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1.
干旱是造成喀斯特地区损失最为严重的自然灾害之一。以我国西南喀斯特集中分布区域为研究区,基于研究区33个气象站1960-2016年的逐日降水数据,利用PA指数和Mann-Kendall检验方法分析了1960-2016年干旱时空分布特征。结果表明:研究区降雨量有减少趋势,PA指数呈减小趋势,干旱呈增强趋势,2011年PA均值最小;研究区各季干旱强度均呈上升趋势,且冬旱强度最强、发生干旱年份最多,秋旱次之,春旱和夏旱强度较弱、发生干旱的年份较少;年际干旱频次高发区集中于研究区南部、西北部及中东部地区;仅秋、冬季西部和东南部部分地区出现特旱且频次低,秋、冬季发生重旱、中旱和轻旱的频次高,春、夏季较低;春季干旱频次西高东低,夏季中部高,秋季南高北低,冬季西高东低;干旱与地形因子显著相关,重、特旱易发生在高陡地区。综上所述,研究区干旱有增强趋势且秋、冬季趋势较强,空间上呈现明显的季节性和区域性,且与地形因子显著相关。 相似文献
2.
基于近 100 多年来的均一化气温数据,从趋势变化、季节差异、突变特征、周期振荡方面诊断香港和澳门的气温变化特征。结果表明: ( 1) 港澳年平均气温和不同季节气温在近 100 多年来均呈显著增加趋势,其中春冬季节增加速率较大,夏秋季节增加速率较小。除秋冬季节外,其它时间上的香港气温增加趋势均大于澳门。港澳夏冬季节气温差异均呈减少趋势。( 2) 香港和澳门年平均气温分别于 1963 年和 1991 年发生突变。在季节上,港澳地区的气温突变均在秋季发生年份最晚,冬季次之,夏季再次之,春季最早。( 3) 香港年平均气温分别存在 3 a、7 a、15 a 和 30 a、60 a 和 120 a 的周期振荡特征。澳门年平均气温存在 3 a、6 a、12 a、24 a 和 48 a 左右的周期振荡特征。( 4) ENSO 与香港年平均气温在 4 a 以下尺度以同位相或提前 1 a 位相变化关系为主,在 4 a 以上尺度以同位相变化关系为主。ENSO 与澳门年平均气温在不同时频域均以同位相变化关系为主。 相似文献
3.
To help in clarifying the relationship between the time lag and attenuation of nitrogen (N) loads generated in agricultural catchments, long-term trends in activities that generate N loads and in environmental N loads were estimated in catchments in Japan and Korea dominated by non-point-source emissions. Our approach used statistical data and geographical information system software to analyze pollutant loads. The method was successful in both countries because of the availability of well-developed statistics, geographical information, and weather and water quality monitoring systems, and the accumulation of research data concerning the generation of N loads and the fate of N in soils. Comparison of environmental loads with the loads observed in river water at the outlet of each catchment revealed that: (1) the effect of changes in the environmental load in a catchment appeared almost immediately in the river water quality in Korea, but did not appear clearly even 10 years later in Japan; and (2) the strength of the attenuation appeared to be much lower in Korea than in Japan. These findings suggest that regional characteristics play important roles in the sensitivity of water quality to load-generating activities. 相似文献
4.
主要研究了东亚冬、夏季风不同长度的年代际振荡特点及其对夏季百太平洋副高和贵州降水的影响。分析表明:冬季风与赤道东太平洋海温存在着大体一致的约30年左右年代际振荡,70年代末发生突变;夏季风与青藏高原位势高度存在着大体一致的约20年左右的年代际振荡,60年代末和80年代末发生突变。由于冬、夏季风不同长度的年代际振荡,它们同位相增阶段夏季西太平洋副高位置容易偏北,贵州降水偏少;它们同位相减弱阶段夏季西太平洋副高易偏南,贵州降水偏多;但它们反位相组合时夏季西太平洋副高位置偏北、偏南的机会及贵州降水偏少、偏多几乎均等。 相似文献
5.
湖北省水资源压力与经济发展脱钩的时空演化 总被引:1,自引:0,他引:1
以水资源压力指数为指标,采用Mann-Kendall检验分析2011—2020年湖北省水资源压力的变化趋势及突变点,并利用Tapio脱钩模型揭示水资源压力与经济发展脱钩关系的时空演化规律。结果表明:除2016年与2020年外,湖北省水资源压力整体偏大,空间上呈现鄂西最大、鄂东居中、鄂中最小的态势;湖北省水资源压力整体呈下降趋势,突变点在2012年与2019年前后;全省水资源压力与经济发展之间的脱钩关系因水文特征波动,在时序上从2012—2016年的强脱钩发展到2017—2019年的扩张负脱钩,再到2020年的衰退脱钩;因自然气候及发展战略差异,在空间上各区域的平均脱钩率从2012—2016年鄂西最低、鄂东居中、鄂中最高,发展到2017—2019年鄂东最低、鄂中居中、鄂西最高,2020年趋于平衡。为此,湖北省未来应重视制定基于水文波动的水资源压力变化应对预案,并对鄂东和鄂中地区实施产业结构调整。 相似文献
6.
