The limestone water channels at Humayun's Garden Tomb are less than two feet wide and about a foot deep. The water level in the channels varies upon the location of the water channel in the garden and what season of the year it happens to be. Some water channels rarely contain moving water.
Humayun's Garden Tomb is divided and defined by its water channels. The garden is first defined as a char bagh plan, with its four celestial river symbolism, by the main west-east and north-south water channels. These are the channels that connect the tomb with the fountains and appear to intersect underneath the tomb.
As a result of this intersection illusion, the garden tomb also becomes like four separate but connected char bagh gardens. Each quadrant has its own central point of interest at a water channel intersection. These are the grave platform in the northwestern quadrant, the Barber's Tomb in the southeastern quadrant, the octagonal tree platform in the northeastern quadrant, and an octagonal pool in the southwestern quadrant that is just like any one of the octagonal pools at the corners of Humayun's Tomb's plinth. These four separate quadrants are linked by a circuit of water channels similar to how the four octagonal pools aroung Humayun's Tomb's plinth's corners are joined by a circuit of water channels. This water channel and pool circuit combination is repeated on a smaller scale on the eight platforms that stand at path intersections.
Wescoat Jr., James L. "The Colors of Water: Hydrology and Human Experience at the Taj Mahal." New Geographies 3, Urbanisms of Color (2010): 174-83.