中国大陆流域分区TRMM降水质量评价

根据中国境内2 257个气象站点1998-2013年逐日降水资料,结合流域分区,采用探测准确性、相关系数以及相对误差等指标,对热带降水测量（TRMM）降水精度和一致性进行系统评价。结果表明:① TRMM日降水准确性从东南沿海向西北内陆递减;② 气象站点年均降水日数显著大于TRMM年均降水日数;③ 西北片区以外气象站点降水量和TRMM降水量在月尺度和年尺度上均具有较好的相关关系;④ 各流域年均TRMM面降水量均高于气象站点面降水量,且TRMM面降水量相对误差雨季较小,枯季较大;⑤ 各流域TRMM面降水量与气象站点面降水量演变趋势基本一致,南方各流域年降水量均呈减少趋势,北方各流域年降水量均呈增加趋势,全国尺度上年降水量呈微弱的减少趋势。     

A comparative frequency analysis of three standardized drought indices in the Poyang Lake basin,China

Regional drought frequency analysis was carried out in the Poyang Lake basin (PLB) from 1960–2014 based on three standardized drought indices: the standardized precipitation index (SPI), the standardized precipitation evapotranspiration index (SPEI) and the standardized Palmer drought index (SPDI). Drought events and characteristics were extracted. A Gumbel–Hougaard (GH) copula was selected to construct the bivariate probability distribution of drought duration and severity, and the joint return periods (T _a ) were calculated. Results showed that there were 50 (50 and 40) drought events in the past 55 years based on the SPI (SPEI and SPDI), and 9 (8 and 10) of them were severe with T _a more than 10 years, occurred in the 1960s, the 1970s and the 2000s. Overall, the three drought indices could detect the onset of droughts and performed similarly with regard to drought identification. However, for the SPDI, moisture scarcity was less frequent, but it showed more severe droughts with substantially higher severity and longer duration droughts. The conditional return period (Ts|d) was calculated for the spring drought in 2011, and it was 66a and 54a, respectively, based on the SPI and SPDI, which was consistent with the record. Overall, the SPI, only considering the precipitation, can as effectively as the SPEI and SPDI identify the drought process over the PLB under the present changing climate. However, drought is affected by climate and land-cover changes; thus, it is necessary to integrate the results of drought frequency analysis based on different drought indices to improve the drought risk management.     

Identifying rainfall threshold of flash flood using entropy decision approach and hydrological model method

Natural Hazards - Flash flood disaster, with strong suddenness and tremendous destructiveness, is one of the most severe natural disasters in China that seriously threaten the lives and property...     

Extreme precipitation events identified using detrended fluctuation analysis (DFA) in Anhui,China

Extreme weather events include unusual, severe or unseasonal weather, and weather at the extremes of the historical distribution. They have become more frequent and intense under global warming, especially in mid-latitude areas. They bring about great agricultural and economic losses. It is important to define the threshold of extreme weather event because it is the starting point of extreme weather event research, though it has been of seldom concern. Taking extreme precipitation events in Anhui, China as an example, the detrended fluctuation analysis (DFA) method is introduced to define the threshold of extreme weather events. Based on it, the spatial and temporal distributions of extreme precipitation events are analyzed. Compared to the traditional percentile method, DFA is based on the long-term correlation of time series. Thresholds calculated by DFA are much higher than the 99th percentile and the values are higher in the south and lower in the north. This spatial pattern is similar to the annual precipitation spatial pattern. There is an obvious increasing trend in the number of days with extreme precipitation, especially after the 1980s. This observation supports the point that more extreme events happen under global warming.     

1961-2010年中国400mm和800mm等雨量线时空变化

以中国1961-2010年逐日降水数据为基础,利用等值线加权平均位置的方式对400 mm和800 mm等雨量线的空间位置进行定量化处理。采用Kendall 秩次相关检验法、Morlet小波分析法、滑动t-检验法和Yamamoto法时间序列分析方法,对全国50年来 400 mm和800 mm等雨量线的空间位移特征进行了系统揭示:1961-2010年期间,400 mm和800 mm等雨量线加权平均位置坐标分别为（106°07'12"E,39°25'13"N）和（110°16'31"E,34°12'04"N）。趋势性结果表明,全国400 mm和800 mm等雨量线有向西和向南发生移动的趋势,其中400 mm等雨量线向西移动明显,800 mm等雨量线向南移动明显;周期性结果表明,全国400 mm等雨量线在经向和纬向上发生迁移的主周期分别为9年和 12年,800 mm等雨量线在经向和纬向变化均存在7年的主周期;突变性结果表明,400 mm等雨量线空间位置的突变年为1995-1996年（纬度）,800 mm等雨量线空间位置的突变年为1975年、2002年（经度）和1980年、1982年和1987年（纬度）。     

