Water cycle

[edit] Introduction

The water cycle (or hydrological cycle) is a sequence of processes that drive the movement of the earth’s water, which is constantly transforming as it goes through different states of matter - from gaseous water vapour to liquid water and sometimes ice, and back again. The water cycle (sometimes referred to as the hydrologic cycle or the hydrological cycle) has no starting point or ending point, and the total amount of water within the cycle is essentially constant.

[edit] Characteristics of the water cycle

The Corps of Engineers - Portland District explains, “The global water cycle can be described with nine major physical processes which form a continuum of water movement. Complex pathways include the passage of water from the gaseous envelope around the planet called the atmosphere, through the bodies of water on the surface of earth such as the oceans, glaciers and lakes, and at the same time (or more slowly) passing through the soil and rock layers underground. Later, the water is returned to the atmosphere."

The nine primary physical processes of the water cycle are: evaporation, condensation, precipitation, interception, infiltration, percolation, transpiration, runoff and storage.

The water cycle is also involved in seven other processes related to geology and affiliated sciences: subduction and mineral hydration, snow melt, subsurface flow, sublimation, deposition, advection and plate tectonics.

Hydrology is concerned with the origin, distribution and properties of water on the globe and is one of the interdisciplinary sciences that is the basis for water resources development and water resources management.

NB Global Warming of 1.5 ºC, Glossary, published by the Intergovernmental Panel on Climate Change (IPCC) in 2018, defines the hydrological cycle as: ‘The cycle in which water evaporates from the oceans and the land surface, is carried over the earth in atmospheric circulation as water vapour, condenses to form clouds, precipitates as rain or snow, which on land can be intercepted by trees and vegetation, potentially accumulates as snow or ice, provides runoff on the land surface, infiltrates into soils, recharges groundwater, discharges into streams, flows out into the oceans, and ultimately evaporates again from the ocean or land surface. The various systems involved in the hydrological cycle are usually referred to as hydrological systems.’

Watercycle installation at the Millennium Dome, 2000. Water from the roof of the Dome was collected and used to flush the toilets. Waste from the toilets was processed to generate electricity that was used to power the Dome.

[edit] Related articles on Designing Buildings

• Condensation.
• Damp.
• Evaporation.
• Hydrology.
• Integrated water management.
• Millennium Dome.
• Rainwater harvesting.
• Surface water run-off.
• Sustainable water management.
• Water management.
• Water treatment.