The evolution analysis of flood and drought in Huai River Basin of China based on monthly precipitation characteristics

Based on the daily precipitation data of 38 weather stations in the Huai River Basin from 1961 to 2010, this study used SPI index, P-III curve to determine the flood/drought years, under what situations for droughts and floods easily happen, and to analyze the evolution law of flood and drought during inter-annual and intra-annual based on the characteristic of monthly precipitation. The results showed that: (1) annual rainfall of the Huai River Basin presented decreasing trend, maximum rainfall appeared from June to August, and multi-year average precipitation increased gradually from north to south; (2) the variation of monthly precipitation during flood years was more severe than other typical years, and precipitation in drought years showed nearly 50 % decline compared with normal years; (3) high rainfall of flood years was mainly caused by the increase in rainfall in flood season, and the strategy of flood control and drought relief was “short-term flood prevention and long-term drought relief”; (4) while precipitation of most months in drought year was reduced, the relevant strategies “annual basin-wide of long-term drought prevention” should be carried out; (5) combination events of floods and droughts occurred frequently. Persistent drought dominated in spring and summer while droughts and floods that happened alternately were mainly in summer and autumn.     

长江流域降水极值的变化趋势

依据1960-2005年长江流域147个气象站逐日降水,ECHAM5/MPI-OM气候模式模拟的长江流域79个格点20世纪实验期(1941-2000年)以及未来3种排放情景(SRES-B1,A1B,A2)下21世纪前50年逐日降水数据,建立年最大强降水和汛期<1.27 mm/d的最长干旱持续天数序列。运用广义极值分布,广义帕雷托分布,广义逻辑分布与韦克比分布等4种分布函数定量拟合了长江流域降水极值的概率分布。研究表明:韦克比分布函数能够较好地拟合长江流域降水极值的概率分布。在3种排放情景下,未来降水极值的重现期呈现不同的空间分布特征。长江流域,尤其是中下游大部地区,1951-2000年间的50年一遇强降水和干旱事件,在2001-2050年间发展成为25年一遇降水极值事件。未来气候变暖条件下,降水极值重现期出现的这种变化趋势,将会对水资源趋势产生重大的影响。     

卫星资料在暴雨数值模拟中的应用研究

分析研究了2001年5月15日～8月15日3个月GMS卫星资料在湖南资水流域实时数值预报中的应用以及将TRMM(Tropical Rainfall Measuring Mission)卫星上的TMI(Microwave Imager)雨水资料适时融入数值模式改变当时模式中雨水分布场,数值模拟还研究了发生在淮河流域的10次暴雨过程。结果表明:资水流域3个月的实时预报效果良好,准确预报出其中出现的3次致洪暴雨和1次特大暴雨;对淮河流域暴雨,由于TMI资料空间分辨率较高,能够很好地反映中小尺度系统的空间结构,加入模式后使得模拟出来的降雨强度,雨量中心时空分布更接近实际情况,10次暴雨过程的TS评分较不使用TMI资料更好。     

A 1286‐year hydro‐climate reconstruction for the Balkan Peninsula

We present a June–July drought reconstruction based on the standardized precipitation index (SPI) for the Balkan Peninsula over the period 730–2015 CE. The reconstruction is developed using a composite Pinus heldreichii tree‐ring width chronology, from a high‐elevation network of eight sites in the Pindus Mountains in northwest Greece, composed of living trees and relict wood. The dataset includes the ring width series of Europe's currently oldest known living tree, dendrochronologically dated to be more than 1075 years old. The spatial coverage of the reconstruction is improved by using an averaged gridded SPI data target derived from a response field that is located north of the study region. Justification for this approach includes the remoteness of instrumental data, the spatial variability of precipitation and synoptic scale circulation patterns. Over the past 1286 years, there have been 51 dry and 43 pluvial events. The driest year during the 1286‐year‐long period was 1660 and the wettest year was 1482. Comparison with shorter reconstructions and documentary evidence validates the new reconstruction, and provides additional insight into socioeconomic impacts and spatial patterns of extreme events. Fifty‐nine of 72 previously undescribed extremes occurred prior to the 17th century. The new reconstruction reveals long‐term changes in the number of extremes, including substantially fewer drought and pluvial events in the 20th century. Additional tests on the long‐term effects of age structure, replication and covariance changes support the heteroscedastic nature of the reconstructed hydro‐climatic extremes.     

