基于CWSI的安徽省干旱时空特征及影响因素分析

安徽省是我国的农业大省和重要商品粮食基地,因受自然地理位置等因素的影响,安徽省旱灾频发。论文基于MOD16产品,利用作物缺水指数CWSI,结合气象数据和MOD13数据,分析2000—2014年安徽省干旱时空分布特征和影响因素,结论如下：1）基于MOD16产品计算的作物缺水指数可用于安徽省干旱的监测。2）2000—2014年间安徽省CWSI多年均值为0.524,最大值在2011年（0.569）,最小值在2003年（0.458）,整体上呈现弱增加趋势;具有较强的空间分异性,表现为南部湿润、北部干旱。各市多年CWSI年均值相差不大,但变化趋势各异,淮北平原地区和江淮之间地区呈现显著增加趋势,而皖南地区呈显著下降趋势。3）安徽省CWSI年内月变化整体上呈先减少后增加的单谷型趋势,1—6月和10—12月CWSI值较高,最大值在3月,为0.66,7—9月CWSI值较低,最小值在8月,为0.27,具有明显的季节性差异,淮北平原易出现春旱、秋旱和冬旱,江淮丘陵易出现春旱及秋旱,沿江地区易出现春旱。4）不同土地利用类型的CWSI年内变化特征差异明显,林地和草地整体上呈现先减少后增加的单谷趋势,其月均最大值在3月,城镇和耕地则表现为多峰趋势,最大月均值在6月。5）CWSI与降雨、温度以及植被的关系密切,在降雨较多的地区,温度较低,植被指数较高,CWSI值较小,干旱程度较轻,说明降雨对CWSI变化的影响较大。     

旱涝灾害的门限神经网络预报模型

根据旱涝灾害具有非线性和突变性的演变特征，提出了利用门限值和门限变量构造神经网络的旱涝灾害预报新方法。由于该方法可以根据预报量与预报因子间的不同相关关系构成不同的神经网络学习矩阵，因此实际的预报计算结果表明，该方法对历史样本的拟合和预报精度比一般的逐步回归方法有明显提高。     

上海地区主要农作物气象灾害评估预测警示系统的研究

主要农作物气象灾害评估预测警示系统网页共有二部分内容：历年灾害动态对比和早涝趋势预测与警示。历年灾害动态对比是对比1991年以后上海地区主要表l作物气象灾害的变化情况。早涝趋势预测是在降水趋势预测基础上，对未来月或农时段降水量进行预测。     

IMPLICATIONS OF CLIMATIC VARIABILITY FOR REGULATORY LOW FLOWS IN THE SOUTH PLATTE RIVER BASIN,COLORADO1

ABSTRACT: The maximum concentration of a regulated substance that is allowed in a wastewater effluent usually is determined from the amount of dilution provided by the receiving water. Dilution flow is estimated from historical data by application of statistical criteria that define low flow conditions for regulatory purposes. Such use of historical data implies that the past is a good indicator of future conditions, at least for the duration of a discharge permit. Short records, however, introduce great uncertainty in the estimation of low flows because they are unlikely to capture events with recurrence frequencies of multiple years (e.g., ENSO events or droughts). We conducted an analysis of daily flows at several gages with long records in the South Platte River basin of Colorado. Low flows were calculated for successive time blocks of data (3‐, 5‐, 10‐, and 20‐years), and these were compared with low flows calculated for the entire period of record (> 70 years). In unregulated streams, time blocks of three or five years produce estimates of low flows that are highly variable and consistently greater than estimates derived from a longer period of record. Estimates of low flow from 10‐year blocks, although more stable, differ from the long term estimates by as much as a factor of two because of climate variation. In addition, the hydrographs of most streams in Colorado have been influenced by dams, diversions, or water transfers. These alterations to the natural flow regime shorten the record that is useful for analysis, but also tend to increase the calculated low flows. The presence of an upward trend in low flows caused by water use represents an unanticipated risk because it fails to incorporate societal response to severe drought conditions. Thus, climate variability poses a significant risk for water quality both directly, because it may not be represented adequately in the short periods of the hydrologic record that are typically used in permits, and indirectly, through its potential to cause altered use of water during time of scarcity.     

