文非一致性诊断、水文模型还现、设计洪水计算与水库调度规则优化于一体的水库适应性调控方法体系，并应用于沂沭泗水系仕阳水库.结果表明，仕阳水库入库洪水变异点发生在1975年；利用新安江模型对水文序列还现处理，得到满足一致性的设计洪水，其洪峰、最大24 h和最大72 h洪量均值，较原设计分别增大了19.7%、14.5%和10.0%；建立了以防洪效益最大为目标函数的水库优化调度模型，采用动态规划进行求解.提出的适应性调度方案在20年、100年、1000年和5000年一遇设计洪水条件下，较水库现行设计方案最高洪水位分别降低了0.32、0.11、0.19和0.11 m.;To improve reservoir operation rules under changing environment, this paper proposed adaptive operation methodologies that include the hydrological series inconsistent testing→backwards restore by hydrological model→design flood calculation→optimal operation of reservoir for flood control safety. The proposed methodologies were applied to the Shiyang Reservoir, which located at the Yi-Shu-Si river system. The results have shown that the change-point of this reservoir inflow flood is 1975. The inflow flood that satisfies the assumption of hydrological stationery were calculated by the Xin'anjiang model, and the hydrological consistent design floods acquired based on it. Compared with the original design, the mean values of flood peaks, maximum flood volume during 24 hours and 72 hours of the new design floods increased 19.7%, 14.5% and 10.0%, respectively. The optimal reservoir operation model based on the objective function of maximizing the flood control benefit is established and solved by dynamic programing. Under design flood with 20-year, 100-year, 1000-year and 5000-year return periods, the maximum flood level of Shiyang Reservoir decrease by 0.32, 0.11, 0.19 and 0.11 m, respectively, compared with the current design scheme.

Investigating an Innovative Sea-Based Strategy to Mitigate Coastal City Flood Disasters and Its Feasibility Study for Brisbane, Australia

This study examines an innovative Coastal Reservoir (CR) technique as a feasible solution for flood adaptation and mitigation in the Brisbane River Estuary (BRE), Australia, which is vulnerable to coastal flooding. The study analysed the operation of a CR by using the MIKE 21 hydrodynamic modelling package. The 2D hydrodynamic model was calibrated and validated for the 2013 and 2011 flood events respectively, with a Nash-Sutcliffe coefficient (Ens) between 0.87 to 0.97 at all gauges. River right branch widening and dredging produced a 0.16 m reduction in water level at the Brisbane city gauge. The results show that by suitable gate operation of CR, the 2011 flood normal observed level of 4.46 m, with reference to the Australian Height Datum (AHD) at Brisbane city, could have been reduced to 3.88 m AHD, while under the improved management operation of the Wivenhoe Dam, the flood level could be lowered to 4 m AHD at Brisbane city, which could have been reduced with CR to 2.87 m AHD with an overall water level reduction below the maximum flood level. The results demonstrated that the innovative use of a CR could considerably decrease the overall flood peak and lessen flood severity in the coastal city of Brisbane.

An Event-Based Approach to Explore Selected Present and Future Atmospheric River–Induced Floods in Western Norway

AbstractThe aim of this study is to investigate extreme precipitation events caused by atmospheric rivers and compare their flood impact in a warmer climate to current climate using an event-based storyline approach. The study was set up by selecting four high-precipitation events from 30 years of present and future climate simulations of the high-resolution global climate model EC-Earth. The two most extreme precipitation events within the selection area for the present and future climate were identified, and EC-Earth was rerun creating 10 perturbed realizations for each event. All realizations were further downscaled with the regional weather prediction model, AROME-MetCoOp. The events were thereafter used as input to the operational Norwegian flood-forecasting model for 37 selected catchments in western Norway, and the magnitude and the spatial pattern of floods were analyzed. The role of the hydrological initial conditions, which are important for the total flooding, were analyzed with a special emphasis on snow and soil moisture excess. The results show that the selected future extreme precipitation events affected more catchments with larger floods, compared to the events from present climate. In addition, multiple realizations of the meteorological forcing and four different hydrological initial conditions, for example, soil saturation and snow storage, were important for the estimation of the maximum flood level. The meteorological forcing (e.g., the internal variability/perturbed output) accounts for the highest contribution to the spread in flood magnitude; however, for some events and catchments the hydrological initial conditions affected the magnitudes of floods more than the meteorological forcing.

