Definition of waterlogging
When the water table rises to such heights that the soil pores in the root zone become saturated, thus displacing the air, the land is said to be water logged.
Waterlogging is happened when the soil is so filled or soaked with water that caused the roots of the plant to rot.
Waterlogging is 100% when water table rises to the surface. However the process of waterlogging starts even when the water table is quite below the surface. In this case there exists a capillary fringe. For example presence of water due to capillary action above the saturation line. Capillary fringe depth depends upon the type of soil. If the soil is coarse and sandy, then its depth is low. Depth of capillary fringe is large for fine grained soil. The other important factor is the depth of root-zone which varies from crops to crops. In case of wheat, the depth of root zone is about 2 feet, and if there is a height of capillary fringe is 4ft. Then water logging process will start if the water table is at 6 meter from the surface.