The 2009/2010 Caribbean drought: a case study

The impacts of drought in the Caribbean have not been as dramatic as in some other parts of world, but it is not exempt from the experiences of drought. As a result of the effects of a prolonged drought in 2009/2010, the agenda for the 21st Inter‐Sessional Meeting of the Caribbean Community (CARICOM) paid particular attention to the issue of drought. This paper reviews the management framework for responding to drought disasters in five CARICOM countries. The paper also reports on some of the effects of the 2009/2010 drought with particular reference to Grenada and the Grenadines. During the drought in these islands there were numerous bush fires with devastating effects on agriculture, severe water shortages that impacted on the tourism industry and other social effects. It is evident that there was inadequate preparation for the event. Greater planning and investment are therefore required to reduce future impacts.     

水利工程群应对干旱能力评价方法及应用

基于水利工程群应对干旱能力的影响因素分析,从水利工程的布局、规模和运行管理两个层面构建水利工程群应对干旱能力评价指标体系。综合层次分析法和熵值法两种确定权重的方法,确定各评价指标的组合权重,采用模糊综合评价法构建了水利工程群应对干旱能力评价模型。该评价模型在漳卫河流域的应用结果表明,该流域整体应对干旱能力水平较弱,未来需要加强对现有水利工程体系的科学调度管理,并充分利用流域外调水提高干旱应对能力。     

基于MODIS的湖南省农业干旱监测模型

诸多遥感干旱监测指数已被成功应用于中国北方地区,但在南方湿润地区的应用则相对较少。以湖南省为研究区,结合遥感(RS)、地理信息系统(GIS)技术,利用MODIS增强植被状态指数(EVCI)和温度状态指数(TCI)的复合信息,并根据EVCI和TCI对干旱信息的敏感程度不同,赋予不同的权重值,建立干旱状态指数(DCI)遥感监测模型,并将该模型应用于湖南省农作物的旱情监测,得到了湖南省耕地旱情等级的空间分布图。通过与该省97个气象台站同期获取的综合气象干旱指数(CI)的相关分析与验证,表明DCI与CI指数的线性相关显著,EVCI和TCI的权重分别取值0.4和0.6时为最佳组合,并论证了该模型适宜南方地区的干旱监测。     

干旱对辽宁省玉米产量影响及风险区划

以辽宁省14个市1967-2006年降水量逐月数据和玉米产量数据为基础,应用滑动直线平均法、相关分析等数理统计方法,结合GIS技术对各地区玉米因旱减产程度及风险大小进行分析。结果表明,不同地区干旱对产量的制约程度不同,据此划分为两类地区:A类地区干旱是玉米产量的主要制约因素,B类地区干旱对玉米产量影响不明显。根据A类地区确定因旱减产指标:当降水负距平分别为20%、20%～40%、40%～60%时对应的玉米减产率分别为5%、5%～11%、11%～17%。综合产量波动、减产强度、抗旱能力三要素进行干旱灾害风险区划,结果显示辽宁省因旱减产风险由西向东逐渐减弱。     

陕西省大旱年发生概率及可能发生的年份预测

应用数理统计方法及三元、四元、五元可公度法分别推算了21世纪陕西省大旱年发生的概率和预测了该省未来30多年间可能发生大旱灾的年份.运算结果显示:陕西省在21世纪的100年中,大旱年发生次数至少为一次、两次、三次、四次、五次的概率分别为94.52%、86.65%、72.91%、54.78%、35.57%;在未来30多年间陕西省有可能在2006年、2008年、2024年、2031年发生重大旱灾.     

