Climatic Characteristics Analysis of Flood-producing Rainstorm in Duhe River Basin

Based on the data from 1998 to 2005,area rainfall,flow of main hydrologic stations in Duhe River and upstream water level of the dam of Huanglongtan Reservoir in the lower reaches of Duhe River were analyzed,and the standard of flood-producing rainstorm in Duhe River was given,while temporal and spatial distribution and circulation flow situation characteristic of flood-producing rainstorm in Duhe River were studied.The results showed that the flood-producing rainstorm in Duhe River was mainly continuous intensive precipitation with the characteristic of long duration.There was most rainfall in Zhuxiquan River,Zhushanguandu River and southwest part of the middle and upper reaches of Duhe River,and next came Zhuxi River.Flood-producing rainstorm occurred in Duhe River with some favorable circulation features.For example,it was more favorable in the west Pacific subtropical high,and the convergence zone at northeast-southwest direction was formed between subtropical high and continental high pressure at 700 hPa,while southwest vortex moved eastward.Low pressure system at 850 hPa in south part of plateau developed and moved eastward to Chongqing region and formed low vortex or shear near Duhe River basin.Moreover,the characteristics of physical quantity field were analyzed,the results showed that temperature in plateau area and the south area of Duhe River basin increased obviously before rainstorm,and east pathway was the main path of cold air which affected flood-producing rainstorm in Duhe River.There was a θse intensive belt with NEE-SWW direction at 30°-40° N at 925-500 hPa,and moisture convergence was beneficial to the occurrence of rainstorm in Duhe River.

The Relation between Atmospheric Intraseasonal Oscillation and Summer Severe Flood and Drought in the Changjiang-Huaihe River Basin

The intraseasonal oscillation (ISO) is studied during the severe flood and drought years of the Changjiang-Huaihe River Basin with the NCEP/NCAR reanalysis data and the precipitation data in China. The results show that the upper-level (200 hPa) ISO pattern for severe flood (drought) is characterized by an anticyclonic (cyclonic) circulation over the southern Tibetan Plateau and a cyclonic (anti-cyclonic) circulation over the northern Tibetan Plateau. The lower-level (850 hPa) ISO pattern is characterized by an anticyclonic (cyclonic) circulation over the area south of the Changjiang River, the South China Sea, and the Western Pacific, and a cyclonic (anticyclonic) circulation from the area north of the Changjiang River to Japan. These low-level ISO circulation patterns are the first modes of the ISO wind field according to the vector EOF expansion with stronger amplitude of the EOF1 time coefficient in severe flood years than in severe drought years. The analyses also reveal that at 500 hPa and 200 hPa, the atmospheric ISO activity over the Changjiang-Huaihe River basin, North China, and the middle-high latitudes north of China is stronger for severe flood than for severe drought. The ISO meridional wind over the middle-high latitude regions can propagate southwards and meet with the northward propagating ISO meridional wind from lower latitude regions over the Changjiang-Huaihe River Basin during severe flood years, but not during severe drought years.

Torrential flood prevention in the Kolubara river basin

One of the most vulnerable parts to natural hazards in Serbia is Kolubara river basin. In the past, during the period from 1929 to 2013, 121 torrential flood events in the Kolubara river basin were recorded which show that this territory is extremely vulnerable to the torrential floods. The extreme event which occurred in May 2014 causing the catastrophic material damages and casualties was the latest and historical flood. The analysis of natural conditions in the Kolubara basin uniformly showed that this area is predisposed to a greater number of torrential floods due to its geomorphological, hydrological and land use properties. Torrential floods are closely related to the intensity and spatial distribution of erosive processes in the upper part of the Kolubara basin. The estimation of soil erosion potential is generally achieved by Erosion Potential Model(EPM). For the purposes of determining the degree of torrential properties in various water streams in the Kolubara basin, the calculation ofsusceptibility to torrential floods was assessed by Flash Flood Potential Index(FFPI). More than half of the basin area(57.2%) is located within the category of very weak and weak erosion(Z_(sr) = 0.35), but the category of medium erosion is geospatially very common. Such a distribution of medium erosion category provides conditions for generating, i.e. production of sediment which would boost torrential properties of water streams. After the classification of the obtained FFPI values it was determined that 25% of the Kolubara basin is very susceptible to torrents and this data should be seriously taken into consideration. Based on the analyses, the best and most successful manner of defence is prevention which consists of the integrated river basin management system(integrated torrent control system) so that technical works in hydrographic networks of torrents and biological and biotechnical works on the slope of the basin would be the best solution. Permanent control of erosive and torrential processes in the river basin will be not only important for flood control but it can also protect the existing and future water reservoirs and retentions fromsiltation with erosion sediment which is of great significance to the water management, agriculture, energy sector, and the entire society.