Simulation of overflow thresholds in urban basins: Case study in Tuxtla Gutiérrez, Mexico

AbstractThe space–time dynamics and the effect of urban growth on territory transformation were simulated with Iber 2D to analyze flooding events in the lower basin of the Sabinal River, Mexico. We classified the main coverages and land uses of the study area. Soil roughness and water infiltration in the soil were evaluated. Both values were used as input data in a simulation model with Iber 2D to analyze and compare the levels of water height and maximum flood level area with different precipitation values in two reference years, 1986 and 2014. Residential use land cover increased considerably while tree, pasture and agricultural use covers decreased. Consequently, in 2014, precipitation of similar magnitude led to higher values of direct runoff, increasing water levels and therefore the risk of overflowing. The water levels and moments of river overflow provided feedback for flood‐risk warning systems and tools to monitor basins lacking adequate infrastructure.

Mapping of Maximum and Minimum Inundation Extents in the Amazon Basin 2014–2017 with ALOS-2 PALSAR-2 ScanSAR Time-Series Data

Seasonal inundation is an important effect that governs the distribution of ecosystems in the tropics. In the Amazon Basin, the seasonal flood pulse causes a difference in high and low water levels that can exceed 15 m. The associated flood duration and extent play an important role in land-atmosphere carbon exchange and affect the ecosystem’s carbon pool that originates from organic matter transported from upland and flooded forests. Studies of wetlands inundation across the Amazon Basin have utilized dual season mosaics from JERS-1 and wide-swath ScanSAR data from ALOS PALSAR to characterize inundation across the basin. This study builds upon past efforts with JERS-1 and ALOS PALSAR and uses ALOS-2 PALSAR-2 ScanSAR data to generate annual maximum and minimum inundation extent maps over the full Amazon Basin for the period spanning November 2014–October 2017. The study uses decision tree classification to create a maximum and a minimum inundation extent map for each year over this time period. The results show that a generalized algorithm that fits the entire basin has an 86% overall accuracy compared with a classification made for a local region from the same PALSAR-2 datasets. Comparisons with previous full-basin inundation maps by other L-band radars shows similar results for inundated areas during maximum inundation. The maps derived previously from JERS-1 and ALOS PALSAR show 7.3% and 6.9% inundated vegetation, respectively, and this study using PALSAR-2 shows values ranging between 5.5% and 7.0% across the three study years. Comparisons between the stage data across the basin and acquisition dates/periods for JERS-1 and PALSAR-2 show that the sensors capture the nature of the maximum and minimum flooding across the basins but have not successfully captured the exact maximum and minimum flood levels that have been recorded in the stage data. The inundation maps are publicly available under a Creative Commons (CC BY 4.0) licensefrom the Alaska Satellite Facility.

Современные изменения водного режима и морфометрии рек Верхнедонского бассейна

The article substantiates the methodology of distinction between the Upper and the Middle basins of the Don river. The suggested demarcation line, undefined until now, should coincide with the administrative border of the Voronezh oblast in the south, south-east, east and north-east. This approach allows us to analyze the water regimen of the Don river proper and it’s tributary, Khoper river, as an integrated Upper Don river basin. The annual river flow of the rivers Don and Khoper is diminishing, but the trend is weak and statistically insignificant. The duration of the spring snow floods is increasing due to its earlier onset and later ending. The peak water volumes have been steadily declining because of a change in the maximum water flow genesis under conditions of a steady increase of air temperature and decrease in frost penetration in the soil. The maximum flood levels are observed to occur more often in March, that was not registered before early 70's, with the increase of floods repetition in May, whereas the April prevalence is diminishing. The absolute spring-fall low water minimums are shifting mostly towards September, while the winter ones tend to happen in February and March, right before the spring flood season. This leads to decreases in seasonal unevenness of the river runoff volume and increases the length of a relative “average water” periods throughout the year. The resulting negative dynamics in the river morphometry is due to the pre-spring thaws and floods, changes in the spring floods’ genesis and character, lesser depth of the frost penetration, less contact between the soil and the flood waters, as well as destruction of the creek network and the slope runoff. We have registered the accelerated decrease in small watercourses, as well as the increase in the number of waterless valleys, dry waterbeds, and sporadic watercourses. The rivers Sosna and Kamenka, right-bank tributaries of the Don river, have demonstrated the 8.2 and 45% respective decrease in the riverbeds’ length, the most prominent in the current century.

