城镇化下流域不透水面扩张对洪峰的影响——以南京秦淮河为例

长江下游秦淮河流域近年来由于城市化崛起导致不透水面迅速扩张,改变了流域水文过程,导致暴雨洪水灾害风险增大.本文以南京秦淮河流域为例,基于1988—2015年间下垫面和水文气象资料建立了流域水文模型,通过不透水面扩张情景分析,探讨了 1988—2015年间不透水面空间扩张及对流域洪水过程的影响.研究结果表明:(1)秦淮河全流域1988—2015年不透水率从3.92%增长到19.11%,且不同区域扩张速度有所差异;(2)2006—2015年不透水面情景下的洪峰流量平均涨幅大于城市化初期;受流域上下游位置和下垫面地形条件的影响,流域溧水河和句容河两河源处的不透水面变化对洪峰的影响较流域下游出口处更显著;(3)秦淮河流域及不同位置的不透水面扩张情景下,小洪水的洪峰响应均大于大洪水,且不透水面扩张发生在下游主干河流域时的大、小洪水洪峰涨幅差距略大于河源流域.     

长江流域历史水旱灾害分析

长江流域有丰富和长期的水旱灾害史料,最早的水灾和旱灾记载有2000余年的历史,经过系统整理和分析的历史水旱灾害资料有1000余年的旱涝型年表和500余年的旱涝分布图集.在以上资料基础上,对长江流域历史水旱灾害的地域分布特性和时间变化规律进行了初步分析:500余年历史水旱灾害的地域分布显示,流域水旱灾害总体特征是水灾重于旱灾,各级水旱灾害频率的地域分布极不均匀,存在着显著的灾害多发和少发地带,它们与自然地理环境、水系特征、气候条件和社会经济条件等因素有关;1000余年旱涝型年表分析表明,长江流域洪涝和干旱频次在时间上的非均匀分布并非完全随机,表现出多种时间尺度的年际变化特征,其中主要表现为约100a上下的大干湿气候期变化及40a左右的小旱涝期振动.     

Nonstationarity-based evaluation of flood risk in the Pearl River basin: changing patterns,causes and implications

Nonstationary GEV-CDN models considering time as a covariate are built for evaluating the flood risk and failure risk of the major flood-control infrastructure in the Pearl River basin, China. The results indicate: (1) increasing peak flood flow is observed in the mainstream of the West River and North River basins and decreasing peak flood flow is observed in the East River basin; in particular, increasing peak flood flow is detected in the mainstream of the lower Pearl River basin and also in the Pearl River Delta region, the most densely populated region of the Pearl River basin; (2) differences in return periods analysed under stationarity and nonstationarity assumptions are found mainly for floods with return periods longer than 50 years; and (3) the failure risks of flood-control infrastructure based on failure risk analysis are higher under the nonstationarity assumption than under the stationarity assumption. The flood-control infrastructure is at higher risk of flood and failure under the influence of climate change and human activities in the middle and lower parts of Pearl River basin.

EDITOR D. Koutsoyiannis

ASSOCIATE EDITOR G. Thirel     

长江全流域大洪水下三峡水库对洞庭湖区防洪贡献分析

基于长江中下游一、二维耦合水动力学模型,以1954和1998年洪水为典型,模拟了三峡水库调蓄前后洞庭湖区的洪水过程,定量分析了三峡水库对洞庭湖区防洪的贡献.结果表明:在长江发生1954和1998年全流域大洪水期间,三峡水库实施兼顾对城陵矶河段的防洪补偿调度,可有效缓解荆南三口河系及湖区的防洪压力,减少荆南三口 1.58...     

