Design Values for Precipitation and Floods from M5 Values

The M5 method, originally proposed by the Natural Resource Council in UK, is used for estimating precipitation in Iceland. In this method the M5 (24-hour precipitation with 5-year return period) is used as an index variable. Instead of the usual approach in estimating regional values of the coefficient of variation another coefficient, Ci is used. The M5 and the Ci define together a generalised distribution that can be utilised to estimate the statistical distribution of precipitation anywhere in the country. M5 maps have been prepared for this purpose by the Engineering Research Institute of the University of Iceland. Methods have been devised to derive PMP values from the M5 values. This paper describes the method and gives examples of calculation. It is also shown that the same CDF applies for the observations of shorter duration precipitation available in Iceland. By applying the principle of identical statistical distribution for standardised annual maxima of any duration, IDF (Intensity – Duration – Frequency) curves have been derived. This allows the IDF – values to be calculated on basis of M5 and Ci, which are the two-parameters that define the generalised precipitation distribution.

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Bayesian estimation of intensity–duration–frequency curves and of the return period associated to a given rainfall event

Stochastic Environmental Research and Risk Assessment ◽

10.1007/s00477-009-0323-1 ◽

2009 ◽

Vol 24 (3) ◽

pp. 337-347 ◽

Cited By ~ 31

Author(s):

David Huard ◽

Alain Mailhot ◽

Sophie Duchesne

Keyword(s):

Bayesian Estimation ◽

Return Period ◽

Rainfall Event ◽

Intensity Duration Frequency ◽

Frequency Curves

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Intensity–duration–frequency curves from remote sensing rainfall estimates: comparing satellite and weather radar over the eastern Mediterranean

Hydrology and Earth System Sciences ◽

10.5194/hess-21-2389-2017 ◽

2017 ◽

Vol 21 (5) ◽

pp. 2389-2404 ◽

Cited By ~ 28

Author(s):

Francesco Marra ◽

Efrat Morin ◽

Nadav Peleg ◽

Yiwen Mei ◽

Emmanouil N. Anagnostou

Keyword(s):

Remote Sensing ◽

Return Period ◽

Eastern Mediterranean ◽

Rain Gauge ◽

Catchment Scale ◽

Weather Radars ◽

The Earth ◽

Idf Curves ◽

Intensity Duration Frequency ◽

Frequency Curves

Abstract. Intensity–duration–frequency (IDF) curves are widely used to quantify the probability of occurrence of rainfall extremes. The usual rain gauge-based approach provides accurate curves for a specific location, but uncertainties arise when ungauged regions are examined or catchment-scale information is required. Remote sensing rainfall records, e.g. from weather radars and satellites, are recently becoming available, providing high-resolution estimates at regional or even global scales; their uncertainty and implications on water resources applications urge to be investigated. This study compares IDF curves from radar and satellite (CMORPH) estimates over the eastern Mediterranean (covering Mediterranean, semiarid, and arid climates) and quantifies the uncertainty related to their limited record on varying climates. We show that radar identifies thicker-tailed distributions than satellite, in particular for short durations, and that the tail of the distributions depends on the spatial and temporal aggregation scales. The spatial correlation between radar IDF and satellite IDF is as high as 0.7 for 2–5-year return period and decreases with longer return periods, especially for short durations. The uncertainty related to the use of short records is important when the record length is comparable to the return period ( ∼  50, ∼  100, and ∼  150 % for Mediterranean, semiarid, and arid climates, respectively). The agreement between IDF curves derived from different sensors on Mediterranean and, to a good extent, semiarid climates, demonstrates the potential of remote sensing datasets and instils confidence on their quantitative use for ungauged areas of the Earth.

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Peak flows from thin sedum-moss roof

Hydrology Research ◽

10.2166/nh.2005.0020 ◽

2005 ◽

Vol 36 (3) ◽

pp. 269-280 ◽

Cited By ~ 58

Author(s):

L. Bengtsson

Keyword(s):

Return Period ◽

Field Capacity ◽

Rainfall Runoff ◽

Percolation Process ◽

Drainage Layer ◽

The Mean ◽

Intensity Duration Frequency ◽

High Runoff ◽

High Precipitation ◽

Frequency Curves

The runoff from real 3 cm thick sedum-moss roofs and from laboratory roof plots in southern Sweden is measured and analysed. Real rains and artificial storms are used for the analysis. The probability of high runoff is compared with the probability of high precipitation intensity. Intensity–duration–frequency curves for runoff are derived and it is found that the runoff of 1.5 year return period corresponds to rain of 0.4 year return period. The storage of water in the soil–vegetation cover on the roof is determined. The storage at field capacity, when runoff is initiated, is about 9 mm. Water in excess of that is temporary stored during storms. The runoff distribution during prolonged storms can be related to the mean rain intensity over 20–30 min. The influence of the slope and length of the roof on the runoff peak is investigated as is the effect of the drainage layer. Neither slope nor length seems to significantly influence the runoff distribution, which indicates that the vertical percolation process through the vegetation and the soil dominates the rainfall–runoff process. The presence of a drainage layer below the soil results in somewhat faster runoff compared to when there is no drainage layer, and thus results in an increased runoff peak.