公元1500—2000年印度尼西亚—菲律宾强火山喷发对中国中东部旱涝格局的影响*

强火山活动是气候变化的重要自然驱动因素,可导致中国降水出现年际或年代际变化,甚至极端的旱涝现象。探究位于中国邻域的印度尼西亚—菲律宾一带的强火山喷发与中国旱涝分布格局的关系,有助于阐释中国旱涝发生的时空规律及机制,为预测未来火山爆发可能导致的降水异常提供借鉴。本文基于1500—2000年期间世界强火山活动和中国旱涝资料,运用时序叠加分析的方法辨识了印度尼西亚—菲律宾一带的强火山喷发后中国旱涝在年际尺度上的时空变化特征,并对1815年Tambora火山喷发进行案例分析。结果表明印度尼西亚—菲律宾一带的强火山喷发对中国的旱涝格局有一定的影响:强火山喷发后第0年至第2年,中国中东部各站点的整体变化为偏涝;在第3年,整体出现了偏旱的转变,且变化幅度相比其他年份较大;就地区而言,喷发后华北、华南地区分别出现了由旱转涝、由涝转旱的变化,并且这些变化大概持续了2~3年,随后2个区域均恢复了喷发前的旱涝趋势;印度尼西亚1815年Tambora火山喷发后0~3年,中国以涝情为主,但发生涝情的区域逐年在发生变化。     

近1 000年长江中下游旱涝与气候变化关系

文章利用旱涝灾害历史记载与现代器测降水资料重建长江中下游旱涝灾害等级序列 ,并通过相关分析与波谱分析、交叉谱分析等分别探讨了长江中下游旱涝灾害发生与东太平洋海水表面温度 (SST)以及太阳活动 (太阳黑子数 )的关系。结果表明 ,长江中下游涝灾多发生于气候过渡期 ,即涝灾在气候由一种气候状态向另一种气候状态转变时期多发。谱分析与交叉谱分析结果表明 ,长江中下游旱涝灾害等级序列在 10～ 11年周期上与太阳黑子数存在相关 ,但两者有近 1年的滞后性。长江中下游旱涝灾害与SST的相关关系分析表明 ,SST正距平年份 ,往往对应着长江中下游的涝灾 ;而SST负距平年份往往对应着长江中下游旱灾。因而可以认为 ,SST与太阳活动变化(太阳黑子数量变化 )在不同周期频度上对长江中下游旱涝灾害具有明显影响。     

我国北方4kaB.P.前后异常洪水事件的初步研究

史前异常洪水事件的初步调查表明,4kaB.P.前后是我国北方异常洪水多发的时期,黄河流域、淮河流域和海河流域在这一时期普遍出现不同形式的史前异常洪水事件.异常洪水事件的出现与当时的降温事件有密切的关系,气候变冷引发的相对湿度加大和降雨量增多可能是造成这次异常洪水事件的主要原因.出现于华夏文明诞生前夕的史前异常洪水事件对华夏文明的演进势必会产生重大影响,在黄河上游的山间盆地和下游的黄淮海平原,异常洪水给人类生存环境带来严重的破坏,导致这些地区早期文明的衰落;而位于我国地貌大势二级阶梯与一级阶梯之间的中原地区,尽管洪水也给人类生存环境造成严重的威胁,但它并没有导致早期文明的衰落,恰恰相反,先民们利用有利的地貌条件,通过与洪水的争斗,促进了文化的发展和华夏文明的诞生.     

Space-based monitoring of severe flooding of a southern state in India during south-west monsoon season of 2018

Kerala, a southern state of India, experienced a severe flooding due to multi-day extreme rain events during July and August months of 2018. This disaster was one of the worst floods to hit the state and resulted in heavy losses of lives and property. Natural Disaster Management Authority of India reported that 483 people lost their lives and more than 50 lakhs population were affected severely. This short communication focuses on examining this flood event using satellite remote sensing. It is reported that Kerala received an excess of about 56% rainfall during July and August from multi-day extreme rainfall episodes. Few regions of Kerala received the rainfall in the range of 270–300 mm on August 14 and 15. Hourly rainfall events in the excess of 25 mm have also been reported during heavy rainy days. The present study reports that multi-day heavy rainy events during July and August brought an accumulated rainfall of about 1600 mm, which resulted in extreme flooding over Kerala.

