Erosión y desertificación.-Pinhole test for identifying susceptibility of soils to piping erosion: effect of water quality and hydraulic head

Abstract

ABSTRACT Piping has been observed in both natural and anthropogenic landscapes, in different climates, lithologies and soils, as well as under different types of land uses and vegetation covers. Despite its importance, no standard widely-applied methodology exists to assess susceptibility of soils to piping. This study aims at evaluating the pinhole test for assessing the susceptibility of soils to piping under different conditions. More precisely, the effects of hydraulic head and water quality are being assessed. Topsoil samples (remoulded specimens) with a small range of water contents were taken in Central Belgium (Heverlee) and the susceptibility of these soil samples are investigated under standardized laboratory conditions with a pinhole test device. Three hydraulic heads (50, 180 and 380 mm) and two water qualities (tap and distilled water) were used, reflecting dominant field conditions. The results indicate significant differences between different hydraulic heads and water qualities. Maximum flow discharge was recorded at 380 mm, showing small differences between tap and distilled water. Maximum sediment discharges were recorded at 380 mm and significant higher sediment discharges were observed for distilled water compared to tap water. The tests indicate that the tested soil has an intermediate susceptibility to piping.