Rivers – Sites classification in studied areas

INHABIT project

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Rivers – Sites classification in studied areas

Deliverable D1d1 is dedicated to the presentation of the results of classification of investigated stream water bodies. Classifications have been obtained according to the most up to date WFD classification tools available in Italy, related to different attributes of the ecosystem, i.e. benthic macroinvertebrates community, habitat and water chemico-physical features. An important aspect of this activity is the simultaneous application of methods recently developed and included into national Italian legislation. It must be noted that it is not among the aims of INHABIT project to provide an official classification of the investigated sites, while it is intended to highlight possible problematic aspects of ecological quality definition through the analysis of classification results.
The whole set of water bodies investigated during INHABIT project is included in this activity. For Sardinia an extra set of river reaches investigated by CNR-IRSA during MICARI project (2002-2004) is also included, extending the demonstration exercise to a more complex reality characterized by a relatively high number stations, in few water bodies, sampled in three different seasons.

Sardegna – Macroinvertebrati
Sardegna – Habitat e Chimico-fisica
Sardegna – Macroinvertebrati
Sardegna – Macroinvertebrati
Sardegna – MacroinvertebratiSardegna – Habitat e Chimico-fisicaPiemonte – Macroinvertebrati
Piemonte – Habitat e Chimico-fisica

The difficulty in the attribution of the sites to a defined category of water persistence has been one of the main issues related to sites classification in Sardinia. In this area some discrepancies were observed between the conditions expected by regional water body types (obtained through the application of a model) and the state of water observed on the field. Such complex situation can have potential consequences on classification results, since it is possible to obtain classification values more adequate to the observed conditions by assigning the considered water body to a different river type (i.e. using different reference conditions for classification).

Classification results have confirmed some of the requirements of the INHABIT experimental plan, that has considered the selection of water bodies not affected by water pollution but showing morphological and habitat degradation to a wide range of extent. IQH index (synthetic index of habitat quality) generally showed a good correspondence to biological classification (macroinvertebrates), when chemico-physical water conditions were not altered (e.g. in few cases of Piedmont region, HER06).

Sites classification according to benthic macroinvertebrates ranges from High to Moderate status in Sardinia, High to Good (in few cases only) in Piedmont HER01 and from High to Bad in Piedmont HER06. Considering separately classifications obtained for pool and riffle (where present), similar results were obtained in the two mesohabitats. Where discrepancies in classification of the two mesohabitats were observed, these could be explained as a possible different sensitivity of the two mesohabitats to the type of alteration, related to the different aspects of habitat quality (morphology, aquatic habitats and land use).

Example of water body classification trough different options of combining sampling stations information

Deliverable D1d1 presents (par. 3.4) an example of possible combinations of information collected in the different river reaches included in a given water body. It is shown how such different alternatives can lead to different assessments of the water body quality, with potential effects on the overall evaluation of the ecological status. The example is related to streams included in the Mulargia basin (Sardinia). The example considers the following options: i) inclusion or exclusion in the monitoring activity of small or very small sized streams and ii) consideration of one or more sampling stations within the water body. When more than one station is considered, classification of the water body is assigned according to the weighted average of the values obtained for the different reaches/stations.
The observed variability in the classification of the sites within the same water body do suggest some considerations about the number of sampling stations to be selected and their positioning along the water body. If such variability is related to an actual variation in the anthropic pressures within the river basin, it could be appropriate, in particular for the purpose of the surveillance monitoring, to perform the monitoring in different reaches of the water bodies or to change the location of the sampling station over time, e.g. in different monitoring cycles or seasons.