Analysis of the effects of climatic factors on flood peak formation

Spring flooding is an annual significant overflow of water in the central Russia rivers. As a rule, the maximum flood levels in the Tambov region rivers are reached in the late March - early April. However, this parameter is very variable. Moreover, the maximum flood water level varies from year to year. In this paper, we study the effects of various climatic parameters on the spring flood peak formation. We consider the Tsna River (the Oka basin) near Tambov as the model object of our study. Using methods of multiple correlation analysis, we determine the most significant climatic factors which affect the maximum flood level. In the research, 16 climatic and hydrological parameters from 1970 to 2018 are analyzed. We assess the contribution of the various factors to flood wave formation by using multiple regression analysis. Using the analysis, we have identified the most significant flooding factors.

Changes in land use cover and its effects on hydrometeorological risk in Tuxtla Gutiérrez (Mexico)

To better understand the space-time dynamics and the effect of urban growth on the transformation of territory, this article presents the results of Iber 2D simulation tests to analyze flood events in the lower Sabinal river basin, Tuxtla Gutiérrez, Chiapas, Mexico. First, Landsat 5 and Landsat 8 satellite images from 1986 and 2014 years were processed to generate classified images of the land cover of the study area. From the identified coverages, the soil roughness values were defined, as well as the infiltration parameter of water in the soil. Both values were used as input data in an Iber 2D simulation model to analyze and compare the maximum flood level with different precipitation values in the two reference years. Between 1986 and 2014, the coverage of urbanizations increased considerably, while the coverage of trees, pastures and agriculture decreased. Due to this change in coverages, in 2014 rainfall caused higher values of direct runoff, increasing water heights levels and therefore the risk of overflowing the Sabinal River. With the model shown here, it is possible to calculate the depth and water heights reached and identify the points and moments of overflow of the river. This model can be used to provide feedback to flood risk warning systems and to analyze basins that lack monitoring infrastructure.

Исследование влияния паводков и некоторых биотических факторов на распространение моллюсков семейства Bithyniidae

Исследована зависимость плотности популяций моллюсков семейства Bithyniidae, первого промежуточного хозяина Opistorchis felineus (кошачьей двуустки), от максимального уровня половодья, концентрации загрязняющих веществ и наличия улитковой пиявки в водоемах Ханты-Мансийского автономного округа. Исследование проводилось на реках Обь (г. Сургут), Иртыш (г. Ханты-Мансийск) и Большой Юган (с. Угут). Показано, что плотность популяций этих моллюсков положительно коррелирует с уровнями паводков и отрицательно – с загрязненность вод и наличием улитковой пиявки. Полученные данные могут быть использованы для прогноза плотности популяций моллюсков Bithyniidae и целесообразности особых мер против заражения описторхозом населения.

A Forecast-Based Operation(FBO) Mode for Reservoir Flood Control Using Forecast Cumulative Net Rainfall

With advance of up-to-date hydrology measuring and forecasting system, reservoir operations are no longer required to be as conservative as they once were. The incorporation of flood inflow and weather forecasts allows for greater flexibility in the management of reservoir space and inherently increases opportunities for acquiring additional water supply and reducing flood risks effectively advance. In this paper, taking Ankang Reservoir as an example, a forecast-based operation (FBO) mode for flood control is developed with cumulative net rainfall in the real-time rolling prediction as the primary indicator and the water level in the reservoir as the auxiliary indicator. Based on the accuracy of flood forecasting data, FBO rules for reservoir flood control are formulated by using the stepwise regulation method considering the actual situation of Ankang Reservoir. For verification, a flood routing simulation is conducted for designed and typical flood processes with different recurrence intervals using the formulated rules. The results show that the maximum flood level is lower than for conventional regulation and that the duration of the maximum discharge under the forecast operation mode is slightly shorter than the conventional discharge, which indicates that the flood risk is reduced to some extent by applying the formulated FBO rules and, correspondingly, demonstrates the merits and applicability of implementing FBO mode for Ankang reservoir.