Evaluation of groundwater resources in wide inundation areas of the Mekong River basin

Severe floods can have disastrous impacts and cause wide ranging destruction in the Mekong River basin. At the same time groundwater resources are significantly influenced and extensively recharged by flood water in inundation areas of the basin. This study determines the variation of groundwater resources caused by flooding over inundated areas located in lower part of the Mekong River basin using numerical modeling and field observations. The inundation calculations have been evaluated using satellite image outputs. Comparing large, medium and small flood events, we conclude that flood control which reduces the area of inundation, results in a reduction of groundwater resources in the area. In 1993, a 19% reduction in inundation areas resulted in a 31% reduction in groundwater storage. In 1998, a 44% reduction in inundation areas led to a 42% reduction in groundwater storage. Thus, while flood control activities are vital to reduce negative flood impacts in the Mekong River basin, they also negatively impact groundwater resources in the area.     

A new era of flood control strategies from the perspective of managing the 2020 Yangtze River flood

Flood control of the Yangtze River is an important part of China’s national water security.In July 2020,due to continuous heavy rainfall,the water levels along the middle-lower reaches of the Yangtze River and major lakes constantly exceeded the warning levels,in which Taihu Lake exceeded its highest safety water level and some stations of Poyang Lake reached their highest water levels in its history.In August 2020,another huge flood occurred in the Minjiang River and the Jialing River in the upper Yangtze River,and some areas of Chongqing Municipality and other cities along the rivers were inundated,resulting in great pressure on flood control and high disaster losses.The 2020 Yangtze River flood has received extensive media coverage and raised concerns on the roles of the Three Gorges Dam and other large reservoirs in flood control.Here we analyze the changes in the pattern of the Yangtze River flood control by comparing the strategies to tackle the three heavy floods occurring in 1954,1998,and 2020.We propose that the overall strategy of the Yangtze River flood control in the new era should adhere to the principle of"Integration of storage and drainage over the entire Yangtze River Basin,with draining floods downstream as the first priority"by using both engineering and non-engineering measures.On the basis of embankments,the engineering measures should use the Three Gorges Dam and other large reservoirs as the major regulatory means,promote the construction of key flood detention areas,keep the floodways clear,and maintain the ecosystem services of wetlands and shoals.In terms of non-engineering measures,we should strengthen adaptive flood risk management under climate change,standardize the use of lands in flood detention areas,give space to floods,and promote the implementation of flood risk maps and flood insurance policies.The ultimate goal of this new flood control system is to enhance the adaptability to frequent floods and increase the resilience to extreme flood disasters.     

柘林水库修河流域降水时空分布特征与旱涝研究

根据1953—1983年降水资料,分析了柘林水库修河流域降水时空分布特征和旱涝规律。降水主要集中在6月中、下旬,有时可推迟到7月中旬,此时暴雨频数高,强度大,历时长,是柘林水库洪水运行管理的关键时期。为此,需要了解梅雨晚期发生的大暴雨的形成条件和时空分布,以及梅雨期旱涝情况和采用预报的风险程度。本文在这方面进行了一些综合性分析,特别是对5,6月旱涝年份的统计规律、环流特征作了较详细的气候学对比研究。     

Development of a thresholds approach for real‐time flash flood prediction in complex geomorphological river basins

Flash floods represent one of the deadliest and costliest natural disasters worldwide. The hydrological analysis of a flash flood event contributes in the understanding of the runoff creation process. This study presents the analysis of some flash flood events that took place in a complex geomorphological Mediterranean River basin. The objective of the present work is to develop the thresholds for a real‐time flash flood forecasting model in a complex geomorphological watershed, based on high‐frequency data from strategically located hydrological and meteorological telemetric stations. These stations provide hourly real‐time data which were used to determine hydrological and meteorological parameters. The main characteristics of various hydrographs specified in this study were the runoff coefficients, lag time, time to peak, and the maximum potential retention. The estimation of these hydrometeorological parameters provides the necessary information in order to successfully manage flash floods events. Especially, the time to peak is the most significant hydrological parameter that affects the response time of an oncoming flash flood event. A study of the above parameters is essential for the specification of thresholds which are related to the geomorphological characteristics of the river basin, the rainfall accumulation of an event, the rainfall intensity, the threshold runoff through karstic area, the season during which the rainfall takes place and the time intervals between the rainstorms that affect the soil moisture conditions. All these factors are combined into a real‐time‐threshold flash flood prediction model. Historical flash flood events at the downstream are also used for the validation of the model. An application of the proposed model is presented for the Koiliaris River basin in Crete, Greece. Copyright © 2011 John Wiley & Sons, Ltd.     

