River basin management, Bulgarian case study     

Strahil Gerassimov 《Physics and Chemistry of the Earth》2008,33(5):395-402

The master plans for the management of river basins have been elaborated. The territory of Bulgaria is divided into four main hydrological zones - Danube, Black Sea, East and West Mediterranean hydrological zones. The rivers from Danube zone discharged directly to the Danube river, the North boundary of the country. All rivers from the eastern part of Bulgaria discharged directly to the Black Sea. The rivers from East and West Mediterranean hydrological zones discharged to Mediterranean Sea after flowing trough Greece and/or Turkey. The main river basins in Bulgaria were subjects to the evaluation of master plans.During the elaboration of the master plans the following elements have been investigated:

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Demographical characteristics of the stakeholders in the river basin.

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Economical overview of the stakeholders.

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Estimation of surface water availabilities and resources; Water quantity.

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Groundwater overview and estimation of available groundwater resources.

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Water quality of surface and ground water; sediment load.

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Estimation of water use for domestic, irrational, agricultural and industrial water supply.

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Ecosystems in the river basin; Tundja river basin ecosystems.

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Master Plans elaboration for 2010.

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Water balance calculations for 1998 and 2010.

The aim of this paper is to present an overview of Tundja river basin management. Tundja is one of the biggest tributaries of Mariza river and it is join it in the territory of Turkey. The basin belongs to the East Mediterranean hydrological zone. The hydrological investigations and estimations of natural river flow along the main river body and it’s tributaries will be discussed in details. The calculations concern 1961-2004 study period. Long-term assessment has been performed. The characteristics of the monthly, annual, minimum and maximum river discharges have been obtained.  相似文献   

Modification of the Sm–Nd isotopic system in garnet induced by retrogressive fluids          下载免费PDF全文

Shi‐Chao An  Shu‐Guang Li  Zhen Liu 《Journal of Metamorphic Geology》2018,36(8):1039-1048

Garnet, as a major constitutive mineral of eclogite, is important for Sm–Nd dating of eclogite due to its high Sm/Nd ratio and its stability during retrogression. However, a comprehensive study of the petrography, mineral chemistry, garnet water content, and Sm–Nd isotopic composition of eclogites from the Bixiling massif, Central Dabie Zone (CDZ), reveals significant modification of the Sm–Nd isotopic system in garnet as a result of retrogression. This problem constitutes a challenge for Sm–Nd dating of the Bixiling eclogites, with the Sm–Nd isochron ages of 218 ± 4 to 210 ± 9 Ma reported in the literature being younger than 226 ± 3 Ma, which is the generally accepted peak metamorphic age of the CDZ. Petrographic analysis reveals heterogeneity in colour within single fractured garnet grains. There are light‐pink garnet (Grt‐P) and red garnet (Grt‐R) types that possess distinct chemical compositions. Compared to Grt‐P, Grt‐R has higher Fe and andradrite contents but lower Al and grossular contents. Grt‐P also has lower water contents (15–35 ppm) than Grt‐R (34–65 ppm), which, together with the spatial association between Grt‐R and fractures, suggests that the colour change is related to fluid alteration. Grt‐P is an ultra‐high‐pressure (UHP) mineral, and Grt‐R is the product of the interaction between Grt‐P and a fluid during retrogression. Moreover, Grt‐R features lower Sm and Nd contents but higher Sm/Nd ratios than Grt‐P. The Sm–Nd isochrons defined by UHP minerals (Grt‐P+Omp+Rt or Grt‐P+Cpx+WR) from three eclogite samples yield consistent ages of 226.0 ± 3.8 Ma, 225.0 ± 3.9 Ma and 226.2 ± 6.9 Ma, which are identical to the peak metamorphic age of 226 ± 3 Ma for the CDZ. The retrogressed garnet (i.e., Grt‐R), omphacite and rutile, together define a pseudoisochron with younger ages of 218.9 ± 5.9 to 202.8 ± 4.8 Ma, which are geologically meaningless. The increase in the Sm/Nd ratio with constant or lower ¹⁴³Nd/¹⁴⁴Nd ratios during the transformation of Grt‐P to Grt‐R was probably the cause of these younger ages.  相似文献   

