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1.
An analysis of spatial and temporal trends of precipitation in Beijiang River basin, Guangdong Province, China during 1959–2003 was performed using 17 time series (including monthly, annual, wet season, dry season, early flood period and late flood period totals) both on station based and sub‐basin based data sets. Two nonparametric methods (Mann–Kendall and Sen's T) were used for data analysis. The results showed that (1) downward trends of temporal distribution were mostly detected during the early flood period, especially in May, while upward trends were observed in July and the dry season; (2) downward trends of spatial distribution were mostly detected in the southern Beijiang River basin, while upward trends were observed north of this area. Our results indicated a delayed rainy season and a northward trend of the precipitation belt compared to recent years. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
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《水文科学杂志》2013,58(5):863-877
Abstract The method of L-moment ratio diagrams and the average weighted distance (AWD) are used to determine the probability distribution type of annual, seasonal and monthly precipitation in Japan. For annual precipitation, the log-Pearson type III (LP3) distribution provides the best fit to the observations with the generalized-extreme value (GEV), three-parameter lognormal (LN3) and Pearson type III (P3) distributions as potential alternatives. For seasonal precipitation, the P3 distribution shows the best fit to the observations of spring precipitation; the LP3 the best fit for summer and winter precipitation; and the LN3 the best fit for autumn precipitation with the LP3 as a potential alternative. For monthly precipitation, the P3 distribution fits the precipitation best for January, February, March, May, July, October and December; the LP3 for June; and the LN3 for April, August, September and November. The identified probability distribution types of annual, seasonal and monthly precipitation are basically consistent. Overall, the P3 and LP3 distributions are acceptable distribution types for representing statistics of precipitation in Japan with the LN3 distribution as a potential alternative. 相似文献
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AbstractThis study investigates the terrestrial hydrological processes during a dry climate period in Southwest China by analysing the frequency-dependent runoff and soil moisture responses to precipitation variability. Two headwater sub-basins, the Nanpan and Guihe basins of the West River (Xijiang), are studied to compare and contrast the terrestrial responses. The variable infiltration capacity (VIC) model is used to simulate the hydrological processes. Using wavelets, the relationships between observed precipitation and simulated runoff/soil moisture are expressed quantitatively. The results indicate that: (a) the Guihe basin shows a greater degree of high-frequency runoff variability in response to regional precipitation; and (b) the Nanpan basin exhibits less capability in accommodating/smoothing extreme precipitation deficits, reflected in terms of both higher scale-averaged (for 3–6 months) and time-averaged (for the year 1963) wavelet power of soil moisture.Editor Z.W. Kundzewicz; Associate editor C.-Y. XuCitation Niu, J. and Chen, J., 2013. Terrestrial hydrological responses to precipitation variability in Southwest China with emphasis on drought. Hydrological Sciences Journal, 59 (2), 325–335. 相似文献
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On the basis of daily precipitation records at 76 meteorological stations in the arid region, northwest of China, the spatial and temporal distribution of mean precipitation and extremes were analysed during 1960–2010. The Mann–Kendall trend test and linear least square method were utilized to detect monotonic trends and magnitudes in annual and seasonal mean precipitation and extremes. The results obtained indicate that both the mean precipitation and the extremes have increased except in consecutive dry days, which showed the opposite trend. The changes in amplitude of both mean precipitation and extremes show seasonal variability. On an annual basis, the number of rain days (R0.1) has significantly increased. Meanwhile, the precipitation intensity as reflected by simple daily intensity index (SDII), number of heavy precipitation days (R10), very wet days (R95p), max 1‐day precipitation amount (RX1day) and max 5‐day precipitation amount (RX5day) has also significantly increased. This suggests that the precipitation increase in the arid region is due to the increase in both precipitation frequency and intensity. Trends in extremes are very highly correlated with mean trends of precipitation. The spatial correlation between trends in extremes and trends in the mean is stronger for winter (DJF) than for annual and other seasons. The regional annual and seasonal precipitation and extremes are observed the step jump in mean in the late 1980s. Overall, the results of this study are good indicators of local climate change, which will definitely enhance human mitigation to natural hazards caused by precipitation extremes. