Extraction methods Criterion Minimum recession length (days) Excluding exterior parts of recession segment Exclusion of anomalous recession decline
Kir \(dQ/dt<0\) 1
Vog Decreasing 3-d moving average 10 First 30% \(\frac{\left(Q_{i}-Q_{i+1}\right)}{Q_{I+1}}>30\%\)
Bru \(dQ/dt<0\) 6–7 First 3—4, last 2 \(\frac{dQ_{t+1}}{\text{dt}}>\frac{dQ_{t}}{\text{dt}}\)
Aks \(dQ/dt<0\) 5 First 2 CV > 0.20