北极中央区经向水汽输送的主要通道     

徐道欢  杜凌  马靖凯  史荒原 《海洋学报(英文版)》2020,42(5):55-64

Atmospheric moisture transport plays an important role in latent heat release and hydrologic interactions in the Arctic. In recent years, with the rapid decline in sea ice, this transport has changed. Here, we calculated the vertically integrated atmospheric moisture meridional transport(AMTv) from two global reanalysis datasets, from1979–2015, and found moisture pathways into the central Arctic. Four stable pathways showed an occurrence frequency greater than 70%, and these pathways exhibited a perennial seasonal pattern in the atmosphere above the Laptev Sea Pathway(LSP), Canadian Arctic Archipelago Pathway(CAAP), both sides of the Greenland plateau. Another seasonal pathway appeared above the east of the Chukchi Sea(CSP) during the melting/freezing months(March to September). Through these pathways, AMTv contributed a total moisture exchange of60%–80%—averaged over a 75°N circle—and focused on the low troposphere. Transports across the LSP, CSP and CAAP pathways likely create an enclosed moisture route. Meridional moisture fluxes are intensified in the Pacific sector of Arctic(PSA), especially during melting/freezing months. AMTv interannual variabilities are illustrated mainly in the Laptev Sea and the east Greenland pathway. Results indicate that accompanying a tendency for a stronger Beaufort Sea High in this sea level pressure field, AMTv through PSA pathways, switched from output to input, and approximately 960 km~3 of equivalent liquid water was transferred into the central Arctic during each decade. The detrended AMTv increment is highly correlated with the rapid decline of old ice areas(correlation coefficient is –0.78) for their synchronous fluctuations in the 1980 s and the last decade.  相似文献   

江门地区初春大雾的预报预警业务系统   总被引：2，自引：1，他引：1  

梁敏妍  林卓宏  黄晓东  张贤坤  袁锡沛  胡丽华 《广东气象》2009,31(3):13-15

介绍江门地区大雾天气分型预报业务系统。该系统采用Delphi语言编写程序、应用Access作为数据库进行开发,并采用人机交互方式,简化了预报流程,减少工作量,为及时、准确发布大雾预报和预警信息提供依据。该系统通过自动读取Micaps实时数据,以人工判断锋面、倒槽、切变线等有利于春季大雾的天气形势为辅助,对江门地区初春大雾天气做出客观预报,并对预报结果进行自动检验。  相似文献   

华东极端高温气候特征及成因分析     

史军  丁一汇  崔林丽 《大气科学》2009,33(1)

基于华东气象站点1960～2005年逐日最高地面气温和同期西太平洋副高环流指数、赤道太平洋海温和登陆华东及我国的台风个数,分析了华东极端高温日数和高温日平均最高气温的时空动态变化特征及高温成因。结果表明：华东每年高温日数和高温日平均最高气温表现出较大的时间动态变化和空间地域差异。在过去45年间,华东高温日数发生了多-少-多的年代际变化,高温日平均最高气温发生了高-低-高的年代际变化。高温日数在华东中南及西南部较多,而在华东东部沿海和北部较少。高温日平均最高气温在华东中西部的浙江、安徽和江西大部分地区较高。高温日数和高温日平均最高气温在不同地区表现出不同类型的跃变和跃变时间。在华东南部一些地区,高温日数与夏季西太平洋副高面积和强度指数、上年下半年Niño4区海温和当年登陆我国的台风个数呈显著正相关。城市化也增加了华东高温事件的发生。  相似文献   

深层地温变化规律及在汛期气候预测中的应用   总被引：2，自引：0，他引：2  

张红英  张磊  杨建民  李鸿飞  吴素芬 《山西气象》2009,(1):25-27

利用1980年以来不同深度地温资料,研究分析历年的月、季、年度变化特征。并统计分析了地温与汛期降水和气温的相关关系,选用显著相关因子建立汛期总降水量、汛期平均气温、各月降水量及各月平均气温的最优子集回归方程。经检验,不仅其历史拟合率比较高,而且对2002年-2008年的试预报也取得了较好的效果。  相似文献   

