Hydrologic parameters used in the indicators of hydrological alteration (IHA) and their grouping definition and abbreviation. Adapted from IHA Manual (Nilsson & Berggren 2000)
| IHA statistics group . | Hydrologic parameters . | Abbreviated name . |
|---|---|---|
| Group 1: Magnitude of monthly water conditions (12 indices) | Mean value for January | January |
| Mean value for February | February | |
| Mean value for March | March | |
| Mean value for April | April | |
| Mean value for May | May | |
| Mean value for June | June | |
| Mean value for July | July | |
| Mean value for August | August | |
| Mean value for September | September | |
| Mean value for October | October | |
| Mean value for October | October | |
| Mean value for December | December | |
| Group 2: Magnitude and duration of annual extreme water conditions (12 indices) | Annual minima 1-day means | 1-day min |
| Annual minima 3-day means | 3-day min | |
| Annual minima 7-day means | 7-day min | |
| Annual minima 30-day means | 30-day min | |
| Annual minima 90-day means | 90-day min | |
| Annual maxima 1-day means | 1-day max | |
| Annual maxima 3-day means | 3-day max | |
| Annual maxima 7-day means | 7-day max | |
| Annual maxima 30-day means | 30-day max | |
| Annual maxima 90-day means | 90-day max | |
| Base flow index | Base flow | |
| Number of zero flow days | Zero flow days | |
| Group 3: Timing of annual extreme water conditions (2 indices) | Julian date of each annual,1-day maximum | Date min |
| Julian date of each annual,1-day minimum | Date max | |
| Group 4: Frequency and duration of high and low pulses (4 indices) | Number of low pulses within each water year | Lo pulse # |
| Mean or median duration of low pulses (days) | Lo pulse L | |
| Number of high pulses within each water year | Hi pulse # | |
| Mean or median duration of high pulses (days) | Hi pulse L | |
| Group 5: Rate and frequency of water condition changes (3 indices) | Rise rates: Mean or median of all positive differences between consecutive daily values | Rise rate |
| Rise rates: Mean or median of all negative differences between consecutive daily values | Fall rate | |
| Number of hydrologic reversals | Reversals |
| IHA statistics group . | Hydrologic parameters . | Abbreviated name . |
|---|---|---|
| Group 1: Magnitude of monthly water conditions (12 indices) | Mean value for January | January |
| Mean value for February | February | |
| Mean value for March | March | |
| Mean value for April | April | |
| Mean value for May | May | |
| Mean value for June | June | |
| Mean value for July | July | |
| Mean value for August | August | |
| Mean value for September | September | |
| Mean value for October | October | |
| Mean value for October | October | |
| Mean value for December | December | |
| Group 2: Magnitude and duration of annual extreme water conditions (12 indices) | Annual minima 1-day means | 1-day min |
| Annual minima 3-day means | 3-day min | |
| Annual minima 7-day means | 7-day min | |
| Annual minima 30-day means | 30-day min | |
| Annual minima 90-day means | 90-day min | |
| Annual maxima 1-day means | 1-day max | |
| Annual maxima 3-day means | 3-day max | |
| Annual maxima 7-day means | 7-day max | |
| Annual maxima 30-day means | 30-day max | |
| Annual maxima 90-day means | 90-day max | |
| Base flow index | Base flow | |
| Number of zero flow days | Zero flow days | |
| Group 3: Timing of annual extreme water conditions (2 indices) | Julian date of each annual,1-day maximum | Date min |
| Julian date of each annual,1-day minimum | Date max | |
| Group 4: Frequency and duration of high and low pulses (4 indices) | Number of low pulses within each water year | Lo pulse # |
| Mean or median duration of low pulses (days) | Lo pulse L | |
| Number of high pulses within each water year | Hi pulse # | |
| Mean or median duration of high pulses (days) | Hi pulse L | |
| Group 5: Rate and frequency of water condition changes (3 indices) | Rise rates: Mean or median of all positive differences between consecutive daily values | Rise rate |
| Rise rates: Mean or median of all negative differences between consecutive daily values | Fall rate | |
| Number of hydrologic reversals | Reversals |