CEN/TR 16469:2013
(Main)Hydrometry - Measurement of the rainfall intensity (liquid precipitation): requirements, calibration methods and field measurements
Hydrometry - Measurement of the rainfall intensity (liquid precipitation): requirements, calibration methods and field measurements
This Technical Report describes a method for calibrating rainfall intensity (RI) gauges and the measurement requirements to obtain accurate and compatible data sets from hydro-meteorological networks, as a forerunner to the development of full hydro-meteorological data collection standards.
This Technical Report deals exclusively with catching-type RI gauges (see Clause 3). It concentrates on the generic calibration, performance checking and estimation of uncertainties for RI gauges. It does not cover specific gauge measurement principles, technical characteristics and technology adopted in the design of RI gauges.
Hydrometrie - Messung der Regenintensität (flüssiger Niederschlag): Anforderungen, Kalibrierverfahren und Feldmessungen
Dieser Technische Bericht beschreibt ein Verfahren zur Kalibrierung von Geräten zur Messung der Regenintensität und legt die Messanforderungen fest, um genaue und kompatible Datensätze aus hydrometeorologischen Netzwerken zu erhalten, und stellt einen Vorläufer für die Entwicklung von vollwertigen Normen zur Sammlung hydrometeorologischer Daten dar.
Dieser Technische Bericht behandelt ausschließlich auffangende Regenmesser (siehe Abschnitt 3). Er konzentriert sich auf die generische Kalibrierung, die Überprüfung der Leistungsfähigkeit und die Abschätzung von Messunsicherheiten von Regenmessern. In diesem Technischen Bericht nicht behandelt werden spezielle Messprinzipien von Regenmessern, technische Eigenschaften und bei der Konstruktion von Regen-intensitätsmessern angewendete Verfahren.
Mesurage de l'intensité pluviométrique (précipitations liquides) : exigences, méthodes d'étalonnage et mesures de terrain
Hidrometrija - Merjenje intenzivnosti padavin (tekoče padavine): zahteve, kalibracijske metode in terenske meritve
V tem tehničnem poročilu so opisane kalibracijska metoda za kontrolnike intenzivnosti padavin (RI) in merilne zahteve za pridobivanje točnih in združljivih nizov podatkov iz hidrometeoroloških mrež, kot predhodnik razvoja standardov za popolno zbirko hidrometeoroloških podatkov. To tehnično poročilo obravnava izključno kontrolnike intenzivnosti padavin s posodo za zbiranje padavin (glej točko 3). Osredotočeno je na splošno kalibracijo, preverjanje delovanja in oceno negotovosti za kontrolnike intenzivnosti padavin. Ne vključuje načel merjenja za specifične kontrolnike, tehničnih lastnosti in tehnologije, ki so del načrtovanja kontrolnikov intenzivnosti padavin.
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
01-maj-2013
+LGURPHWULMD0HUMHQMHLQWHQ]LYQRVWLSDGDYLQ WHNRþHSDGDYLQH ]DKWHYH
NDOLEUDFLMVNHPHWRGHLQWHUHQVNHPHULWYH
Hydrometry - Measurement of the rainfall intensity (liquid precipitation): requirements,
calibration methods and field measurements
Hydrometrie - Messung der Regenintensität (flüssiger Niederschlag): Anforderungen,
Kalibrierverfahren und Feldmessungen
Mesurage de l'intensité pluviométrique (précipitations liquides) : exigences, méthodes
d'étalonnage et mesures de terrain
Ta slovenski standard je istoveten z: CEN/TR 16469:2013
ICS:
07.060 Geologija. Meteorologija. Geology. Meteorology.
Hidrologija Hydrology
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
TECHNICAL REPORT
CEN/TR 16469
RAPPORT TECHNIQUE
TECHNISCHER BERICHT
January 2013
ICS 07.060
English Version
Hydrometry - Measurement of the rainfall intensity (liquid
precipitation): requirements, calibration methods and field
measurements
Mesurage de l'intensité pluviométrique (précipitations Hydrometrie - Messung der Regenintensität (flüssiger
liquides) : exigences, méthodes d'étalonnage et mesures Niederschlag): Anforderungen, Kalibrierverfahren und
de terrain Feldmessungen
This Technical Report was approved by CEN on 27 November 2012. It has been drawn up by the Technical Committee CEN/TC 318.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United
Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2013 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TR 16469:2013: E
worldwide for CEN national Members.