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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There is increasing interest in the magnitude of the flow of freshwater to the Arctic Ocean due to its impacts on the biogeophysical and socio‐economic systems in the north and its influence on global climate. This study examines freshwater flow based on a dataset of 72 rivers that either directly or indirectly contribute flow to the Arctic Ocean or reflect the hydrologic regime of areas contributing flow to the Arctic Ocean. Annual streamflow for the 72 rivers is categorized as to the nature and location of the contribution to the Arctic Ocean, and composite series of annual flows are determined for each category for the period 1975 to 2015. A trend analysis is then conducted for the annual discharge series assembled for each category. The results reveal a general increase in freshwater flow to the Arctic Ocean with this increase being more prominent from the Eurasian rivers than from the North American rivers. A comparison with trends obtained from an earlier study ending in 2000 indicates similar trend response from the Eurasian rivers, but dramatic differences from some of the North American rivers. A total annual discharge increase of 8.7 km3/y/y is found, with an annual discharge increase of 5.8 km3/y/y observed for the rivers directly flowing to the Arctic Ocean. The influence of annual or seasonal climate oscillation indices on annual discharge series is also assessed. Several river categories are found to have significant correlations with the Arctic Oscillation, the North Atlantic Oscillation, or the Pacific Decadal Oscillation. However, no significant association with climate indices is found for the river categories leading to the largest freshwater contribution to the Arctic Ocean. 相似文献
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The statistical properties of annual runoff in major rivers of China are studied based on the theory of stochastic process and technology of time series analysis. These properties include the characteristics of intra‐annual and inter‐annual variations of runoff, trends, abrupt changes and periodicities. The new findings from the intensive calculations and appropriate analysis of data in longer period are as follows: (i) compared with the nonuniformity of intra‐annual runoff before 1980, the nonuniformity of intra‐annual runoff in China generally decreased after 1980, except for Huaihe River and Songhua River; (ii) compared with the annual runoff before 1980, the annual runoff in China generally decreased after 1980 except for WangJiaba station in Huaihe River and Ha‐Erbin station in Songhua River; the frequency of continuous low flow and continuous high flow in Haihe River and the downstream of Yellow River is higher than those in other rivers in China; (iii) annual runoff shows a downward trend in major rivers of China especially in Haihe River, Liao River and the midstream and downstream of Yellow River; (iv) there exist certain abrupt changes of annual runoff in major rivers of China; the abrupt change‐points are different among different river basins; and (v) almost periodicities of annual runoff sequences in major rivers of China are generally 20 years below, that is, 3~7 and 12~20 years. The reasons for these changes are mainly caused by climate change and human activities. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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选取广东省数字化地磁观测以来的地磁资料和一定震中距的显著地震事件,计算地震前1~2年的地磁垂直分量加卸载响应比,结果显示,显著地震前1个月至1年不等,地磁加卸载响应比值有明显超经验阈值2.8的现象。 相似文献
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Regional difference of annual precipitation and discharge variation over west China during the last 50 years 总被引:8,自引:0,他引:8
Using annual precipitation and discharge data measured in the past five decades,this paper analyzed the regional differences over west China in terms of climate and discharge variations,and investigated the relationship between the regional characteristics and the activities of South and East Asian sum-mer monsoon. Results revealed that the precipitation and discharge in the upper reaches of the Yellow River (Central West China) have a negative correlation with those in Xinjiang (northwest China) and the Yarlung Zangbo River (the upper reaches of the Brahmaputra Rive,southwest China) regions. The geographical patterns of precipitation and discharge variations are different over west China,i.e. the regional climate displays the alteration of dry-wet-dry or wet-dry-wet from north to south in west China. The negative correlation of annual discharges between Xinjiang and the upper reaches of the Yellow River is found statistically significant in the decadal scale,and that between the Yarlung Zangbo River and the upper reaches of the Yellow River is found active in the interannual scale. The regional char-acteristics indicate that the discharge/precipitation variations in the upper reaches of the Yellow River are dominated by the East Asian summer monsoon while their variations in Xinjiang are affected by both the west wind and East Asian summer monsoon. 相似文献
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粤闽地区水化学地震前兆异常特征分析 总被引:3,自引:0,他引:3
研究了粤闽两省及其近海近年来2次强震以及6个中等地震水化学前兆资料,结果表明,中等地震与强震的水化学前兆异常在数量上有着显著的差异,中等地震震前以中短期及短临异常变化为主,而强震前则超过三分之一的水化学测项出现持续1~4年的长趋势异常变化。同时研究表明,单凭水化异常出现的集中程度对未来震中作出预测是无统计依据的。 相似文献
