Table 2.

Indicators of hydrological alteration (IHA) in the range of variability approach.

IHA Group	Hydrological Indicators
Group 1: Magnitude of monthly water conditions	Mean value for each calendar month.
Group 2: Magnitude and duration of annual extreme water conditions	Annual minima 1-day means; Annual maxima 1-day means; Annual minima 3-day means; Annual maxima 3-day means; Annual minima 7-day means; Annual maxima 7-day means; Annual minima 30-day means; Annual maxima 30-day means; Annual minima 90-day means; Annual maxima 90-day means.
Group 3: Timing of annual extreme water conditions	Julian date of each annual 1 day maximum; Julian date of each annual l day minimum.
Group 4: Frequency and duration of high and low pulses	No. of high pulses each year; No. of low pulses each year; Mean duration of high pulses within each year; Mean duration of low pulses within each year.
Group 5: Rate and frequency of water condition changes	Means of all positive differences between consecutive daily means; Means of all negative differences between consecutive daily values; Number of rises; Number of falls.