《Journal of Great Lakes research》2005,31(4):492-508
Restoration of self-sustaining populations of lake trout is underway in all of the Great Lakes and Lake Champlain, but restoration has only been achieved in Lake Superior and in Parry Sound, Lake Huron. We evaluated progress toward restoration by comparing spawning habitat availability, spawner abundance, egg and fry density, and egg survival in Parry Sound in Lake Huron, in Lake Michigan, and in Lake Champlain in 2000–2003. Divers surveyed and assessed abundance of spawners at 5 to 15 sites in each lake. Spawning adults were sampled using standardized gill nets, eggs were sampled using egg bags, and fry were sampled using emergent fry traps and egg bags left on spawning reefs overwinter. Spawning habitat was abundant in each lake. Adult lake trout abundance was low in Lake Michigan and Parry Sound, and very high at one site in Lake Champlain. Egg deposition was lowest in Lake Michigan (0.4–154.5 eggs•m−2, median = 1.7), intermediate in Parry Sound (39–1,027 eggs•m−2, median = 278), and highest in Lake Champlain (0.001–9,623 eggs•m−2, median = 652). Fry collections in fry traps followed the same trend: no fry in Lake Michigan, 0.005–0.06 fry•trap−1 day−1 in Parry Sound, and 0.08–3.6 fry•trap−1 in Lake Champlain. Egg survival to hatch in overwinter egg bags was similar in Lake Michigan (7.6%) and Parry Sound (2.3–8.9%) in 2001–02, and varied in Lake Champlain (0.4–1.1% in 2001–02, and 1.8–18.2 in 2002–03). Lake trout restoration appears unlikely in northern Lake Michigan at current adult densities, and failure of restoration in Lake Champlain suggests that there are sources of high mortality that occur after fry emergence. 相似文献
7.
利用云南中北部地区6个气象站点1954-2012年资料,选用标准化指数计算各站点干旱指数,统计分析了云南中北部地区1954-2012年发生干旱的年份及发生不同干旱的频次。研究结果表明:1临沧站出现干旱的年份较多,但蒙自站出现极端干旱的年份明显高于其他5站;2各站点在不同季节出现干旱的频次不同,其中腾冲在春季相比于其他5站,发生干旱的频率较高35.6%,临沧站在夏季和冬季发生干旱频率均较大,分别为35.6%和37.9%,蒙自站在秋季发生干旱频率最大,为34.8%。研究成果可为云南中北部地区的干旱评价分析和水资源保护提供一定的参考价值。 相似文献
8.
《Journal of Great Lakes research》2014,40(3):618-639
We describe recent trends in phytoplankton composition and abundance in the Laurentian Great Lakes using synoptic spring (April) and summer (August) sampling events from 2001 through 2011, a period of rapid shifts in pelagic food webs and water quality. Data analysis identified qualitative and quantitative changes in algal densities, biovolume, and taxonomic composition of assemblages. Since 2001, Lake Superior has changed subtly with an increase in small-celled blue-green algae in spring and a recent decline in summer centric diatoms, possibly a result of lake warming and changes in water quality. Spring phytoplankton declines mainly attributed to diatoms occurred in Lakes Huron and Michigan, a probable result of invasions by non-native dreissenids that have reduced pelagic nutrients and selectively consumed certain taxa. The decline in Lake Huron's spring phytoplankton biovolume was earlier and more severe than that in Lake Michigan, despite a faster and more abundant dreissenid invasion in Lake Michigan. Lake Erie's central basin had a notable increase in spring centric diatoms (largely Aulacoseira), while the whole of Lake Erie shows a summer increase in cyanobacteria, complementing that found in coastal regions. The composition of Lake Ontario's species assemblage shifted, but little overall change in algal abundance was observed with the exception of higher summer densities of cyanophytes. Additional mechanisms for shifts in the pelagic primary producers are described or hypothesized in the context of concurrent shifts in water quality and invertebrate populations. Tracking these trends and explaining driving factors will be critical to the management of lake conditions. 相似文献
9.
Alfred M. Beeton 《Journal of Great Lakes research》1984,10(2):106-113
Most of the large lakes lie in glacial scour basins in the northern hemisphere. These lakes are closely similar in physicochemical characteristics and in their biota. Most of the other large lakes are tectonic in origin and they differ greatly among themselves and from other lakes since they occur in a diversity of terrestrial environments under a broad range of climatic conditions. Large lakes have a great diversity of habitats resulting in great species diversity and endemism in ancient lakes. The pronounced horizontal gradients in physicochemical conditions in large lakes contribute to the diversity of habitats. Conditions found in Lakes Michigan and Skadar are examples. 相似文献
10.