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PCBs equivalent to Aroclor 1242 and 1254 in soft tissues of oysters Crassostrea rivularis from the Guangdong coast, China, were measured using a GC-ECD. PCB concentrations (ng g−1 d.w.) ranged from 30 to 2040 with an average of 315 in 2003-2007, and 0.35-1.43 with an average of 0.56 in 1989-1991. Annual averages were 0.61, 0.65, 313, 290 and 342 ng g−1, respectively in 1989, 1991, 2003, 2006 and 2007. In east Guangdong, the Pearl River Estuary, and west Guangdong, regional means were 444, 273, 194 ng g−1, respectively in 2003-2007, and 0.43, 0.78, 0.38 ng g−1, respectively in 1989-1991, indicating PCB levels in oysters have risen greatly by ratios of 350-1032 compared with earlier data. PCB sources may derive from older transformers, printing materials and pressworks. Fortunately, current residual PCBs in the oysters were 0.004-0.253 mg kg−1 (w.w.), still below hygienic criteria of China and developed countries. 相似文献
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Wavelet and cross-wavelet analysis are used to identify and describe spatial and temporal variability in Canadian seasonal precipitation, and to gain further insights into the dynamical relationship between the seasonal precipitation and the dominant modes of climate variability in the Northern Hemisphere. Results from applying continuous wavelet transform to seasonal precipitation series from 201 stations selected from Environment Canada Meteorological Network reveal striking climate-related features before and after the 1940s. The span of available observations, 1900–2000, allows for depicting variance and covariance for periods up to 12 years. Scale-averaged wavelet power spectra are used to simultaneously assess the temporal and spatial variability in each set of 201 seasonal precipitation time series. The most striking feature, in the 2–3-year period and in the 3–6-year period—the 6–12-year period is dominated by white noise and is not considered further—is a net distinction between the timing and intensity of the temporal variability in autumn, winter and spring–summer precipitation. It is found that the autumn season exhibits the most intense activity (or variance) in both the 2–3 year and the 3–6 year periods. The winter season corresponds to the least intense activity for the 2–3 year period, but it exhibits more activity than the spring–summer for the 3–6 year period.Cross-wavelet analysis is provided between the seasonal precipitation and four selected climatic indices: the Pacific North America (PNA), the North Atlantic Oscillation (NAO), the Northern Hemisphere Annular Mode (NAM) originally called the Arctic Oscillation, and the sea surface temperature series over the Niño-3 region (ENSO). The wavelet cross-spectra revealed coherent space–time variability of the climate–precipitation relationship throughout Canada. It is shown that strong climate/precipitation activity (or covariance) in the 2–6 year period starts after 1940 whatever the climatic index and the season. Prior to year 1940, only local and weaker 2–6 year activity is revealed in western Canada essentially in winter and autumn, but overall a non-significant precipitation/climate relationship is observed prior to 1940. Correlation analysis in the 2–6 year band between the seasonal precipitation and the selected climatic indices revealed strong positive correlations with the ENSO, the NAO, and the NAM in eastern and western Canada for the post-1940 period. For the period prior to 1940, the correlation tend be negative for all the indices whatever the region. A particular feature in the correlation analysis results is the consistently stronger and positive NAM–precipitation correlations in all the regions since 1940. The cross-wavelet spectra and the correlation analysis in the 2–6 year band suggest the presence of a change point around 1940 in Canadian seasonal precipitation—that is found to be more likely related to NAM dynamics. 相似文献
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This paper reports SHRIMP zircon U-Pb ages of 196±2 Ma for granite, and 195±1 Ma for gabbro from the Xialan complex in the Meizhou area, northern Guangdong Province. These results shed new light on the calm stage of magmatic activity in southeastern China during 200-180 Ma, and revealed that the back-arc extension induced by the subduction of the western Pacific plate may have begun at 195 Ma at least. Field observation on the fresh outcrops allows us to recognize some features formed by magma mixing. A par... 相似文献
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广东省揭西金坑矿区目前已初步查明的(333+334)级矿石量为2245464.8吨,其中金属量Cu:17596.7吨、Sn:5945.3吨、Pb:31536.9吨、Zn:58095.2吨。矿区主要矿体为脉状,均受滑动破碎构造带控制,总体上可分为两种类型:一类分布于灰白色花岗闪长斑岩中,在空间分布上受滑动破碎构造带控制,矿体顶底板为片理化带,蚀变强,呈脉状、透镜状产于花岗闪长斑岩体内的片理化带所产生的滑动破碎带中。另一类则产于石英片岩、粉砂岩、炭质泥岩层间滑动破碎构造带中,主要由多个连续的或间断的扁豆状、透镜体状的矿脉组成。矿体赋存严格受岩层控制,矿脉与围岩界线清楚。本文旨在通过对矿体特征、成矿机理的深入分析,为矿区为进一步扩大资源量提供理论上的启示。 相似文献
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Spatial and temporal variations of precipitation in Haihe River Basin,China: six decades of measurements 总被引:1,自引:0,他引:1
