橘全爪螨春季高峰发生程度与气象因素的关系

本文探讨了橘全爪螨高峰发生程度与气象因素及天气过程的关系。结果表明：春季高峰由２次连续的高峰组成,且第二次高峰大于第一次高峰;第一次高峰发生在４月下旬到５月中旬,其发生程度主要受 ３月 ２０日～ ４月 ３０日气象因子和天气过程的影响,即日均温度≥ １２℃,降雨≤ ２ｍｍ、相对湿度（ＲＨ）≤８５％,持续时间越长发生程度越重;第二高峰发生在５月下旬至６月中旬,主要受５月１１日～６月 １０日气象因子和天气过程的影响,即日均温度 ２０～ ３０℃、降雨≤ １０ｍｍ的持续时间越长该螨的发生程度越严重。说明重庆地区橘全爪螨春季高峰严重发生的主要因素是在相应的时间内降雨少、气温变幅低,积温多和特定气象因子组合的天气持续过程。     

基于土地利用变化情景的城市暴雨洪涝灾害风险评估——以深圳市茅洲河流域为例

近年来频发的暴雨洪涝成为威胁城市可持续发展的主要灾害类型,而土地利用变化改变了区域原有的景观结构和水文过程,是城市暴雨洪涝灾害风险加剧的重要诱因,定量探讨土地利用变化对暴雨洪涝灾害及其风险影响具有重要意义。以深圳市茅洲河流域为例,基于CLUE-S模型、SCS模型及等体积淹没算法等,对12种暴雨洪涝致灾-土地利用承灾情景下的城市暴雨洪涝灾害风险进行定量模拟。研究结果显示,相同土地利用空间格局下城市暴雨洪涝灾害随暴雨致灾危险性增加风险加剧显著;在同等致灾危险性水平下随建设用地面积增加,中等风险和高风险区面积均呈现较为明显的增加趋势,中、高风险区面积与建设用地面积的增加率表现出较高的协同变化特征;以50年遇危险性水平为例,随着建设用地面积由基期的15368.85hm~2增加至近期16076.07hm~2和远期16750.89hm~2,高风险区面积由254.07hm~2增加至276.48hm~2和286.2hm~2。由此可见,尽管暴雨强度的增加是城市暴雨洪涝灾害风险加剧的根本诱因,但是以建设用地面积增加为表征的土地利用变化对暴雨洪涝灾害风险的影响不容忽视。     

基于GIS的四川盆周北部山区夏玉米农业气象灾害风险评估——以旺苍县为例

气象灾害是制约我国农业发展的主要因素之一,明确夏玉米农业气象灾害风险对于防灾减灾具有重要意义。本研究基于自然灾害风险理论,以四川盆地北部山区的典型区域(旺苍县)1981—2018年气象数据和玉米产量数据为基础,确定影响夏玉米生产的主要致灾因子,并结合孕灾环境敏感性及承灾体脆弱性构建夏玉米综合农业气象灾害风险评估模型,对四川盆地北部山区夏玉米生产过程中的农业气象灾害风险进行评估。结果表明: 研究期间,成熟期高温、花期暴雨、成熟期暴雨、灌浆期连阴雨和孕穗期干旱是影响研究区夏玉米生长发育的主要农业气象灾害。旺苍县夏玉米农业气象灾害综合风险分布大致呈西南-东北走向,高风险和较高风险区分布区域约占旺苍县总面积的二分之一;灾害风险高值区主要位于研究区西南部,基本与致灾因子危险性高值区一致;灾害风险低值区多集中在西部边缘,此区域亦为成熟期高温、成熟期暴雨、花期暴雨气象灾害的低风险区。     

