BS EN 14184-2003 pdf download.Water quality Guidance standard for the surveying of aquatic macrophytes in running waters.
The first approach requires relatively little time and is recommended for the routine assessment of ecological status. Only the short reach of a RepS can be described, but it can be used for spatial and temporal monitoring. When defining RepS a longer stretch of a river should be surveyed first using the second approach to prove evenness” within this stretch of a) physical and b) biological variables.
The last approach fulfils more specialist needs. For example, this can be part of the procedure to find reference sites (Ref S) for different ecological river types. It Is a labour-intensive approach not to be applied for routine surveys. It is for use in special cases, e.g. single-river long-term monitoring and for detailed background information for ecological classification.
6.3 Selection of reference sites
Ecological reference conditions for each type of river need to be established before the ecological status of representative sites (RepS) can be assessed. This can be achieved either by the surveying of reference sites (RefS) or, where suitable Ref S cannot be found, by modelling or expert opinion. Reference sites should be as close as possible to natural conditions with respect to their species composition and the abundance of each species, physical and chemical variables and hydromorphological background. Usually the location of reference sites will be selected from regional or national surveys with data on species composition, distribution, and diversity of the aquatic vegetation. Appropriate statistical methods can be used to differentiate numerically, reference sites in different river reaches following the natural continuum from the source to the mouth of a running water system. The length of river surveyed for the Ref S should be of sufficient length to adequately reflect the diversity of plant species characteristic of this river type.
6.4 Selection of river reaches
Select the river reaches to be surveyed. The selection should be dictated by factors including the objectives of the survey, degree of confidence required from the data, resources and expertise available etc. These decisions should be made before the initiation of fieldwork.
Ensure that sufficient reaches of river are surveyed to enable the changes in the macrophyte assemblage due to anthropogenic factors to be distinguished from changes due to natural factors, such as differences in geology, slope or stream order, or changes in land use.
NOTE 1 To monitor specifically the impact of a point discharge, the control length should be as close upstream as practicable and yet in terms of geomorphological conditions as comparable as possible. The downstream location should be below the predicted effluent river-water mixing zone within the river or stream. The area of the mixing zone can be located by dye tracing or similar studies. Dye tracing should be undertaken under a range of flow conditions as these will influence the extent of the mixing zone in the receiving river reach.
To assist this process and the subsequent selection of representative sites, gather relevant background information on the river(s) to be surveyed. Inspecting the area on foot, examination of detailed maps. aerial photographs and investigation of any other sources of relevant information such as water quality data sets is highly recommended. Identify potential point sources of pollution such as waste water treatment plants, fish farms, centres of high population density etc.
6.5 Selection of representative sites
Within these river reaches select representative sites (RepS), which are the river lengths to be surveyed. The ecological status of the representative site (RepS) is measured in terms of the deviation of the biological quality elements at the RepS compared with the reference conditions. The number and location of sites should allow a representative flora to be recorded, reflecting the human impact within a river reach and including exposed and shaded stretches (within the resources available). Natural conditions of substrate, water depth, bank site shading, flow type, etc. should usually be similar to the conditions at the reference site, so that differences in the flora due to anthropogenic impact can be distinguished more easily from changes due to hydromorphological factors.
Structures such as bridges, gauging stations, weirs, locks, concrete channels etc. can affect substrate type. low pattern and other physical parameters. In turn these can influence aquatic macrophyte colonisation and, therefore, give rise to man-induced patterns of plant communities. Areas of river with such structures often have a higher density of macrophytes due to the lack of shading on the banks upriver and downriver of these constructions. The ecological status of these stretches of river is measured by assessing their deviation from the close to natural reference conditions.
If shaded stretches are typical for ecological types of river reaches, the sparse growth or even the total lack of aquatic vegetation shall be mapped.
Where river reaches have reference sites for other quality elements, such as reaches with dense woodland vegetation for hydromorphological quality elements, then it is reasonable to locate representative sites (RepS) for the estimation of as many quality elements as possible in the same river reach.
Where back channels and navigation channels are present within the river reaches being surveyed, the former will usually be closer to the reference condition than the latter. Where the main channel is used for boat traffic, this is likely to have an adverse impact on the macrophyte community. In this case both back and navigation channels will have to be surveyed. The deviation of the condition of both channels combined from the reference conditions will indicate the human impact on the whole river at this point. The difference between the condition of the main channel and that of the back channel will allow boating impacts to be separated from background impacts, for example of eutrophication, which will be expressed in the vegetation of the back channel.
The selection of only back channels with conditions of quality elements much closer to the natural, and thus failing to present the human impact on the main channel, would prevent a meaningful evaluation of the overall conditions. Such surveys may be acceptable, however, if the main channel is declared an artificial water body and evaluated with respect to its corresponding ecological potential.
The actual river length surveyed, the representative site (RepS), should be of sufficient length to reflect adequately the diversity of plant species characteristic for this ecological type of river reach.
The lengths of individual survey stretches need not be the same since much of the data can be compared directly by mathematical scaling. Surveyors should be aware that the number of species recorded will increase with increasing length of river surveyed.BS EN 14184-2003 pdf download.
BS EN 14184-2003 pdf download
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