This study aims to determine temporal trends and spatial distribution of the annual and monthly precipitation in the Haihe River Basin, China, during 1951–2008. A significant decreasing trend was observed for the annual precipitation, mainly attributed to the abrupt decrease in the flood‐season precipitation (June–September) around the year of 1979. No significant trend was revealed for precipitation within Period I of 1951–1979 and Period II of 1980–2008. Results of this study indicated that the relative contributions of the flood‐season precipitation decreased temporally with time and spatially with elevation. This study also identified a potential movement of storm centers from east to west portions of the basin. In addition, analysis on the precipitation anomalies also suggested a redistribution of the non‐flood season precipitation over the study area. Compared with the west portion of the basin, generally, the east received relatively more precipitation during the non‐flood season, while similar trend of precipitation redistribution was not observed in the flood season. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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The spatial and temporal variations of precipitation in the desert region of China (DRC) from 1951 to 2005 were investigated using a rotated empirical orthogonal function (REOF), the precipitation concentration index (PCI) and the Mann–Kendall trend test method (M‐K method). In addition, the association between variation patterns of precipitation and large‐scale circulation were also explored using the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis data. The results indicated that the spatial pattern of precipitation was primarily the local climate effect significant type, with the first three EOFs explaining a total of 55·3% of the variance, and the large‐scale climate system effect type, which explained 9·8% of the variance. Prior to the 1970s, the East Asian summer monsoon was stronger, which resulted in abundant precipitation in the Inner Mongolia region. Conversely, the climate of the Xinjiang region was controlled by westerly circulation and had lower precipitation. However, this situation has been reversed since the 1980s. It is predicted that precipitation will decrease by 15–40 and 0–10 mm/year in the Inner Mongolia plateau and southern Xinjiang, respectively, whereas it will likely increase by 10–40 mm/year in northern Xinjiang. Additionally, 58–62% of the annual rainfall occurred during summer in the DRC, with precipitation increasing during spring and summer and decreasing in winter. The intra‐annual precipitation is becoming uniform, but the inter‐annual variability in precipitation has been increasing in the western portions of the DRC. The probability of precipitation during the study period increased by 30% and 22·2% in the extreme‐arid zones and arid zones, respectively. Conversely, the probability of precipitation during the study period decreased by 18·5% and 37·5% in the semi‐arid zones and semi‐wet zones, respectively. It is predicted that the northwest portion of the DRC will become warmer and wetter, while the central portion will become warmer and drier and the northeast portion will be subjected to drought. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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广东省地震海啸危险分析与监测预警系统构想 总被引:1,自引:0,他引:1
对广东省地震海啸的潜在危险进行了分析,认为广东省可能面临的海啸威胁主要来自南海东部。一旦发生地震海啸,将出现重大的灾害,并对广东省的社会和经济产生巨大的影响。提出了建立广东省地震海啸监测预警系统的初步构想。 相似文献
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The spatio‐temporal variability of annual precipitation and its local impact factors during 1724–2010 in Beijing,China
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Rapid population growth and increased economic activity impose an urgent challenge on the sustainability of water resources in Beijing. Understanding the spatial and temporal variability of precipitation is of the upmost importance in order to sustain the region's water resources. Two time series, one long term (1724–2010) from a single meteorological station and a shorter time series (1980–2010) from 20 different meteorological stations within the Beijing area, were analysed using Linear Regression, Moving Average, Mann–Kendall, Rescaled Range and Spatial Interpolation methods. Results from both the long‐ and short‐term meteorological data show a mean annual precipitation rate of 600 mm and 540 mm respectively. Annual precipitation rates have decreased during the 21st century by an estimated 100 mm or 16% in comparison to the 1990s. The 1980–2010 data show an increase in precipitation during the early 1990s followed by a sharp decrease during the subsequent years. The change of annual precipitation with time is more random and diverse in comparison to space. The main local impact factors (terrain, urbanization and elevation) and how they work on the local precipitation especially the spatial diversity are identified qualitatively. Generally speaking, (1) the annual precipitation of the plain area is more than that of the mountainous area (terrain effect), (2) the annual precipitation of the urban area in the plain area is obviously more than that of the surrounding suburb area (urbanization effect) and (3) the annual precipitation of the lower location is approximately more than that of the higher location (elevation effect). Copyright © 2013 John Wiley & Sons, Ltd. 相似文献