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1.
长江中游荆江的水沙通过三口洪道分流入洞庭湖,三口分流是荆江-洞庭湖关系调整的驱动因子,为揭示其变化特征及三峡工程运用的影响,基于大量的原观数据,系统研究了近60年三口分流比的变化过程,提出其显著调整特征及诱发因素,引入径流还原计算方法,量化了三峡水库不同运用方式对三口分流量的影响幅度。结果表明:①特大洪水及重大人类活动等诱发因素作用下,三口分流比出现4~5年持续性减小的趋势调整期,之后进入分流比稳定恢复的平衡调整期;②2003-2014年,三峡水库汛前枯水补偿调度使得三口分流量年均增加8.000亿m3,汛后蓄水使得三口分流量年均减小29.00亿m3,对三口分流综合影响量为年均减少21.00亿m3,占同期三口年均分流量的4.29%。  相似文献   
2.
5.12大地震对国家造成了一次重大的损失,则对地震预报的研究则显得尤为重要。本文认为地震发生的机理是板块挤压破裂学说。在地震动发生前后都会出现一些宏观或微观异常,在地震发生前其微观异常主要表现为电磁波、地壳倾斜、地应力等异常。本方通过对低频电磁波和地倾斜进行测量和研究,可通过数据多台站共享来进行地震预报分析。  相似文献   
3.
目的:运用文献数据挖掘方法分析云南名医吴佩衡含附子处方的用药规律。方法:通过检索《吴佩衡医案》,将含附子的处方录入中医传承辅助平台,构建处方数据库,运用关联规则分析等数据分析方法对药物使用频次、剂量与药物配伍进行分析。结果:纳入164首含附子的处方,其中包含107味药物,频次由高到低依次为:附片、甘草、干姜、肉桂、茯苓、细辛等,附子单次使用剂量10~450 g。频次分析结果显示,排前3位的药物组合为:甘草-附子、附子-干姜、附子-肉桂等;关联规则结果显示,排前3位的药物组合为附子-茯苓,附子-茯苓、干姜,附子-肉桂、干姜,附子-肉桂、干姜、甘草。《吴佩衡医案》中常用处方的核心药物与四逆汤、苓桂术甘汤、赤丸三方具有一定的相似性。结论:吴佩衡应用附子多与温补药干姜、肉桂相伍,强调脾肾阳气双补,重视健运脾阳对恢复人体阳气的重要意义,为辨治各种危急重症提供了借鉴。  相似文献   
4.
Yang  Lin  Yu  Pan  You  Qingmin  Li  Guisheng  Wang  Quanxi 《中国海洋湖沼学报》2022,40(2):712-728
Journal of Oceanology and Limnology - Melosira is one of the most common diatom genera found in freshwater ecosystems. There are many freshwater species of Melosira, of which M. varians is the most...  相似文献   
5.
Future changes in reference evapotranspiration (ET0) are of increasing importance in assessing the potential impacts on hydrology and water resources systems of more pronounced climate change. This study assesses the applicability of the Statistical Downscaling Model (SDSM) in projecting ET0, and investigates the seasonal and spatial patterns of future ET0 based on general circulation models (GCMs) across the Haihe River Basin. The results indicate that SDSM can downscale ET0 well in term of different basin-averaged measures for the HadCM3 and CGCM3 GCMs. HadCM3 has a much superior capability in capturing inter-annual variability compared to CGCM3 and thus is chosen as the sole model to assess the changes in future ET0. There are three homogeneous sub-regions of the Haihe River Basin: Northwest, Northeast and Southeast. Change points are detected at around 2050 and 2080 under the A2 and B2 scenarios, respectively. The Northwest is revealed to have a slight to strong increase in ET0, while the Northeast and the Southeast tend to experience a pattern change from decrease to increase in ET0.
EDITOR M.C. Acreman

