Water Sector Overview

• Author: Elaine L. Hughes, Arlene J. Kwasniak, Alastair R. Lucas
• Pages: 351-376

351

CH A PTE R 17

WAT ER

SECTOR

OVERVIEW

Arlene J Kwasniak

A. ABOUT WATER

Everywhere on eart h, the ultimate water source is precipitation — rain,

snow, sleet, and hail. Precipitation can be adsorbed (inf‌iltrated) into

the soil, which allows water to seep into the ground and to be stored

underground as groundwater. Water can become runoff and f‌low into

rivers, streams, and other water bodies or be stored in areas such as ice

caps, puddles, ditches, or depressions. Water is returned to the atmos-

phere through evaporation or transpiration through plants (together

evapo-transpir ation), and then returns back through precipitation. The

entire process is ca lled the hydrological cycle or water cycle.1

A key concept in water management is watershed or drainage ba sin.

A watershed or drainage basin i s an area where all water and whatever

is carried with water (sediment and dissolved materials) drain from

the land to a common body of water such as a river, lake, or ocean.

The Canadian Atla s identif‌ies f‌ive major drainage basins in Canada.

Such drainage basin s may be huge, for example the Hudson Bay drain-

age basin, which measures 3,861,400 square kilometres, or relatively

1 For information on t he hydrological cycle, see, for example, E nvironment and

Climate Cha nge Canada, “The Hydrologic Cycle,” online: www.ec.gc.ca/eau-water/

default.asp?lang=En& n=23CEC266-1; United States Geological Sur vey Water

Science School, “Sum mary of the Water Cycle,” online: http://water.usgs.gov/

edu/waterc yclesummary.html; and t he Foundation for Water Research, “The

Hydrological Cycle,” online: w ww.euwfd.com/html /hydrological-cycle.ht ml.

PUBLIC LANDS A ND RESOURCES LAW IN CAN ADA352

small, for example, the Milk R iver Basin in the Canadian Prairies,

which measures 21,600 square kilometres.2 Drainage ba sins may be

divided into smaller ba sins, sub-basins, sub-sub-basins and so on. In

each case, there w ill be a watershed. For example, Alberta water man-

agement identif‌ies eleven major basins in the province.3 With each of

the basins, water f‌lows to a common river, and then, depending on the

basin, water eventually w ill f‌low to the Arctic Ocean, Hudson Bay, or

Gulf of Mexico.

The water cycle and watershed are affected by many factors. One is

the rate of rainfall — t he slower and lighter it rains, generally spe aking,

the more opportunity to inf‌ilt rate soil; the faster and harder it rains, the

more apt it is to become runoff, and the more quickly it will reach r ivers

and water bodies. Natural topology is a lso a factor; grade or slope will

inf‌luence whether water inf‌iltrates or becomes r unoff. Human activities

and development may greatly impact water cycle and watershed. For

example, constructing i mpermeable surfaces (such as roads and pave-

ment) will result in runoff or water gather ing instead of inf‌iltration.

Drainage of water bodies and development on drained areas can block

groundwater replenishment (recharge). Dams, diversions, and storage

projects all affect how water travels th rough a watershed and water

cycle (for example, inf‌luences on rate of evaporation). Water quality in

a watershed is impacted by everyt hing that goes on in it, such as min-

ing, forestry, development, urban and rural pesticide use, other agricul-

tural runoff, ma lfunctioning municipal sewage discharges, and so on.

Generally, water is categorized as surf ace water or groundwater. Sur-

face water is water on the ground surface, including r unoff, that gath-

ers in a stream, la ke, river, wetlands, ocean, or reservoir. Groundwater

is water under the surface of the ground. Groundwater is rech arged

by precipitation that seeps into the ground. It seeps downward until it

reaches a depth where water has f‌illed a ll of the porous areas in the soil

or rock (the saturated zone). The top of the saturated zone is the water

table. The porous area between the water table and the la nd surface is

the unsaturated zone. Some groundwater is hydrologically connected

to surface water and some is not. At common law, groundwater that is

not hydrologically connected with surface water in law is called “per-

colating groundwater.”4 An aquifer is water-bearing rock, sand, gravel,

2 See the Can adian Atlas, “This Water-rich La nd,” online: ww w.canadia ngeo-

graphic.ca /atlas/themes .aspx?id=WATERRICH&sub=WATERRICH _BASICS_

DRAINAGE&lang=En .

3 Water Act, RSA 2000, c W-3, s 1(1)(ff) def‌inition of “major river b asin.”

4 Chasemore v Richards (1859), [1843–60] All E R Rep 77 (HL).