Palmer旱度模式在渭北旱塬泾惠渠灌区的应用研究

依据泾惠渠灌区的水文气象历史资料,应用待定系数和回归方法,建立了适用于泾惠渠灌区的Palmer旱度模式.将该旱度模式应用于灌区干旱系列特征分析,分析结果给出不同干旱程度可能发生的频率及年内分布,验证了灌区有较明显的旱化倾向及冬灌期和春灌期大旱的出现机率较大等特征,这些均与灌区多年来的实际干旱情况相符,表明了所建立的Palmer旱度模式合理,具有较明确的物理意义且能够反映灌区的干旱特征.     

三种干旱指标在泾惠渠灌区的适用性分析

为了正确评价灌区的干旱状况,利用泾惠渠灌溉试验站1953—2011年的降水资料,分析了降水距平百分率、标准化降水指数SPI、降水Z指数三种干旱指标在灌区的适用性。结果表明,三种指标均能较好地体现降水的年际变化趋势,但SPI对于降水变化的反映比降水Z指数和降水距平百分率更准确。在干旱出现年份的判定方面,三种指标得到的结果一致;在干旱程度的判定上,在发生中旱及以上干旱的1969、1986、1993、2000年,SPI和降水Z指数比降水距平百分率判定准确,在发生重旱的1977、2000年,SPI的判定比Z指数更符合实际。分析泾惠渠灌区SPI变化趋势发现,灌区在1990年后干旱发生次数占研究期内总干旱次数的55.6%,干旱程度也有增加的趋势,采取合理措施抗旱将成为灌区未来发展的关键。     

基于标准化降水指数SPI的泾惠渠灌区干旱演变对冬小麦气候产量的影响

为了研究干旱变化对于作物产量的影响机制,以泾惠渠灌区为例,选用标准化降水指数SPI作为干旱评判指标,采用Mann-Kendall趋势检验、最大熵谱分析等方法分析了灌区干旱的变化特征,以及干旱演变下冬小麦气候产量的变化规律。研究表明:(1)灌区冬小麦实际产量呈显著增加趋势(Z=7.6482),气候产量呈不明显减少趋势(Z=-0.5686);(2)灌区总体干旱化趋势明显(通过了99%的显著性检验),这种趋势在春、夏、秋三季都达到了显著水平;(3)干旱存在16 a的年代际周期波动,4~5 a的年际周期;(4)播种前7—9月份和播种后的10、11月的干旱情况对于冬小麦气候产量的影响最大,是影响作物气候产量的关键期;(5)SPI3-9与冬小麦气候产量关系最密切,可以解释46.21%的产量变异;(6)随着干旱的年代际周期变化,SPI3-9与冬小麦气候产量之间的相关系数从0.44上升至0.74,干旱对于冬小麦气候产量的影响有增强的趋势。     

陕西泾惠渠灌区土壤质量综合评价研究

以陕西省主要的粮食、蔬菜生产基地泾惠渠灌区为研究对象,通过对土壤质量现状的调查、现场采样和试验分析,选取土壤总盐量,pH,土壤有机质,碱解氮,速效磷,速效钾,Cu,Zn,Pb,Cd,Cr,As,Hg以及地下水硝酸盐含量14个指标,基于层次分析法在确定其权重的基础上,利用综合指数法对泾惠渠灌区的土壤质量进行了综合评价。结果表明:灌区75.3%的土壤质量处于优良水平,20.8%的土壤质量处于中等水平。总体看,泾惠渠灌区的土壤质量综合指数均值为0.82,属于二等,质量为良好土壤。指标选取得当,研究结果与灌区的实际情况相吻合,研究方法可靠。     

基于COMGIS和Matlab的泾惠渠灌区灌溉决策支持系统

以泾惠渠灌区为研究对象,采用动态规划、神经网络、遗传算法等多种优化算法基于Matlab完成了系统优化模型,并采用GIS的三维可视化和空间分析技术基于COMGIS完成了灌溉仿真模型,同时利用COM技术,建立了系统与MatlabArcGIS无缝集成的泾惠渠灌区灌溉决策支持系统。系统能够有效地协助决策人员解决泾惠渠灌区灌溉水资源优化调度的难题,显著提高了灌溉水资源的管理水平。通过将2008年实际数据输入运行结果分析来看,系统能够胜任辅助灌溉决策之重任。     

