pastas.stats.dutch.q_gvg
========================

.. py:function:: pastas.stats.dutch.q_gvg(series: pandas.Series, tmin: pandas.Timestamp | str | None = None, tmax: pandas.Timestamp | str | None = None, by_year: bool = True) -> pandas.Series

   
   Gemiddeld Voorjaarsgrondwaterstand (GVG) also called MSGL (Mean Spring GW Level).

   :param series: Series to calculate the GVG for.
   :type series: pandas.Series
   :param tmin: A string or pandas.Timestamp with the start and end dates for the
                period (E.g. '1980-01-01 00:00:00' and '2020-01-01 00:00:00').
   :type tmin: pandas.Timestamp or str, optional
   :param tmax: A string or pandas.Timestamp with the start and end dates for the
                period (E.g. '1980-01-01 00:00:00' and '2020-01-01 00:00:00').
   :type tmax: pandas.Timestamp or str, optional
   :param by_year: Take average over quantiles per year (default True)
   :type by_year: bool, optional

   .. rubric:: Notes

   Approximated by taking the median of the values in the period between 14 March
   and 15 April (after resampling to daily values). This function does not care
   about series length!















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