全国干旱灾害风险区划的思路方法及防治策略

干旱灾害是全球面临最主要的自然灾害之一，干旱灾害风险管理是现代抗旱工作发展的必然趋势。提出干旱灾害风险区划的思路，基于干旱灾害风险度提出干旱灾害区划方法，分别从农业干旱灾害、因旱人饮困难和城镇干旱灾害三个方面及综合角度揭示了全国干旱灾害风险空间分布特征，提出了不同地区的防治等级，为不同区域干旱灾害防治及提出针对性应对措施提供科学依据。     

安徽省干旱灾害风险区划研究

为提出区域旱灾风险应对措施提供依据,进一步推动干旱灾害防治区划研究,从风险管理角度定量评估和区划干旱灾害风险,以县级行政区为区划单元计算农业干旱灾害和因旱人饮困难风险度,并采用等分间距法开展农业干旱和因旱人饮困难风险区划,最后根据最不利原则确定干旱灾害综合风险区划。结果表明：安徽省农业干旱灾害高风险区主要集中在淮北平原北部地区和江淮分水岭地区;因旱人饮困难高风险区位于皖西皖南山区;城镇干旱灾害无高风险区;6个县级行政区干旱灾害综合为高风险区。风险区划成果有助于掌握安徽省干旱灾害风险分布情况,可为干旱灾害风险管理提供科学依据和技术支撑。     

基于乡镇尺度的旱灾风险区划研究——以贵州播州区为例

贵州是全国唯一没有平原支撑的喀斯特山地省份，因其特殊的地理位置、气候特征和下垫面性质，干旱灾害频发。为掌握干旱灾害风险分布情况及分布规律，将风险区划单元进一步延伸至乡镇，以指导各乡镇防旱抗旱工作高效开展。以贵州省播州区为对象，以乡镇为区划单元，分析和筛选干旱灾害风险代表性指标。基于自然灾害风险理论和GIS技术构建干旱灾害风险区划模型，开展乡镇尺度的干旱灾害风险区划研究。结果表明，播州区各乡镇干旱灾害风险等级以中风险及以下为主，占比60%，中高风险区和高风险区累积占比为40%。干旱灾害风险高的乡镇主要分布在播州区的东部、南部和西部。多年平均降水量可以反映干旱灾害危险性。林草覆盖率高的乡镇的地形条件较差，旱地占比较高，干旱灾害风险一般较高。地形条件好是干旱灾害风险低的必要条件。     

基于自然灾害系统理论的甘肃省农业旱灾风险评估

甘肃省干旱灾害频发,对农业生产的影响很大。基于自然灾害系统理论,利用模糊评价方法,对甘肃省87个区县的农业干旱灾害的危险性、暴露性、脆弱性及风险进行了定量计算和定性评估,从而得到甘肃省农业旱灾风险分布。风险分布具有较明显的流域特征,即黄河流域内陆河流域长江流域。根据上述分析,针对降低甘肃省农业旱灾暴露性、脆弱性提出了一些建议,以期减轻农业旱灾风险。     

湖南省农业干旱水资源风险评价

以湖南省的14个地州市为研究对象，从水资源风险管理的可靠性、恢复性、易损性出发，结合其抗旱减灾能力，利用灰色关联聚类法、层次分析法等方法，建立了湖南农业干旱水资源风险评价模型。引用干旱风险指数法对湖南农业干旱水资源风险进行了评价。结果表明：张家界、湘西自治州、益阳、娄底等地州市水资源风险高，长沙、邵阳、岳阳等地州市水资源风险低，并绘出了风险分布图。评价结果可为湖南省水资源合理配置、保障区域农业经济可持续发展战略实施提供科学依据。     

我国农业干旱灾害风险评估及分布特征分析

基于水资源量分析干旱灾害危险性空间分布情况，通过分析不同干旱频率下现状年供水与历史典型年供水能力的差异，计算不同干旱频率下的农业干旱灾害影响，揭示全国农业干旱灾害风险分布特征。结果表明，我国干旱灾害危险性较高的地区大多分布在粮食主产区；在5年一遇、10年一遇、20年一遇的情况下，农业干旱灾害高风险区主要分布在黄淮海地区、东北地区、西北地区等北方地区；在50年一遇和100年一遇的情况下，西南地区和长江中下游地区等水资源相对丰沛的地区农业干旱灾害风险剧增，区域粮食安全、供水安全甚至生态安全将面临严峻挑战。     

湖南省山洪灾害防治区划研究

山洪灾害防治区划是开展山洪灾害防治规划的前提和工作基础。文章通过对湖南省山洪灾害致灾原因的系统分析和山洪灾害时间、空间分布特征研究,按照一定的区划等级系统,应用地理信息系统技术,在降雨区划、地形地质区划、经济社会区划的基础上,将湖南省山洪灾害防治区划分为若干个具有一定共同特征的区域,以期科学地反映山洪灾害地域分布差异,为山洪灾害防治提供依据。     

