A stochastic study of floods in Canada: truncation level by region

1991 ◽  
Vol 18 (2) ◽  
pp. 328-330
Author(s):  
Daniel Caissie ◽  
Nassir El-Jabi
Keyword(s):  
Regression Analysis ◽  
Flood Frequency ◽  
Point Of View ◽  
Flood Frequency Analysis ◽  
Truncation Level ◽  
Partial Duration Series ◽  
Practical Point ◽  
The Mean ◽  
Physiographic Parameters ◽  
Selection Of

The main problem in applying a partial duration series model in flood frequency analysis lies in the selection of the truncation level. From a practical point of view, it is important to have a simple and effective way of selecting this level. A truncation level study was conducted on hydrometric stations across Canada and regional equations were developed for estimating the truncation level using regression analysis. The homogeneous region was selected based on previous countrywide hydrological studies. From the hydrologic and physiographic parameters used in the regression analysis, the mean annual flood best explained the truncation level for all of the regions. Key words: flood, partial duration series, truncation level.

Der Sommer und Herbst 2003 aus phänologischer Sicht | Summer and autumn 2003 from a phenological point of view

2004 ◽  
Vol 155 (5) ◽  
pp. 142-145 ◽  
Author(s):  
Claudio Defila
Keyword(s):  
Time Series ◽  
New Record ◽  
Point Of View ◽  
Late Spring ◽  
Mean Deviation ◽  
Leaf Shedding ◽  
The Mean ◽  
Very High ◽  
Selection Of

The record-breaking heatwave of 2003 also had an impact on the vegetation in Switzerland. To examine its influences seven phenological late spring and summer phases were evaluated together with six phases in the autumn from a selection of stations. 30% of the 122 chosen phenological time series in late spring and summer phases set a new record (earliest arrival). The proportion of very early arrivals is very high and the mean deviation from the norm is between 10 and 20 days. The situation was less extreme in autumn, where 20% of the 103 time series chosen set a new record. The majority of the phenological arrivals were found in the class «normal» but the class«very early» is still well represented. The mean precocity lies between five and twenty days. As far as the leaf shedding of the beech is concerned, there was even a slight delay of around six days. The evaluation serves to show that the heatwave of 2003 strongly influenced the phenological events of summer and spring.

scholarly journals Use of capital budgeting practices: an integrative review

2021 ◽  
Vol 40 (3) ◽  
pp. 139-157
Author(s):  
Paula de Souza Michelon ◽  
Rogério João Lunkes ◽  
Antonio Cezar Bornia
Keyword(s):  
Decision Making ◽  
Capital Budgeting ◽  
Point Of View ◽  
Integrative Review ◽  
Research Gaps ◽  
Practical Point ◽  
Practice Gap ◽  
Theory Practice Gap ◽  
Selection Of

This article aimed to highlight the relationships between these characteristics and the use ofcapital budgeting practices. For the selection of articles published on “capital budgeting” it wasused the Proknow-C tool. It was found that the theory-practice gap is both related with the organizationaland managerial characteristics from the practical point of view, but requires a reviewby academicians. Organizations should seek professionals with experience in capital projectsappraisal and who are familiar with and knowledgeable in the use of adequate practices for decision-making. This research contributes by indicating the research gaps that need to be explored by researchers and by trying to identify the difficulties found by managers that interfere in the capital budgeting results. 

Comparison of quality-control rules used in clinical chemistry laboratories

1993 ◽  
Vol 39 (8) ◽  
pp. 1638-1649 ◽  
Author(s):  
J Bishop ◽  
A B Nix
Keyword(s):  
Quality Control ◽  
Random Error ◽  
Control Charts ◽  
Clinical Chemistry ◽  
Point Of View ◽  
Practical Point ◽  
Control Rules ◽  
Control Schemes ◽  
The Mean ◽  
Fundamental Formula