     

Spatiotemporal variation of meteorological droughts based on the daily comprehensive drought index in the Haihe River basin,China

Meteorological droughts can affect large areas and may have serious environmental, social and economic impacts. These impacts depend on the severity, duration, and spatial extent of the precipitation deficit and the socioeconomic vulnerability of the affected regions. This paper examines the spatiotemporal variation of meteorological droughts in the Haihe River basin. Meteorological droughts events were diagnosed using daily meteorological data from 44 stations by calculating a comprehensive drought index (CI) for the period 1961–2011. Based on the daily CI values of each station over the past 50 years, the drought processes at each station were confirmed, and the severity, duration and frequency of each meteorological drought event were computed and analyzed. The results suggest the following conclusions: (1) the use of the CI index can effectively trace the development of drought and can also identify the duration and severity of each drought event; (2) the average drought duration was 57–85 days in each region of the Haihe River basin, and the region with the highest average values of drought duration and drought severity was Bohai Bay; (3) drought occurred more than 48 times over the study period, which is more than 0.95 times per year over the 50 years studied. The average frequencies of non-drought days, severe drought days and extreme drought days over the study period were 51.2, 3.2 and 0.4 %, respectively. Severe drought events mainly occurred in the south branch of the Hai River, and extreme drought events mainly occurred in the Shandong Peninsula and Bohai Bay; (4) the annual precipitation and potential evapotranspiration of the Haihe River basin show decreasing trends over the past 50 years. The frequency of severe drought and extreme drought events has increased in the past 20 years than during the period 1961–1990. The results of this study may serve as a reference point for decision regarding basin water resources management, ecological recovery and drought hazard vulnerability analysis.

     

Spatiotemporal variation of meteorological droughts based on the daily comprehensive drought index in the Haihe River basin,China

Meteorological droughts can affect large areas and may have serious environmental, social and economic impacts. These impacts depend on the severity, duration, and spatial extent of the precipitation deficit and the socioeconomic vulnerability of the affected regions. This paper examines the spatiotemporal variation of meteorological droughts in the Haihe River basin. Meteorological droughts events were diagnosed using daily meteorological data from 44 stations by calculating a comprehensive drought index (CI) for the period 1961–2011. Based on the daily CI values of each station over the past 50 years, the drought processes at each station were confirmed, and the severity, duration and frequency of each meteorological drought event were computed and analyzed. The results suggest the following conclusions: (1) the use of the CI index can effectively trace the development of drought and can also identify the duration and severity of each drought event; (2) the average drought duration was 57–85 days in each region of the Haihe River basin, and the region with the highest average values of drought duration and drought severity was Bohai Bay; (3) drought occurred more than 48 times over the study period, which is more than 0.95 times per year over the 50 years studied. The average frequencies of non-drought days, severe drought days and extreme drought days over the study period were 51.2, 3.2 and 0.4 %, respectively. Severe drought events mainly occurred in the south branch of the Hai River, and extreme drought events mainly occurred in the Shandong Peninsula and Bohai Bay; (4) the annual precipitation and potential evapotranspiration of the Haihe River basin show decreasing trends over the past 50 years. The frequency of severe drought and extreme drought events has increased in the past 20 years than during the period 1961–1990. The results of this study may serve as a reference point for decision regarding basin water resources management, ecological recovery and drought hazard vulnerability analysis.     

堵河流域水文特征分析

对堵河竹山水文站1959~2007年降水量、径流量、输沙量等资料进行了统计分析,描述了堵河流域降雨、径流和暴雨洪水的主要特征以及河流泥沙受人类活动影响。为堵河流域水资源管理、防汛抗旱提供参考。     

