- interannual_variation(series, normalize=True)#
Interannual variation after Martens et al. .
- Return type
The average between the range in annually averaged 3 highest monthly groundwater heads and the range in annually averaged 3 lowest monthly groundwater heads.
Inter-yearly variation of high and low water table (y):
y = ((max_HW - min_HW) + (max_LW - min_LW)) / 2
Warning: In this formulating the water table is references to a certain datum and positive, not as depth below the surface!