三江源区大气可降水量时空特征及其与降水关系     

强安丰  汪妮  解建仓  姜仁贵 《干旱气象》2019,37(1):22-30

利用1979—2016年欧洲中期天气预报中心(ECMWF) ERA-Interim (1°×1°)再分析资料中的经、纬向水汽通量和大气可降水量(precipitation water vapor,PWV)数据,采用相关性分析、趋势分析法、累积距平、IDW等方法,分析三江源地区PWV与水汽通量的时空分布特征、降水转化率(precipitati-on conversion efficiency,PCE)变化规律。结果表明:过去的38 a,经、纬向多年平均水汽通量分别为50. 2、196. 7 kg·m-1·s^(-1),纬向水汽通量气候倾向率比经向大。南边界为纬向主要水汽输入边界,东边界为经向主要水汽输出边界,纬向水汽输送大于经向输送。多年平均PWV为1998. 3 mm,近38 aPWV呈现微弱增加趋势,1979—1997年,PWV呈下降趋势,1998年后PWV呈增加趋势,同期降水也在增加,说明该时段三江源地区气候转湿。PWV与水汽通量的年际变化趋势和转折年相一致。三江源区多年平均PCE为24. 57%,1989年PCE最高,达32. 76%,各季节平均PCE空间分布与年平均PCE分布一致,均表现出南部、东南部高,西部、东北部低的变化特征,各季节PCE大小差异明显,春季多年平均PCE为15. 92%,夏季25. 67%,秋季21. 01%,冬季仅7. 03%。  相似文献   

Assessing the potential of reservoir outflow management to reduce sedimentation using continuous turbidity monitoring and reservoir modelling     

Casey Lee  Guy Foster 《水文研究》2013,27(10):1426-1439

In‐stream sensors are increasingly deployed as part of ambient water quality‐monitoring networks. Temporally dense data from these networks can be used to better understand the transport of constituents through streams, lakes or reservoirs. Data from existing, continuously recording in‐stream flow and water quality monitoring stations were coupled with the two‐dimensional hydrodynamic CE‐QUAL‐W2 model to assess the potential of altered reservoir outflow management to reduce sediment trapping in John Redmond Reservoir, located in east‐central Kansas. Monitoring stations upstream and downstream from the reservoir were used to estimate 5.6 million metric tons of sediment transported to John Redmond Reservoir from 2007 through 2010, 88% of which was trapped within the reservoir. The two‐dimensional model was used to estimate the residence time of 55 equal‐volume releases from the reservoir; sediment trapping for these releases varied from 48% to 97%. Smaller trapping efficiencies were observed when the reservoir was maintained near the normal operating capacity (relative to higher flood pool levels) and when average residence times were relatively short. An idealized, alternative outflow management scenario was constructed, which minimized reservoir elevations and the length of time water was in the reservoir, while continuing to meet downstream flood control end points identified in the reservoir water control manual. The alternative scenario is projected to reduce sediment trapping in the reservoir by approximately 3%, preventing approximately 45 000 metric tons of sediment from being deposited within the reservoir annually. This article presents an approach to quantify the potential of reservoir management using existing in‐stream data; actual management decisions need to consider the effects on other reservoir benefits, such as downstream flood control and aquatic life. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

The role of eddies in solute transport and recovery in rock fractures: Implication for groundwater remediation          下载免费PDF全文

Seung Hyun Lee  In Wook Yeo  Kang‐Kun Lee  Won Sang Lee 《水文研究》2017,31(20):3580-3587

A better understanding of solute transport and retention mechanism in rock fractures has been challenging due to difficulty in their direct observations in microscale rough‐walled fractures. Six representative troughs in a rough‐walled fracture were selected for microscale observations of eddy formation with increasing flow velocity and its effect on spatiotemporal changes of solute concentration. This experimental study was enabled by a microscale visualization technique of micro particle image velocimetry. With increasing flow velocity (Re ≤ 2.86), no eddies were generated, and solutes along the main streamlines transported rapidly, whereas those near the wall moved slowly. A larger amount of solutes remained trapped at all troughs at Re = 2.86 than Re < 1. For Re = 8.57, weak eddies started to be developed at the troughs on the lee side, which little contributed to overall solute flushing in the fracture. Accordingly, a large of amount of water was needed for solute flushing. The flow condition of 1 < Re < 10, before a full development of eddies, was least favourable in terms of time and amount of remediation fluid required to reach a target concentration. After large eddies were fully developed at troughs on the lee side for Re = 17.13, solutes were substantially reduced by eddies with less amount of water. Fully developed eddies were found to enhance solute transport and recovery, as opposed to a general consensus that eddies trap and delay solutes. Direct inflow into troughs on the stoss side also made a great contribution to solute flushing out of the troughs. This study indicates that fully developed eddies or strong inflows at troughs are highly possible to form for Re > 10 and this flow range could be favourable for efficient remediation.  相似文献   