Precipitation,temperature and runoff analysis from 1950 to 2002 in the Yangtze basin,China / Analyse des précipitations,températures et débits de 1950 à 2002 dans le bassin du Yangtze,en Chine

Abstract

Abstract Monthly precipitation and temperature trends of 51 stations in the Yangtze basin from 1950–2002 were analysed and interpolated. The Mann-Kendall trend test was applied to examine the monthly precipitation and temperature data. Significant positive and negative trends at the 90, 95 and 99% significance levels were detected. The monthly mean temperature, precipitation, summer precipitation and monthly mean runoff at Yichang, Hankou and Datong stations were analysed. The results indicate that spatial distribution of precipitation and temperature trends is different. The middle and lower Yangtze basin is dominated by upward precipitation trend but by somewhat downward temperature trend; while downward precipitation trend and upward temperature trend occur in the upper Yangtze basin. This is because increasing precipitation leads to increasing cloud coverage and, hence, results in decreasing ground surface temperature. Average monthly precipitation and temperature analysis for the upper, middle and lower Yangtze basin, respectively, further corroborate this viewpoint. Analysis of precipitation trend for these three regions and of runoff trends for the Yichang, Hankou and Datong stations indicated that runoff trends respond well to the precipitation trends. Historical flood trend analysis also shows that floods in the middle and lower Yangtze basin are in upward trend. The above findings indicate that the middle and lower Yangtze basin is likely to face more serious flood disasters. The research results help in further understanding the influence of climatic changes on floods in the Yangtze basin, providing scientific background for the flood control activities in large catchments in Asia.     

Input-output Balances of Nutrients and Plankton in a Flooded Area of the Lower Odra

The retention of particulate matter of the Odra River in flooded areas was estimated by determining suspended particulate matter (SPM) elimination and particle-bound nutrient retention in a polder area of the Lower Odra Valley national park. Water and suspended matter samples collected before, during, and after the 1997 summer flood at the inlet and the outlet of the investigated polder (Polder A/B close to Schwedt) offer the opportunity to balance the matter retention inside the floodplain. The maximum level of retained SPM (more than 80%) was calculated for the record flood of summer 1997, while in ordinary winter floods retention differs between 33% and 70%. Basic properties of the flowing particles like settling velocity, density, loss on ignition etc. change on their way through the polder area. In the investigated Polder A/B a retention of at least 50% of particle-bound phosphorus which was independent of the incoming suspended matter load from the Odra River was observed. The retention of particle-bound nitrogen and carbon varied seasonally to different extents. The presented balance demonstrates that particle-bound nutrient retention in polders is an important factor in the self-purification process of the river system. Some additional effort was done to study changes of plankton composition: during a joint field experiment in spring 1998, the authors determined biological parameters (abundance and biomass of phytoplankton and zooplankton) of water samples at polder inflow and outflow points.     

Relative velocities of discharge and sediment waves for the River Severn,UK

Abstract

It is generally accepted that the celerity of a discharge wave exceeds that of a floodwave. The discharge wave is the initial wavefront (shown by an increase in stage at a particular site), whereas the floodwave refers to the body of water moving downstream. Yet, few studies have investigated the varying relationship between discharge and suspended sediment concentration as floods propagate downstream. This paper examines the relative velocities of the discharge and sediment waves for natural flood events on the River Severn, UK. Four monitoring stations were established within the upper 35 km reach of the River Severn (drainage basin area 380 km2). Discharge was monitored using fixed structures, and suspended sediment concentrations were monitored at similar locations using Partech IR40C turbidity meters. Results showed discharge wave celerity increased with flood magnitude, but relationships were more complex for sediment wave celerity. Sediment wave celerity was greater than discharge wave celerity, and is attributed to the dominant source of sediment, which is most probably bank erosion.     