Water level regime of the Maima River (Altai Mountains) in the context of modern climate change

Changes in the water level regime of the Maima River are studied in relation to observed climatic changes. The increased air temperature and decreased precipitation during the cold period leads to a decrease in the maximum flood level and a shift to later dates. A high correlation between the water level and precipitation is revealed in the period of summer and autumn low water. The trends in the mean and minimum water levels of the summer and autumn low-water periods are determined by the trends in the air temperature. Positive trends of the air temperature in the summer and autumn low-water periods contribute to the accumulation of water heat. Thus, due to the increase in the heat content of water mass and temperatures of November and December, the maximum water levels in the floods caused by sludge formation and ice jamming are becoming lower. Our analysis of the hydrological regime is based on Roshydromet monitoring data from 1940 to 2015 at a gauging station located in a village called Maima. The data on the monthly averaged air temperature and rainfall were obtained from a weather station in a village called Kyzyl-Ozek.

On Maximum Likelihood Estimation for the Three Parameter Gamma Distribution Based on Left Censored Samples

This paper deals with a Maximum likelihood method to fit a three-parameter gamma distribution to data from an independent and identically distributed scheme of sampling. The likelihood hinges on the joint distribution of the n − 1 largest order statistics and its maximization is done by resorting to a MM-algorithm. Monte Carlo simulations is performed in order to examine the behavior of the bias and the root mean square error of the proposed estimator. The performances of the proposed method is compared to those of two alternatives methods recently available in the literature: the location and scale parameters free maximum likelihood estimators (LSPF-MLE) of Nagatsuka & al. (2014), and Bayesian Likelihood (BL) method of Hall and Wang (2005). As in several papers on the three-parameter gamma fitting (Cohen and Whitten (1986), Tzavelas (2009), Nagatsuka & al. (2014), etc.), the classical dataset on the maximum flood levels data in millions of cubic feet per second for the Susquehanna River at Harrisburg, Pennsylvania, over 20 four-year periods from 1890–1969 from Antle and Dumonceaux’s paper (1973) is consider to illustrate the proposed method.

Araguaia River Floodplain: Size, Age, and Mineral Composition of a Large Tropical Savanna Wetland

The Araguaia River floodplain is a large wetland in the tropical savanna belt (cerrado) in the southern Amazon basin. Studies using multitemporal satellite Landsat 5 TM images with a spatial resolution of 30 m indicate a surface area at maximum flood level of 88,119 km2. During the low-water period, only 3.3 % of the area is covered by water. Flooding is the result of the annual rise in the water level of the Araguaia River and of local rainfall and insufficient drainage during the rainy season. Sedimentology studies have distinguished between an active recent and sub-recent floodplain, which covers ~20 % of the area, and a paleo-floodplain probably several hundreds of thousand years in age. Paleo-floodplain sediments are strongly weathered and marked by the clay mineral association of kaolinite, gibbsite, goethite, and Al-chlorite, predominantly formed from feldspars and micas. The active paleo-floodplain participates in the hydrological cycle but does not receive recent sediments from the river. Higher-lying, not flooded areas (inactive paleo-floodplain) are probably the remnants of paleo-levees, now in an advanced stage of erosion. A hypothesis to explain the genesis of the floodplain is proposed herein.