湖南省山共灾害防治区划研究

山洪灾害防治区划是开展山洪灾害防治规划的前提和工作基础.文章通过对湖南省山洪灾害致灾原因的系统分析和山洪灾害时间、空间分布特征研究,按照一定的区划等级系统,应用地理信息系统技术,在降雨区划、地形地质区划、经济社会区划的基础上,将湖南省山洪灾害防治区划分为若干个具有一定共同特征的区域,以期科学地反映山洪灾害地域分布差异,为山洪灾害防治提供依据.     

基于AHP和GIS的广东省干旱风险分析与区划

为了减轻干旱灾害造成的影响,提高应对干旱灾害的风险评价和决策分析能力,结合广东省气候环境及社会经济等资料,选取致灾危险性、环境敏感性、承灾易损性3类评估要素为准则层,构建了广东省干旱灾害风险分析系统,运用层次分析法（AHP）和地理信息系统（GIS）对多指标环境作用下的研究区域进行干旱风险空间分析,得出广东省干旱综合风险区划图。结果表明,总体上看,广东省干旱综合风险区域呈高、中、低交错分布,中风险及以上区域比例较高,占总体面积的75.5%。结合历史旱灾统计数据分析,风险区划分布与实际情况基本相符。在应对干旱灾害时,分析成果可为广东省科学抗旱、精准施策提供参考依据。     

辽宁省农业干旱风险评价研究

农业干旱灾害是辽宁省乃至全国范围内频繁发生的慢性自然灾害,严重威胁人类生产生活、抑制社会经济发展、破坏生态环境。文章以辽宁省为研究对象,构建了农业干旱风险指标体系,利用农业干旱风险指数法,对全省农业干旱风险进行了评估。结果表明,低风险主要分布在东部的15个县区;较低风险主要分布在中部的21个县区;中等风险主要分布在北部铁岭和南部大连的9个县区;较高风险主要分布在辽西丘陵区向中部平原的过渡地带及辽南的18个县区;高风险等级主要分布在辽西的15个县区。农业干旱风险评价结果可为辽宁省农业干旱风险管理提供重要依据。     

地下厂房施工过程的三维非线性数值模拟分析

根据冗各电站地下厂房开挖支护的施工顺序,以隐式杆单元模拟锚杆,以壳单元模拟混凝土喷层,采用三维非线性有限元技术,对洞室群的开挖支护动态过程进行了模拟计算。通过三维非线性有限元计算分析得到:洞室群动态开挖过程中围岩应力变形的分布规律,围岩塑性区的发展规律,锚杆受力变化情况。计算结果表明:整个开挖过程中,洞周围岩位移变化规律正常,量值较小,塑性区主要分布在洞室周边,围岩稳定性较好;但在洞室交叉口处围岩的变形较大,出现较大范围的塑性区,在此基础上提出了支护措施优化方案,并对优化方案的效果进行了评价。     

Evaluation of freshwater mussel relocation as a conservation and management strategy

The relocation of unionacean mussels is commonly used as a conservation and management tool in large rivers and streams. Relocation has been used to recolonize areas where mussel populations have been eliminated by prior pollution events, to remove mussels from construction zones and to re-establish populations of endangered species. More recently, relocation has been used to protect native freshwater mussels from colonization by the exotic zebra mussel Dreissena polymorpha. We conducted a literature review of mussel relocations and evaluated their relative success as a conservation and management strategy. We found that 43% of all relocations were conducted because of construction projects that were forced to comply with the Endangered Species Act 1973 and that only 16% were monitored for five or more consecutive years. Most (43%) relocation projects were conducted from July to September, presumably a period when reproductive stress is relatively low for most species and the metabolic rate is sufficient for reburrowing in the substrate. The mortality of relocated mussels was unreported in 27% of projects; reported mortality varied widely among projects and species and was difficult to assess. The mean mortality of relocated mussels was 49% based on an average recovery rate of 43%. There is little guidance on the methods for relocation or for monitoring the subsequent long-term status of relocated mussels. Based on this evaluation, research is needed to develop criteria for selecting a suitable relocation site and to establish appropriate methods and guidelines for conducting relocation projects.     

