Groundwater, Head, Headstream, Headwater: Origins, Forms, Histories of Words Meaning River, Lake

The natural features of a region are its topography (Greek topos, "place").

Among the most important topographic features of a region are its rivers, lakes, and other freshwater bodies. Many words relating to freshwater features have little-known meanings and/or colorful etymologies.

In the current alphabetic series of such terms, here are the origins, forms, and histories of groundwater, head, headstream, and headwater. The dates of forms and meanings come from the Oxford English Dictionary and Merriam-Webster's Collegiate Dictionary.

Groundwater
Groundwater is the water within the earth that supplies wells and springs. The word was first recorded about 1889.

Most groundwater comes from precipitation, which gradually seeps into the earth. In many areas 10-20 percent of precipitation eventually becomes groundwater.

Groundwater (also known as subsurface water) is a zone of saturation where water occupies all the spaces in soils and geologic strata. Generally, groundwater supplies are not affected by short droughts, and such water remains available in many areas that do not have dependable surface water supplies.

The groundwater level (or groundwater table or water table) is the surface, or upper limit, of the groundwater zone of saturation. Above the groundwater level is the basically dry area called the zone of aeration.

Head
Modern English head (16th century) comes from Middle English hed (13th century), from Old English heafod (before 12th century). The word is akin to Old High German houbit ("head") and Latin caput ("head").

The original meaning of head is the top part of the human body (9th century).

A head is also the source of a river or stream (14th century), often used in the form fountainhead (a fountain or spring that is the head of a stream).

Since the 15th century, head has been used in various other water-related extensions, such as a body of water kept in reserve at a height (as in a reservoir) or a mass of water in motion (as in a rip current).

Headstream
A stream that is the source of a river is a headstream (14th century).

Headwater
The source and upper part of a stream is a headwater (1802). The word is usually used in the plural, as in "The Nile's headwaters drain into Lake Victoria."
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Encyclopaedia Britannica Ready Reference 2004. CD-ROM. Encyclopaedia Britannica, 2004.

Merriam-Webster's Collegiate Dictionary. 11th ed. Springfield, Mass.: Merriam-Webster, 2006.

Merriam-Webster's Geographical Dictionary. 3rd ed. Springfield, Mass.: Merriam-Webster, 2007.

The Oxford English Dictionary. 2nd ed. Oxford, England: Clarendon Press, 1989.