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A two-parameter design storm for Mediterranean convective rainfall

Hydrology and Earth System Sciences ◽

10.5194/hess-21-2377-2017 ◽

2017 ◽

Vol 21 (5) ◽

pp. 2377-2387 ◽

Cited By ~ 7

Author(s):

Rafael García-Bartual ◽

Ignacio Andrés-Doménech

Keyword(s):

Return Period ◽

Geographic Location ◽

Auxiliary Variable ◽

Rainfall Regime ◽

High Temporal Resolution ◽

Design Storm ◽

Starting Point ◽

Intensity Duration Frequency ◽

Two Parameters ◽

Two Parameter

Abstract. The following research explores the feasibility of building effective design storms for extreme hydrological regimes, such as the one which characterizes the rainfall regime of the east and south-east of the Iberian Peninsula, without employing intensity–duration–frequency (IDF) curves as a starting point. Nowadays, after decades of functioning hydrological automatic networks, there is an abundance of high-resolution rainfall data with a reasonable statistic representation, which enable the direct research of temporal patterns and inner structures of rainfall events at a given geographic location, with the aim of establishing a statistical synthesis directly based on those observed patterns. The authors propose a temporal design storm defined in analytical terms, through a two-parameter gamma-type function. The two parameters are directly estimated from 73 independent storms identified from rainfall records of high temporal resolution in Valencia (Spain). All the relevant analytical properties derived from that function are developed in order to use this storm in real applications. In particular, in order to assign a probability to the design storm (return period), an auxiliary variable combining maximum intensity and total cumulated rainfall is introduced. As a result, for a given return period, a set of three storms with different duration, depth and peak intensity are defined. The consistency of the results is verified by means of comparison with the classic method of alternating blocks based on an IDF curve, for the above mentioned study case.

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Design Inflow Intensity and Design Inflow Profiles for Storm Sewers

Water Science & Technology ◽

10.2166/wst.1984.0192 ◽

1984 ◽

Vol 16 (8-9) ◽

pp. 207-218 ◽

Cited By ~ 1

Author(s):

Frans H M van de Ven

Keyword(s):

Return Period ◽

Gumbel Distribution ◽

Extreme Value Distribution ◽

Data Series ◽

Design Discharge ◽

Common Location ◽

Housing Area ◽

Parking Lot ◽

Box Cox Transformation ◽

Frequency Curves

Twelve year records of rainfall and of sewer inflow data in a housing area and in a parking lot in Lelystad were available. These data series contained 5-minute depths of rainfall and sewer inflow. Depth-duration-frequency curves were calculated from the monthly extremes, using Box-Cox transformation and a Gumbel distribution. The differences between the curves for rainfall and for inflow are explained by inertia and rainfall losses. These differences are the reason to use inflow as a sewer design parameter. Forthe choice of the design discharge (or inflow) intensity the curves are not well suited. Storage-design,discharge-frequency curves proved to be better interprétable. The selected design discharge is 4 or 5 m3/s/km2. For non-steady flow calculations in sewer systems an inflow profile has to be provided. The prof ileshould be peaked. The most common location of the peak lies between 20 and 50% of the event duration. The return period of the profile has to be known. A bivariate extreme value distribution is used to estimate this return period. From these distributions synthetic inflow profiles could be calculated.

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Impact of Scene Content on High Resolution Video Quality

Sensors ◽

10.3390/s21082872 ◽

2021 ◽

Vol 21 (8) ◽

pp. 2872

Author(s):

Miroslav Uhrina ◽

Anna Holesova ◽

Juraj Bienik ◽

Lukas Sevcik

Keyword(s):

Video Compression ◽

Spatial Information ◽

Video Quality ◽

Video Sequences ◽

Compression Efficiency ◽

Opinion Score ◽

Scene Description ◽

Two Parameters ◽

The University ◽

The Impact

This paper deals with the impact of content on the perceived video quality evaluated using the subjective Absolute Category Rating (ACR) method. The assessment was conducted on eight types of video sequences with diverse content obtained from the SJTU dataset. The sequences were encoded at 5 different constant bitrates in two widely video compression standards H.264/AVC and H.265/HEVC at Full HD and Ultra HD resolutions, which means 160 annotated video sequences were created. The length of Group of Pictures (GOP) was set to half the framerate value, as is typical for video intended for transmission over a noisy communication channel. The evaluation was performed in two laboratories: one situated at the University of Zilina, and the second at the VSB—Technical University in Ostrava. The results acquired in both laboratories reached/showed a high correlation. Notwithstanding the fact that the sequences with low Spatial Information (SI) and Temporal Information (TI) values reached better Mean Opinion Score (MOS) score than the sequences with higher SI and TI values, these two parameters are not sufficient for scene description, and this domain should be the subject of further research. The evaluation results led us to the conclusion that it is unnecessary to use the H.265/HEVC codec for compression of Full HD sequences and the compression efficiency of the H.265 codec by the Ultra HD resolution reaches the compression efficiency of both codecs by the Full HD resolution. This paper also includes the recommendations for minimum bitrate thresholds at which the video sequences at both resolutions retain good and fair subjectively perceived quality.

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