厄尔尼诺事件对太湖流域降水的影响

为了揭示1951~2016年厄尔尼诺事件影响下太湖流域夏季(6~8月)降水特征,分析了厄尔尼诺事件开始年与结束年的降水状况。结果表明:太湖流域降雨与厄尔尼诺事件存在一定的关系:(1)弱强度厄尔尼诺事件起始年的6月与6~8月、结束年的6月与7月降水均以正常、大旱与极旱为主;中等强度厄尔尼诺事件起始年的6月与6~8月以正常与大涝为主,结束年同时段以正常、偏旱与大旱为主;(超)强厄尔尼诺事件起始年6月以正常或大旱为主,8月以正常或大涝为主,结束年刚好相反。(2)(超)强厄尔尼诺起始年的夏季,西太平洋副热带高压面积偏小,位置偏东,而结束年的夏季,西伸脊点加强西伸,利于太湖流域降雨偏多。(3)(超)强厄尔尼诺起始年的全年编号台风以偏少为主,登陆台风正常略偏少,但事件的起始年夏季6~8月编号台风却以偏多为主,结束年秋季9~11月登陆台风以偏多为主;结束年6月降雨偏多,登陆台风向秋季集中,易造成流域持续洪涝,对防洪产生不利影响。     

Riverine flood assessment in Jhang district in connection with ENSO and summer monsoon rainfall over Upper Indus Basin for 2010

Pakistan has experienced severe floods over the past decades due to climate variability. Among all the floods, the flood of 2010 was the worst in history. This study focuses on the assessment of (1) riverine flooding in the district Jhang (where Jhelum and Chenab rivers join, and the district was severely flood affected) and (2) south Asiatic summer monsoon rainfall patterns and anomalies considering the case of 2010 flood in Pakistan. The land use/cover change has been analyzed by using Landsat TM 30 m resolution satellite imageries for supervised classification, and three instances have been compared, i.e., pre-flooding, flooding, and post-flooding. The water flow accumulation, drainage density and pattern, and river catchment areas have been calculated by using Shutter Radar Topography Mission digital elevation model 90 m resolution. The standard deviation of south Asiatic summer monsoon rainfall patterns, anomalies and normal (1979–2008) has been calculated for July, August, and September by using rainfall data set of Era interim (0.75° × 0.75° resolution). El Niño Southern Oscillation has also been considered for its role in prevailing rainfall anomalies during the year 2010 over Upper Indus Basin region. Results show the considerable changing of land cover during the three instances in the Jhang district and water content in the rivers. Abnormal rainfall patterns over Upper Indus Basin region prevailed during summer monsoon months in the year 2010 and 2011. The El Niño (2009–2010) and its rapid phase transition to La Niña (2011–2012) may be the cause of severity and disturbances in rainfall patterns during the year 2010. The Geographical Information System techniques and model based simulated climate data sets have been used in this study which can be helpful in developing a monitoring tool for flood management.     

Mechanism of post-seismic floods after the Wenchuan earthquake in the upper Minjiang River,China

By analyzing the multi-year runoff and rainfall data at 15 hydrological stations from 1980 to 2007, as well as monthly runoff data from 1964 to 1984 at the Zipingpu hydrologic station, the relationship between precipitation and runoff has been established and the trend was explored. Based on the catastrophic floods of August 13 and August 18, 2010, characteristics and control factors on the post-seismic floods are summarized. Firstly, the Wenchuan earthquake and rupture zone provides the background for post-seismic floods to develop in the upper Minjiang River, which follows a post-seismic disaster-chain pattern: earthquake collapse to landslide debris flows to floods. Secondly, heavy rainfall controlled by the orographically-enhanced precipitation after the Wenchuan earthquake is the trigger factor for the development of devastating post-seismic floods. Thirdly, the post-seismic floods contain high sediment discharge, cause abrupt and severe damages, and have a large of volume and higher frequency.     

海河流域严重干旱500hPa信号场异常信号分析

基于严重少雨旬的定义,分析海河流域1961～2009年严重少雨旬的分布特征,进而对汛期40个典型严重少雨旬的500hPa信号场进行经验正交分解(EOF分析).结果表明:EOF第一模态的方差贡献率达到35.3％,远高于其他模态;第一模态呈现出2个负异常区和1个正异常区,在对应的环流背景下,海河流域受暖性高压控制,高纬冷空气及低纬暖湿气流难以到达流域上空交绥,持续高温少雨造成流域严重干旱.     

Assessment of uncertainty in regional and at-site precipitation frequency analysis for the localized region of Ellicott City,Maryland

Natural Hazards - Recent heavy rainfall events and flash floods in Ellicott City, Maryland, highlight the importance of having robust and up-to-date estimates of precipitation frequency. NOAA Atlas...     

