Title: Biological River Quality Map 1994 and Land Drainage Byelaws 1981
Author: Tessa Wardley
Document Type: Monograph
Abstract:
This report is written specifically to accompany the water quality map produced annually for the Thames catchment. The aims are: 1) To clarify the biological status of watercourses in the region as shown in the map and analyse the distribution of water quality; 2) To provide information on the location of the extremes of biological quality at the regional, area, sub-catchment and reach scales; 3) To highlight individual catchments and sites where changes are occurring, where possible with likely reasons. The report analyses all the data collected as part of the routine biological surveys of the regions rivers and streams. Where more than one sample was taken at a site the highest BMWP score was recorded. For some of the stretches that are represented on the map no sample was taken in 1994, in these cases the results from the 1993 survey were used as an indication of the water quality of the river stretch and data from the previous sampling occasion were used for comparison. Those stretches which exhibited class changes or unusual score value changes over the last two sampling occasions were examined over a longer time scale to observe whether the change was a long term trend rather than relating to sampling error or temporary conditions. The methods for analysis are explained in more detail in sections 1.4.0 to 1.6.0.
Publisher: National Rivers Authority
Publication Date: 1994
Publication Place: Reading
Subject Keywords: Rivers; Drainage; Byelaws; Water quality surveys; Maps; Biological indicators; Catchment basins
Geographic Keywords: EA South East; Thames
Extent: n.p. [90]
Permalink: http://www.environmentdata.org/archive/ealit:3245
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