LEEGRAM: a program for normalized Stiff diagrams and quantification of grouping hydrochemical data
A Fortran-coded software package, LEEGRAM, is developed for pattern recognition of subsurface hydrochemistry and quantification of grouping groundwater masses. For pattern recognition in areas with high variability in total dissolved solids (TDS), it introduces a new means of graphic representation by normalizing Stiff diagram and using concentric rings and arc to denote TDS concentration. For diagnosis of data quality, it displays charge imbalance in the normalized Stiff diagram with a combination of solid and dashed curves and questionable TDS measurement or chemical analysis with an open circular arc. It employs a newly devised concept of correlation and group indices to quantify the grouping initiated by pattern recognition. The usage of the program is demonstrated with field examples in southern California that show incursion of high-TDS water from one groundwater basin into another with low-TDS water.
stiff diagram pattern recognition hydrochemistry correlation coefficient groundwater types san jacinto river