Effects of AO and Pacific SSTA on severe droughts in Luanhe River basin,China

Natural Hazards - In the (re)insurance industry, the risk from natural hazards such as earthquakes or floods is quantified by models for natural catastrophes, also called NatCat models. One...     

黄河流域分布式水文模型初步研究与进展

结合国家重点基础研究规划项目"黄河流域水资源演化规律与可再生性维持机理"的研究,综述了黄河流域分布式水文模型研究的主要进展,包括分布式水文模型的特点和基本结构、分布式水文模型中的数字高程模型(DEM)和水文学基础、地理信息系统(GIS)和遥感(RS)在分布式水文模拟中的应用等方面的内容,对未来分布式水文模型的研究提出几点认识。     

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.

     

黄河小花区间暴雨径流过程分布式模拟

提出了一种松散偶合型结构的分布式水文模型,模型以小时为时段,主要用于洪水模拟。模型构建在DEM的基础上,由数字流域、单元网格模型、河网汇流模型、水库调蓄模型和图形用户界面(GUI)等5部分构成。通过GUI可以实现模型的输入、参数选择和运行输出。模型适用于人类活动较少的、半湿润和半干旱地区,在黄河小浪底-花园口区间洛河卢氏以上流域得到应用。     

Effect of different soil data on hydrological process modeling in Weihe River basin of Northwest China

Hydrological process modeling depends on the soil data spatial resolution of the watershed. Especially, in a large-scale watershed, could a higher resolution of soil data contribute to a more accurate result? In this study, two soil datasets with different classification systems FAO (World Reference Base) and GSCC (the Genetic Soil Classification of China) were used as inputs for the SWAT model to study the effects of soil datasets on hydrological process modeling in Weihe River basin, China. Results show that the discharge simulated using FAO soil data was better than one simulated using GSCC soil data before model calibration, which indicates that FAO soil data needed less effort to calibrate. After model calibration, discharges were simulated better by both of FAO and GSCC soil data but statistical parameters demonstrate that we can make a relatively more accurate estimation of discharge using the GSCC rather than FAO soil data. Soil water content (SW) simulated using GSCC soil data was statistically significantly higher than those simulated using FAO soil data. However, variations in other hydrological components (surface runoff (SURQ), actual evapotranspiration (ET), and water yield (WYLD) were not statistically significant. This might be because SW is more sensitive to soil properties. For studies aiming to simulate or compare SW, merely calibrating and validating models using river discharge observations is not enough. The hydrological modelers need to identify the key hydrological components intrinsic to their study and weigh the advantages and disadvantages before selecting suitable soil data.     

Spatial characteristics of surface water quality in the Haicheng River (Liao River basin) in Northeast China

Spatial variations of the water quality in the Haicheng River during April and October 2009 were evaluated for the national monitoring program on water pollution control and treatment in China. The spatial autocorrelation analysis with lower Moran’s I values displayed the spatial heterogeneity of the 12 physicochemical parameters among all the sampling sites of the river. The one-way ANOVA showed that all variables at different sampling sites had significant spatial differences (p < 0.01). Based on the similarity of water quality characteristics, cluster analysis grouped the 20 sampling sites into three clusters, related with less polluted, moderately polluted and highly polluted sites. The factor analysis extracted three major factors explaining 76.4 % of the total variance in the water quality data set, i.e., integrated pollution factor, nitrogen pollution factor and physical factor. The results revealed that the river has been severely polluted by organic matter and nitrogen. The major sources leading to water quality deterioration are complex and ascribed to anthropogenic activities, e.g., domestic and industrial wastewater discharges, agricultural runoff, and animal rearing practices.     

Comparison between bivariate and trivariate flood frequency analysis using the Archimedean copula functions,a case study of the Karun River in Iran

Natural Hazards - Historically, severe floods have caused great human and financial losses. Therefore, the flood frequency analysis based on the flood multiple variables including flood peak,...     