关中盆地降水量变化趋势的Mann-Kendall分析 总被引:3,自引:0,他引:3
采用关中盆地1959—2006年的气象资料,应用Mann-Kendall检验方法分析了关中盆地降水量的年季变化趋势和突变情况。结果表明:关中盆地降水量总体呈减少趋势;春、秋季节降水量呈下降趋势,夏、冬两季降水量均呈上升趋势;年降水量的突变发生在1992年,之后降水量总体开始下降,到21世纪依旧呈减少趋势;春季降水量在1994年发生突变,降水量明显下降;夏季降水量突变于1978年,之后降水量开始上升;秋季突变于1973年,之后降水量转变为下降趋势;冬季降水量总体呈增加趋势。 相似文献
11.
溢流面板堆石坝应遵循的若干设计准则与施工要求 总被引:1,自引:1,他引:0
通过研究和总结国内已建溢流混凝土面板堆石坝工程的建设经验,就坝身溢洪道的平面布置、坝料的选择与变形控制、溢洪道泄槽结构设计、地基排水措施与渗流控制等方面提出了在设计中应遵循的若干准则以及施工过程中应注意的事项;除此之外,对已建工程的设计和施工经验也进行了相关介绍。 相似文献
12.
Signs of increasing oligotrophication have been apparent in the open waters of both Lake Huron and Lake Michigan in recent years. Spring total phosphorus (TP) and the relative percentage of particulate phosphorus have declined in both lakes; spring TP concentrations in Lake Huron are now slightly lower than those in Lake Superior, while those in Lake Michigan are higher by only about 1 μg P/L. Furthermore, spring soluble silica concentrations have increased significantly in both lakes, consistent with decreases in productivity. Transparencies in Lakes Huron and Michigan have increased, and in most regions are currently roughly equivalent to those seen in Lake Superior. Seasonality of chlorophyll, as estimated by SeaWiFS satellite imagery, has been dramatically reduced in Lake Huron and Lake Michigan, with the spring bloom largely absent from both lakes and instead a seasonal maximum occurring in autumn, as is the case in Lake Superior. As of 2006, the loss of cladocerans and the increased importance of calanoids, in particular Limnocalanus, have resulted in crustacean zooplankton communities in Lake Huron and Lake Michigan closely resembling that in Lake Superior in size and structure. Decreases in Diporeia in offshore waters have resulted in abundances of non-dreissenid benthos communities in these lakes that approach those of Lake Superior. These changes have resulted in a distinct convergence of the trophic state and lower food web in the three lakes, with Lake Huron more oligotrophic than Lake Superior by some measures. 相似文献
13.
龙滩水电站工程在西部大开发战略中的地位和作用 总被引:1,自引:1,他引:0
龙滩水电站工程是国家实施西部大开发和“西电东送”的重要标志性工程,是红水河上最闪亮的一颗明珠。它的开发建设,对于推进“西电东送”,促进全国联网,在全国范围内实现能源资源的优化配置,对于满足广东和广西地区电力增长的需要,优化华南地区电源结构和电网结构,减轻红水河下游及西江两岸地区的洪水威胁,促进广西和贵州少数民族地区经济和社会的全面发展,具有巨大的作用。 相似文献
14.
积雪时空变化作为表征增暖背景下冰冻圈的重要指标之一,在全球气候变化科学研究中具有重要作用。采用1961—2016年中国545个气象观测站的积雪日数、积雪深度日值数据和3个海气环流因子,通过多种统计方法,诊断中国积雪的时空演变特征及积雪与海气环流因子的时频相关性。结果表明:(1)1961—2016年中国积雪日数和深度在波动中呈缓慢增加趋势,且具有明显的年代分段变化特征。中国积雪日数和深度均具有30a和50a的周期振荡特征,其中积雪深度在1969年发生突变。(2)1961—2016年中国气候态积雪日数和深度具有明显的南低北高的空间分异特征,尤其是东北、内蒙古东部和新疆北部的积雪较多分布。中国积雪多寡具有明显的年代和区域分异特征。(3)在变化趋势上,1961—2016年中国积雪日数在东北和内蒙古东部趋于增多;而积雪深度除上述区域外,在华北、西北和江淮东部也趋于增多。在波动特征上,中国积雪日数和深度在华南南部、云南和四川东部波动较大,其它地区波动相对较小。(4)与海气因子时频关联性上,中国积雪与不同海气因子关联性不同,且与同一因子在不同时段的关联性也有一定差异。 相似文献
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16.