冬季PM2.5的气象影响因素解析

气象因素能够显著影响PM_(2.5)浓度,可减轻或加剧城市空气污染,尤其是在雾霾严重的冬季。同时由于城市间污染物排放强度和扩散条件的差异,雾霾的发生往往具有较强的区域性。选择了石家庄、西安、北京、太原、广州5个不同污染区域的典型城市,首先分析多个气象因子与PM_(2.5)浓度的关系,进而研究气象因素对PM_(2.5)浓度变异解释度的差异,以及气象因子对PM_(2.5)浓度影响的相对重要性,进一步对比分析气象因素对PM_(2.5)浓度影响在不同污染程度的城市之间的差异,解析了不同城市的主要气象影响因素和气象因素的综合影响程度。研究结果表明:(1)气象条件与PM_(2.5)日浓度显著相关,且在不同污染程度的城市与PM_(2.5)浓度相关的气象因子不同。与石家庄冬季PM_(2.5)浓度相关的气象因素为相对湿度、平均风速;与西安PM_(2.5)浓度相关的主要气象因素为相对湿度、平均风速和最大持续风速;与北京PM_(2.5)浓度相关的主要气象因素相对湿度、日均温度、平均风速、最大持续风速和最低温;与太原PM_(2.5)浓度相关的主要气象因素为日均温、相对湿度、平均风速、最高温、最低温和最大持续风速;与广州PM_(2.5)浓度相关的主要气象因素为相对湿度、平均风速、最高温和降雨量。(2)PM_(2.5)浓度越高的地区,气象因素能够解释的PM_(2.5)浓度变异越小。严重污染区的石家庄气象因素多元回归分析的R~2为0.27,重污染区的西安气象因素多元回归分析R~2为0.29,中污染区的北京气象因素多元回归分析R~2为0.46,污染地区的太原气象因素多元回归分析R~2为0.67。研究结果揭示了不同城市的主要气象影响因素及其综合影响程度,可为城市PM_(2.5)控制和预测精度提高提供理论参考,并为区域生态环境规划和城市协调发展提供科学依据。     

广西南宁桉树人工林降雨再分配特征

为了解桉树人工林生态系统的降水再分配特征,改进桉树人工林经营方案,以提高林地保水保肥能力,本文依托广西南宁桉树林生态系统定位观测研究站,通过观测2015年7月—2016年5月历时11个月的尾巨桉林外降雨、林内降雨、穿透雨和树干径流,分析尾巨桉林冠降雨再分配特征。结果表明,研究期间的降雨总量1536 mm,穿透雨总量1042mm,占降雨总量68%;树干径流总量9.2 mm,占降雨总量0.6%;林冠截留总量490 mm,占降雨总量32%。月降雨量与穿透雨呈对数函数关系,当月降雨量超过25 mm即产生穿透雨;穿透雨和穿透率随降雨强度的增加而增加,当次降雨强度达暴雨以上时,林外降雨几乎全部形成林内降雨。在小雨、中雨、大雨和暴雨4种降雨强度条件下,累计降雨量与累计穿透雨均呈二次多项式递增函数,其中小雨和中雨的穿透雨初始时间滞后初始降雨分别约20min和10 min,而大雨和暴雨的穿透雨初始时间与降雨同步。树干径流虽在本文降雨分配计算过程中忽略不计,但其作用不可忽视。月降雨量与截留量呈递增幂函数关系,与截留率呈递减指数函数关系。     

基于RS和GIS的珠江三角洲生态环境脆弱性综合评价

使用空间主成分分析法构建评价指标体系,采用层次分析法确定指标权重,结合遥感数据和地理信息系统软件,对珠江三角洲2004-2008年生态环境脆弱性进行了综合评价并对脆弱性成因进行分析.结果表明:生态环境极度和重度脆弱区主要分布在珠江三角洲中部,占整个研究区面积的34.0％;生态环境中度脆弱区主要分布在珠江三角洲东部,占25.5％;生态环境轻度和微度脆弱区主要分布在珠江三角洲西部,分别占28.7％和l1.8％.中度和轻度脆弱区占整个研究区面积的54.2％,表明珠江三角洲大部分区域的生态环境属中度和轻度脆弱.影响珠江三角洲生态环境脆弱性的自然因素主要有海拔高度、大暴雨日数、水土流失比率、易涝耕地面积比率、归一化植被指数、景观多样性指数,人为因素主要有人口密度、单位面积废水排放量、单位面积废气排放量、土地利用变化、化肥施用强度、农药使用强度、万人机动车拥有量、环保投资指数.极度和重度脆弱区的主要特征是海拔低、洪涝灾害发生频率高、易涝耕地面积多、植被破坏严重、污染强度大和环保投资指数小等.     

