柳林泉水化学特征及动态分析   总被引：1，自引：1，他引：0  

裴捍华  梁树雄 《中国岩溶》2005,24(3):232-238

柳林泉由100多个泉点组成,水质类型复杂、水温变化大。本文将其分为五个泉组,分别对各个泉组的水化学、水温及动态特征进行了分析,阐述了它们的分布规律及变化特征;对泉群流量的动态变化进行了相关分析、趋势分析和周期分析。结果表明: 自东向西,泉水水质逐渐变差,水温逐渐增高,泉水动态渐趋稳定。位于三川河南岸的泉点水温低,水质好;北岸的泉点水温高,水质差。泉流量的总体变化趋势呈指数曲线形式衰减,变化周期为16年,主要影响因素是降水入渗、河流渗漏及人工开采。   相似文献   

The Pacific Decadal Oscillation   总被引：60，自引：1，他引：60  

Nathan J. Mantua  Steven R. Hare 《Journal of Oceanography》2002,58(1):35-44

The Pacific Decadal Oscillation (PDO) has been described by some as a long-lived El Niño-like pattern of Pacific climate variability, and by others as a blend of two sometimes independent modes having distinct spatial and temporal characteristics of North Pacific sea surface temperature (SST) variability. A growing body of evidence highlights a strong tendency for PDO impacts in the Southern Hemisphere, with important surface climate anomalies over the mid-latitude South Pacific Ocean, Australia and South America. Several independent studies find evidence for just two full PDO cycles in the past century: “cool” PDO regimes prevailed from 1890–1924 and again from 1947–1976, while “warm” PDO regimes dominated from 1925–1946 and from 1977 through (at least) the mid-1990's. Interdecadal changes in Pacific climate have widespread impacts on natural systems, including water resources in the Americas and many marine fisheries in the North Pacific. Tree-ring and Pacific coral based climate reconstructions suggest that PDO variations—at a range of varying time scales—can be traced back to at least 1600, although there are important differences between different proxy reconstructions. While 20th Century PDO fluctuations were most energetic in two general periodicities—one from 15-to-25 years, and the other from 50-to-70 years—the mechanisms causing PDO variability remain unclear. To date, there is little in the way of observational evidence to support a mid-latitude coupled air-sea interaction for PDO, though there are several well-understood mechanisms that promote multi-year persistence in North Pacific upper ocean temperature anomalies.  相似文献   

What determines the institutional performance of environmental regimes?: A case study of the Mediterranean Action Plan     

Sofia Frantzi   《Marine Policy》2008,32(4):618-629

Although there is fierce debate about how best to evaluate the effectiveness of international regimes, most writers regard institutional effectiveness as the best measure. This article examines the institutional effectiveness of one regime—the Barcelona Convention (or the Mediterranean Action Plan)—where there are sharply contrasting views of its institutional effectiveness. The study finds that the regime was indeed successful when created, but its contemporary institutional performance is inadequate. The article demonstrates that there is no simple answer as to whether a regime is effective; instead, in most cases it depends on the specific criteria each approach employs.  相似文献   

REGIME MORPHOLOGY OF EQUILIBRIUM ALLUVIAL CHANNELS     

Panayiotis DIPLAS 《国际泥沙研究》1999,(2)

IINTRODUCTIONThequestfordeterminingthedesigncharacteristicsofregimechannelshasbeengoingonforalongtime.Peoplehavebeenexcavatingnewormodifyingexistingchannelstousethemforirrigation,watersupply,navigation,floodcontrolandotherpurposes.Recently,archeologistsdiscoveredwhatiscurrentlybelievedtobetheoldestman(madecanalsystem.ItwasfoundintheareawhereMesopotamiausedtoexistanditisdatedbacktoabollt4,000BC.Ifachanne]isnotproperlydesigned,erosionofitsbanksordepositionofsedimentwithinitscross-sectionw…  相似文献   

Management of karst aquifers in Serbia for water supply     

Zoran Stevanović  Igor Jemcov  Saša Milanović 《Environmental Geology》2007,51(5):743-748

Karst aquifers represent one of the main sources of water supply in Serbia. Wide distributions of karstic areas, abundant reserves, and excellent quality of karst groundwater have been the reasons for its extensive use in water supply systems throughout the country. In Serbia, 70 karstic sources have been tapped for centralized water supply, with the assessed minimal capacity exceeding 4.5 m³/s. Most of the large cities of Eastern and Western Serbia currently use karst groundwater for water supply; however, due to unstable flow regime when only natural springflow is tapped, numerous problems arise during the recession period (summer–autumn). During the last two decades, after favorable conditions had been confirmed through hydrogeological survey and feasibility studies, several newly constructed systems for artificial control of karst aquifers (mostly in Eastern Serbia) resulted in significantly improved water supply.  相似文献   

对大灰厂台形变异常的再认识     

杨炳顺 《内陆地震》1992,(3)

按照文献[1]的思路和方法,利用历史观测数据,通过建立大灰厂台形变资料动态预估方程,对唐山地震前后两次形变异常重新作了分析。结果表明,1975年前后和1980年前后的两次形变异常情况类似,且具有较好的预估关系,其它年份的资料也有重复的特点。其特点与地震孕育引起的地壳形变关系不大。因此把1975年形变异常作为唐山地震的前兆信息依据不足,两次异常都是由于干扰因素影响所致。  相似文献   

Consequences of regime shifts for marine food webs   总被引：1，自引：0，他引：1  

Jürgen Alheit 《International Journal of Earth Sciences》2009,98(2):261-268

Climate-mediated ecological regime shifts can re-structure entire ecosystems from primary producers to top predators. As a consequence, major trophodynamic pathways change with the altered mix of dominating species. Four cases of ecosystem regime shifts forced by climate variability are presented (North Sea, central Baltic Sea, central North Pacific and Humboldt Current ecosystems) and the effect on food chains is elucidated. Different types of trophodynamic control mechanisms set in motion through the impact of climate variability and the potential impact of regime shifts on biogeochemical cycles are discussed.  相似文献   

Thermal waters of the Hornonitrianska kotlina depression and their utilization     

O. Franko  J. Franko 《Environmental Geology》2000,39(5):501-515

 Slovakia has many areas rich in thermal waters one of which is the Hornonitrianska kotlina depression. At four localities three types of waters are found. The first belongs to the Ca–Mg–HCO₃ type with T.D.S. 0.7 g/l, the second to the Ca–Mg–SO₄ type with T.D.S. 1.37–2.01 g/l and the third to the Ca–Mg–SO₄–HCO₃ type with T.D.S. 0.97 g/l. Discharge at individual localities varies up to 30 l/s and temperatures of water reach 32.5–66.6  °C. The waters are predominantly used for healing, rehabilitation purposes, recreation and heating. Received: 8 March 1999 · Accepted: 7 June 1999  相似文献   

The measurement of watertable levels in structured clay soils by means of open auger holes     

Adrian C. Armstrong 《地球表面变化过程与地形》1983,8(2):183-187

In structured clay soils, water levels in open auger holes (dipwells) respond to water movement through macropores and may mask the existence of drier zones either at depth or within peds. Variability between replicated dipwells expresses the small scale variation in the soil, and statements about soil water regimes should be made in statistical terms. Suitably replicated dipwells give sufficiently precise measurements of mean watertable position for studies of soil water regimes.  相似文献