1840年以来长江大洪水演变与气候变化关系初探

长江洪水灾害是我国频率高、为患严重的自然灾害之一.本文依据可靠资料,选择1840年至2000年间32次大洪水记录,探讨其演变与气候变化的关系.认知1910s前的19世纪冷期出现大洪水13次(包括1870年的极值大洪水事件)频率为1.9次／10a.1921-2000年间出现了大洪水19次,频率为2.4次／10a.20世纪暖期又分出两个变暖时段,前一变暖时段的峰值期1920s-1940s出现大洪水9次,包含1931年全流域大洪水.后一变暖时段,即1980s与1990s出现大洪水8次.实测记录到的最大洪水1954年位于前一变暖时段结束阶段.1990s是全球,也是我国近百年中最暖年代,受东南季风影响大的中下游地区夏季降水量是近百年最多的,大暴雨频率也是有较多记录的40年来最高的.以此出现了10年5次大洪水高频率现象,包含1998年全流域型大洪水,表明了全球变暖的显著影响.也指示30-40年问周期性振荡中多雨年代.如此可预期21世纪初期降水会有小幅度下降与大洪水频率在短期内降低的可能性.长江上游受西南季风影响较大,19世纪下半期与20世纪上半期为多降水期,大洪水频率较高.20世纪下半期为少降水期,大洪水频率较低.关于气候变化研究有待深入,前景不易预估.     

Model Simulations of the Transport of Odra Flood Water through the Szczecin Lagoon into the Pomeranian Bight in July/August 1997

The Odra river flood of July through August 1997 transported a large additional volume of water into the Szczecin Lagoon area for a period of about one month. The dispersion of this water in the Szczecin Lagoon and Pomeranian Bight was simulated using the operational hydrodynamic model of the North Sea and Baltic Sea operated by the Federal Maritime and Hydrographic Agency of Germany (BSH). The model system receives as input meteorological forecast fields from the EUROPA model of the German Weather Service. As a result of the model simulation, the temporal development of the river plume can be described as follows: First the eastern part of Szczecin Lagoon, the Zalew Wielki, filled with flood water displacing θnormalρ Odra river water from that area. After about a week, Odra river flood water started to flow into the Pomeranian Bight. Its dispersion within Szczecin Lagoon was by no means uniform. The Kleines Haff, the western part of the Lagoon, was not much affected at first. When large labelled water masses had already left the Zalew Wielki area through the Swina river, at most only about half the water volume in Kleines Haff had been replaced by Odra flood water. In the Pomeranian Bight, the concentration was higher at the coast of Usedom – at least initially – than at the coast of Wolin. After 30 August 1997, northwesterly winds caused undiluted Baltic water to flow from the northern to the southern part of the Pomeranian Bight, pushing the water body marked, or distinguished, by Odra water eastward along the coast of Wolin. At the same time, outflow began from Kleines Haff through the Peenestrom into the Greifswalder Bodden. Due to light winds, and hence limited vertical mixing in summer, the proportion of freshwater in Baltic surface water reached about 50% in the southern Pomeranian Bight. Near Rügen, it fell below 10%. Within 2 months of stronger wind caused major shifts of the water bodies concerned. The scale considerations and model simulations discussed in this paper allowed qualitative estimates to be made in the course of the flood event, which were later confirmed by measurements, presented at a HELCOM (Helsinki Commission, Baltic Marine Environment Protection Commission) Scientific Workshop in January 1998.     