ASSOCIATE EDITOR J. Thompson  相似文献   
6.
Six new chrysophycean stomatocysts ornamented with reticulum were illustrated based on SEM observation. They were described following the guidelines of the International Statospore Working Group (ISWG). All samples were collected from the Great Xing’an Mountains, China. Their taxonomic characteristics and habitats were described to provide new information on the biodiversity of chrysophycean stomatocysts. As is common with many morphotypes, their biological affinities remain unknown.  相似文献   
7.
Great emphasis is being placed on the use of rainfall intensity data at short time intervals to accurately model the dynamics of modern cropping systems, runoff, erosion and pollutant transport. However, rainfall data are often readily available at more aggregated level of time scale and measurements of rainfall intensity at higher resolution are available only at limited stations. A distribution approach is a good compromise between fine-scale (e.g. sub-daily) models and coarse-scale (e.g. daily) rainfall data, because the use of rainfall intensity distribution could substantially improve hydrological models. In the distribution approach, the cumulative distribution function of rainfall intensity is employed to represent the effect of the within-day temporal variability of rainfall and a disaggregation model (i.e. a model disaggregates time series into sets of higher solution) is used to estimate distribution parameters from the daily average effective precipitation. Scaling problems in hydrologic applications often occur at both space and time dimensions and temporal scaling effects on hydrologic responses may exhibit great spatial variability. Transferring disaggregation model parameter values from one station to an arbitrary position is prone to error, thus a satisfactory alternative is to employ spatial interpolation between stations. This study investigates the spatial interpolation of the probability-based disaggregation model. Rainfall intensity observations are represented as a two-parameter lognormal distribution and methods are developed to estimate distribution parameters from either high-resolution rainfall data or coarse-scale precipitation information such as effective intensity rates. Model parameters are spatially interpolated by kriging to obtain the rainfall intensity distribution when only daily totals are available. The method was applied to 56 pluviometer stations in Western Australia. Two goodness-of-fit statistics were used to evaluate the skill—daily and quantile coefficient of efficiency between simulations and observations. Simulations based on cross-validation show that kriging performed better than other two spatial interpolation approaches (B-splines and thin-plate splines).  相似文献   
8.
Low-flow indices have been determined from long-term daily streamflow data for 13 catchments in Dongjiang Basin in southern China. The Brutsaert-Nieber method was applied to estimate catchment-scale effective groundwater parameters; representative values were 4.5?×?10?4 ms?1 for the hydraulic diffusivity; 3.19?×?10?5 m2 s?1/2 for the hydraulic desorptivity; 2.27?×?10?4 m s?1 for the hydraulic conductivity; and 0.2617 for the drainable porosity. The response constants correlate well with the total stream length and catchment area. Solutions of the linearised Boussinesq equation were used to guide the development of regional multivariate regression models for estimating low-flow indices from the catchment-scale effective parameters. Results showed that these catchments exhibit similar low-flow characteristics. The 7-day lowest average streamflows with return periods of 10 and 2 years (7Q10 and 7Q2) are highly correlated with the catchment-scale response constants. The low-flow ratio Q95/Q50 (ratio of daily streamflow exceeded 95 and 50% of the time, respectively) varied between 0.3 and 0.5, indicating a high proportion of groundwater in the streamflow. The advantage of the regional regression model is its conceptual basis and use of the catchment-scale effective parameters. The method has the potential to be applied to ungauged catchments for estimating low-flow statistics from stream length and catchment area.  相似文献   
9.
Abstract

The trends of annual, seasonal and monthly precipitation in southern China (Guangdong Province) for the period 1956–2000 are investigated, based on the data from 186 high-quality gauging stations. Statistical tests, including Mann-Kendall rank test and wavelet analysis, are employed to determine whether the precipitation series exhibit any regular trend and periodicity. The results indicate that the annual precipitation has a slightly decreasing trend in central Guangdong and slight increasing trends in the eastern and western areas of the province. However, all the annual trends are not statistically significant at the 95% confidence level. The average precipitation increases in the dry season in central Guangdong, but decreases in the wet season, meaning that the precipitation becomes more evenly distributed within the year. Furthermore, the analysis of monthly precipitation suggests that the distribution of intra-annual precipitation changes over time. The results of wavelet analysis show prominent precipitation with periods ranging from 10 to 12 years in every sub-region in Guangdong Province. Comparing with the sunspot cycle (11-year), the annual precipitation in every sub-region in Guangdong province correlates with Sunspot Number with a 3-year lag. The findings in this paper will be useful for water resources management.

Editor Z.W. Kundzewicz; Associate editor Sheng Yue

Citation Dedi Liu, Shenglian Guo, Xiaohong Chen and Quanxi Shao, 2012. Analysis of trends of annual and seasonal precipitation from 1956 to 2000 in Guangdong Province, China. Hydrological Sciences Journal, 57 (2), 358–369.  相似文献   
10.
受上游水库运行的影响,自2003年后长江中游河段河床调整,引起河道自身过流能力的变化.本文选取长江中游城陵矶—汉口河段作为研究对象,根据实测资料计算了 2003-2016年两个水文断面的水位—流量关系及特征流量变化,并采用一维水动力学模型计算了河段尺度的平滩流量.结果表明:(1)螺山站及汉口站2003-2016年的水位...  相似文献   
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