Influence of Floodplain Area on Fish Species Richness in Waterbodies of the Chao Phraya River Basin, Thailand

River-floodplain ecosystems are in delicate balance and are impacted by even minor changes in water availability. In this study, we surveyed fish assemblages and investigated environmental and landscape parameters in a total of 135 floodplain waterbodies (rivers, diversion canals, ponds, irrigation ditches, paddy fields, and wetlands) in the Chao Phraya River Basin in rainy (September 2014) and dry (March 2015) seasons. Factors affecting fish species richness in each type of waterbody were analyzed using generalized linear mixed models. Floodplain area around each surveyed waterbody was a major factor determining fish species richness in rivers, diversion canals, and ponds in the region. The contribution of floodplain area was equivalent to that of hydrology (current velocity, water depth) and water quality (dissolved oxygen, turbidity) in the waterbodies. The population of juvenile fishes was increased in temporarily connected floodplain waterbodies to main rivers compared with isolated waterbodies, and fluvial and lacustrine fishes were observed in the temporary inundated floodplain waterbodies during the rainy season. The high dependence of fish species richness on floodplain area in the region appeared to be a result of the use of inundated floodplains by fish species to forage and breed. Our results highlight the impact of flood control measures that reduces floodplain area. These measures must be reviewed to ensure the conservation of fish biodiversity in the Chao Phraya River Basin, one of the world’s most threatened floodplain systems.

THE FLOOD OF THE NENJIANG RIVER AND THE SONGHUA RIVER IN 1998 AND THE COMPREHENSIVE MANAGEMENT OF THE RIVER BASINS

In the summer of 1998, an exceptionally serious flood, with the characteristics of high water level, large volume of flow, long duration and serious losses caused by the disaster, occurred in the Nenjiang River basin and the Songhua River basin. Greater flood peak occurred three times in the trunk stream of the Nenjiang River for the floods occurred in its tributaries one after another. At Jiangqiao Hydrometric Station, the water level was 141.90 m and the rate of flow was 12?000 m 3/s. The flood is ranged to a catastrophic one, which occurs once in 50 years. Ranged to a catastrophic flood at Qiqihar Hydrometric Station that occurs once in 400 years, its water level, 0.89 m higher than the former all time highest, was 149.30?m and the corresponding rate of flow was 14?800?m 3/s. The water level that exceeded the all time highest lasted for 7 days. At Harbin Hydrometric Station, the water level, 0.59?m higher than the former all time highest, was 120.89?m and the corresponding rate of flow was 17?400?m 3/s. The water level that exceeded the all time highest lasted for 9 to 10 days. The flood here is ranged to a catastrophic one, which occurs once in 150 years. The flood of the Nenjiang River damaged 456×10 4?ha of crops and 115×10 4 rooms and the direct loss of economy exceeded 40 billion yuan(RMB). The main reasons of the flood are great rainfall, long flood season, unreasonable land use, regional ecological environment degradation and lack of water control projects. It is obvious that the following measures are greatly needed: the comprehensive management of the river basins; the formulation of development planning of the river basins, especially the water control projects; the development of agriculture based on ecological security.

