摘要：干旱是干旱和半干旱地区最普遍和最具破坏性的灾害，在气候变化的作用下，其表现更为复杂。为了全面了解黄土高原地区的干旱状况，利用标准化降水指数(SPI)和标准化降水蒸散指数(SPEI)，对1957年至2012年的干旱状况进行了区域时空特征识别。通过主成分分析，确定具有独立干旱特征的分区和相应的代表气象站，为区域干旱监测提供依据。基于SPEI的干旱严重程度增长趋势强度弱于基于SPI的干旱严重程度增长趋势。基于SPEI的干旱严重程度有显著增加趋势的区域仅出现在西南地区，且远小于基于SPI的区域。总体而言，旱情发生频率由东南向西北呈现为空间递减趋势，在冬季中期、春末夏初旱情频率较高。受干旱影响的地区也随时间发生变化，但主要集中在中部和西北部地区。

关键词：干旱严重；空间变化；时间趋势；水资源

Spatiotemporal analysis of drought characteristics across the Loess Plateau of China

Abstract：Drought is the most widespread and destructive hazard in arid and semiarid regions, with behaviors that become more complicated under climate change. To provide an overall view of drought conditions across the Loess Plateau of China, two multiscalar drought indices, the Standardized Precipitation Index (SPI) and the Standardized Precipitation Evapotranspiration Index (SPEI), were used to identify the regional spatiotemporal characteristics of drought conditions from 1957 to 2012. Subregions with independent drought characteristics and the corresponding representative meteorological stations were identified by principal component analysis to facilitate regional drought monitoring. The intensity of the increasing trend of drought severity based on the SPEI was weaker than that based on the SPI. The area with a significant increasing trend of drought severity based on the SPEI was only found in the southwest of the region and was much smaller than that based on the SPI. The regional distributions of the drought frequency were mapped for different months. Generally, the drought frequency spatially decreased from southeast to northwest and was higher in the middle of the winter, late spring and early summer. While the drought-hit area also changed with time, it was generally within the central and northwest areas of the region.

Key words: Drought severity；spatial variation；Temporal trend；Water resources

目  录

摘要1

关键词1

Abstract1

Key words1

引言1

1材料与方法3

1.1研究区域 3

1.2数据收集和准备4

1.3干旱指数4

1.3.1利用标准化降水指数(SPI)4

1.3.2标准化降水蒸散指数(SPEI)5

1.4 统计方法 6

1.4.1描述性统计6

1.4.2主成分分析6

1.4.3趋势分析6

1.4.4空间内插7

2结果与分析7

2.1气候的时空变化7

2.2 SPI和SPEI时间序列的PCA分析9

2.3干旱时间趋势的时空格局11

3讨论 13

3.1结论 13

致谢14

参考文献14

黄土高原地区干旱时空特征分析

引言 干旱是一种无声的、渐进的、反复发生的自然灾害，在世界各地干旱和潮湿地区都会造成大量的农业、经济和环境破坏[1]。干旱通常被认为是由于长期缺乏降水/可用水资源或过量蒸散造成的负水平衡[2]。干旱是不可避免的，但准确了解干旱的时空特征是干旱研究的重要内容为减轻潜在影响而制定干旱应急计划。然而，由于干旱的各种定义及其在空间和时间上的巨大变异性，很难客观地量化干旱的强度、持续时间和空间范围等特征[3]。

在过去的几十年里，许多研究致力于制定客观的指标来确定干旱的开始、结束点和严重程度，用于干旱的量化、有效的管理和预警系统的建立[4]。大多数指数是基于气象变量，特别是降水与历史标准的偏差。在各种应用的干旱指数中，Palmer干旱严重程度指数(PDSI)是干旱量化的一个里程碑[5]。它是基于一种供需概念，由每月的水平衡方程表示为一个包含降水、径流、蒸发蒸腾和土壤水分的两层模型[6]。PDSI及其变体如改进的PDSI (PMDI)、Palmer水文干旱指数(PHDI)和Z指数在干旱监测和水资源综合管理中得到了广泛的应用[7]。