Statistical Characteristics of Ground‐Water Quality Variables

The emerging problem of contamination of ground-water resources has created a need for information which can be supplied by properly designed ground-water quality monitoring programs. The effective design of monitoring programs and the subsequent utilization of data obtained depends upon an understanding of the general statistical characteristics of ground-water quality variables. In order to provide some background information on these characteristics, a synthesis of current literature and a statistical analysis of existing ground-water quality data were conducted. Specifically, the purpose of the study was to determine whether ground-water quality variables: (1) are normally distributed, (2) exhibit seasonal patterns, and (3) are correlated in time. The results of the investigation suggest that many ground-water quality variables: are not normally distributed, but have skewed right distributions; can exhibit seasonal fluctuations of various shapes and magnitudes, especially in shallow or highly permeable aquifers; and can exhibit significant serial correlation when samples are collected quarterly.