REAPPRAISAL OF WATER SUPPLY RESOURCES IN DELAWARE RIVER BASIN USING SYNTHETIC HYDROLOGY1

ABSTRACT The 60's drought (1961 1966) which hit the Northeastern United States, had its center over the Delaware River Basin and caused water supply shortages to New York City, Philadelphia, and many other towns and industries in the Basin. Until this event occurred, the existing water supply sources and those planned for the future had been considered adequate, as they were designed for the worst drought of record (usually the 1930-31 drought). In view of this “change in hydrology,” the Delaware River Basin Commission authorized a study (DRBC Resolution 67-4) to re-evaluate the adequacy of existing and planned water supply sources of the Delaware River Basin and its Service Area (New York City and northern New Jersey). Synthetic hydrology is a tool which can be used to overcome many of the limitations of the traditional approach. By analyzing generated streamflow traces in this study, it has been determined that there is a definite relationship between the accumulated rainfall deficiency during the drought and the return periods associated with various durations of runoff in the drought. This indicated that generated traces can be used to standardize the hydrology over an area where the intensity of drought varied. This represented an important facet in the study, because it provided a means to equalize the effects of this drought over the study area, and gave the Delaware River Basin Commission more information so that it could better plan and manage its water resources equitably, not only for the people within the Basin, but for the New York City and northern New Jersey areas as well. Synthetic hydrology was used to determine yield-probability relationships for 50-year periods, and storage-yield-frequency relationships for existing and planned water-supply reservoirs. It was also used to determine yield-probability relationships for reservoir systems within the Basin. In the study, it was determined that monthly streamflow traces and uniform draft rates could be used in yield analysis because of the magnitude of the reservoirs and because seasonal variations of draft rate are small in the study area. Although it was found that with the streamflow generating models (first order Markov) in common use today, it is not possible to definitely determine the actual frequency of a very severe historic drought, it is possible to place a drought in perspective by using synthetic hydrology. The study showed that it is a useful tool in determining water availability over a basin and is useful in studying water management problems such as interbasin transfers, and reservoir systems operations.     

河南省境内淮河流域历史时期旱涝等级序列的重建

本文根据旱涝史料，运用旱涝等级评定法，对河南省境内淮河流域１４７０～１９４９年逐年的旱涝状况进行了评定；并采用“区域综合法”，重建了河南省境内淮河流域１４７０～１９４９年的旱涝等级序列。     

华北异常干旱气候事件及其对农业影响评估模式的研究

分析了华北地区旱灾的特点;采用降水量距平百分率和干旱指数分别确定了单站及区域于旱等级标准,并对近３７ａ这一地区各年主要干旱事件强度（等级）进行了评定,最后建立了干旱受灾面积和成灾面积评估模式。     

天津地区旱涝灾害危险性评价及区划研究

根据自然灾害风险理论,自然灾害危险性评价的目的是确定区域内某类潜在危害发生的可能性大小.根据旱涝灾害危险性特点,以天津近16年的降水距平百分率为样本,借助信息扩散理论等方法对天津地区旱涝灾害危险性进行评价及区划研究.结果给出了天津十三个区/县每年遭受重涝、大涝、偏涝,重旱、大旱、偏早六种不同强度危害威胁的可能性.通过区...     

基于信息扩散和模糊评价方法的四川盆地气候干旱综合评价

利用1961~2005年历史气象资料,以受旱天数、湿润度指数、标准化降水指数、温度距平、日照距平百分率等5个要素作为干旱评价指标,应用信息扩散方法建立了各单个评价指标的春、夏、伏旱旱情等级划分标准,采用模糊综合评价方法对1961~2006年四川盆地气候干旱进行评价,并给出了各市干旱出现的频率。结果表明:2006年四川盆地发生了严重的春旱、夏旱和特别严重的伏旱,盆区17个市均有伏旱发生,其中有13个市伏旱特别严重;伏旱期少雨天气平均为30年一遇,高温天气平均为60年一遇,约29%的台站的少雨和90%的台站的高温为50年以上一遇;春、夏旱主要出现在盆地西北部和盆地南部,约2.5年出现一次,伏旱则主要出现在盆地东部,约2年出现一次。     

长三角地区地表干湿状况及极端干湿事件特征研究

利用Penman-Monteith模型及1957—2014年长三角地区43个气象站点逐日降水、气温、风速、日照时数及空气相对湿度实测数据,对参考作物蒸散量、地表湿润指数和极端干旱/湿润事件进行了计算和统计。运用线性回归、Trend-free pre-whitening (TFPW) Mann-Kendall趋势检验、Morlet小波分析等方法,分析了研究区地表湿润指数及极端干湿事件的时空分布特征。结果显示：1）近58 a长三角地区年及季节平均湿润指数在空间上呈南高北低分布格局;2）年湿润指数呈波动下降趋势,变化倾向率为-0.021/10 a,气候趋于干旱化。湿润期集中在20世纪80、90年代。突变年为2003年,并存在多个振荡周期。四季中,春秋季气候趋于干旱化,冬夏季反之。年际湿润指数变异系数和变化趋势存在明显的空间差异;3）年极端干旱事件发生频率呈波动上升趋势,年极端湿润事件则呈现微弱的下降趋势,均存在空间差异。