POINT-PROCESSES AND RANDOM SETS FOR ANALYZING PATTERNS OF METHYLENE-BLUE COLORED SOIL

We consider the problem of quantitatively characterizing horizontal pa tterns of dye following infiltration. Such patterns display important information on the movement of possibly contaminated solutes from the soil surface to the ground water, which may cause risks for human heal th. The stains were made visible by means of methylene blue dye tracer s. Different spatial statistical techniques are compared. First, a sta ndard point pattern analysis is applied. Since the stains usually have a non-point type appearance, geostatistical techniques were used to a ccount for positive areas. Next, more advanced point pattern technique s have been applied on replicate samples from different land managemen t and land use types, focusing on the hazard rate for spatial patterns . As it turned out, point patterns analysis and geostatistics could be used in a complementary way, the point pattern analysis by considerin g colouring as basically generated by single points, the geostatistics by taking the spatial extension into account as well. The spatial haz ard rate was useful to detect changes in the effects of land use. (C) 1998 Elsevier Science B.V. All rights reserved.