淮河流域近500年洪旱事件演变特征分析

为了认识淮河流域过去500年洪旱事件发生规律并鉴别当前的洪旱情势,收集并对比分析了流域实测降雨资料、重建历史雨季降雨资料、历史旱涝等级资料、历史洪旱文献记录和历史调查洪水资料等多源洪旱灾害数据。以重建历史雨季降雨资料和历史旱涝等级资料为主要依据,通过滑动平均、频率计算、小波分析和突变检验等方法,分析流域过去500年洪水干旱时空分布特征和演变规律。结果表明,17世纪淮河流域洪旱灾害最严重,但20世纪极端洪旱事件发生频次最多。淮河流域洪旱事件存在40年左右的稳定长周期,主周期从18世纪的15~20年逐渐减少到19世纪的5年周期,近20年来出现2~3年的主周期,洪旱灾害事件呈增加趋势,流域社会经济发展面临着严峻的洪旱灾害威胁。     

Effect of climatic oscillations on flood occurrence on Papaloapan River,México,during the 1550–2000 period

This study presents a chronology of historical and measured flood events in the Papaloapan River basin of Mexico during 450 years. Twenty-eight historical floods were recorded during the period 1550–1948 on this river and one flood event (1969) in the instrumental era (1949–2000), of which 14 were extraordinary floods and only 15 were catastrophic ones. There were several flood-rich decades during 1860–1870, 1880–1890, 1920–1930 and 1940–1950. Wavelet analysis found a significant flooding periodicity of 58 years. The wavelet coherence analysis found that flooding had an in-phase relationship with the Atlantic Multidecadal Oscillation and also with the Pacific Decadal Oscillation. Logistic regression corroborated that there exists a positive relationship between floods events and these two natural climatic oscillations. The logistic regression model predicted correctly 92% of flood events.     

从2020年长江上游洪水看流域防洪对策

2020年长江上游和中下游先后发生特大洪水,其中干流编号洪水全部发生在上游,构成了长江流域洪水的主要部分。首先回顾2020年洪水及洪灾情况,然后根据历史上几次特大洪水过程和历年实测资料,分析长江上游洪水特征、洪灾类型及特点,最后提出新时代长江流域洪水整体防御战略及山洪灾害防治战术。研究表明:金沙江洪水是长江上游洪水基础部分,岷江、嘉陵江和干流区间是洪峰的主要来源,三者洪水遭遇是产生上游特大洪水的主因,上游洪水又是全流域特大洪水的基础和重要组成部分。目前造成洪灾死亡人数最多的是山洪以及山洪引起的地质灾害,财产损失最大的是中下游及湖泊地区。未来堤防仍然是防洪的基础,提高沿江城市防洪标准主要手段是控制性水库的联合优化调度,而减少洪涝灾害损失最有效的途径是给洪水以空间的自然解决方案等非工程措施。     

Multiscale modelling of rainstorm-induced historical intermediate floods (June–November) in the Rhone River Basin

This study reveals the changes and evolution of rainstorm-driven intermediate floods occurring and driving multiple damaging hydrological events in the Rhone River Basin (RRB), since 1500 until 2010. A parsimonious approach was developed to simulate the major hydroclimatological flood-producing forcing, the Multiscale Rainstorm Climate Model (STORMCLIMM). We collected the frequency of intermediate floods—a type of particularly hazardous floods commonly taking place between June and beginning of November—from the RCB to be compared to STORMCLIMM estimates. The latter, smoothed by a moving window of 21 years, results in a high-pass filter in the time domain, which magnifies the signal of forcing variations causing intermediate floods. The RRB showed large temporal variations in both extreme rainstorms and associated multidecadal intermediate-floods (MUDIF) frequency at different climatic periods and land-use systems through historical times. An important peak was observed in the Maunder Minimum (1645–1715 AD). The model allowed detecting MUDIF occurred in the historical times. The situation becomes interesting with respect to recent times, because the Rhone landscape looks more vulnerable in the last decades as a consequence of land-use changes and climate shift towards more erratic and intensive storms. This evidence suggests that the interactions of land-use and climatic changes may turn into considerable vulnerability to fluvial flooding and agro-ecosystem connected to them for upcoming years. The Rhone, for example, provides basis for use of hydrological indicators (such as the one represented by STORMCLIMM) for one site or region and which, through minor modifications, can be made relevant to specific needs.