A method for temporally determining a maximum allowable water volume that can be withdrawn from a groundwater source, said water volume being withdrawn at a withdrawal point and the hydrogeological state of the groundwater source being qualified by piezometric height measurements on a reference piezometer, said method being characterised in that it comprises the following steps: a) continuously measuring, by a first level sensor, piezometric heights on the withdrawal point, said sensor having a first available data history over a predetermined past period; b) continuously measuring, by a second level sensor, piezometric heights on the reference piezometer, said second sensor having a second available data history over the predetermined past period; said method further comprising the following steps implemented by a computing machine: c) processing the data from the first level sensor to create a chronicle of pseudo-static piezometric heights and a chronicle of dynamic piezometric heights over the predetermined past period; d) determining a drawdown chronicle at the withdrawal point over said predetermined past period, a drawdown being defined as the difference, at a given instant, between the pseudo-static piezometric height and the dynamic piezometric height; e) determining apparent transmissivity values at the withdrawal point, allowing to better reproduce the chronicle of drawdowns determined over said predetermined past period, using the Cooper-Jacob analytical relationship in order to associate an apparent transmissivity value with different classes of said pseudo-static piezometric heights, the association constituting a first relationship; f) determining a critical operating level at said withdrawal point; g) selecting a reference piezometer having piezometric height measurements over said predetermined past period; h) computing temporal averages of said pseudo-static piezometric heights and piezometric heights measured on the reference piezometer over said predetermined past period; i) determining a second relationship between said temporal averages of said pseudo-static piezometric heights and the temporal averages of said piezometric heights measured on the reference piezometer over said predetermined past period; j) determining a maximum allowable drawdown for each pseudo-static piezometric height value, a maximum allowable drawdown being defined as the difference between a pseudo-static piezometric height and said critical operating level; k) determining the maximum allowable volume that can be withdrawn from said groundwater source withdrawn at said withdrawal point using the Cooper-Jacob relationship and said first and second relationships. a) continuously measuring, by a first level sensor, piezometric heights on the withdrawal point, said sensor having a first available data history over a predetermined past period; b) continuously measuring, by a second level sensor, piezometric heights on the reference piezometer, said second sensor having a second available data history over the predetermined past period; c) processing the data from the first level sensor to create a chronicle of pseudo-static piezometric heights and a chronicle of dynamic piezometric heights over the predetermined past period; d) determining a drawdown chronicle at the withdrawal point over said predetermined past period, a drawdown being defined as the difference, at a given instant, between the pseudo-static piezometric height and the dynamic piezometric height; e) determining apparent transmissivity values at the withdrawal point, allowing to better reproduce the chronicle of drawdowns determined over said predetermined past period, using the Cooper-Jacob analytical relationship in order to associate an apparent transmissivity value with different classes of said pseudo-static piezometric heights, the association constituting a first relationship; f) determining a critical operating level at said withdrawal point; g) selecting a reference piezometer having piezometric height measurements over said predetermined past period; h) computing temporal averages of said pseudo-static piezometric heights and piezometric heights measured on the reference piezometer over said predetermined past period; i) determining a second relationship between said temporal averages of said pseudo-static piezometric heights and the temporal averages of said piezometric heights measured on the reference piezometer over said predetermined past period; j) determining a maximum allowable drawdown for each pseudo-static piezometric height value, a maximum allowable drawdown being defined as the difference between a pseudo-static piezometric height and said critical operating level; k) determining the maximum allowable volume that can be withdrawn from said groundwater source withdrawn at said withdrawal point using the Cooper-Jacob relationship and said first and second relationships.