The term drainage means the natural runoff water from an area in rivers and streams. The four main types of steam drainage patterns are dendritic, radial, rectangular, and trellis. The dendric pattern develops where the river channel follows the slope of the terrain.
A trellis drainage pattern assembles when tributaries join the main river at right angles. Radial begins from a center point, usually on a mountaintop, and it works downward in all directions. Rectangular drainage patterns form distinct changes in direction because streams follow less strong rocks.