基于核熵成分分析的综合干旱指数的构建与应用

针对传统单变量干旱指数难以全面表征干旱及部分综合干旱指数难以反映多变量之间的非线性关系等问题，采用标准化降水蒸散发指数（SPEI）、标准化径流指数（SRI）及标准化土壤湿度指数（SSMI）3个单变量指数分别表征气象干旱、水文干旱和农业干旱，利用核熵成分分析法（KECA）构造综合干旱指数（SMDI），采用M-K趋势检验、小波分析及典型历史旱情验证等方法分析干旱的时空变化特征以及干旱指数的适用性。以黑河流域中上游为例，结果表明：研究区全年77.6%的区域表现为干旱不显著加重的趋势；在流域尺度上，干旱存在43 a的长周期，15~23 a的中周期，3~8 a的短周期；20世纪90年代夏、秋两季及21世纪以来春、冬两季干旱发生频率较高，且整体夏旱发生频率最高；1969年春、1997年秋和2009年冬的典型历史旱情验证表明SMDI优于其他3种单变量干旱指数。说明基于KECA构建的SMDI是一种有效的干旱监测指数，在黑河流域中上游干旱监测中有好的适用性。     

基于MODIS TVDI和模糊数学方法的藏北地区旱情等级遥感监测

为了实现对藏北区域范围内春夏旱情的动态连续监测,基于温度植被干旱指数(TVDI)和模糊数学方法建立了遥感干旱的划分标准,研究时段为1980-2017年。首先利用MODIS产品数据计算TVDI,然后根据气象干旱等级监测结果,采用模糊数学法建立基于MODIS TVDI的干旱等级划分标准,并对监测结果进行精度验证,最后分析了近年来藏北地区旱情的时空变化特征。得到的主要结论:①基于归一化植被指数(NDVI)和增强植被指数(EVI)计算得到的温度植被干旱指数TVDIN和TVDIE,均与20 cm实测土壤水分含量在0.05的水平达到显著相关,TVDIE的决定系数更高;②基于TVDIE将旱情划分为无旱、轻旱、中旱、重旱、特旱5个等级,其中,据此标准获得的藏北地区旱情等级与气象干旱等级监测结果大体一致;③近年来藏北地区旱情整体不太严重,且总体趋缓,其中,2009年最严重,发生中旱及以上旱情的区域面积达24%,年内旱情在6月最严重。就旱情的空间分布特征而言,研究区西南部和中部干旱比较严重,北部和东南部相对较轻。研究成果可为藏北地区干旱监测提供数据支撑,遥感干旱等级的划分方法可为其他地区的干旱研究提供参考。     

考虑多水源的灌区水文干旱预警系统及其评价

为提高大中型灌区水资源管理水平,引入模糊综合评价及信息熵方法,建立了考虑降雨、径流及地下水等多水源的灌区水文干旱预警系统。预警系统以现状水文干旱评估和未来水源形势分析为两大基础,针对其中未来水源形势的非确定性,采用超越概率方法进行处理,评估给出未来多种情况下的可能干旱水平,并进入下一个计算环节,从而较大程度的避免了预测的片面性。最终整合现状干旱指标和未来形势指标形成干旱预警指标DAI,并以不同颜色灯号表示预警等级。以泾惠渠灌区水文干旱预警为例,选取典型干旱年份对预警流程及关键技术指标进行分析示例,结果表明其能够反映干旱发生发展的蠕变特性,表明该预警方法合理清晰,具有简单易用的特点。     

宁夏旱涝灾害动态监测指标及其应用

利用标准化降水指数 ,参考修正的帕默尔 ( Palmer)干旱指数 ,建立适合于实时监测的旱涝指标体系。试验表明该指数具有一定物理意义 ,实时资料可得 ,逻辑关系严密 ,计算方法科学 ,具有客观、定量的优点 ,能运用于干旱半干旱地区的干旱监测业务     

河西走廊地区五个典型站干旱指数对比和气候分析

利用1953—2010年河西走廊地区酒泉、高台、张掖、山丹、武威5个气象站点的月平均气温和降水资料计算年、季降水距平百分率、相对湿润指数和帕默尔干旱指数,通过三种干旱指标的对比,分析河西走廊地区典型站点的气候变化情况。发现近58年来河西走廊地区总体的气候变化存在以"气温升高,降水略增"为主要特点的变化趋势,气候演变存在着季节性和地域性差异,且趋势在冬季表现得更为明显。地区间酒泉和高台的旱情相对严重,张掖、山丹和武威旱情较轻。各季节中以秋季旱情相对明显,不利于农业秋季收获。     