Water reservoirs and the risk of accidental flood occurrence. Case study: Stanca–Costesti reservoir and the historical floods of the Prut river in the period July–August 2008, Romania

In the summer of 2008 the Prut river recorded a historical flow of 7140 m³/s at its entrance into Romania. This flow was the highest ever recorded of any Romanian river. The high value was generated by high amounts of rainfall recorded first on the territory of Ukraine and then in Romania. Unfortunately, there were some discrepancies between the data transmitted and intercepted from the Meteorology National Agency and Hydrology and Water Management National Agency. This is why the amount of precipitation which fell over the territory of Ukraine could not be monitored in time and punctually. Nor could the high flood wave moving rapidly from the upper basin to the lower basin. The high flow of the upper Prut caused the accumulation of an immense quantity of water in the Stanca–Costesti reservoir. Under the conditions of precipitation occurring in the lower river basin as well, the levels reached the flood quota and the reservoir reached the maximum accepted capacity, with 0·1% insurance. The release of supplementary water quantities from the reservoir would have produced catastrophic floods downstream. Keeping the water in the reservoir could have broken it and the flooding, through backwater eddies, or the riverbank settlements. In such a case, it would have produced the greatest tragedy in the hydrological history of Europe. The most significant damage was produced upstream of the barrage, next to the localities of Radauti Prut and Baranca–Hudesti, as well as in the area of the reservoir, as a result of the phenomenon known as ‘remuu’, or backwater eddies. The floods of the Prut river occurred between the end of July and the end of August. Copyright © 2011 John Wiley & Sons, Ltd.     

Flood changes during the past 50 years in Wujiang River,South China

Changing trends of peak flood and flood duration in the Wujiang River Basin are detected with the help of the Mann–Kendall test and the Pettitt analysis during the past 50 years. Results indicate that the peak flood and the flood duration at Lishi Station have different changing features. The peak flood showed only marginally increasing trend, whereas the flood duration exhibited decreasing trend at the significance level of 90%. The result shows a weak positive correlation between the peak flood and the flood duration. The changes of flood duration are influenced by the total rainfall duration, which is in downward trend at significance level 90%. In addition, the changing trends of peak flood are similar to the total rainfall amount. In the change‐point analysis, it was found that the change points for the peak flood and flood duration series were in the years 1993 and 1966, respectively. Human activities such as the construction of reservoirs were the main driving forces causing the change of flood duration. The periodicity of the peak flood during the period 1955–2007 at Lishi Station is detected by using the wavelet analysis. The result indicates that the peak flood at Lishi Station displayed alternation between big floods and small floods on the 25‐ to 26‐year period. At the same timescale, the peak flood of Wujiang River showed an evidence of change between big floods and small floods. It was essential to be prepared and aware of the consequences of climate changes and human influences affecting the water resources in the Wujiang River Basin. This result is expected to draw more attention from the local governments in its decision making and water resource management. Copyright © 2012 John Wiley & Sons, Ltd.     

A data-based regional scale autoregressive rainfall-runoff model: a study from the Odra River

This paper aims to compare the performances of multivariate autoregressive (MAR) techniques and univariate autoregressive (AR) methods applied to regional scale rainfall-runoff modelling. We focus on the case study from the upper and middle reaches of the Odra River with its main tributaries in SW Poland. The rivers drain both the mountains (the Sudetes) and the lowland (Nizina Śląska). The region is exposed to extreme hydrologic and meteorological events, especially rain-induced and snow-melt floods. For the analysis, four hydrologic and meteorological variables are chosen, i.e., discharge (17 locations), precipitation (7 locations), thickness of snow cover (7 locations) and groundwater level (1 location). The time period is November 1971–December 1981 and the temporal resolution of the time series is of 1 day. Both MAR and AR models of the same orders are fitted to various subsets of the data and subsequently forecasts of discharge are derived. In order to evaluate the predictions the stepwise procedure is applied to make the validation independent of the specific sample path of the stochastic process. It is shown that the model forecasts peak discharges even 2–4 days in advance in the case of both rain-induced and snow-melt peak flows. Furthermore, the accuracy of discharge predictions increases if one analyses the combined data on discharge, precipitation, snow cover, and groundwater level instead of the pure discharge multivariate time series. MAR-based discharge forecasts based on multivariate data on discharges are more accurate than AR-based univariate predictions for a year with a flood, however, this relation is reverse in the case of the free-of-flooding year. In contrast, independently of the occurrence of floods within a year, MAR-based discharge forecasts based on discharges, precipitation, snow cover, and groundwater level are more precise than AR-based predictions.     