气候变暖背景下东南地区暴雨洪涝灾害风险变化

基于中国东南地区9省(区)1972—2013年的暴雨洪涝灾情资料,采用灰色关联法、正态信息扩散法,分别构建了基于受灾面积比重和成灾面积比重的暴雨洪涝灾害相对灾情指数及其风险估算模型,分析了气候变暖前(1972—1992年)、后(1993—2013年)东南地区暴雨洪涝灾害的风险变化。结果表明:东南地区暴雨洪涝灾害在20世纪80年代有较大范围的突变性增加,较东南地区变暖突变时段(1993年)有所提前;20世纪90年代,各省均先后出现了暴雨洪涝灾害相对灾情指数最大值;东南地区各省在变暖后大体上发生大灾和中灾的概率有所增加,出现小灾和微灾的概率有所变小,总体来看仍以中灾发生最为频繁,基本为不到2年一遇;除江苏外,东南地区其他省份变暖后大灾及以上级别暴雨洪涝灾害发生频率为变暖前的2~8倍,以广西增幅最大;在考虑了东南地区热带气旋带来的暴雨洪涝灾害影响后,变暖背景下各省的相对灾情风险指数除江苏减小7%外,其他均增大;增幅最大的是广西,达21%,变暖前后的高风险中心由原来的广东变为广西。     

应对暴雨洪涝灾害的平原城市生态水文调节服务供需评估——以天津市为例

生态水文调节服务是生态系统服务的重要组成,能够有效调节地表径流,缓解暴雨洪涝灾害。但由于城市建设扩张、生态环境退化、极端降雨频发等因素,导致生态水文调节服务出现供需失衡。平原城市中地形水动力较弱及城市发展需求高的特征更是加剧了这种现象。基于生态系统供需视角,以生态水文调节率表征城市生态水文调节服务的生态供给,以暴雨洪涝风险表征城市生态水文调节服务的社会需求,构建应对暴雨洪涝灾害的平原城市生态水文调节服务供需研究框架。以典型平原城市天津市为例,应用SWAT模型、随机森林模型和ArcGIS定量测度城市生态水文调节服务供需水平,划分四种供需空间匹配类型,识别供需失衡关键区域,并进行五级规划干预等级分区。结果表明：(1)供给能力呈现“东南沿海高,西北近山低”的空间分布;需求水平表现出“多中心聚集,圈层向外递减”的分布规律。(2)供需空间分布呈现正相关关系,低供-低需在四种供需匹配类型中占据主导,同时空间聚集性最明显。(3)规划干预分区存在明显的空间差异,优先干预区占比5.41%,整体与建成区分布一致,大部分集中在市内六区,其次分布在滨海新区核心区,是未来规划治理的重点。研究结果为城市规划管理从...     

深圳市土地利用变化对流域径流的影响

土地利用所引起的流域下垫面变化严重影响着洪涝灾害的致灾过程,以深圳市为例,探讨下垫面条件对流域径流过程的影响,应用美国农业部水土保持局（Soil Conservation Service)研制的小流域设计洪水模型-SCS模型对深圳市部分流域进行了径流过程的模拟,重点分析 了土地利用方式、土壤类型、前期土壤湿润程度等下垫面因素以及降雨因素对降雨-径流关系的影响。结果表明,随着人类活动的加剧,土地利用的变化使径流量趋于增大;降雨强度越大、前期土壤湿润程度而发生变化,CN值（Curve Number)的高值区主要集中在城市用地和水体;低值区主要出现在林地、灌草地、果园等植被覆盖较好,地势起伏较大的地区。     

热带山地雨林生态系统的水分生态效应

基于对尖峰岭热带山地雨林集水流域的定位研究,分析了３年间该群落冠层对大雨、暴雨及大暴雨势能的消减、缓冲耗能效应以及年暴雨携带养颁系统中贮存效应,其冠层消减大雨、暴雨及大暴雨势能占总消减能在６１．８－７１．８％之间,其中大暴雨势能量占年总消减势能的４３．９％;大雨、暴雨及大暴雨雨水的年均养分一为５５．１２２ｋｇ／ｋｍ＾２,其产流流失为４２．９１７ｋｇ／ｈｍ＾２,年均净积累１２．２０５ｋｇ／ｈｍ＾２,     