层次分析法在致密油有利区优选中的应用——以川中侏罗系大安寨段为例

层次分析法常用于解决复杂系统分析与决策中目标优选、排序等问题,也适用于油气勘探领域。在前人致密油地质特征研究的基础上,总结了致密油有利区优选指标。使用层次分析法优选有利区的核心内容是建立层次结构模型和构建2类矩阵。以四川盆地中部侏罗系大安寨段为例,介绍了使用层次分析法优选有利区5个主要步骤:1根据研究区地质特征,确定目标及方案,构建目标层和方案层;2根据影响致密油富集的要素,确定准则层;3构建准则层中各要素的成对比较矩阵,确定各准则要素的相对权重;4构建各准则要素对不同方案的判断矩阵,确定不同方案中各准则要素的权重;5将不同方案各准则要素的权重矩阵与准则要素的相对权重矩阵相乘,得到各方案的层次排序,进而选出最佳方案。优选的川中侏罗系大安寨段致密油最有利勘探区为金华—莲池区。操作简单、不需考虑下限值、适用范围广是层次分析法优选有利区的优点,但由于层次分析中的标度根据人为经验赋值,不同评价人员给出的评价结果有所不同。将层次分析法与GIS、特尔菲法、模糊数学法相结合,可以提高准则要素的优选合理性及赋值准确性。     

Dam break threshold value and risk probability assessment for an earth dam

In dam safety assessment, it is customary to focus on stability analysis, and the safety factor is regarded as an assessment index that cannot correctly reflect the effect of multi-factors and variable uncertainty. The factors that induce dam breaks are complex and uncertain; however, three primary ones can be identified: hydrological factors, seepage and bank slope instability. In this paper, the risk probability and the dam break threshold value for each factor individually, as well as coupled factors, are studied. The threshold value is acquired using the relationship formula between risk probability and dam type. The Dongwushi reservoir located in the Hebei province of China is taken as a case study. The results show that the dam break threshold values for hydrological factors, seepage and bank slope instability are 2.53, 2.02 and 2.69, respectively. The integrated dam break threshold value for the coupled factors is 1.25, which indicates that the dam is under serious stress according to the established risk assessment standard. The safety factor is calculated as 1.15 using the Bishop method, which indicates that the dam is under serious stress. The results obtained by the proposed method are consistent with those of the Bishop method. Finally, the proposed theory and method are introduced into a dam safety evaluation system (DSES) for convenient and efficient dam safety management.     

基于GIS的宜昌市近50年来气温与降水时空演变规律研究

基于ArcGIS的Spatial Analyst Tools反距离加权平均方法,对宜昌市7个站点1960-2009年气温和降水日数据进行时空演变规律分析和空间化展示,结果表明:(1)宜昌市近50年年均气温为16.26℃,1977-2009年变化较为剧烈,各区均呈增温态势;代际变化与总体变化趋势相同,自20世纪80年代后...     

黄淮海流域旱涝时空分布及组合特性

以黄淮海流域及其周边地区204个气象站点1961-2010年逐日降水过程资料、国家1:25万DEM数据和1:20万土地利用数据为基础,在利用降水Z指数对黄淮海流域旱涝进行评价的基础上,采用下垫面数据对结果进行修正,并分析黄淮海流域旱涝面积的时间变化特征,对黄淮海地区的易旱区、易涝区进行了划分,进一步选取集对分析法划分了流域内季节间旱涝交替的易发区。结果表明:黄淮海流域内夏秋两季旱涝问题较为严重,且秋旱面积上升趋势较为明显;黄河和海河流域以干旱居多,淮河则是干旱和雨涝并存,季节间的旱涝交替多集中在淮河流域中上游地区。