Water cycle basics ManagingWholes.com Use keys to change slides

In the next few minutes, you’ll learn about basic processes that cause most of the world’s floods and droughts. These processes are widely ignored or misunderstood.

These basic processes determine whether landscapes end up like this:

…or like this. (Two rivers in the same area, with the same soils and rainfall, on the same day.)

The key isn’t how much rain falls, but what happens after it falls.

Let’s see how it works…

water table Non-effective water cycleEffective water cycle Soil bare between plantsSoil covered with plants and mulch

water table Demonstration: three falls of rain with dry periods in between Non-effective water cycleEffective water cycle

Soil protected from erosionFlash floods and erosion water table Non-effective water cycleEffective water cycle First rainfall Little evaporation from covered soil Water evaporates from bare soil Soil absorbs remaining water Little runoff Heavy runoff of water Water transpired by living plants Large raindrops hit bare soil like bombs, causing erosion Plants and soil cover break raindrops into small droplets that do not erode soil Drier surface soil sucks moisture toward it via capillary action (wicking), a powerful force that allows trees to pull sap to great heights Dry surface soil can pull moisture from deep underground

water table Second rainfall

water table Third rainfall Water to wells and river flow

water table

With no recharge, groundwater falls, even with little pumping

As existing plants die, bare ground increases Seedlings die on dry soil, so new plants are scarce

Bare soil absorbs even less rain, so water problems get worse Rivers and wells go dry, land suffers drought Rivers and wells flow, soil has moisture, so no drought! Rainfall is the same! Dams, irrigation, and deeper wells cannot solve the real problem: wasted rainfall

The difference is whether soil is exposed, or covered with plants and composting mulch

Research shows that bare soil like this can lose up to 83% of rainfall to evaporation.

Many landscapes lose over 90% of rainfall from a combination of evaporation and runoff.

Healthy grasslands can absorb 75% of rainfall. That’s 7 1 / 2 times more rain to grow plants and recharge rivers!

Managed to regenerate grasslands, grazing animals can increase soil’s ability to absorb water by 600%.

…and turn even severely damaged areas like this:

… into thriving places like this. It’s our choice.

Find out more on the web: Take the Managing Wholes water cycle quiz water cycle quiz Learn how damaged land can be restoreddamaged land can be restored Read about the restoration project shown at rightrestoration project shown at right Discover more about how ecosystems really workhow ecosystems really work Brought to you by: ManagingWholes.com Concept + photos this page: Holistic Management International Other photos: Dan Dagget of EcoResults!, Judi Earl, Jim Howell, Peter Donovan, WEPP 95 CDEcoResults!WEPP 95 CD Slide show: Wilma Keppel Some rights reserved