Watershed Delineation

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Delineating watersheds:

Accuracy is important because the areas and perimeters of watershedsare used in climate interpolation and runoff calculations

A digital elevation model (DEM) is used to generate two grids

- Flow Direction grid assigns a value to a cell indicating the direction of steepest descent

- Flow Accumulation grid contains a running total of all cells contributing to a given cell

- A drainage basin is defined by specifying a threshold accumulation value