Assessing the effects of climate change on the hydrological regime of the Limay River basin

The electricity generation capacity in the Limay River basin is approximately 26% of the total electrical power generation in Argentina. Assessing the potential effects of climate change on the hydrological regime of this basin is an important issue for water resources management. This study explores the presence of trends in streamflow series, evaluates climate sensitivity and studies the effects on the flow regime of predicted changes in precipitation in the basin. In order to identify and quantify changes in observed streamflow series, the Mann–Kendall test, with a modification for autocorrelated data, and an estimator of the magnitude of the trend are applied. In order to evaluate the sensitivity of streamflow to changes in climate, the concept of elasticity is used. Precipitation elasticity of streamflow is used to quantify the sensitivity of streamflow to changes in precipitation and is estimated using a power law model and a linear statistical model in two sub-basins, Aluminé and Nahuel Huapi. The effects on flow regime of the predicted changes in precipitation under different scenarios are studied. Climatic results for different scenarios of growth in greenhouse gases from some General Circulation Models are used as inputs into the proposed models. The analysis identifies decreasing trends in mean and minimum annual flows and in the low flow season. The estimates of the precipitation elasticity imply that changes in precipitation produce similar changes in streamflow and the climatic results for different scenarios show that the variations are moderate.     

嫩江流域沼泽湿地景观变化及其水文驱动因素分析

借助ArcGIS空间分析工具,以嫩江流域1978年、1990年、2000年和2008年4期遥感湿地分布图为基础,采用SWAT (Soil and Water Assessment Tool)水文模型将嫩江流域划分为43个子流域,并以沼泽湿地类型为例,将各个子流域内降水和径流信息与湿地退化遥感信息作对比筛选,对全流域以及湿地面积减少严重所在子流域作进一步分析。另外,利用两期土地利用类型数据生成嫩江流域土地利用转移矩阵。结果表明:1978—2008年间嫩江流域沼泽湿地退化严重,尤其以1990—2000年间最为显著。这与流域内降水、径流的变化密切相关,并受到土地利用类型转化以及水利工程建设等人类活动的影响。其中,沼泽湿地面积变化与流域径流系数变化在0.01水平上呈极显著正相关,pearson相关系数为0.90。气候变化和人类活动影响下对湿地水文过程以及水资源的变化,导致湿地日益萎缩,对流域内湿地生态系统平衡产生了负面影响。     

Understanding the impact of droughts in the Yarmouk Basin,Jordan: monitoring droughts through meteorological and hydrological drought indices

This article assesses drought status in the Yarmouk Basin (YB), in northern Jordan, using the Standardized Precipitation Index (SPI), the Standardized Water-Level Index (SWI), and the Percent Departure from Normal rainfall (PDNimd) during the years 1993–2014. The results showed that the YB suffers from frequent and irregular periods of drought as variations in drought intensity and frequency have been observed. The SPI results revealed that the highest drought magnitude of ??2.34 appeared at Nuaimeh rainfall station in 1991. This station has also experienced severe drought particularly in years 1995, 1999, 2005, and 2012 with SPI values ranging from ??1.51 to ??1.59. Some other rainfall stations such as Baqura, Ibbin, Khanasiri, Kharja, Mafraq police, Ramtha, Turra, and Umm Qais have also suffered several periods of drought mostly in 1993. The SWI results show the highest extreme drought events in 2001 in Souf well while other extreme drought periods were observed at Wadi Elyabis well in 1994 and at Mafraq well in 1995. As compared to SPI maps, our SWI maps reflect severe and extreme drought events in most years, negatively impacting the groundwater levels in the study area.     

Extreme hydrological events in karst areas of Slovenia,the case of the Unica River basin