Application of satellite products and hydrological modelling for flood early warning

Floods have caused devastating impacts to the environment and society in Awash River Basin, Ethiopia. Since flooding events are frequent, this marks the need to develop tools for flood early warning. In this study, we propose a satellite based flood index to identify the runoff source areas that largely contribute to extreme runoff production and floods in the basin. Satellite based products used for development of the flood index are CMORPH (Climate Prediction Center MORPHing technique: 0.25^° by 0.25^°, daily) product for calculation of the Standard Precipitation Index (SPI) and a Shuttle Radar Topography Mission (SRTM) digital elevation model (DEM) for calculation of the Topographic Wetness Index (TWI). Other satellite products used in this study are for rainfall-runoff modelling to represent rainfall, potential evapotranspiration, vegetation cover and topography. Results of the study show that assessment of spatial and temporal rainfall variability by satellite products may well serve in flood early warning. Preliminary findings on effectiveness of the flood index developed in this study indicate that the index is well suited for flood early warning. The index combines SPI and TWI, and preliminary results illustrate the spatial distribution of likely runoff source areas that cause floods in flood prone areas.     

The Pollution Load from the River Odra in Comparison to That in Other Polish Rivers in 1988–1997

The discharge of organic matter, nutrients, and heavy metals from the river Odra into the Baltic Sea is compared with the combined discharge of the same substances from other Polish rivers into the Baltic during 1988–1997. The impact of the summer flood of 1997 is also discussed. The discharges of organic matter, nitrogen and phosphorus compounds were closely correlated with the flow rate. The annual loads of these nutrients measured in 1988 and 1996 under similar flow conditions decreased by 15 to 40% in these rivers as a result of the reduction of point sources. A steady decrease in the heavy metal load, independent of weather conditions, has been recorded during the past decade. Zinc decreased by up to 85% in the Odra and 99% in the Wisła. Although the water outflow from the Odra was half that of the Wisła, it transported a proportionally higher load of chemical compounds. Despite the differences in flow rates, the contribution of both rivers to the total riverine phosphorus discharge was approximately the same. The total water outflow during the flood (from 1 July to 28 August 1997) increased by 65% near the mouth of the Odra in comparison to 1996. The phosphate discharge increased by 34%, that of nitrite nitrogen by 88%     

Extreme hydrological events in the Danube River basin over the last decades

The article discusses the considerable changes in hydrometeorological conditions that occurred in the Danube River basin over the period from the late XX century to the early XXI century. Mention is made of the air and water temperature rise, softening of ice conditions, and, above all, the noticeable increase in the river water runoff. Particular attention is given to the recent extreme hydrological events in the Danube River basin: the disastrous rainfall flood that occurred in August 2002, the extremely high spring-summer floods in 2006 and 2010, and the extraordinary low-flow period in summer 2003. The meteorological reasons for these events have been analyzed. Specific features in the development and transformation of flood waves along the Danube River are discussed in detail, including the impact of the Iron Gate-1 Reservoir on these processes.     

日地水文学与灾害预测

研究地球水文变化的日地物理成因和规律的日地水文学（Solar-TerrestrialHydrology），用于水、旱灾害预测多次获得证实.本文从日地水文物理基础、长江淮河22年周期性大洪水、黄河大洪水和太阳活动关系、太阳活动双重衰减期北方大旱、17世纪日地水文异常变化、太阳活动对暴雨洪水中短期影响、台湾海峡两侧大暴雨洪水落区转移、全球最大洪水日地水文研究以及学科发展和应用前景九个方面，对中国近70多年来的主要成果加以回顾和总结.基础科学、高科技和应用紧密结合，促成对国民经济发展直接相关的新学科，是当代科学进步的一个显著标志，这里又是一个例证．