Table 1 Description of Italian river macro-types considered in this paper (modified from EC, 2018 and DM 260/2010)

A1

Pre-Alpine, small- to medium- sized, calcareous

 < 75 km

10–1000 km²

800–2500 m; boulders/cobble

High (but not extremely high) alkalinity

A2

Alpine, small- to medium-sized, high altitude, siliceous

 < 75 km

10–1000 km²

max 3000 m, mean 1500 m; boulders

Non-calcareous (granite, metamorphic) medium to low alkalinity

Nival–-glacial

A2_GH

Alpine, small-sized, high altitude, siliceous, with glaciers influence

 < 25 km

 < 150 km²

max 3000 m, mean 1700 m; boulders

Non-calcareous (granite, metamorphic) medium to low alkalinity

Nival–glacial

C1

Very small siliceous lowland rivers in the Po plain (North of the Po River)

 < 15 km

 < 15 km²

Mean ≈ 150 m; sandy to gravel

Siliceous

Spring-fed origin

C_mix

Other lowland rivers (excluding C1 and non-wadeable rivers) in the Po plain (North of the Po River)

Any

Any

Mean ≈ 200 m; sandy to gravel/ rock

Mixed

Not spring-fed

M1

Small-sized Mediterranean streams

 < 25 km

≈ < 160 km²

Any

Mixed (except siliceous)

Highly seasonal

M4

Medium-sized Mediterranean mountain (no lowlands) streams

25–75 km

≈ 160 – 760 km²

Mean ≈ 400 m/Any

Non-siliceous

Highly seasonal

M5

Temporary streams (Mediterranean region)

Any

Any

Any

Any

Temporary