红石岩堰塞湖水位变化特征及成因分析

2014年，鲁甸803地震后形成红石岩大型堰塞湖，堰塞湖的水位变化成为国内外关注的焦点，采用红石岩堰塞湖水位监测资料，通过8月3日至10月4日堰塞湖水位过程、水位变化特征和成因分析，得出堰塞湖水位变化的特征是涨落急剧，水位变幅达45.06 m，最低水位1137.5 m，最高水位1182.56 m；堰塞湖持续高水位时间长，且峰谷交错，呈现多峰型的水位变化特征；水位变化特征的主要成因是上游暴雨洪水过程、泄流量的大小和上游德泽水库的调蓄等综合影响；通过年际变化分析，堰塞湖形成后，水位超过1170 m以上的日数为60 d，最高水位为1182.56 m，大大超过了校核洪水位；通过堰塞湖水位变化趋势预测，20年一遇洪水，目前泄流条件能满足施工度汛的要求，100年一遇洪水，达不到设计洪水标准，不能满足施工和下游的安全。因此，堰塞湖永久整治施工期，1178.29 m泄洪洞需要加紧施工，尽快达到设计过流能力，才能确保安全。 A large Hongshiyan landslide lake was formed after the earthquake in Ludian in August, 2014. The lake water level change has become the attention focus at home and abroad. Based on the Hongshiyan lake water level monitoring data from August 3rd to October 4th, the change of water level process and cha-racteristic analysis, it was found that the lake water level was sharp fluctuation reaching 45.06 m, and the lowest and highest levels were 1137.5 m and 1182.56 m, respectively. The lake continued high level for a long time, and was peak-valley staggered, showing multi-peak changes of water level. The main causes of water level change characteristics are the upstream storm flood process, flood discharge and the storage function of Zede Reservoir upstream. Through annual variation analysis, there were 60 days that the water level was more than 1170 m, and the highest level was 1182.56 m, greatly exceeding the maximum flood level. Through forecasting the water level change trend, the current discharge conditions can meet the requirements of the construction for 20-year design flood, but cannot meet the construction and the downstream safety for 100-year design flood. Therefore, 1178.29 m spillway channel needs to be constructed as soon as possible to achieve the design flow capacity in order to ensure the safety.

Research on the Calculation of the Security of High Concrete Arch Dam Based on the Finite Element Method

The study on the calculation of the security of high concrete arch dam based on the finite element method will be studied and analyzed in this paper. For high concrete arch dam deformation and stability under normal water level and maximum flood level will be calculated, and the stress of each section of the dam and batholith around will be checked and analyzed, then this paper will come to the dam security conclusion finally.

LH-moment estimation of a four parameter kappa distribution with hydrologic applications

The study of distribution tails is a fundamental research in statistical frequency analysis relevant to many research fields, such as insurance, hydrological events, earthquake, etc. Here, we describe and investigate the effect and feasibility of the high-order L-moment (LH-moment) method for estimating heavy-tail conditions by fitting a four parameter kappa distribution. Details of parameter estimation using LH-moments for the four parameter kappa distribution (K4D) are described and formulated. Monte-Carlo simulation is performed to illustrate the performance of the LH-moment method in terms of heavy-tail quantiles over all quantiles using K4D and non K4D samples, respectively. The result suggests that the method is either useful (when the method of L-moment estimation fails to give a feasible solution) or as effective as the L-moment approach in handling data following K4D. Applications to the annual maximum flood and sea level data are presented.