棉花抗旱品种筛选鉴定及抗旱性综合评价方法

从甘肃敦煌、新疆的棉花栽培品种和国内外引进材料中选出76个遗传来源不同的棉花品种(系)作为参试材料,在年降雨量不足40 mm的甘肃省敦煌市设置了干旱胁迫和正常灌水两个处理,筛选出与棉花抗旱性密切相关的10个农艺性状和产量指标,采用综合抗旱系数(CDC)、综合抗旱指数(CDI)、综合隶属函数值(CDM)、抗旱性综合评价值(D)等四种综合评价方法对76份种质材料进行抗旱性评价。结果显示,四种综合评价方法两两之间的Pearson相关系数都在0.88以上,相关性均达到了极显著水平;再利用四种抗旱评价体系得分值对76个受试棉花品种(系)进行K-means划分聚类,最终将76个品种分为高抗(Ⅰ类,5个品种)、抗(Ⅱ类,9个品种)、中等(Ⅲ类,17个品种)、敏感(Ⅳ类,31个品种)、高敏(Ⅴ类,14个品种)5个抗旱等级。为进一步方便育种家简单准确地评价选育材料的抗旱性,利用筛选出的10个农艺性状指标的抗旱系数作为自变量,四种抗旱性综合评价体系得分值为因变量,采用逐步回归的方式建立了棉花抗旱性预测模型回归方程。     

Spatial-temporal characteristics of drought detected from meteorological data with high resolution in Shaanxi Province,China

The spatial pattern of meteorological factors cannot be accurately simulated by using observations from meteorological stations (OMS) that are distributed sparsely in complex terrain. It is expected that the spatial-temporal characteristics of drought in regions with complex terrain can be better represented by meteorological data with the high spatial-temporal resolution and accuracy. In this study, Standard Precipitation Evapotranspiration Index (SPEI) calculated with meteorological factors extracted from ITPCAS (China Meteorological Forcing Dataset produced by the Institute of Tibetan Plateau Research, Chinese Academy of Sciences) was applied to identify the spatial-temporal characteristics of drought in Shaanxi Province of China, during the period of 1979-2016. Drought areas detected by SPEI calculated with data from ITPCAS (SPEI-ITPCAS) on the seasonal scale were validated by historical drought records from the Chinese Meteorological Disaster Canon-Shaanxi, and compared with drought areas detected by SPEI calculated with data from OMS (SPEI-OMS). Drought intensity, trend and temporal ranges for mutations of SPEI-ITPCAS were analyzed by using the cumulative drought intensity (CDI) index and the Mann-Kendall test. The results indicated that drought areas detected from SPEI-ITPCAS were closer to the historical drought records than those detected from SPEI-OMS. Severe and exceptional drought events with SPEI-ITPCAS lower than -1.0 occurred most frequently in summer, followed by spring. There was a general drying trend in spring and summer in Shaanxi Province and a significant wetting trend in autumn and winter in northern Shaanxi Province. On seasonal and annual scales, the regional and temporal ranges for mutations of SPEI-ITPCAS were different and most mutations occurred before the year 1990 in most regions of Shaanxi Province. The results reflect the response of different regions of Shaanxi Province to climate change, which will help to manage regional water resources.     

基于干旱指数与主成分分析的干旱评价——以锡林河流域为例

利用锡林河流域逐月气象数据,分析了历年降水与气温的最值变化;计算了标准化降水指数(SPI)与综合气象干旱指数(CI)并用其对研究区干旱状况进行表征;利用主成分分析法对锡林河流域的干旱情况进行评价。结果表明:1981-2016年的最高气温变化呈微弱的升高趋势,最低气温的变化趋势基本持平。最大降水量的变化趋势是减小的,各月的最小降水量基本趋于0。CI指数表明,36 a中只出现过轻旱事件,且春季最多,其次为秋季,夏季发生的最少。SPI指数表明,36 a中出现了重涝、中涝、轻涝、重旱、中旱、轻旱事件,且事件的危害程度越高发生的概率相对越小,冬季发生的旱涝事件大多危害程度相对较高。主成分分析结果表明,研究区气象因素的第一主成分主要反映水分胁迫对干旱的影响,第二主成分主要反映日照对干旱的影响,第三主成分主要反映气温对干旱的影响;综合得分结果表明,各地的干旱情况排名为:扎鲁特>巴林左旗>翁牛特旗>多伦县>化德>西乌珠穆沁>锡林浩特>林西县>东乌珠穆沁>朱日和>阿巴嘎旗>二连浩特>苏尼特左旗。     

Spatiotemporal analysis of drought variability based on the standardized precipitation evapotranspiration index in the Koshi River Basin,Nepal