PRELIMINARY STUDY ON FLASH FLOODS IN TARIM RIVER BASIN

Flash floods are the important events of the hydrological regime of rivers in arid areas. In the Tarim River, northwestern china, flash flood are being monitored. The observed data and investigation demonstrate the difference in time, place, fraquency and intensity of their occurrences. In this paper two main flash fled are put forward, they are rainstorm flash flood (RFF) and glacier lake outburst flood(GLOF). Two cases of flash flood in the two tributaries of the Tarim River presented in this paper. It analyses and compares the causes and the development of the two kinds of flash floods.Through further discussion about influence of flash floods on the main channel of the Tarirn River, conclusion can be drawn that the greatest flood in record of the main channel come from the GLOF of the upper reaches of the Kunmalik River, especially augmented by great ablation flood. Finally the advantages and disadvantages from flash floods to the environment of the catchment are demonstrated in the paper.

Analysis and Zoning of Rainstorm Flood Disaster Risk in Huaihe River Basin

Taking the rainstorm flood disaster of Huaihe River basin as the research object,according to the principles of risk assessment for natural disasters,starting from the fatalness of inducing factors and the vulnerability of hazard bearing body,the weight of each impact factor was calculated by using AHP. By using spatial analysis and statistical function of GIS,the integrated risk chart of rainstorm flood disaster in Huaihe River basin was obtained. The results showed that the high risk areas of rainstorm flood disaster in Huaihe River basin mainly distributed in the southern part of Henan,the central northern part of Anhui and eastern part of Jiangsu Province. Due to higher fatalness of inducing factors in southern Henan,there was high risk in the region. Central Anhui and east Jiangsu were not only high-fatalness zones but also high vulnerability zones of population and economy.

Risk Assessment and Simulation on Storm Flood of the 100-Year Return Period in Hunhe River Basin

Based on the meteorological and geographic information data, with statistical method and the FloodArea model, the extreme daily rainfall of the 100-year return period in Hunhe River basin was established, through the simulation of rainstorm and flood disaster, characteristics of flood depth in warning spot Cangshi village in the upstream of the river were analysed, and possible effect on community economy was also evaluated. Results showed that, the precipitation of 100-year return period occurred, the flood depth has been below 1.0 meter in the most areas of Hunhe River basin, the depth was between 1.0 meter and 2.5 meters in the part areas of Hunhe River basin, and the flood depth has been exceed 2.5 meters in a small part of Hunhe River basin. After the beginning of precipitation, the flood was concentrated in the upper reaches of the river. With the accumulation of precipitation and the passage of time, the flood pools into midstream and downstream. Precipitation lasted for 24 hours, the warning spot was flooded in the beginning of precipitation. With the accumulation of precipitation, water level of the river increases gradually. The depth of warning spot has passed 1.0 meter at the 07 time of the whole process, and the maximum value of flood depth at warning spot was 1.083 meters that occurred at the 19 time. The flood depth of warning spot decreased gradually after the precipitation stopping, and the depth has been below 0.2 meters, the flood of upstream ended. Up to the end of the upstream flood process, in the whole river, about one million five hundred and sixty thousand people were affected by flooding, and thirty-eight billion and two hundred million RMB of gross domestic product were lost, in addition, dry land and paddy field were affected greatly, but woodland and grassland were less affected.

Analysis of Causes and Seasonal Prediction of the Severe Floods in Yangtze／Huaihe Basins during Summer 1991

The present paper shows that a seasonal prediction for the large scale flooding and waterlogging of the mid-lower Yangtze/ Huaihe River basins in the summer of 1991 made successfully in early April 1991.The seasonal forecasting method and some predictors are also introduced and analyzed herein. Because the extra extent of the abnormally early onset of the plum rain period in 1991 was unexpected,great efforts have been made to find out the causes of this abnormality. These causes are mainly associated with the large scale warming of SST surrounding the south and east part of Asia during the preceding winter,while the ENSO-like pattern of SSTA occurred in the North Pacific.In addition,the possible influence of strong solar proton events is analyzed.In order to improve the seasonal pre4iction the usage of the predicted SOl in following spring/summer is also introduced.The author believes thatthe regional climate anomaly can be correctly predicted for one season ahead only on the basis of physical understanding of the interactions of many preceding factors.