一种可考虑历史洪水的马氏权函数法研究   总被引：1，自引：0，他引：1       下载免费PDF全文

陈元芳 《水科学进展》1994,5(3):174-178

导出了非连序样本下,马氏权函数法(适用于P-Ⅲ型分布)参数估计公式.在不偏性、有效性的标准下,统计试验结果表明,推导的非连序样本下的计算公式是较为有效的,且拓宽了马氏权函数法的使用范围.  相似文献   

船舶气象导航随船验证     

杨良华 《气象》1993,19(9):52-55

通过横流太平洋往返两个航次随船调查，研究了采用气象导航对减少燃油消耗和保证船舶安全、班期等，不但有定的经济效益，而且是一种非常有效的航运管理方法。  相似文献   

聚四氟乙烯平板型气态膜回收淡盐水中氯气          下载免费PDF全文

于伯杉 《盐湖研究》1993,1(4):75-79

本文以离子膜电解氯化钾制取碳酸钾工艺产生的淡盐水为原料,系统地研究了聚四氟乙烯平板型气态膜回收氯过程中膜性能和次氯酸钠水溶液的制备。初步研究表明,次氯酸钠含量大于100g/L,氢氧化钠有效利用率为90％;聚四氟乙烯膜有传质快、对离子截留性能好、使用寿命长等优点,在工业上有较好的应用前景。  相似文献   

Valency Study of Vanadium in Stone Coal Ash of Jiangxi Province     

Xu Guozhen Ge Naie Li Jigui 《中国地质大学学报(英文版)》1990,(1)

Vanadium-bearing stone coal is a new vanadium resource;recovery ofV_2O_5 from the coal has been investigated.It has been found that a satisfactoryextraction of V_2O_5 depends on both the oxidation of V and its reaction with so-dium salt.V in the coal ash of Yushan mainly exists in two oxidation states:98％V(Ⅲ)and2％V(Ⅳ).The distribution of valency of V shows that organicmatter determines V valency at low temperatures,at about470℃,V(Ⅲ)iscompletely oxidized to V(Ⅳ);above500℃,the temperature is the most impor-tant factor for the oxidation of V .At higher temperatures no more V is oxidizedto V(Ⅴ);an equilibrium is established after92％of V is oxidized to V(Ⅴ).The roles of NaCl in the recovery of V_2O_5 from the coal ash were discussed.The best conditions for roasting are temperature750-800℃for1 h.underthe oxidation-chlorination atmosphere.When the ore:NaCl=100:10 by weight,η_roast reaches85.5％.According to the results,a flowsheet for V_2O_5 extrac-tion from coal ash has been proposed.  相似文献   

新疆前兆震群ρ值的研究     

周仕勇  王桂岭 《内陆地震》1990,(4)

研究新疆伊宁——乌鲁木齐和乌什——库尔勒1972年以来发生的49个震群的ρ值表明,ρ<0.55可作为前兆震群的判据指标。分析了ρ<0.55标准下的前兆震群的预测能力,认为,震群序列的ρ值具有一定的预报效能。  相似文献   

农桐间作地热量平衡和水分利用状况研究   总被引：5，自引：0，他引：5  

景元书  刘乃壮 《南京气象学院学报》1995,18(4):560-565

由实测资料系统分析了农桐间作地热量平衡各分量复杂的时空变化特征。结果表明：间作内外蒸发耗热（ＬＥ）仍是主要耗热项，湍流耗热（Ｈ）低于ＬＥ，但高于土壤热通量（Ｑ）；间作地各分量小于对照，但ＬＥ、Ｑ占净辐射（Ｒｎ）比值高于对照；泡桐林带对各分量的影响与间作结构及测点位置有关。然后计算了间作中小麦、棉花水分利用率（ＷＵＥ），其值与作物类型，生长期等因子有关，且间作地高于对照。  相似文献   

珠江三角洲宏观经济发展与震后恢复方案     

黄昭庆  黄贯虹 《华南地震》1995,15(3):75-86

在投入产出综合平衡模型的基础上，在充分考虑珠江三角洲地区资源的条件下，结合该区未来经济发展的战略目标，建立了宏观经济发展的动态递推模型。利用该模型，借助系统优化算法，对珠江三角洲地区宏观经济的发展作出了最优规划，对该区未来的震害提出了最佳的恢复方案。由震害所致间接经济损失的系统分析，是结合原发展规划方案的对投资结构、产业结构作出的动态分析，可作为未来珠江三角洲地区产业的调整、投资、方向的改变，以主  相似文献