Drought is an inevitable condition with negative impacts in the agricultural and climatic sectors, especially in developing countries. This study attempts to examine the spatial and temporal characteristics of drought and its trends in the Koshi River Basin(KRB) in Nepal, using the standardized precipitation evapotranspiration index(SPEI) over the period from 1987 to 2017. The Mann-Kendall test was used to explore the trends of the SPEI values. The study illustrated the increasing annual and seasonal drought trends in the KRB over the study period. Spatially, the hill region of the KRB showed substantial increasing drought trends at the annual and seasonal scales, especially in summer and winter. The mountain region also showed a significant increasing drought trend in winter. The drought characteristic analysis indicated that the maximum duration, intensity, and severity of drought events were observed in the KRB after 2000. The Terai region presented the highest drought frequency and intensity, while the hill region presented the longest maximum drought duration. Moreover, the spatial extent of drought showed a significant increasing trend in the hill region at the monthly(drought station proportion of 7.6%/10 a in August), seasonal(drought station proportion of 7.2%/10 a in summer), and annual(drought station proportion of 6.7%/10 a) scales. The findings of this study can assist local governments, planners, and project implementers in understanding drought and developing appropriate mitigation strategies to cope with its impacts.     

基于SPEI和时空立方体的中国近40年干旱时空模式挖掘

利用1980—2019年中国612个气象站点逐月降水量和温度数据计算多尺度标准化降水蒸散指数(SPEI),根据中国气温条件划分7大地理分区并结合时空立方体、时空热点分析、时空聚类和时空异常值来探究中国近40年多尺度标准化降水蒸散指数SPEI的时空分布特征.结果表明:(1)通过干旱频率的计算,发现轻度干旱和极端干旱最为严...     

华北段农牧交错带气候变化特征及其响应

依据华北段农牧交错带1961-2010年气象资料,利用标准化降水指数(SPI)、Mann-Kendall检验等方法对研究区的气候变化特征进行了分析。结果显示:1)近50a来,华北段农牧交错带以1987年为界划分为两个时期,此前为冷期,此后为暖期。其年平均气温线性增温速率为0.35℃/10a,冬季增温最显著,其次为春季、秋季、夏季。气温在1993年发生突变。2)年降水量呈下降趋势,倾向率为-6.51mm/10a,夏季降水的减少对其贡献率最大。3)气温突变后,极端旱涝灾害事件减少,中旱灾害频率在增加,气候变化整体呈现暖干趋势。     

咸阳市气候暖干化及干旱灾害趋势判断

依据咸阳市1961-2009年气象资料,利用Z指数和Mann-Kendall气候突变检验法对咸阳市的气候变化特征进行了分析。结果显示：（1）近49年来,咸阳市出现3年重旱、2年大旱、8年偏旱,重旱大旱年份出现在20世纪80年代中期以后,偏旱年份大部分出现在90年代和21世纪初的几年。（2）各季节重旱年份主要出现在20世...     

Response of hydrological drought to meteorological drought in the eastern Mediterranean Basin of Turkey

The hydrographic eastern Mediterranean Basin of Turkey is a drought sensitive area. The basin is an important agricultural area and it is necessary to determine the extent of extreme regional climatic changes as they occur in this basin. Pearson's correlation coefficient was used to show the correlation between standardized precipitation index(SPI) and standardized streamflow index(SSI) values on different time scales. Data from five meteorological stations and seven stream gauging stations in four sub-basins of the eastern Mediterranean Basin were analyzed over the period from 1967 to 2017. The correlation between SSI and SPI indicated that in response to meteorological drought, hydrological drought experiences a one-year delay then occurs in the following year. This is more evident at all stations from the mid-1990 s. The main factor causing hydrological drought is prolonged low precipitation or the presence of a particularly dry year. Results showed that over a long period(12 months), hydrological drought is longer and more severe in the upper part than the lower part of the sub-basins. According to SPI-12 values, an uninterrupted drought period is observed from 2002–2003 to 2008–2009. Results indicated that among the drought events, moderate drought is the most common on all timescales in all sub-basins during the past 51 years. Long-term dry periods with moderate and severe droughts are observed for up to 10 years or more since the late 1990 s, especially in the upper part of the sub-basins. As precipitation increases in late autumn and early winter, the stream flow also increases and thus the highest and most positive correlation values(0.26–0.54) are found in January. Correlation values(ranging between –0.11 and –0.01) are weaker and negative in summer and autumn due to low rainfall. This is more evident at all stations in September. The relation between hydrological and meteorological droughts is more evident, with the correlation values above 0.50 on longer timescales(12-and 24-months). The results presented in this study allow an understanding of the characteristics of drought events and are instructive for overcoming drought. This will facilitate the development of strategies for the appropriate management of water resources in the eastern Mediterranean Basin, which has a high agricultural potential.