HOMS COMPONENT

A HYDROMETRICALLY ORIENTATED STATION NUMBERING SYSTEM

1.   Purpose and objectives

     A system for determining station reference numbers for use in the storage of observational and other data from regions, countries or states, based upon river catchments and permitting the inclusion of additional stations, past and future, in their correct numerical position. The system can be used to assign numbers to all types of hydrological stations, including rain gauges and water level stations.

2.   Description

     The detail of the system is explained; guidance notes are included on factors to be taken into account when implementation is planned together with some suggestions for possible modifications to suit the hydrological characteristics of the country.

3.   Input

     Station location to an accuracy compatible with an adequately detailed, semi-permanent library of topographical maps for the area of adoption; an areal planimetering system.

4.   Output

     Station numbers in an ordered sequence permitting identification of:

     -  the stream catchment in which the site is located

     -  all other stations within that catchment, upstream or downstream

     -  all stations upstream of any defined point on a river (e.g. upstream of a river-gauging site)

     The system is suitable for manual records (e.g. card-index systems) or a computer-based readily updatable permanent archive.

5.   Operational requirements and restrictions

     Reliable topographical maps with sufficient detail to enable observational sites to be accurately located, river and stream catchment limits to be defined, capable of being planimetered to sufficient accuracy for likely density of the observing network and the total area of the region, country or state of adoption.  Master working maps need to be stored unfolded in near-stable environmental conditions.  A manual or semi-automated computer-linked planimetering facility is essential, capable of being operated (after initial local operating rules have been defined) by graduates of secondary schools, particularly with a qualification in, or a specific interest in, geography.

6.   Form of presentation

     Printed manual in English with explanatory diagrams and worked and text examples.

7.   Operational experience

     Developed 1958-60 in the United Kingdom and in operational use from 1 January 1961 for all UK Meteorological Office hydrometeorological purposes (e.g. current data, computerisation of old data, identification of station site and environmental changes affecting exposure of equipment both current and historical).

8.   Originator and technical support

     United Kingdom Meteorological Office.

9.   Availability

     From the HOMS National Reference Centre for the United Kingdom.

10.  Conditions on use

     None.

Last updated: 20 APR 90)
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