a. The hydrologic cycle is the term used to describe the natural circulation of raw
water in, on, and above the earth. (Raw water is classified as fresh, brackish, or salt
(seawater) based upon the concentration of total dissolved solids). Water occurs in
many forms as it moves through this cycle. Figure 1-1A is a simplified illustration
showing the steps in the cycle.
Figure 1-1. Basic hydrology