What is a hydrological Cycle?

The new hydrological cycle describes the exchange of water through the land, ocean and atmosphere, depicting human influences.

The water cycle defines the interchange (cycling) of water through Earth’s land, ocean, and atmosphere. Water can be found in all three phases and in a variety of forms, including lakes and rivers, glaciers and ice sheets, oceans and seas, underground aquifers, and vapour in the atmosphere and clouds.

What update is in the new water cycle?

First of all, the older diagram of the hydrological cycle lacked human impacts! With the depth of human activities felt everywhere on the planet, it is now apparent that impacts can alter the hydrological cycle as we know it.

The new version replaces one that has been used by hundreds of thousands of educators and students worldwide since 2000. So, what’s the deal with the new water cycle? This representation incorporates humans into the picture, depicting the water cycle as a complex interplay of small, interrelated cycles with which people engage and affect rather than as a single large circle.

The USGS researchers created the new diagram with more than 100 educators and 30 hydrologic experts. The massive volumes of water data acquired by the USGS in recent decades have generated a more sophisticated understanding of the water cycle, illustrating how its human and natural components are interrelated. Whereas the previous water cycle diagram solely portrayed the natural aspects of the cycle, the new version displays how water moves and is stored on Earth, both naturally and as a result of human actions.

What human impacts are captured in the hydrological cycle?

The revised model features the following aspects:

  • Reduced infiltration as a result of impermeable urban surfaces
  • Cloud and precipitation systems are being altered as a result of anthropogenic aerosols, urbanization, irrigation, deforestation, and other land use changes.
  • Increased ice melt as a result of black carbon aerosols (soot) in the cryosphere
  • Water cycle components have been accelerated as a result of greenhouse gas-related heat.

The new hydrological cycle diagram not only depicts a more comprehensive perspective of the water cycle but also uses information design principles to concentrate attention on the water as it travels through the natural and manmade environments. It demonstrates how diverse habitats, including a coastal plain, dry basin, wet basin, and agricultural basin, are linked across watersheds and at the continental scale.

Zoom the image at the USGS website.