排序方式： 共有35条查询结果，搜索用时 31 毫秒
1.
2.
3.
4.
ABSTRACTSeries of observed flood intervals, defined as the time intervals between successive flood peaks over a threshold, were extracted directly from 11 approximately 100-year streamflow datasets from Queensland, Australia. A range of discharge thresholds were analysed that correspond to return periods of approximately 3.7 months to 6.3 years. Flood interval histograms at South East Queensland gauges were consistently unimodal whereas those of the North and Central Queensland sites were often multimodal. The exponential probability distribution (pd) is often used to describe interval exceedence probabilities, but fitting utilizing the Anderson-Darling statistic found little evidence that it is the most suitable. The fatigue life pd dominated sub-year return periods (<1 year), often transitioning to a log Pearson 3 pd at above-year return periods. Fatigue life pd is used in analysis of the lifetime to structural failure when a threshold is exceeded, and this paper demonstrates its relevance also to the elapsed time between above-threshold floods. At most sites, the interval medians were substantially less than the means for sub-year return periods. Statistically the median is a better measure of the central tendency of skewed distributions but the mean is generally used in practice to describe the classical concept of flood return period.
Editor Z.W. Kundzewicz; Associate editor I. Nalbantis 相似文献
5.
Citation Abrahart, R.J. & Mount, N.J. (2011) Discussion of “Neuro-fuzzy models employing wavelet analysis for suspended sediment concentration prediction in rivers by S.A. Mirgagheri et al. (2010, Hydrol. Sci. J. 55(7), 1175–1189).” Hydrol. Sci. J. 56(7), 1325–1329. 相似文献
6.
Deepak Jhajharia Brijesh K. Yadav Sunil Maske Surajit Chattopadhyay Anil K. Kar 《Comptes Rendus Geoscience》2012,344(1):1-13
Trends in rainfall, rainy days and 24 h maximum rainfall are investigated using the Mann-Kendall non-parametric test at twenty-four sites of subtropical Assam located in the northeastern region of India. The trends are statistically confirmed by both the parametric and non-parametric methods and the magnitudes of significant trends are obtained through the linear regression test. In Assam, the average monsoon rainfall (rainy days) during the monsoon months of June to September is about 1606 mm (70), which accounts for about 70% (64%) of the annual rainfall (rainy days). On monthly time scales, sixteen and seventeen sites (twenty-one sites each) witnessed decreasing trends in the total rainfall (rainy days), out of which one and three trends (seven trends each) were found to be statistically significant in June and July, respectively. On the other hand, seventeen sites witnessed increasing trends in rainfall in the month of September, but none were statistically significant. In December (February), eighteen (twenty-two) sites witnessed decreasing (increasing) trends in total rainfall, out of which five (three) trends were statistically significant. For the rainy days during the months of November to January, twenty-two or more sites witnessed decreasing trends in Assam, but for nine (November), twelve (January) and eighteen (December) sites, these trends were statistically significant. These observed changes in rainfall, although most time series are not convincing as they show predominantly no significance, along with the well-reported climatic warming in monsoon and post-monsoon seasons may have implications for human health and water resources management over bio-diversity rich Northeast India. 相似文献
7.
A non-parametric method is used in this study to analyze and predict short-term rainfall due to tropical cyclones(TCs) in a coastal meteorological station. All 427 TCs during 1953-2011 which made landfall along the Southeast China coast with a distance less than 700 km to a certain meteorological station- Shenzhen are analyzed and grouped according to their landfalling direction, distance and intensity. The corresponding daily rainfall records at Shenzhen Meteorological Station(SMS) during TCs landfalling period(a couple of days before and after TC landfall) are collected. The maximum daily rainfall(R-24) and maximum 3-day accumulative rainfall(R-72) records at SMS for each TC category are analyzed by a non-parametric statistical method, percentile estimation. The results are plotted by statistical boxplots, expressing in probability of precipitation. The performance of the statistical boxplots is evaluated to forecast the short-term rainfall at SMS during the TC seasons in 2012 and 2013. Results show that the boxplot scheme can be used as a valuable reference to predict the short-term rainfall at SMS due to TCs landfalling along the Southeast China coast. 相似文献
8.
恢复额济纳旗生态系统的总经济价值——条件估值非参数估计方法的应用 总被引：10，自引：4，他引：10
条件估值方法是当前国际上流行的衡量环境物品非利用经济价值的方法, 通过调查居民针对不同环境状况变化的支付意愿,从而定量确定环境状况变化带来的经济效益和损失. 针对黑河流域额济纳旗生态系统恶化的现状,以投标支付卡的方法设计了700份调查问卷,调查了黑河流域居民恢复额济纳旗生态系统的支付意愿,并采用非参数分析方法对结果进行分析. 结果表明,用20 a的时间将额济纳旗的生态系统恢复到20世纪80年代初的水平,黑河流域总共有92.3%的居民家庭存在支付意愿,有支付意愿家庭的平均支付意愿为每年每户43.39元,同时采用列联表检验的方法辨明了被调查者的年龄、学历、收入、户籍和居住的地理区域等因素对支付意愿的影响. 最后在综合不同区域居民支付意愿差异的基础上,采用当前的市场利率将计算结果在时空尺度上加总,得到恢复黑河下游额济纳生态系统的总经济价值的现值为2.94×10+8元. 相似文献
9.
Sylvia R. Esterby 《水文研究》1996,10(2):127-149
Methods for the detection and estimation of trends which are suitable for the type of data sets available from water quality and atmospheric deposition monitoring programmes are considered. Parametric and non-parametric methods which are based on the assumption of monotonic trend and which account for seasonality through blocking on season are described. The topics included are heterogeneity of trend, missing data, covariates, censored data, serial dependence and multivariate extensions. The basis for the non-parametric methods being the method of choice for current large data sets of short to moderate length is reviewed. A more general definition of trend as the component of gradual change over time is consistent with another group of methods and some examples are given. Spatial temporal data sets and longer temporal records are also briefly considered. A broad overview of the topic of trend analysis is given, with technicalities left to the references cited. The necessity of defining what is meant by trend in the context of the design and objectives of the programme is emphasized, as is the need to model the variability in the data more generally. 相似文献
10.