Quantitative Assessment of Vulnerability to Flood Hazards in Downstream Area of Mono Basin, South-Eastern Togo: Yoto District

The population located along Mono River in the Yoto district faces great challenges in terms of repeated flood disasters in recent years. This paper aims at assessing the conditions which influence flood damage in the study area by using indicators to compute a Flood Vulnerability Index (FVI). The study relies on Turner?et al.’s vulnerability framework and distinguishes three main components (exposure, susceptibility and resilience) that allow a more in-depth analysis and interpretation of local indicators. As a result flood disaster in the study area is not only due to the extreme variability in terms of flood magnitude and frequency in the Mono River, but also to the interaction between human and the environment. The lack of vegetation along the river bank, the closeness of households’ farmlands to the river body, the type of construction and the position of settlements, the household size, the low level education of household head, the lack of diversification of livelihood strategies, the lack of adequate flood warning system, the lack of willingness and ability to take responsive actions coupled with inadequate emergency services, are identified as main determinants increasing communities’ vulnerability to flood disaster. Furthermore, the computation of Flood Vulnerability Index (FVI) offers easy comparison of communities’ vulnerability to flood disaster and pinpoints the most vulnerable communities. At the end of the study, flood exposure, susceptibility, resilience and vulnerability maps were generated.

Overview of flooding damages and its destructions: a case study of Zonguldak-Bartin basin in Turkey

A number of devastating flood events have oc-curred in the various river basins of Turkey in the last decade. Because floods caused deaths, suffering and extensive damages to both public and private properties in the flood areas, the government had to most of the damage in addi-tion to losing significant revenues due to the consequences of costly social and economic disruption. On the other hand, some social structures such as socioeconomic activities, land-use patterns and hydro-morphological processes are destroyed. Whereas flood control structures are considered as one of the basic strategies that can reduce flood damages and in this context flood protection planning should consider the full range of the hazard mitigation activities. In Turkey, between 1945 and 1990, 737 flooding events were occurred and at least 830 people were killed. In 1998, there was a major flooding in Zonguldak-Bartin region located on north of Turkey. Due to this devastated flooding, people lost their life and numbers of engineer-ing structures built on the river and surrounding area were totally destroyed or heavily damaged. Both side of the canal were covered with muddy soil having 0.10-0.15 m thickness. Cleaning up process took sometimes in the region. In this paper, all these subjects have been investigated in the basin and some engineering proposals have been presented.

Simulating and Prediction of Flow Using by WetSpa Model in Ziyarat River Basin, Iran

The spatially distributed hydrologic model WetSpa that works on daily, hourly, and minutely timescales is used to predict the flood hydrographs and spatial distribution of the hydrologic characteristics in a river basin by combining elevation, soil and land-use data within Geographical Information System. This model was applied in Ziarat river basin (95.15 km2) located in Golestan Province of Iran. Hourly hydro-meteorological data from 2008 to 2010 consist of precipitation data of two stations, temperature data of one station and evaporation data measured at one station, which were used as input data of the model. Three base maps namely DEM, land-use and soil types were produced in GIS form using 30 × 30 m cell size. Results of the simulations revealed a good agreement between calculated and measured hydrographs at the outlet of the river basin. The model predicted the hourly hydrographs with a good accuracy between 62% - 74% according to the Nash-Sutcliff criteria. To evaluate the model performance during the calibration and validation periods an Aggregated Measure (AM) was introduced that measures different aspects of the simulated hydrograph such as shape, size, and volume. The statistics of Ziarat river basin showed that the results produced by the model were very good in the calibration and validation periods.

新阶段完善海河流域防洪工程体系的思考

海河流域水系复杂,暴雨洪水集中,极易形成洪水灾害,防洪任务重。文章回顾了海河流域防洪工程体系建设成就,分析了京津冀协同发展、雄安新区建设等国家重大战略的实施以及水利高质量发展、应对气候变化对流域防洪减灾能力提出的新要求,结合“23·7”流域性特大洪水等近年来洪水防御情况,全面检视了流域防洪工程体系存在的突出短板和薄弱环节,提出了完善流域防洪工程体系的思路举措。

