Hydrology is the applied science concerned with the occurrence, distribution, and circulation of the waters of the earth.
Less than three percent of the earth's water resources is fresh and little more than one-hundredth of one percent of the earth's water is in lakes, rivers, the soil and the atmosphere.
Water evaporates from the earth's surface and is transpired from plants, it falls as rain or snow, it percolates into the ground, it travels through rivers and lakes and eventually returns to the ocean.
This continuous recycling process, which is so vital to life on earth, is called the hydrological cycle and is illustrated in the above figure.
The Hydrologic Modelling Section has a number of products available via the web or in print: