As an alternative to modelling the recession curve
mathematically, one can derive other parameters such as the exact cap diameter for a particular seasonal date, or the maximum recession velocity, enabling comparisons over successive years.
However, conditions have changed and all economies are at one point or another on the recession curve
. And, considering the acceleration in its evolving slump as well as the troubles that are emanating out of Eastern Europe, the Euro Zone may actually be behind the curve.
In addition, by partitioning the stream discharge into the runoff and groundwater baseflow components, one can estimate the portion of the precipitation that recharges the groundwater and the portion that becomes direct runoff The application variations of the two classical groundwater recharge calculation methods based on the stream discharge, i.e., seasonal recession and recession curve displacement, are discussed for this purpose.
KEY WORDS: Precipitation, groundwater recharge, runoff, evapotranspiration, seasonal recession method, and recession curve displacement method.
Two popular, inexpensive and independent methods, which use the stream flow partition techniques, are the seasonal recession method by Meyboom (1961) and the recession curve displacement method by Rorabaugh (1964).
Based on the method of similar triangles, from the semilogarithmic hydrography recession curve (Figure 3), one could derive the discharge Q at any time of t during the recession by:
Recession Curve Displacement Method (RCDM) (or Rorabaugh Method)
The Recession Curve Displacement method by Rorabaugh (1964) identifies multiple recharge events in a recharge season or a 12-month cycle.
(10,11,12) With the recession curve it is possible to compute the ice thickness between the cap edge and the pole (for a simple procedure see Geneslay's article).
Several recession curves (R-Ls), determined from visual telescopic observations made over a period of 140 years, between 1862 and 2010, are examined here.
Equation  can therefore be used as an analytical function for the interpolation of points in recession curves. A similar formula was obtained by De Mottoni, who used a simpler exponential function of Ls.