近50a江西省旱、涝变化趋势及驱动因素研究

基于江西省5个气象站(赣县、吉安、南城、南昌、景德镇)近50 a(1961~2010年)平均气温、最高、最低平均气温、相对湿度、风速、日照时数、降雨量等逐月平均资料,计算江西省干旱侦测指数(Reconnaissance drought index,RDI),分析旱情、涝情变化趋势。同时,运用多元回归法分析主要驱动因素。研究结果表明,1961~2010年江西省年及四个季节的降雨量、平均相对湿度与RDIst值均呈现极显著的正相关关系(p0.01),而日照时数则与RDIst值呈现极显著的负相关关系(p0.01)。降雨量对江西省旱、涝变化的贡献率最大,为42%~58%;其次是平均气温和相对湿度,分别为11%~19%和7%~19%;平均风速和日照时数对江西省旱、涝变化的贡献率较小。降雨量、相对湿度的增加,日照时数的减少共同导致了1961~2010年江西省年际尺度和春季RDIst值的增加,表明江西省总体从偏旱向偏涝转变。1961~2010年江西省夏季、秋季和冬季RDIst没有明显的增长或降低趋势。     

近52年来洞庭湖流域气象干旱的时空分布特征

基于洞庭湖流域84个气象站点1962~2013年的逐日气象资料,利用综合干旱指数(CI)对洞庭湖流域气象干旱的时间和空间特征进行分析。结果表明:在过去52 a,区域性干旱强度较强的时段以夏季、秋季、夏秋和秋冬时节为主;区域干旱强度在春季、夏季、夏秋、冬季呈上升趋势;秋冬时节和年干旱强度变化不明显;春夏时节、夏秋时节、秋冬时节和冬春时节的平均干旱强度比春、夏、秋、冬单个季节的平均干旱强度大。小波分析表明,区域干旱强度的周期以10a为主周期,5 a和22 a为次周期。近52 a来,历年干旱站次比主要集中于10%~30%之间,多表现为区域性干旱,以夏季和秋季的干旱范围较大;干旱频率高发时期主要为夏季、夏秋时节和秋季。干旱频率高发地主要以流域的南部山地和北部的洞庭湖平原为主,西北部的山地发生干旱相对较少,衡邵盆地随季节变化干旱频率易发生高低值转换。     

重庆市特大旱灾的自然与社会机制分析

文章针对2006年的特大旱灾探讨了2006年的特大旱灾的特征,分析了2006年特大旱灾的形成自然机制和社会机制,并提出了今后重庆市抗御旱灾的策略。认为2006年的特大旱灾是自然因素与社会因素叠加的结果,是人类社会经济系统自身易损性的体现。     

El Niño platforms: participatory disaster response in Peru

Climate change is expected to lead to greater extremes (droughts and floods) in river regimes around the world. While the number of major calamities is predicted to rise, the efforts of the public sector, experts and local stakeholders are badly coordinated. Consequently, aid does not reach target groups, resulting in unnecessary losses. Hence, there is a need for more participatory and integrative approaches. To ensure a more concerted response to climate-induced disasters, stakeholders could coordinate and negotiate within Multi-Stakeholder Platforms. Such roundtables are increasingly being established for vision-building and integrated water resource management, but could be employed in disaster management as well. After discussing the advantages and disadvantages of participation, this article trace the rise of and the problems facing two 'El Ni?o' platforms: one in Ica, a city on the Peruvian coast that flooded unexpectedly in January 1998, and one in Ayacucho, which saw a climate change-induced drought around the same time. The issue of internal and external legitimacy receives particular emphasis.     

Adaptation of Climate Model Projections of Streamflow to Account for Upstream Anthropogenic Impairments

A statistical procedure is developed to adjust natural streamflows simulated by dynamical models in downstream reaches, to account for anthropogenic impairments to flow that are not considered in the model. The resulting normalized downstream flows are appropriate for use in assessments of future anthropogenically impaired flows in downstream reaches. The normalization is applied to assess the potential effects of climate change on future water availability on the Rio Grande at a gage just above the major storage reservoir on the river. Model‐simulated streamflow values were normalized using a statistical parameterization based on two constants that relate observed and simulated flows over a 50‐year historical baseline period (1964–2013). The first normalization constant is a ratio of the means, and the second constant is the ratio of interannual standard deviations between annual gaged and simulated flows. This procedure forces the gaged and simulated flows to have the same mean and variance over the baseline period. The normalization constants can be kept fixed for future flows, which effectively assumes that upstream water management does not change in the future, or projected management changes can be parameterized by adjusting the constants. At the gage considered in this study, the effect of the normalization is to reduce simulated historical flow values by an average of 72% over an ensemble of simulations, indicative of the large fraction of natural flow diverted from the river upstream from the gage. A weak tendency for declining flow emerges upon averaging over a large ensemble, with tremendous variability among the simulations. By the end of the 21st Century the higher‐emission scenarios show more pronounced declines in streamflow.     

