Significance of Negative Matric Suction Pressures on Infiltration in the Swash Zone

Abstract

The swash zone's complex hydrodynamics can be influenced by infiltration and exfiltration
processes, which are not yet fully understood. This study explores the role of negative matric
suction pressures in swash-zone infiltration, focusing on seven naturally occurring beach
media samples. Using a combination of tensiometer and in-contact filter paper methods, we
examine the prevalence of matric suction pressures for beach media ranging from fine
pebbles to fine sand. The results highlight the existence of matric suction pressures within
the range 0-2 kPa for the examined media samples, with maximum values observed within
the grain-size range 0.85-0.71 mm. Our results reveal a previously underexamined aspect of
swash-zone infiltration, highlighting the potential significance of matric suction in influencing
coastal processes. The findings suggest that omitting matric suction effects is shown to be
an invalid assumption under certain conditions, as these pressures can exceed gravitational
potential.