IHA Parameter Group Hydrologic Parameters
1. Magnitude of monthly water conditions Mean value for each calendar month: Mean flow in January; Mean flow in February; Mean flow in March; Mean flow in April; Mean flow in May; Mean flow in June; Mean flow in July; Mean flow in August; Mean flow in September; Mean flow in October; Mean flow in November; Mean flow in December
2. Magnitude and duration of annual extreme water conditions 1-day minimum;3-day minimum; 7-day minimum; 30-day minimum; 90-day minimum; 1-day maximum; 3-day maximum; 7-day maximum; 30-day maximum; 90-day maximum; Base flow index (7-day minimum flow/mean flow for year)
3. Timing of annual extreme water conditions
Day of year of each annual 1-day maximum: Date of minimum; Day of year of each annual 1-day minimum: Date of maximum;
4. Frequency and duration of high and low pulses
Number of low pulses within each water year: Low pulse count; Mean or median duration of low pulses (days): Low pulse duration; Number of high pulses within each water year: High pulse count; Mean or median duration of high pulses (days) High pulse duration
5. Rate and frequency of water condition changes
Mean of all positive differences between consecutive daily values: Rise rates; Mean of all negative differences between consecutive daily values: Fall rates; Number of hydrologic reversals: Numbers of reversals