水库抗旱调度分期特征确定方法研究

为在一定程度上减轻流域干旱损失,国家防汛抗旱总指挥部提出旱限水位的概念,并开展水库抗旱调度,降低干旱影响程度。旱限水位是水库低水位运行的控制性水位,其合理设置对提高区域水资源利用率意义重大,而水文气象特征在年内的阶段性变化要求基于旱限水位的水库管理应适应其变化特征。此次研究提出水库抗旱调度分期的确定方法,采用核主成分分析法提取指标的非线性特征,结合熵权法赋予指标权重后利用Fisher最优分割法对干旱的年内阶段性变化进行划分。以黄河流域刘家峡和小浪底水库为例,分期结果刘家峡水库分3期为:7月至9月,10月至3月,4月至6月;小浪底水库分3期为:7月至10月,11月至3月,4月至6月。     

基于DEM的山区旱灾风险评价模型——以西南地区为例

旱灾研究中,地形导致的水热再分配容易造成地域间旱灾灾情的明显差异,因此地形因子对于旱灾风险的准确评价及灾情的客观评估至关重要。采用气象站点观测数据和DEM数据,通过模拟复杂地形影响下的下垫面真实水分情况,加入地形因子的影响,建立了以干旱致灾因子(水分条件)、孕灾环境(地形)、承灾体(农作物脆弱性曲线)综合的旱灾风险评价三度模型;并以地形复杂、旱灾多发的西南地区为例,编制了旱灾风险等级图,以期为客观评估旱灾灾情,有效开展区域旱灾风险防范提供科学依据。     

辽西北地区农业干旱灾害风险评价与风险区划研究

以辽西北29个农业县(市、区)为研究区域,选取辽西北最主要的玉米作物作为研究对象,从造成农业干旱灾害的致灾因子危险性、承灾体暴露性、脆弱性和抗旱减灾能力4个方面着手,利用自然灾害风险指数法、加权综合评价法和层次分析法,建立了农业干旱灾害风险指数(ADRI),用以表征农业干旱灾害风险程度;借助GIS技术,绘制辽西北农业干旱灾害风险评价区划图,将风险评价区划图与2006年辽西北受干旱影响粮食减产系数区划图对比,发现两者可以较好的匹配。研究结果可为当地农业干旱灾害预警、保险,以及有关部门的旱灾管理、减灾决策制定提供理论依据和指导。     

Drought,water access,and urban agriculture: a case study from Silicon Valley

In California, the growing popularity of urban agriculture (UA) has unfolded against a backdrop of historic drought. While UA is often celebrated as an urban sustainability strategy, it must be able to persist during drought if it is to perform these functions. Using Santa Clara County – the geographic core of Silicon Valley – as a case study, we use interviews and surveys to explore the implications of drought for UA. We show how developing an understanding of water access for UA during a drought requires examining the social and institutional context of water management and use. In metropolitan California, the highly decentralised water supply system combined with the diverse institutional arrangements that support UA create an uneven landscape of water access. Consequently, the pressure to change water-consuming practices – that is, the stress that institutional drought responses place on different water users – is geographically and socially differentiated. Among UA water users, responses to drought have also varied, in part because the possibilities for change are constrained by the sociotechnical arrangements of UA sites and the different purposes of UA.     

公众灾害风险可接受性与避灾意愿的初探——以川渝地区旱灾风险为例

在综述前人研究的基础上,以川渝地区旱灾为例,通过实地调查与访谈,从公众可接受的旱灾损失与频率、假定旱灾风险情景下的避险意愿等角度,对公众旱灾风险可接受性进行了初步探讨。结果表明,公众合理可接受的旱灾损失与频率分别在26.5%~52.8%与32.0%~64.3%区间范围内;并以一般旱灾、严重旱灾风险情景为限制线,确定了公众合理可接受风险区域;随着灾害损失风险增加,公众规避风险投资意愿呈现出中间高两头低的趋势,当灾害损失达到约50%~70%时,公众避险投资意愿达到最高,意愿避险投资占可能损失的比重约为62%。鉴于川渝地区的旱灾形势,今后旱灾风险管理的关键,一是加强对旱灾的监测与预警预报;二是完善旱灾风险的常规化管理,发展高效灌溉农业,充分利用客水资源,完善提高现有农田水网建设;三是积极探索公众-企业-政府多方共同参与的高效风险管理模式。