Abstract Numerous papers have been written to show which combinations of Shewhart-type quality-control charts are optimal for detecting systematic shifts in the mean response of a process, increases in the random error of a process, and linear drift effects in the mean response across the assay batch. One paper by Westgard et al. (Clin Chem 1977;23:1857-67) especially seems to have attracted the attention of users. Here we derive detailed results that enable the characteristics of the various Shewhart-type control schemes, including the multirule scheme (Clin Chem 1981;27:493-501), to be calculated and show that a fundamental formula proposed by Westgard et al. in the earlier paper is in error, although their derived results are not seriously wrong. We also show that, from a practical point of view, a suitably chosen Cusum scheme is near optimal for all the types and combinations of errors discussed, thereby removing the selection problem for the user.

scholarly journals A study on selection of probability distributions for at-site flood frequency analysis in Australia

2013 ◽  
Vol 69 (3) ◽  
pp. 1803-1813 ◽  
Author(s):  
Ayesha S. Rahman ◽  
Ataur Rahman ◽  
Mohammad A. Zaman ◽  
Khaled Haddad ◽  
Amimul Ahsan ◽  
...  
Keyword(s):  
Frequency Analysis ◽  
Probability Distributions ◽  
Flood Frequency ◽  
Flood Frequency Analysis ◽  
Selection Of

scholarly journals Comparison of two approaches for an estimation of the mean annual flood at ungauged sites in Slovakia

2020 ◽  
Vol 15 (2) ◽  
pp. 130-141
Author(s):  
Zuzana Németová ◽  
Silvia Kohnová ◽  
Romana Marková
Keyword(s):  
Clustering Algorithm ◽  
Optimal Number ◽  
Flood Frequency ◽  
Flood Frequency Analysis ◽  
Ungauged Sites ◽  
Index Flood ◽  
Regional Flood Frequency Analysis ◽  
The Mean ◽  
Essential Problem ◽  
Observation Period

AbstractRegional flood frequency analysis is considered to be an important and popular method for estimating different hydrological variables at ungauged sites. The estimation of the index flood is the essential problem when this method is applied. The objective of the study is a comparison of the estimation of the mean annual flood (or index flood) by using two approaches based on the ‘so-called’ index flood method and top-kriging. The concept behind these methods permits estimating the mean annual flood at ungauged locations using information taken from gauged sites located within the same homogeneous pooling groups. The study area comprises 104 gauging stations on the whole territory of Slovakia. The observation period of the annual maximum discharges of the selected stations was from 1961-2010. The identification of the homogeneous pooling group was performed using a non-hierarchical k-means clustering algorithm. The optimal number of clusters is determined by the Silhouette method. As a result, eight homogeneous pooling group clusters were identified. Finally, the results of the estimated mean annual floods using the index flood method and top-kriging were compared with the observed data. Top-kriging provided better results than the classical index flood method for estimating the mean annual flood at ungauged sites.

scholarly journals Introducing empirical and probabilistic regional envelope curves into a mixed bounded distribution function

2010 ◽  
Vol 7 (4) ◽  
pp. 4253-4290
Author(s):  
B. Guse ◽  
T. Hofherr ◽  
B. Merz
Keyword(s):  
Distribution Function ◽  
Upper Bound ◽  
Inflection Point ◽  
Flood Frequency ◽  
Quantile Estimation ◽  
Flood Frequency Analysis ◽  
Envelope Curve ◽  
Recurrence Intervals ◽  
Flood Quantiles ◽  
Selection Of

Abstract. A novel approach to consider additional spatial information in flood frequency analyses, especially for the estimation of discharges with recurrence intervals larger than 100 years, is presented. For this purpose, large flood quantiles, i.e. pairs of a discharge and its corresponding recurrence interval, as well as an upper bound discharge, are combined within a mixed bounded distribution function. Large flood quantiles are derived using probabilistic regional envelope curves (PRECs) for all sites of a pooling group. These PREC flood quantiles are introduced into an at-site flood frequency analysis by assuming that they are representative for the range of recurrence intervals which is covered by PREC flood quantiles. For recurrence intervals above a certain inflection point, a Generalised Extreme Value (GEV) distribution function with a positive shape parameter is used. This GEV asymptotically approaches an upper bound derived from an empirical envelope curve. The resulting mixed distribution function is composed of two distribution functions, which are connected at the inflection point. This method is applied to 83 streamflow gauges in Saxony/Germany. Our analysis illustrates that the presented mixed bounded distribution function adequately considers PREC flood quantiles as well as an upper bound discharge. The introduction of both into an at-site flood frequency analysis improves the quantile estimation. A sensitivity analysis reveals that, for the target recurrence interval of 1000 years, the flood quantile estimation is less sensitive to the selection of an empirical envelope curve than to the selection of PREC discharges and of the inflection point between the mixed bounded distribution function.

