A more thorough explanation:

Diffused surface water refers to water that collects and flows on the ground but does not form a watercourse. This can include rainfall runoff and other types of water that do not have a defined channel.

For example, after a heavy rain, water may collect in low-lying areas and flow across the ground, eventually seeping into the soil or evaporating. This water is considered diffused surface water.

It is important to note that diffused surface water is subject to different regulations than water flowing in a watercourse. This is because it does not have a defined path and can be more difficult to manage and control.