HEC-RAS를 이용한 오십천의 수위변화 해석: 태풍산바의 영향을 중심으로

최근 기후변화에 의한 영향으로 태풍의 발생빈도가 증가하고 있으며 그 결과 산지하천의 경우 상류부의 유량증가와 하류부에 빈번한 수위상승을 가져오고 있다. 본 연구에서는 2012년 9월 17일~18일에 우리나라에 직접적인 영향을 준 태풍 산바의 영향으로 발생한 집중호우가 산지하천 하류부 수위 변동에 어떤 영향을 주는가를 분석하였다. 삼척 오십천 유역을 대상유역으로 선정하고 HEC-RAS모형을 적용하고 홍수위 분석을 실시하였다. 그 결과 2012년 측정된 관측수위와 HEC-RAS모형에 의해 모의된 수위가 유사한 결과를 나타냈으며 최대 홍수위는 5.32m, 평균유속은 2.33m/sec, 최대수로수심은 7.51m로 모의 되어 태풍산바에 의해 내린 집중호우가 오십천의 수위상승에 영향을 미친 것으로 판단되며, 향후 구축된 자료는 하천정비기본계획 수립시 수공구조물 설계에 기초자료로 유용하게 활용될 것으로 기대된다. Recently, the frequency of typhoons have increased due to the effects of climate change. As a result, in mountain streams, it has caused streamflow increase upstream and frequent water surface elevation downstream. This study analyzed the effects of the heavy rainfalls caused by Typhoon Sanba, which had a direct impact on Korea between September 17 and 18, on the water level variations downstream in mountainous streams. In addition, the drainage basin of Samcheok Oship stream was chosen as the object of this study. This study analyzed the flood level by applying HEC-RAS model. The observed water level measured in 2012 and the water level simulated by HEC-RAS model showed similar results. In addition, the simulation results showed the maximum flood level was 5.32m the mean flow velocity was 2.33m/sec and the maximum channel water depth was 7.51m. The analysis showed that the heavy rainfalls caused by Typhoon Sanba had an impact on the water surface elevation in Oship stream. The final results from this study will give a reasonable and important data to perform the Design of Hydraulic Structure.

A 3D Hydrodynamic Model for Determination of Flood Level inside Saemangeum Embankment

ABSTRACT Jung, J.-S. and Cho, Y.-S., 2013. A 3D Hydrodynamic Model for Determination of Maximum Food Level inside Saemangeum Embankment In this study, the variation of flood water level inside the Saemangeum Embankment is studied. In particular, the maximum flood level inside the Embankment is investigated for design of the land reclamation level. Water level inside the Embankment may be affected by flooding from connected rivers, tides and discharges through gates. The tidal range outside Embankment is about 6.0~7.5m. The water level is numerically simulated by using a commercial hydrodynamic model: Delft3D-Flow. By analyzing measured tidal data measured over 31 years (1981–2011), the smallest tidal difference is selected for simulations. The maximum flood level inside Embankment generally increases as the tidal difference decreases because the sea level outside Embankment is relatively high during the ebb tide.

Tree Phenology in Adjacent Amazonian Flooded and Unflooded Forests1

ABSTRACTMost phenological studies to date have taken place in upland forest above the maximum flood level of nearby streams and rivers. In this paper, we examine the phenological patterns of tree assemblages in a large Amazonian forest landscape, including both upland (terra firme) and seasonally flooded (várzea and igapó) forest. The abundance of vegetative and reproductive phenophases was very seasonal in all forests types. Both types of flooded forest were more deciduous than terra firme, shedding most of their leaves during the inundation period. Pulses of new leaves occurred mainly during the dry season in terra firme, whereas those in the two floodplain forests were largely restricted to the end of the inundation period. Flowering was concentrated in the dry season in all forest types and was strongly correlated with the decrease in rainfall. The two floodplain forests concentrated their fruiting peaks during the inundation period, whereas trees in terra firme tended to bear fruits at the onset of the wet season. The results suggest that the phenological patterns of all forest types are largely predictable and that the regular and prolonged seasonal flood pulse is a major determinant of phenological patterns in várzea and igapó, whereas rainfall and solar irradiance appear to be important in terra firme. The three forest types provide a mosaic of food resources that has important implications for the conservation and maintenance of wide‐ranging frugivore populations in Amazonian forests.

Coherency detection of multiscale abrupt changes in historic Nile flood levels

A scanning algorithm based on the classical Student t‐test is extended to detecting the presence and coherency of multiscale abrupt changes in two time series. It functions similarly to the Haar wavelet transform, but also provides thresholds of the statistical significance for testing change‐points. The algorithm is applied to the historic series (AD 622–1469) of the maximum and minimum flood levels of the Nile River using the “Table‐Look‐Up Test” for correction of dependence in the series. The results reveal several abrupt changes, and separate wet/dry episodes on 30–160 year time‐scales. Most of the episodes coincide with historic records of catastrophe in Egypt. Some changes correspond to changes in China and Europe, and to reconstructions of fish stocks off the west coast of North America, indicating that they are driven and linked by global teleconnection processes.