|WORLD METEOROLOGICAL ORGANIZATION||
|Explanation of the criteria for classification and numbering of components||
|Explanation of the dates on the component's description|
ALLOWANCE FOR DISCRETIZATION IN HYDROLOGICAL AND ENVIRONMENT RISK ESTIMATION
1. Purpose and objectives
To examine how environmental data discretization (such as averaging rainfall over particular time steps) affects risk assessment for extreme events.
This report looks at the effect of data discretization on the
estimation of period maxima. Particular reference is made to rainfall
extremes where underestimation errors can be significant. A correction
The report sets out the problem and gives an historical overview. The theory is examined and the methodology used in the study is described along with the proposed correction model. There is a detailed examination of hourly rainfall data leading to the derivation of correction factors for rainfall maxima occurring over periods of from one to 32 hours. A comparison between these and similar factors for wind speed and air temperature are given and a link to fractals is suggested.
A comparison is made between results from hourly and non-hourly rainfall data. Other investigations incidental to the study which proved to be of interest are included. Appendices contain technical details and information about the data records used in the study.
The report makes practical recommendations on correcting for discretization in data for rainfall and other environmental variables.
5. Operational requirements and restrictions
6. Form of presentation
A report in English of 45 pages with 18 tables and 36 figures.
7. Operational experience
The methodology was applied to numerous sites in the UK, Australia and South Africa.
8. Originator and technical support
Institute of Hydrology, UK.
This report is available as a HOMS component free of charge from the
Centre for Ecology and Hydrology, formerly the Institute of Hydrology,
Wallingford, Oxon OX10 8BB, UK.
10. Conditions on use
|(First entered: DEC 96||
Last updated: DEC 96)