The study presents natural hazards in Slovenia's karst, focusing on flooding in karst poljes. A specific study was done on the flood dynamics of two typical and connected karst poljes (Cerknica and Planina) of the Classical Karst region. In the case of particularly extreme hydrological conditions in the autumn of 2008, detailed analyses of the recharge-discharge regime and the interrelationship of flooding on the two poljes were done. Daily precipitation, discharge, and water level values from several monitoring sites were analyzed and cross-correlated, and additional hydrological analyses were done using a digital elevation model in order to acquire water level increase and decrease intensity, flood water volumes, and the extent of flooding and to understand the conditions controlling karst flooding. The results reveal that the hydrological functioning of the studied karst poljes is influenced by the hydrogeological and temporary hydrological conditions in the catchment area. The response of the binary karst system (i.e., the influence of autogenic and allogenic recharge) is especially distinct. The study shows that during extremely intense recharge, the reactions of karst aquifer systems to precipitation are as rapid as the response of surface waters (the water level of Cerknica Lake increased with an intensity of 38-63 cm/day or 55 m3/s respectively) while retention capacities are negligible. In contrast to flash floods, floods in karst areas may last from several weeks to several months. For the observed period a three-dimensional simulation of the flooding was made. At the maximum recorded water level, the volume of water on the Cerknica polje was 51 million m³, and 26 million m³ on the Planina polje. The maximum extent of flooding on the Cerknica polje was 23 km² and on the Planina polje 9.5 km². On the basis of the study, information was provided regarding future hazard mitigation. However, the study demonstrated that a sufficiently dense monitoring network is necessary to predict the occurrence and duration of floods with greater certainty.     

东海盆地长江凹陷美人峰组的时代归属及其地质意义

东海盆地长江凹陷美人峰组是古近系重要的地层单元之一，但因其缺少精确的古生物化石记录，时代归属和区域地层对比关系长期悬而未决，尚无定论。本文应用LA- ICP- MS定年方法，对长江凹陷CJ- 2井所揭露的美人峰组顶部两套凝灰岩夹层进行了锆石U- Pb同位素测年。结果表明，来自美人峰组顶部两件凝灰岩样品分别形成于61. 0±0. 87 Ma和62. 25±0. 92 Ma，证明该组沉积时代归属于早古新世，区域上对应于丽水- 椒江凹陷下古新统月桂峰组。烃源岩评价结果显示，美人峰组发育较好的烃源岩，有机质丰度达到中等至好，有机质类型为Ⅲ型。基于地震剖面构造精细解析，长江凹陷的美人峰组可以连续追踪到浙东坳陷，该坳陷大规模发育古新统，残余厚度达800~2000 m，指示古新世，浙东坳陷发生大规模伸展裂陷，形成NNE向展布大型裂陷带，美人峰组将是一套潜在的烃源岩层系。首次在东海盆地长江凹陷美人峰组获得高精度年龄，不仅确定了美人峰组沉积时代归属，也为东海盆地古新世区域地层的划分与对比、盆地古地理重建、构造演化、油气勘探与资源评价等提供了新的地质依据。     

东海盆地中、新生代盆架结构与构造演化

基于地貌、钻井、岩石测年和地震等资料,分析盆地地层分布、盆架结构、构造单元划分和裂陷迁移规律,结果表明东海盆地由台北坳陷、舟山隆起、浙东坳陷、钓鱼岛隆褶带和冲绳坳陷构成,是以新生代沉积为主、中生代沉积为辅的大型中、新生代叠合含油气盆地;古元古代变质岩系构成了盆地的基底。该盆地不仅是印度-太平洋前后相继的动力体系作用下形成的西太平洋沟-弧-盆构造体系域一部分,而且也是古亚洲洋动力体系作用下形成的古亚洲洋构造域和特提斯洋动力体系作用下形成的特提斯洋构造域一部分,晚侏罗世至早白垩世经历了构造体制转换,盆地格局发生重大变革,早白垩世以前主要受古亚洲-特提斯洋构造体制影响的强烈挤压造山和地壳增厚作用演变为早白垩世以来主要受太平洋构造体制控制的陆缘伸展裂陷和岩石圈减薄作用,经历侏罗纪古亚洲-特提斯构造体制大陆边缘拗陷和白垩纪以来太平洋构造体制弧后裂陷两大演化阶段。白垩纪以来太平洋构造体制的弧后裂陷演化阶段可细分为早白垩世至始新世裂陷期、渐新世至晚中新世拗陷期和中新世末至全新世裂陷期。     

