The document summarizes an experimental project to determine optimal minimum instream flows in Aosta Valley rivers. The project involved monitoring the impacts of different flow levels on 77 monitoring stations across the river network. Results showed hydromorphological indicators were most responsive to hydropower pressures. While technical factors are considered, the role of public administrators in water protection is also essential for determining minimum vital flows.

1. Experimental releases to determine
scenarios of optimal Minimum Instream
Flow in Aosta Valley river network
Project Final Meeting
Aosta, Italy– 24th May 2012
Raffaele Rocco
Dipartimento Difesa del Suolo e Risorse Idriche
5/30/2012

4. Annual average flow remaining in a
watercourse as a result of lead

5. The regional plan for
water protection
approved in 2006 has
required that any
derivation of water
(new or existing) was
released a range of
minimum vital flow to
be determined on the
hydrology criteria or
experimentally

6. The experiment involves the 28 main branches
of the CVA group: 10 on Dora Baltea

7. 18 on tributary streams of Baltea

8. CRITERIO SPERIMENTALE DI CALCOLO DEL DMV
The basins have been grouped into 4 areas chosen on the
basis of geographical, climatic, hydro-morphological,
human and tourist-recreational special intertessi

9. The experiment comprises a step of
characterization of the area involved
and subjected to pressures for decades
due to the hydroelectric derivations
reference against which to compare and
evaluate the responses related to the
release ecosystem in the river bed.

10. With the monitoring activity of 2011
were measured impacts on the water
course of three levels of flow (2/3%,
10%, 13% of the annual average flow)
in some basins sample taken as
representative of the situations present
in the region, while for all other lead
has worked with a release of around
2% -3% of the annual average flow.
The stations are 77 monitoring stations
covering nearly 80% of the Aosta
Valley.

11. They are measurements of the
following:
• LIM, IBE, pH, flow, turbidity,
temperature and IFF (all sections);
• The detail information of the
hydromorphology of significant parts
of the river system under
consideration;
• As regards the fishes are carried out
in 22 sampling stations

12. At present, taking into account the
human factors, the current Minimum
Instream Flow issued and limiting
natural at higher altitudes, we would
have about a 75% achievement of the
good evaluated with only the chemical
and biological indices.
With an adjustment of discharges
having established production losses is
expected that only 5% of the points
would not be consistent.

13. CONCLUSIONI
Hydromorphological indicators seem to
be the most responsive to the pressures
of hydropower
The minimum vital flow can not be
resolved solely by technical
The role of the programming practices
of public admistrators is essential in a
framework of principles of water
protection

14. THANK YOU FOR
YOUR ATTENTION