Contents Page
Foreword .3
1 Scope .5
2 Normative references .5
3 Terms and definitions .5
4 Standardization of RI raingauge calibration and field requirements .7
5 Accuracy of rainfall intensity .7
5.1 Fundamentals and requirements .7
5.2 Laboratory calibration method (constant flow and step response) .8
5.3 Classification of gauges according to accuracy performances .9
5.4 Field calibration method (calibration verification) .9
5.5 Traceability of the RI measurements . 10
6 Field rainfall intensity measurements . 10
6.1 References gauges and field intercomparisons . 10
6.2 Relevant operational requirements for field RI measurements . 10
th
6.3 General requirements for siting and exposure (as indicated by WMO-No. 8, 7 edition) . 11
6.4 International field intercomparisons: role and outcomes . 12
Annex A (informative) Laboratory tests . 13
Annex B (informative) Field measurements . 17
Foreword
This document (CEN/TR 16469:2013) has been prepared by Technical Committee CEN/TC 318
“Hydrometry”, the secretariat of which is held by BSI.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
The Executive Council of the WMO, noting the working arrangements between the ISO and WMO formally
adopted on 16 September 2008, recognised the wide ranging benefits to National Meteorological and
Hydrological Services and user communities resulting from the implementation of common Standards relevant
for meteorology and hydrology and the need to established the benefit/cost implication to WMO Members of
elevating an existing Technical Regulation/Manual/Guide to a common Standard. The EC finally approved
procedures to be followed in proposing common technical standards (Resolution 8, Abridged Final Report of
the sixty-first session of the WMO Executive Council).
This document is not a European Standard but a Technical Report. It is a document to describe recent
findings in rainfall intensity (RI) measurements and related accuracy aspects, following the results and
outcomes of the most recent international RI gauges intercomparison organised by the World Meteorological
Organisation (WMO). The Technical Report also provides informative documentation (in annexes) containing
methods for laboratory calibrations, field tests and reference field measurements.
In consideration of the requirement for general standardization and homogeneity of precipitation intensity
measurements and the need for instruments development to promote worldwide instrument compatibility and
interoperability, the WMO Lead Centre on Precipitation Intensity “B. Castelli” (Italy) has been designated by
the WMO Commission of Instruments and Methods of Observation (CIMO General Summary of the fifteen
Session, Helsinki, Finland, 2 - 8 September 2011). The Lead Centre is intended as a Centre of Excellence for
instrument development and testing which would be established with the purpose of providing the scientific
community with specific guidance and standard procedures about instrument calibration and their achievable
uncertainty, performing laboratory and field tests and the intercomparison of instruments, and providing
research advances and technical developments about the measurement of precipitation intensity and the
related data analysis and interpretation.
Introduction
The need for, and the importance of accurate and reliable rainfall intensity (RI) measurements is ever
increasing. This is the result of a number of factors, including the increased recognition of scientific and
practical issues related to the assessment of possible climatic trends, the mitigation of natural disasters (e.g.
storms and floods), the slowing down of desertification and the design of structures (buildings, construction
works) and infrastructure (drainage). This has resulted in more rigorous and enhanced quality requirements
for RI measurements.
The volume of rainfall received by a collector through an orifice of known surface area in a given period of
time has traditionally been adopted as the reference variable, namely the rainfall depth. Under the restrictive
hypothesis that rainfall is constant over the accumulation period, a derived variable, “the rainfall rate, or
intensity (RI)”, can be calculated. The estimated RI should get closer to the actual flow of water ultimately
reaching the ground as the recording time interval decreases. In view of the very high variability of RI, field
measurements at short time scales (e.g. 1 min) are crucial to enable high quality measurement be taken to
mitigate the impact of severe events and save lives, property and infrastructures. As the probability of heavy
rainfall events is small, long-term records of RI are required to estimate the frequency of occurrence of very
intense rainfall at a given location and time.