TRMM卫星降水反演数据在珠江流域的适用性研究——以东江和北江为例

为评估最新一代TRMM 3B42-V7卫星降水反演数据产品在珠江流域的精度和适用性,选取位于珠江流域下游的东江和北江流域为研究区域,基于地面雨量站点数据评估了该产品的精度和适用性,并结合可变下渗容量（Variable Infiltration Capacity,VIC）水文模型进行了水文模拟验证。对比分析结果表明,在网格尺度上,大多数网格日尺度相关系数达到0.60以上,月尺度相关系数达到0.90以上,3B42-V7产品表现出较好的精度,在区域尺度上精度得到了进一步提高;水文模拟验证分两种情景下进行,情景Ⅰ的结果表明,当水文模型由地面雨量站点数据率定时,3B42-V7产品数据的水文模拟效果不佳,个别区间内存在对洪峰流量明显的低估;情景Ⅱ的结果表明,由3B42-V7产品数据重新率定水文模型时径流模拟效果有了较大改善,说明该产品可在一定程度上作为资料缺乏地区的降水数据来源。     

长江流域陆地水储量与多源水文数据对比分析

从趋势性、滞后性及相关性三方面,对2002—2013年间GRACE重力卫星反演的长江上游与中游陆地水储量与模型模拟土壤含水量、实测降水和实测径流数据进行了对比分析,并从干旱强度及发展时间两方面评估了标准化陆地水储量指数SWSI、标准化降水指数SPI、标准化径流指数SRI和标准化土壤含水量指数SSMI对区域性干旱的表征能力.结果表明:长江上游地区陆地水储量与降水、径流和土壤水蓄量均无显著变化,而中游地区陆地水储量则与水库蓄量同样具有显著性增加,反映人类活动对中游地区陆地水储量变化有很大影响;各指标指示的各等级干旱月份数量基本相当,但各指标反映的特旱具体月份有较大差别,基于GRACE数据构建的SWSI指标对特大干旱的指示性不好;对比各指标对上游与中游地区干旱事件发展时间,体现出水文干旱、农业干旱对气象干旱存在一定的迟滞关系.     

变化环境下东江流域水文干旱特征及缺水响应

在干旱事件不确定性和枯期径流变异性的双重影响下,水文干旱特征时序非一致性问题为其联合分布模拟带来困难。基于东江干流测站日径流过程数据,采用游程理论提取水文干旱事件,并结合干旱特征均值变化、时序一致性分析及边缘分布模拟,以确定干旱事件融合及剔除评判标准的合理取值。基于Rosenblatt变换Cramer-von Mises检验统计量拟合方法,构建水文干旱特征两变量联合分布Copula模型,并根据同频法设计两变量组合值。通过对比枯期径流变点分隔子序列干旱特征,分析变化环境下东江流域水文干旱特征及缺水响应。结果表明:水文干旱事件融合和剔除的评判标准值分别取0.1和0.3比较合理。干旱特征两变量之间具有较高的正相关性,但不同时间系列不同变量之间的联合分布及边缘分布最优模型并不一致。流域水库尤其是新丰江水库的径流调节作用,对于缓解东江中下游水文干旱效果明显,超阈联合重现期为2年的设计干旱持续时间、总缺水量和最大日缺水量分别减少了63%~71%、71%~84%和30%~47%,但如果要满足东江河道内最小管理流量目标,其依然分别达到了12~18 d、6 114万~9 030万m3和715.0万~929.0万m3。     

Luminescence chronology of late Holocene extreme hydrological events in the upper Penner River basin,South India

Field stratigraphy, sedimentology and optically stimulated luminescence (OSL) dating have been used to reconstruct the southwest monsoon variability in the semi‐arid region of southern India during the late Holocene. Facies architecture and OSL dating of the water‐lain sediment suggest prevalence of a weak hydrological regime around 3 ka. Following this, a progressive strengthening of monsoon occurred till 2 ka. After 2 ka and until 1 ka fluvial activity was nearly dormant, indicating weakening of the monsoon. Presence of high‐magnitude flood deposits, overbank sedimentation and pedogenesis during 1–0.6 ka indicate intensification of the southwest monsoon in the basin. The onset of aridity was associated with episodic storm surge events that are manifested in the pond sedimentation and localised aeolian accretion. This phase is bracketed between 0.5 ka and 0.2 ka. A renewed phase of monsoonal activity was observed in the form of floodplain aggradation between 180 and 90 years ago. In the past 70 years no significant change in the monsoon performance has been observed. Copyright © 2007 John Wiley & Sons, Ltd.