基于燕尾洲生态护堤模式的金华江流域防洪效应研究

气候变化背景下,洪水灾害发生频率增加,在全球范围内造成了破坏性影响。以金华江流域为研究区,以燕尾洲公园生态护堤设计模式为典型,探究不同生态护堤模式替代水泥堤防产生的流域防洪效应。研究利用SWAT模型,模拟不同设计形式和面积比例的生态护堤,在金华江流域洪水过程的流量调控、洪峰削减与水位调节3个方面所产生的效应。研究发现,随着流域范围内更多的水泥堤防被生态护堤所取代,洪水过程线变得更为平缓,年最大一日洪峰削减率最高可达63%,燕尾洲公园生态护堤模式较水泥堤防有良好的洪水削减作用。燕尾洲公园水位调控效果表明,公园生态护堤能够成功抵御模拟年份内所有场次洪水,且能够有效避免河道的硬化和白化,具有较强的推广应用价值。     

Global evidence that deforestation amplifies flood risk and severity in the developing world

With the wide acceptance of forest‐protection policies in the developing world comes a requirement for clear demonstrations of how deforestation may erode human well‐being and economies. For centuries, it has been believed that forests provide protection against flooding. However, such claims have given rise to a heated polemic, and broad‐scale quantitative evidence of the possible role of forests in flood protection has not been forthcoming. Using data collected from 1990 to 2000 from 56 developing countries, we show using generalized linear and mixed‐effects models contrasted with information‐theoretic measures of parsimony that flood frequency is negatively correlated with the amount of remaining natural forest and positively correlated with natural forest area loss (after controlling for rainfall, slope and degraded landscape area). The most parsimonious models accounted for over 65% of the variation in flood frequency, of which nearly 14% was due to forest cover variables alone. During the decade investigated, nearly 100 000 people were killed and 320 million people were displaced by floods, with total reported economic damages exceeding US$1151 billion. Extracted measures of flood severity (flood duration, people killed and displaced, and total damage) showed some weaker, albeit detectable correlations to natural forest cover and loss. Based on an arbitrary decrease in natural forest area of 10%, the model‐averaged prediction of flood frequency increased between 4% and 28% among the countries modeled. Using the same hypothetical decline in natural forest area resulted in a 4–8% increase in total flood duration. These correlations suggest that global‐scale patterns in mean forest trends across countries are meaningful with respect to flood dynamics. Unabated loss of forests may increase or exacerbate the number of flood‐related disasters, negatively impact millions of poor people, and inflict trillions of dollars in damage in disadvantaged economies over the coming decades. This first global‐scale empirical demonstration that forests are correlated with flood risk and severity in developing countries reinforces the imperative for large‐scale forest protection to protect human welfare, and suggests that reforestation may help to reduce the frequency and severity of flood‐related catastrophes.     

Effects of increased flow in the main stem of the River Rhine on the invertebrate communities of its tributaries

1. We hypothesised that increased flow in the main stem of the River Rhine would influence the invertebrate communities of its tributaries and therefore investigated the invertebrate fauna of six tributaries over 2 years. 2. We collected quantitative invertebrate samples at three sites in each tributary: in the tributary mouth (influenced by Rhine water whenever flow in the Rhine exceeded mean annual level), in the zone reached by average floods (return period 1.5 years) in the Rhine (average flood level sites), and immediately upstream of the range of extreme Rhine floods (reference sites). Samples were taken in spring, summer and autumn of each year, at different flow levels of the Rhine. We also compared substratum composition at the three sites. 3. Tributary mouth sites had the finest substratum, the lowest total invertebrate density and the lowest taxon richness. At average flood level and reference sites, these three parameters were similar. 4. Taxa known to prefer larger rivers were mostly confined to the tributary mouth sites, and species preferring upland streams dominated at the average flood level and reference sites. 5. Multivariate analyses confirmed the influence of the Rhine on the tributary mouth sites. Invasive invertebrate species, which usually appear only in the Rhine itself, were found at the tributary mouth sites but not further up in the tributaries. 6. Our study shows that increased flow in the main stem of the Rhine influenced substratum composition and invertebrate communities at the tributary mouth sites. These results imply that the relationship between the main stem of a river and its tributaries is not one‐way (from tributary to main stem), but rather a two‐way interaction.     

