THE SPATIAL AUTOCORRELATION RANGE: ESTIMATIONS OF PHYSICAL-CHEMICAL VARIABLES STUDIED AT THE CIÉNAGA GRANDE DE SANTA MARTA, NORTHERN COLOMBIA

Abstract

The spatial autocorrelation range: estimations of physical-chemical variables studied at the Ciénaga Grande de Santa Marta, Northern Colombia.  The spatial  autocorrelation range, understood here as the minimum distance between points at which the spatial correlation becomes zero, is a very useful parameter to design samples that have as goal the study of the spatial behavior of a variable.  In this paper  the estimation  of  the autocorrelation  range by means of  the  correlograms of confidence bands  are discussed in detail, and  estimations for a set of physical-chemical  variables studied at the Ciénaga Grande de Santa Marta, Northern Colombia, are made.  The results of the application show that  for four of the variables  included in the study  (Nitrite, Nitrate, the addition of Nitrite and Nitrate, and Oxygen concentration) it is not possible to analyze their spatial behavior because the autocorrelation range is less than the minimum distance between the points that constituted the sample.  The spatial autocorrelation range for the other variables were, 4900 m for ammonia,  4600 m for salinity, 3900 m for silicate, 2700 m for orthophosphate and 2700 m for chlorophyll. Through the application it can be further noticed the distortion that may result in estimating the ranges if the spatial trend is not previously  removed.