Progress: Selection of sampling sites

For the development of an ecological river assessment system it is necessary to examine a sequence of sampling sites impaired differently heavily (gradient of impairment). Therefore, a pre-classification method was developed in advance to evaluate different river reaches, and consequently to choose the final set of sampling sites for the development of the assessment system.

The method contains a rapid field tool that is quickly applicable in the field. It is a step-by-step procedure with combined abiotic (e.g., smell and colour of water, presence of foam) and biotic (e.g., number of species) features to easily estimate impacts on a river reach and to assign a sampling site to five different pressure gradients ranging from reference status to bad status.

An appropriate manual was produced that describes the latter pre-classification procedure for the stressors organic pollution (industrial and public sewage) and morphological degradation due to river damming (water abstraction and residual flow). The manual also contains a descriptive scheme derived from the classical saprobic approach. For this purpose the saprobic water quality classes were equated with the ecological status classes. Hence, for the pre-classification two tools were available:

The method was extensively tested in the field and adapted to the environmental conditions of the partner countries before it was applied to select ASSESS-HKH candidate sites.

How many samples were taken?

A set of at least 17 sites were sampled per stream type in each country: 4 high quality (reference), 4 good, 3 moderate, 3 poor and 3 bad. In addition, each set of sites was sampled in two seasons: post-monsoon (Nov/Dec 2005) and pre-monsoon (Apr/Mar 2006). The final site selection had to be revised for most stream types, as sites of all targeted ecological status were not always available and accessible. This resulted in a deviation from the originally planned pre-selection scheme 4-4-3-3-3. However, in most cases different countries that are sharing the same stream type supplemented each other. Altogether 390 samples were taken.

1. Eastern Himalayan Broadleaf Forests (IM0401) 1717  
2. Himalayan Subtropical Pine Forests (IM0301) 17171925
3. Western Himalayan Broadleaf Forests (IM0403)    17
4. Gangetic Plains Moist Deciduous Forests (IM0120 Lower Gangetic Plains, IM0166 Upper Gangetic Plains)34 1718 

» Detailed list of sampling sites


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