场次暴雨条件下降雨和植被变化对洪水影响的定量评估——以彭冲涧小流域为例

降雨和植被是影响流域洪水的两个关键性因素,定量研究二者对洪水影响的贡献率,对流域的植被建设及水资源管理具有重要的科学意义。本研究以南方红壤区的彭冲涧小流域为对象,基于1983—2014年的地理信息数据和水文气象数据,利用Mann-Kendall检验法、累积距平法、HEC-HMS模型等分析该流域的暴雨和洪水特征,并定量评估降雨和植被变化对洪水影响的贡献率。结果表明: 1983—2014年间,彭冲涧小流域的暴雨量和洪水总量分别呈非显著上升和下降趋势。HEC-HMS模型对场次暴雨洪水的模拟效果较好,评价结果均在误差范围内。无论是对洪水总量,还是对洪峰流量,不同场次暴雨洪水的降雨和植被变化贡献率均存在差异。降雨和植被变化对洪水总量的平均贡献率分别为66.5%和33.5%,对洪峰流量的平均贡献率分别为58.9%和41.1%。本研究成果可为小流域洪水评价、植被建设和水土流失综合治理提供科学依据。     

区域综合生态风险评价框架——以雄安新区为例

构建区域生态风险评价框架有助于清晰地识别、评估、模拟、预测与管理区域生态风险,进而为区域生态安全网络构建和生态安全格局保障提供支撑。雄安新区的建设,使该区域面临巨大的土地利用变化,对区域生态系统的结构和功能产生不可忽视的影响,洪涝和干旱灾害对雄安新区及其周边区域生态系统具有显著的威胁。以雄安新区为例,构建包含暴露-响应关系、人为源和自然源相结合的区域综合生态风险评价框架,分别对城市化和气候变化背景下的雄安新区土地利用变化、洪涝灾害、干旱灾害三类胁迫引起的区域生态风险进行了评价和预测,确定其生态风险空间分布特征及变化趋势。结果表明：(1)从时间序列上来看,由于气候变化导致洪涝、干旱等自然灾害的影响,加上雄安新区的土地利用变化,雄安新区的生态风险在2025年后有所上升,但有序的规划和良好的地类配置使得雄安新区起步区在2025年后生态风险程度下降;(2)从空间上看,雄安新区风险高值区主要集中在白洋淀区以西和以南,以及新区东北部部分区域。最后,从土地利用管理、洪涝和干旱灾害预防等角度提出了生态风险防控对策：(1)雄安新区应坚持对土地利用的合理规划和严格管理,切实防止土地的无序利用,密切关注景观...     

河岸带土壤重金属元素的污染及危害评价

测定了金水河流域河岸带土壤部分重金属的全量和土壤水溶液的离子含量,运用污染指数和生态风险评价法对流域内土壤重金属进行评价.不同土地利用类型中,漫滩V、Cr含量最高(130.89、363.29 mg·kg-1),草地Ni、Pb、Ti、Mn、Zn、Cu含量最高(32.52、24.61、4378.09、1289.62、91.44、29.71 mg·kg-1).这主要是因为草地、漫滩能够有效吸附和沉积重金属,同时人类活动明显增加重金属生态危害.金水河流域河岸带土壤Cr、Pb、Zn均超过土壤环境质量标准(GB 15618-1995).与此同时,河漫滩白浆化棕壤和钙质粗骨土碳酸钙含量高,对Pb、Zn有较强的吸附和固定作用,能够有效吸附和沉积重金属;河漫滩人类干扰较重,造成其重金属含量较高.评价结果表明,流域河岸带内重金属环境污染达到中、重度污染,生态危害等级为轻微到中等级别.提高土壤腐殖质含量是减轻污染危害及增强土壤自净能力的重要措施.     

