Field measurements of soil cracks

Shrink–swell soils, often classified as Vertisols or vertic intergrades, are found world‐wide and are a leading cause of damage to infrastructure such as buildings, roads, and pipelines. Crack networks act as dominant environmental controls on the movement of water, contaminants, and gases. Numerous methods have been proposed to quantify the size (e.g., width, depth, volume) and connectivity of individual cracks and of larger crack networks. To measure and quantify the size and variability of cracks, we focus on two nondestructive methods, called here the tape and rod and displacement approaches, and one destructive method, called here the cast and excavate protocol. The nondestructive methods are relatively inexpensive and can allow repeated measurements, which makes them conducive to use in larger environmental studies such as observing hydrological partitioning between infiltration and surface runoff. However, the nondestructive methods are often biased toward larger cracks (due to physical limitations on the crack sizes that can be measured), require assumptions of crack geometry to determine crack volumes, and typically do not provide information on subsurface connections between cracks. The destructive cast and excavate method is better suited to sample aoftentimes can only be used once (precluding repeated measurements) and is labor intensive. A combination of measurements may therefore be required to best understand crack dynamics in both time and space. Altogether, the methods surveyed here enable accurate measurement and quantification of soil crack characteristics.