scholarly journals On the relation of the air and evaporation temperatures to the temperature of the dew-point, as determined by Mr. Glaisher's hygrometrical tables founded on the factors deduced from the six-hourly observations made at the Royal Observatory, Greenwich

1851 ◽  
Vol 5 ◽  
pp. 953-953
Keyword(s):  
Personal Experience ◽  
Point Of View ◽  
Dew Point ◽  
Practical Point ◽  
Advantages And Disadvantages ◽  
Royal Observatory ◽  
The Subject ◽  
The Mean ◽  
Annual Amount

After pointing out the importance of the hygrometer, both in a scientific and a practical point of view, the author goes into the question of the advantages and disadvantages attending the use of Daniell’s hygrometer, and the relative merits of this instrument and the dry and wet-bulb thermometers. Although satisfied of the accuracy of Mr. Glaisher’s Tables (founded on the Greenwich Observations), which show at once the relation of the temperature of evaporation to that of the dew-point, he was unwilling to abandon the use of Daniell’s apparatus for that of the wet and dry-bulb thermometers, slight as is the trouble of observing them, without personal experience of the correctness of the tables from which the dew-point was to be deduced. He therefore instituted a series of perfectly comparable observations by the two methods, and in this communication gives the results obtained from them during a period of twenty months. From a comparison of the dew-points determined by the two methods, he concludes that the results show in a striking manner the extreme accuracy of Mr. Glaisher’s Tables, and afford additional testimony to the value of the Greenwich Hygrometrical Observations, and the resulting formula on which those tables are founded. The author then refers to the subject of evaporation, and gives the results of his own observations at Whitehaven during six years, viz. from 1843 to 1848 inclusive. From these he states that the mean annual amount of evaporation is 30·011 inches; and the mean quantity of rain for the same period being 45·255 inches, the depth of the water precipitated exceeds that taken up by evaporation, on the coast in latitude 54½°, by 15·244 inches.

scholarly journals Introducing empirical and probabilistic regional envelope curves into a mixed bounded distribution function

2010 ◽  
Vol 14 (12) ◽  
pp. 2465-2478 ◽  
Author(s):  
B. Guse ◽  
Th. Hofherr ◽  
B. Merz
Keyword(s):  
Distribution Function ◽  
Upper Bound ◽  
Inflection Point ◽  
Flood Frequency ◽  
Quantile Estimation ◽  
Flood Frequency Analysis ◽  
Envelope Curve ◽  
Recurrence Intervals ◽  
Flood Quantiles ◽  
Selection Of

Abstract. A novel approach to consider additional spatial information in flood frequency analyses, especially for the estimation of discharges with recurrence intervals larger than 100 years, is presented. For this purpose, large flood quantiles, i.e. pairs of a discharge and its corresponding recurrence interval, as well as an upper bound discharge, are combined within a mixed bounded distribution function. The large flood quantiles are derived using probabilistic regional envelope curves (PRECs) for all sites of a pooling group. These PREC flood quantiles are introduced into an at-site flood frequency analysis by assuming that they are representative for the range of recurrence intervals which is covered by PREC flood quantiles. For recurrence intervals above a certain inflection point, a Generalised Extreme Value (GEV) distribution function with a positive shape parameter is used. This GEV asymptotically approaches an upper bound derived from an empirical envelope curve. The resulting mixed distribution function is composed of two distribution functions which are connected at the inflection point. This method is applied to 83 streamflow gauges in Saxony/Germany. Our analysis illustrates that the presented mixed bounded distribution function adequately considers PREC flood quantiles as well as an upper bound discharge. The introduction of both into an at-site flood frequency analysis improves the quantile estimation. A sensitivity analysis reveals that, for the target recurrence interval of 1000 years, the flood quantile estimation is less sensitive to the selection of an empirical envelope curve than to the selection of PREC discharges and of the inflection point between the mixed bounded distribution function.

Sign in / Sign up

Export Citation Format

Share Document