根据长江水资源特点,对长江流域水资源配置的理论方法、配置重点、配置管理等方面的几个关键问题进行了初步的探讨。长江流域具有水资源总量相对丰富但时空分布不均的特点,局部地区存在季节性缺水。长江流域水资源配置需要考虑水量分配的时间过程,强调水资源量与质的统一管理,以及水资源和社会、经济、生态环境的联合优化;根据新时期实施最严格水资源管理制度的要求,对重点地区、重点时段的水资源配置进行研究,并结合最严格水资源管理实现水资源的合理配置。 相似文献
17.
Abstract There is increasing recognition of the problems facing China in meeting the growing water demand in the Yellow River basin, the “cradle of Chinese Civilization” and a critically important agricultural and industrial region. Meaningful debate on the range and relative costs of options available to policy-makers in addressing the problem depend fundamentally on an accurate understanding of basin water resources. Unfortunately, the ability of outsiders to participate in the de bate and for Chinese, with their long history of water management, to contribute to similar discussions elsewhere in the world is hindered to some extent by a lack of understanding of differences in water accounting systems and concepts. This paper attempts to address this problem by describing the water accounting system used in the Yellow River basin and elsewhere in China. The paper shows that the primary difference between water accounting methodologies in the Yellow River and those typically applied elsewhere is related to supply accounting in general and groundwater accounting in particular. Although not currently included in its water accounting system, Chinese concepts of environmental water use, when included, will also differ substantially from those familiar to outside researchers. In terms of actual Yellow River balances, the paper highlights the apparent declining trend in basin rainfall and runoff and the dramatic growth in industrial and domestic water use. Together declining supply and rising demand will increasingly cause policy-makers to face hard choices in assessing their water planning options. These choices will only become more difficult as managers in the Yellow River, as elsewhere in the world, try to incorporate ecological needs in the water accounting equation. 相似文献
18.
摘要:为了切实贯彻国家有关安全生产的法律、法规,实现安全生产管理目标,保证参建人员的身体健康和工程安全,监理工程师应做好安全生产监督管理的控制工作。本文主要阐述了作为现场监理工程师如何做好水利在建工程的安全生产监督管理工作。 相似文献
19.
棘洪滩水库浮游藻类变化及富营养化防治 总被引:2,自引:0,他引:2
详细分析了2004~2006年度棘洪滩水库浮游藻类的细胞密度及种群结构变化。2004年进水口与放水口藻类细胞密度年均值分别为3.892×106/L和2.269×106/L,冬季以硅藻为主,春季以隐藻、金藻为主,夏、秋季以蓝藻为主。2005年进水口与放水口藻类细胞密度年均值分别为6.654×106/L和5.903×106/L,冬、春季以硅藻、隐藻为主,夏季以绿藻为主,秋季则以蓝藻为主。2006年进水口与放水口藻类细胞密度年均值分别为3.001×106/L和3.687×106/L,夏末至秋季绿藻占优势,代替了先前在此阶段占优势的蓝藻,其他季节多以硅藻为主,隐藻和金藻分别在冬季和春季占有一定比例,说明2006年的水质状况较2004年、2005年有所改善。棘洪滩水库藻类峰值出现在夏末和秋季,此阶段水库的水质呈中富营养状态,其他月份为中营养或贫营养状态。Shannon-weaver多样性指数显示,目前水库的水质总体呈中度污染。入库的源水质量对水库水质影响很大,控制引入的源水质量并采取相应的生物防治措施可有效避免水库发生富营养化。 相似文献
20.
近年来,鄂州市农药、化肥的不合理施用以及畜禽粪便的不适当处理,造成农业面源污染日益严重。以统计数据为基础,结合GIS技术,对鄂州市2015、2020、2030年农业面源污染中的氮、磷入河量进行分析。结果表明,农药、化肥源中的总氮入河量由2015年的2850. 40 t下降到到2020年的2382. 02 t再到2030年的1590. 74 t,总磷入河量由2015年的1305. 59 t下降到2020年的850. 78 t到2030年的503. 84 t。畜禽养殖源中的总氮入河量由2015年的618. 17 t下降到2020年的313. 17 t再到2030年的604. 37 t,总磷入河量由2015年的351. 71 t下降到2020年的45. 59t再到2030年的145. 75 t。空间上,葛华新城、涂家垴镇的化肥、农药污染削减明显,主城区、葛华新城、东沟镇、沼山镇、杨叶镇的畜禽养殖污染削减明显。畜禽养殖源2030年比2020年污染物入河量增加,这是因为在2020年以前,非规模养殖场关停,规模畜禽养殖逐年增加。利用GIS对污染物入河量的展布,从空间上,能够清晰地反映不同水平年鄂州市污染物入河量的效果,为鄂州市有针对性的农业面源污染的防治提供依据。 相似文献