基于模型试验的河床砂砾石层基本特性研究

为了经济可靠地确定深厚覆盖层的基本特性参数,以大渡河双江口水电站坝基河床砂砾石层基本特性研究为工程背景,进行大尺寸模型试验,研究河床砂砾石层的旁压模量和动探击数随密度、级配以及上覆压力的变化规律。根据室内模型试验结果,结合现场旁压试验及钻孔试验成果,推断出坝址区河床砂砾石相关层位的密度,并依此进行砂砾石室内力学试验,获得设计所需力学参数。研究成果可为深厚覆盖层基本特性测试提供新的方法。     

基于BP神经网络-马尔科夫链模型的隧道围岩位移预测

在隧道工程施工中,围岩位移预测起着很重要的作用。将BP神经网络-马尔科夫链模型引入到隧道围岩位移预测中来,通过对训练样本的学习,利用BP神经网络实现了对位移时间序列的滚动预测,同时得到了实测值与预测值的相对误差;在此基础上利用马尔科夫链对相对误差进行修正,有效地提高了预测结果的精度。并将该模型应用于某公路隧道拱顶下沉位移时序预测中,结果表明该模型具有精度高、科学可靠的特点,为隧道围岩变形的预测提供了新的途径。     

Short communication. Pipelines as a refuge for freshwater snails

In the lower River Murray, Australia, populations of gastropods have declined markedly over the past 40 years. Of the native fauna of about 18 species, only the ancylid Ferrissia petterdi remains common (but in patches), and another five species feature in sporadic local resurgences. Until recently the viviparid Notopala was thought to be extinct. The introduced physid Physa acuta is widespread, but in low numbers. The decline probably is associated with flow regulation, high turbidity and the introduction of common carp. Snail populations have persisted, however, in irrigation pipelines fed from the river, where they periodically cause blockages. This paper reports the discovery of the only known populaion of Notopala hanleyi in a pipeline where the inner wall accumulates microbial and other organic matter, providing high quality food for snails. In the Murray before regulation most of the periphytic biomass was probably microbial, as fluctuating water levels would have maintained littoral communities in a highly productive, early state of succession his postulated that, by stabilizing seasonal water levels, regulation has promoted the production of filamentous green algae, an inferior food source, and so displaced snail populations from the open aquatic environment.     

浙江省水域调查录入系统的设计和应用

浙江省水域调查录入系统将调查数据与电子地图相整合,对分类水域数据进行统计计算,并对输入数据进行合理性和完整性检查,得到调查范围内现有水域的详细数据,实现了水域调查数据输入、计算、统计和查询的数字化管理,提高了工作效率和工作质量,为各地下阶段水域保护规划编制和水域管理工作提供了数据支持。对该系统的设计原则、功能和技术设计等作了介绍。     

基于CT-连续加荷水泥乳化沥青混凝土细观损伤规律研究

利用CT技术对水泥乳化沥青混凝土的细观损伤过程进行实时扫描观测,获得了混凝土试件在连续加荷下的CT图像。通过采用直观分析法、CT数分析法、CT数与损伤变量关系3种方法分析表明,水泥乳化沥青混凝土的破坏过程可分为压密、扩容、裂纹扩展、破坏4个阶段,同时混凝土在受压过程中具有韧性,在极限荷载之前各断面处于压密和微扩容的强化阶段,极限荷载之后混凝土从损伤到破坏发展比较平稳。     

浅谈天湖水电站水轮机运行故障及处理措施

简述天湖水电站投运以来各种故障的表现形式，分析其原因，提出了相应的处理方法及措施，并对合理利用国内外设备提出建议。     

Fish assemblage response to recent mitigation of a channelized warmwater stream

Various designs of low‐head dams are used to rehabilitate streams or forestall upstream channel incision after channelization. We report on the efficacy of using notched sills and grade control structures (GCS) to restore the fish assemblage in Luxapallila Creek, Mississippi. We tested the null hypotheses that habitat variables and species richness, evenness, and assemblage structure would not differ among: (1) a channelized segment with no modifications; (2) a channelized segment mitigated by the installation of sills and GCS; (3) a segment upstream of the installations and undergoing channel incision; and (4) an unaltered segment. Although habitat variables changed, neither species richness, evenness, nor fish assemblage structure differed between mitigated and channelized segments with both exhibiting less richness and different assemblage structures than the unaltered segment. Lack of differences in species richness between the incised and unaltered segments suggest that the GCS may have halted the negative effects of upstream channel incision before species were extirpated. Conspicuous habitat differences between the altered (channelized and mitigated) and unaltered segments were lack of backwaters and canopy coverage and finer substrates in the altered segments. Our results suggest a more comprehensive rehabilitation strategy is required in Luxapallila Creek. Published in 2003 by John Wiley & Sons, Ltd.     

NUMERICAL STUDY OF WAVE EFFECTS ON SURFACE WIND STRESS AND SURFACE MIXING LENGTH BY THREE-DIMENSIONAL CIRCULATION MODELING

1. INTRODUCTION Coastal and continental shelf regions are characterized by intensive interaction between wave and current. These regions are of great economic significance to mankind. Therefore, the modeling of wave and current as well as their mutual int…