INHABIT project

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Home Themes & Results Innovative measures (I3) New measures and ecological quality

Rivers – Proposal of new measures for ecological quality restoration

INHABIT has provided guidelines on what aspects have to be considered for habitat improvement, in terms of selection of potential reference sites and features to be preserved when river management actions are planned. In general, it was emphasized that any measures related to banks are more applicable than  interventions affecting the territory beyond the banktop. On this basis, and considering the actual feasibility of the measure, the best option to determine a significant improvement in the diversification of habitats (e.g. as quantified by HQA descriptor) involves the removal of non-natural features related to land use, coupled with the insertion of features typical of reference conditions. Among the possible suggested actions, reduction of bank and channel resectioning, if accompanied by recovery of naturalness (which could occur as a passive restoration), is a measure that would have a significant effect in reducing morphological alteration (reduction I values of  HMS descriptor) and increasing habitat diversity (increased values of HQA), effective to improve the ecological status, as detected by macrobenthic biotic communities.
INHABIT project has also provided some innovative elements to evaluate, in river ecosystems, the effects of discharge reduction – also as a consequence of water abstraction – on biocoenoses. In general, one can be led to believe that, at least the mountain area, biological methods are unable to detect the effects of morphological alterations and flow reduction due to water abstraction. In reality, INHABIT has demonstrated how this perception is caused by the results of the commonly used indices, which, if interpreted in the ordinary way, are not able to provide useful information in this regard. However, the use of dedicated metrics (for morphological alteration) coupled with habitat information (for the impact of water abstraction) can provide an efficient evaluation of possible adverse effects on biotic communities.
On this regard, the analysis of the lentic-lotic character can once again provide key indications. INHABIT has shown that, for example in the Alps, the reduction in flow (caused for instance by water abstraction) could result in an increase of LRD values (e.g. from negative to neutral), resulting in an apparent "improvement" of the ecological quality, in fact corresponding to a strong alteration of biotic communities, clearly detectable in the presence of information on the lentic - lotic character. In the latter case, many biological metrics show an increase moving from high stress environment (very negative values, i.e. lotic and strong stress on aquatic communities) for many aquatic organisms to a more favorable environment, with a higher number of taxa (including not only taxa colonizing high turbulence areas). In this case, the – obvious – biological response is moving in a direction that we, conventionally, are used to associate with an "improvement" of the state of the environment. In this specific case, however, retaining a "conventional"  vision of the problem we are overlooking WFD conceptual framework,  requiring the evaluation of a "change", not necessarily an increase or a decrease. In this case, given the peculiarities of the impact - whose effects mimic natural situations - it is always necessary to carry out further investigations.
INHABIT has also allowed – with particular reference to Sardinia and by using regression models LRD / STAR_ICMi – a quantification of the amount of water releases, correspondent to the so-called Environmental or Ecologic flows. In facing the problem of definition of ecological acceptable discharges, environmental objectives from both quantitative and qualitative point of view has been considered for biocoenoses (in terms of STAR_ICMi) and habitat. Possible reductions in discharge, observed in comparison to expected natural conditions should allow habitat quantity and quality preservation; also flow reductions should not alter in a significant way  the proportion between lentic and lotic habitats (i.e. lentic-lotic character), expected for a given water body in a natural condition.
Detail information regarding this activity is presented in Deliverable I3d1 (paper .5, in Italian) and I3d4_EN (in English).