On completion of the most recent RI gauges intercomparison organised by the World Meteorological
Organisation (WMO), it has been recommended that RI measurements should be covered by International
Standards. These standards should be based on the knowledge obtained from those latest WMO
intercomparison and other current research and good practice. The adoption of such an approach will assist
rainfall data collection practitioners to obtain homogeneous and compatible data sets. The procedure adopted
for performing calibration tests in the laboratory should become a standard method to be used for assessing
the instruments’ performance. Acceptance tests could be based on the adopted laboratory procedures and
standards. A classification of instrument performance should also be developed to help users in selecting the
most appropriate instrument for their applications.
1 Scope
This Technical Report describes a method for calibrating rainfall intensity (RI) gauges and the measurement
requirements to obtain accurate and compatible data sets from hydro-meteorological networks, as a
forerunner to the development of full hydro-meteorological data collection standards.
This Technical Report deals exclusively with catching-type RI gauges (see Clause 3). It concentrates on the
generic calibration, performance checking and estimation of uncertainties for RI gauges. It does not cover
specific gauge measurement principles, technical characteristics and technology adopted in the design of RI
gauges
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
EN 13798, Hydrometry – Specification for a reference raingauge pit
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
catching raingauge
a raingauge which collects precipitation through an orifice, often a funnel, of well-defined size and measure its
water equivalent, volume, mass or weight that has been accumulated in a certain amount of time
Note 1 to entry: This type of gauge includes storage, level monitoring, tipping bucket and weighing raingauges. This is
the most common type of recording raingauge in use in operational networks at the time of preparing this Technical
Report.
3.2
delay time of the output of a RI measuring gauge
delay of the output message of some RI measuring raingauges
Note 1 to entry: The internal calculation of the rainfall intensity in some raingauges can cause a delay of the output
data message (e.g. 1 minute) which can easily be shifted automatically to the correct time without any degradation in
measurement accuracy. This is typical of software corrected tipping bucket raingauges through embedded electronic chips
or interfaces. The delay time should not be confused with the time constant. If real-time output is not needed, software
induced delay times are less critical than longer time constants or any other effects, because delay times can easily be
corrected to retrieve the original RI information.
[SOURCE: Adapted from WMO – IOM 2009]
3.3
measurand
quantity intended to be measured
[SOURCE: VIM:2008]
3.4
measurement uncertainty
non-negative parameter characterizing the dispersion of the quantity values being attributed to a measurand,
based on the information used
[SOURCE: VIM:2008]
Note 1 to entry: The parameter may be, for example, a standard deviation called standard measurement uncertainty
(or a specified multiple of it), or the half-width of an interval, having a stated coverage probability.
Note 2 to entry: Measurement uncertainty comprises, in general, many components. Some of these may be evaluated
by Type A evaluation of measurement uncertainty from the statistical distribution of the quantity values from series of
measurements and can be characterised by standard deviations. The other components, which may be evaluated by Type
B evaluation of measurement uncertainty, can also be characterised by standard deviations, evaluated from probability
density functions based on experience or other information:
a) Instrumental measurement uncertainty (VIM 2008): component of measurement uncertainty arising from a measuring
instrument or measuring system in use.
Instrumental measurement uncertainty is obtained through calibration of a measuring instrument or measuring
system, except for a primary measurement standard for which other means are used.
Instrumental uncertainty is used in a Type B evaluation of measurement uncertainty.
Information relevant to instrumental measurement uncertainty may be given in the instrument specifications.
b) Achievable measurement uncertainty (WMO no. 8, Part I Annex 1.B): it is intended as the measurement uncertainty
achievable in field and/or operational conditions.
3.5
non-catching raingauge
raingauge where the rain is not collected in a container/vessel
Note 1 to entry: The rainfall intensity or amount is either determined by a contact-less measurement using optical or
radar techniques or by an impact measurement. This type of gauge includes optical disdrometers, impact disdrometers,
microwave radar disdrometers, optical/capacitive sensors.
3.6
resolution
smallest change in a quantity being measured that causes a per
...
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