西藏工布江达县沙让斑岩钼矿床辉钼矿铼-锇同位素年龄及其地质意义   总被引：33，自引：3，他引：30  

唐菊兴  陈毓川  王登红  王成辉  许远平  屈文俊  黄卫  黄勇 《地质学报》2009,83(5):698-704

沙让钼矿是念青唐古拉地区扎雪—亚贵拉成矿带的重要矿床,是西藏第一个达详查程度的独立钼矿,初步的勘查成果表明,钼资源量已经达到大型规模。为了查明念青唐古拉成矿带是否存在主碰撞期的大规模成矿作用,对沙让亚贵拉洞中拉矿集区沙让斑岩钼矿的7件辉钼矿样品进行了ReOs同位素分析,辉钼矿187Re的含量22.75~46.66（μg/g）,187Os的含量为19.98~40.32（ng/g）,辉钼矿的模式年龄分布在51.57~52.69Ma的范围内,模式年龄较为一致,所获ReOs等时线年龄为51±1.0Ma（MSWD=0.55）。该成矿年龄对应于冈底斯带主碰撞期岩浆岩底侵作用事件（介于47.0～52.5Ma之间（大约50Ma的始新世)）,也与形成林子宗群帕那组43.93～53.52 Ma的火山事件一致,由此表明,冈底斯构造岩浆带存在主碰撞期的大规模成矿,沙让花岗斑岩型钼矿形成于始新世早期,而分布于沙让花岗斑岩外4km范围内的矽卡岩型热液脉型铅锌铜银（Mo）多金属矿可能也属该时期成矿的产物。  相似文献   

重庆城区近百余年旱涝变化   总被引：6，自引：0，他引：6  

李永华  高阳华  唐云辉 《高原气象》2008,27(1):162-168

用Z指数作为旱涝等级标准,利用重庆城区百余年降水量资料,分析了历年及四季旱涝出现的频率,采用趋势分析、最大熵谱分析以及小波分析方法,研究了重庆城区年及四季旱涝的变化特征。结果表明:重庆城区年及四季干旱和洪涝发生频率均在25%以上,重庆旱涝灾害较频繁;多项式拟合和周期分析表明,城区年及四季旱涝具有阶段性变化特征,某些阶段年际变化特征也很显著,总体而言,年及夏季旱涝的年代际变化特征较明显,其它三个季节则是年际变化特征较明显。近几年的年旱涝变化处于偏涝阶段;而近几年夏季的旱涝变化,从年代际尺度来看,目前处在偏旱阶段,出现干旱的可能性较大;而其它三季则处于偏涝阶段。  相似文献   

基于相关机延迟测量法的VLBI时频信号光纤传输试验     

裴鑫  陈卯蒸  李健  闫浩 《天文研究与技术》2015,(3)

时频参考信号的传输距离远,环境温度变化造成信号延迟波动较大,精度要求极高的毫米波段VLBI观测需要对传输延迟进行精确的测量与补偿。根据相关机延迟测量法对VLBI时频信号光纤传输中的信号延迟进行了测量试验,采用高性能相关机直接测量往返信号的相位差获得信号的传输延迟,测试结果表明该方法能达到亚皮秒级传输延迟测量精度,系统稳定、可靠。  相似文献   

中国西北东部汛期降水对青藏高原东部春季感热在准3a周期上的响应   总被引：3，自引：0，他引：3  

李潇  李栋梁  王颖 《气象学报》2015,73(4):737-748

利用1960—2010年中国西北东部地区39个气象站的逐日降水资料和NCEP/NCAR月平均地表感热通量再分析资料以及大气环流各要素场资料,通过多锥度-奇异值分解(MTM-SVD)等方法,分析了中国西北东部汛期降水、青藏高原东部春季感热的周期振荡特征以及它们在准周期循环上的协同耦合关系。结果表明,感热与降水均存在显著的准3 a周期,其耦合场在准3 a周期上表现也最为明显。当青藏高原东部春季感热在青藏高原主体上偏强(弱)时,对应中国西北东部汛期降水的异常偏多(少)。该准3 a周期循环上的协同关系在1960—1982年表现最为显著,1983—1990年为调整阶段,90年代之后又逐渐明显。青藏高原东部春季感热对大气环流的持续加热过程影响西北东部汛期降水,且主要体现在8月。  相似文献