北江流域“2022·6·22”暴雨洪水分析

2022年6月19日,北江流域发生“2022年第2号洪水”,为1915年以来最大的洪水。为提高对北江流域暴雨洪水特性的认识,采用定性与定量相结合的方法对该场洪水的雨水工情进行研究。分析暴雨中心、洪水量级、洪水传播时间等特征,并与历史暴雨洪水进行对比。借助种子蔓延算法比较“理想凑泄”和“经验控泄”调度方案的调控效果,同时考虑水库动库容效应进行调洪演算。结果表明:造成本次洪水灾害的主要原因是累计雨量大、降雨强度大以及暴雨区域集中;根据“理想凑泄”规则调度飞来峡水库取得了显著效果,但需要考虑水库动库容的影响。研究成果可为北江流域防洪减灾以及制定调度规则等提供支持。

新阶段海河流域防洪重点内容与举措思路

海河流域水系复杂、暴雨洪水集中,极易形成洪涝灾害,防洪任务重。回顾了2008年海河流域防洪规划实施情况,分析了京津冀协同发展、雄安新区建设等国家重大战略的实施以及水利高质量发展、防灾减灾救灾新理念、应对气候变化对流域防洪减灾能力提出的新要求,全面梳理了本次防洪规划的重难点问题,提出了完善流域防洪体系的思路举措。

海河“23·7”流域性特大洪水防御启示与对策——以永定河为例

在极端天气常态化的背景下,流域应具有承受、化解和抵御洪涝和干旱灾害的韧性。分析了海河“23·7”流域性特大洪水的特点,在此基础上,阐述了此次洪水过程中永定河流域综合治理各项措施发挥的作用、存在的问题,按照建设韧性流域的要求,对提升永定河流域防洪能力提出建议。

面向流域洪灾监测的分层次卫星组网观测任务规划方法

本文提出面向流域洪涝灾害监测的分层次卫星组网对地观测任务规划方法,以长江流域重庆段和城陵矶段为试验区,进行被动、主动规划。结果表明,该方法能够提供流域洪灾区域指定时段的多尺度卫星组网协同的有效观测信息,为及时调动卫星资源、快速响应洪灾监测需求,以及获取灾害预警、决策、评估卫星数据提供重要的技术支撑。

近53 a辽河流域旱涝灾害的时空特征

针对气候变化背景下辽河流域旱涝事件的频繁发生,以国家气象中心提供的地面降水日值数据集V3.0为基础数据,采用Z指数法表征旱涝事件,并应用集合经验模态分解法(EEMD)分析了辽河流域1968—2020年逐年、逐生长季的旱涝事件分布特征及其周期性规律,结果表明:(1)辽河流域近53 a中发生旱涝事件的灾害年份约占总时间序列的2/3以上,集中发生于上世纪80、90年代中后期及本世纪00年代.(2)近53 a中,重度干旱或洪涝事件均以流域东南部的河流下游及入海口区域最为严重,流域东南部的旱涝程度反差最为强烈.(3)对于辽河流域范围的旱涝事件来说,周期特征以短时高频振荡为主,年代际尺度的波动对于周期规律的贡献率相对较低.

黄河流域防洪形势与对策

在全球极端暴雨频发背景下,黄河流域防洪安全对保障全面建设社会主义现代化国家具有十分重要的意义。分析了黄河流域防洪安全现状及存在问题,剖析了保障黄河长治久安面临的严峻挑战,以确保堤防不决口、确保河床不抬高、让黄河成为造福人民的幸福河为目标,提出了新时期黄河流域防洪减灾体系的对策措施,论证了黄河长治久安的前景和保障思路。

珠江流域防洪重难点问题及应对策略研究

珠江流域气候多变,暴雨频繁,洪涝灾害是流域内发生频率最高、危害最大的自然灾害,尤以中下游和三角洲地区为甚。在总结回顾2007年《珠江流域防洪规划》实施以来流域防洪减灾体系建设成效基础上,对照新阶段流域经济社会高质量发展需求与人民群众防洪保安需要,深入分析流域防洪形势,研究提出洪水归槽背景下设计洪水复核与采用、流域蓄滞洪区设置与运用管理优化、思贤滘控导工程建设、龙滩水库防洪能力提升工程等应对策略,为全面提高流域防洪减灾能力提供支撑。