气候变化对淮河流域中上游汛期极端流量影响的SWAT模拟

致洪暴雨主要是3天以上连续强降水,是淮河流域洪涝的直接原因。构建淮河流域中上游SWAT模型,用RegCM3在SRES A2排放情景下的模拟结果(2071-2100年)驱动SWAT模型,研究气候变化对淮河流域中上游汛期极端流量的影响。结果表明:(1)在SRES A2排放情景下,淮河流域中上游未来(2071-2100年)气温升高,降水量增加,降水的空间差异增大;颖河流域中游年降水量有较大幅度的减少,呈现暖干化的趋势;汛期极端过程降水增加,汛期最大9 d降水量平均增幅都在10%以上。(2)在SRES A2排放情景下的气候变化将导致淮河流域中上游汛期极端流量大幅度增加,干流5个水文站汛期最大9 d平均流量的增幅都在20%以上。(3)淮河流域中上游极端流量的概率分布更加集中,更大的极端流量出现的频率更高,研究流域下游更容易出现较大的极端流量。(4)研究流域下游极端流量概率对极端流量变化更敏感,下游也面临着更大的洪涝风险。     

基于SWAT模型的浑河中上游水源涵养服务价值评估

浑河中上游流域的森林覆盖率高达68%,是辽宁省饮用水的重要水源保护地。本研究基于SWAT模型和影子工程法,评估2000—2019年浑河中上游流域的水源涵养量及其服务价值,并分析其时空变化的原因,以期为流域内生态补偿和生态恢复提供依据。结果表明:2000—2019年浑河中上游水源涵养量及其价值量呈先增加后减少趋势;年均水源涵养总量和水源涵养服务价值分别为24.6亿m³和150.4亿元;研究区水源涵养量存在明显的空间差异,高值区主要分布在清原县和新宾县,低值区集中于沈阳市辖区;不同生态系统的水源涵养服务价值差异较大,森林的单位面积水源涵养量远高于草地、农田和城市。     

Flood regime,dam regulation and fish in the Upper Paraná River: effects on assemblage attributes,reproduction and recruitment

The flood regime is the most important force determining seasonality in neotropical rivers. In the Upper Paran River floodplain, it is the primary factor influencing biological processes. The aim of this paper is to summarize information on the influence of dam-controlled floods on some fish assemblage attributes, reproduction and recruitment in the Upper Paran River floodplain, providing preliminary guidelines for dam operation upstream. Fish were collected in different habitats of the Upper Paran River floodplain (river, channels and lagoons) in the period from 1986 to 2001. The high water period in the Paran River usually occurs from November/December to April/May. Annual variation in the hydrograph affects species with distinct life history strategies differently, and influences the composition and structure of fish assemblages. Large floods were associated with higher species richness. Frequencies of individuals with ripe and partially spent gonads, which indicate spawning, were higher during the period of increasing water level. Dependence on floods seems to be lowest in sedentary species that develop parental care, and highest in large migratory species that spawn in the upper stretches of the basin and use flooded areas as nurseries. Migratory fishes were favored by annual floods that lasted more than 75 days, with longer floods yielding larger populations. The occurrence of high water levels at the beginning of summer is fundamental to the spawning success of migratory species. However, the flood may be less important for recruitment of juveniles if it is of short duration. Dam operation upstream (releasing more water during the raining season) has potential to promote greater floods with appropriate duration improving recruitment, particularly for migratory species.     

Detrital layers marking flood events in recent sediments of Lago Maggiore (N. Italy) and their comparison with instrumental data

1. A succession of 20 detrital layers was detected in five short cores from the Pallanza Basin in the western part of Lago Maggiore (Italy) by combining thin‐section analyses and high‐resolution micro‐X‐ray fluorescence (μ‐XRF) scanning techniques. The detrital layers range in thickness from 0.6 to 17.4 mm and appear most distinct in the upper 20–25 cm of each core, where eutrophication since the early 1960s resulted in the deposition of a dark, organic sediment matrix. 2. The age‐depth model of previously dated cores was transferred by precise intra‐basin correlation of distinct marker layers, thus providing a reliable chronology for the 20 detrital layers covering the time period 1965–2006. 3. All detrital layers are related to regional floods as recorded by short‐term lake level rises and peaks in discharge of the River Toce, the main tributary to the Pallanza Basin. 4. Detailed intra‐basin correlation of detrital layers allows us to distinguish river run‐off events from local erosion, as well as evaluate the relation between detrital layer thickness and flood amplitude. Massive clay accumulation on top of the thickest detrital layers might have affected lake ecology by attenuating light and influencing metabolic activity. 5. In the clastic‐dominated sediments deposited before 1965, detrital layers are less clearly discernible because of the predominantly clastic pelagic sediment matrix. The combination of thin‐section and μ‐XRF techniques, however, shows the potential to establish even longer flood layer time series from Lago Maggiore sediments.