| Fundamental to the spatial sampling design of a groundwater quality monitoring
network is the spatial structure of groundwater quality variables. The entropy theory
presents an alternative approach to describe this variability. A case study is presented
which used groundwater quality observations (13 years; 1987-2000) from groundwater domestic
wells in the Gaza Strip, Palestine. The analyses of the spatial structure used the
following variables: Electrical Conductivity (EC), Total Dissolved Solids (TDS),
Calcium (Ca), Magnesium (Mg), Sodium (Na), Potassium (K), Chloride (Cl), Nitrate
(NO3), Sulphate (SO4), alkalinity and hardness. For all these
variables the spatial structure is described by means of Transinformation as a function
of distance between wells (Transinformation Model) and correlation also as a function of
distance (Correlation Model). The parameters of the Transinformation Model analysed were:
(1) the initial value of the Transinformation; (2) the rate of information decay; (3) the
minimum constant value; and (4) the distance at which the Transinformation Model reaches
its minimum value. Exponential decay curves were fitted to both models. The
Transinformation Model was found to be superior to the Correlation Model in representing
the spatial variability (structure). The parameters of the Transinformation Model were
different for some variables and similar for others. That leads to a reduction of the
variables to be monitored and consequently reduces the cost of monitoring.
Keywords: transinformation, correlation, spatial structure, municipal wells, groundwater
monitoring, entropy |