降水概率模型在旱涝监测评价中的应用研究

选择正态、准正态和偏态Gamma多种理论概率分布模型对河南年、月、旬不同统计时段降水概率进行了模型拟合试验，推求了准正态概率分布密度函数的通用公式，提出了二参数Gam—ma分布参数Thom估计方法的修正方案，并对旱涝监测评价分析中有关概率特征量的数值计算方法进行了试验研究。     

AN EARLY WARNING SYSTEM FOR DROUGHT MANAGEMENT USING THE PALMER DROUGHT INDEX1

ABSTRACT: The Palmer Drought Severity Index (PDSI) is used in a non-homogeneous Markov chain model to characterize the stochastic behavior of drought. Based on this characterization an early warning system in the form of a decision tree enumerating all possible sequences of drought progression is proposed for drought management. Besides yielding probabilities of occurrence of different drought severity classes, the method associates a secondary measure in terms of likely cumulative precipitation deficit to provide timely guidance in deciding drought mitigation actions. The proposed method is particularly useful for water availability task forces in various states for issuing drought warnings in advance. The applicability of the technique is illustrated for the Tidewater climatic division of Virginia.     

重要生态功能区干旱时空演变特征及对关键资源的影响:以黄河流域为例

基于温度-植被-降水的综合干旱指数（TVPDI）、地表径流、植被净初级生产力和粮食产量等数据,利用数据空间化方法、Slope趋势分析及Pearson相关分析等方法,探究了黄河流域从2001~2020年这20年间干旱时空变化特征以及对水资源、粮食资源和植被资源的影响,试图探究干旱与关键资源之间的相互影响.结果表明:①黄河流域干旱空间分布由东南向西北呈阶梯状加重,全流域有60.6 %的区域处于干旱状态;从变化看全流域干旱整体上呈逐年下降趋势,有94 %的区域由干旱逐渐向湿润转变,从春季到冬季干旱呈现先减轻后加重的趋势.②从流域重要资源的时空变化看,起关键作用的地表径流量有53 %的区域呈现增加趋势,且主要分布在流域西南地区;表征植被资源的植被净初级生产力（NPP）及表征粮食资源的粮食产量亦呈增长趋势.③干旱与3类资源呈现显著的空间关联度,干旱程度越高对地表径流量、植被生产力和粮食产量产生的影响越显著,但近年来变湿的地区,其重要资源并未显著增加,这说明干旱对3类重要资源的影响具有时间滞后性,且其滞后性在空间分布上具有显著差异性和地域分异规律.研究对于黄河流域农业生产和抗旱减灾、生态保育具有重要理论意义.     

CLIMATE SCIENCE AND DROUGHT PLANNING: THE ARIZONA EXPERIENCE1

ABSTRACT: In response to recent severe drought conditions throughout the state, Arizona recently developed its first drought plan. The Governor's Drought Task Force focused on limiting the economic and social impacts of future droughts through enhanced adaptation and mitigation efforts. The plan was designed to maximize the use of new, scientific breakthroughs in climate monitoring and prediction and in vulnerability assessment. The long term objective of the monitoring system is to allow for evaluation of conditions in multiple sectors and at multiple scales. Stakeholder engagement and decision support are key objectives in reducing Arizona's vulnerability in light of the potential for severe, sustained drought. The drivers of drought conditions in Arizona include the El Nino‐Southern Oscillation, the Pacific Decadal Oscillation, and the Atlantic Multidecadal Oscillation.     

A Long View of Southern California Water Supply: Perfect Droughts Revisited

The impact of drought on water resources in arid and semiarid regions can be buffered by water supplies from different source regions. Simultaneous drought in all major source regions — or perfect drought — poses the most serious challenge to water management. We examine perfect droughts relevant to Southern California (SoCal) water resources with instrumental records and tree‐ring reconstructions for the Sacramento and Colorado Rivers, and SoCal. Perfect droughts have occurred five times since 1906, lasting two to three years, except for the most recent event, 2012–2015. This number and duration of perfect droughts is not unusual in the context of the past six centuries. The modern period stands out for the relatively even distribution of perfect droughts and lacks the clusters of perfect drought documented in prior centuries. In comparison, perfect droughts of the 12th Century were both longer (up to nine years) and more widespread. Perfect droughts of the 20th and 21st Centuries have occurred under different oceanic/atmospheric patterns, zonal and meridional flow, and ENSO or non‐ENSO conditions. Multidecadal coherence across the three regions exists, but it has varied over the past six centuries, resulting in irregular intervals of perfect drought. Although the causes of perfect droughts are not clear, given the long‐term natural variability along with projected changes in climate, it is reasonable to expect more frequent and longer perfect droughts in the future.