The more we alter the landscape, the more we affect the water cycle -- and nature’s ability to deal with runoff.
The Water Cycle
Nature continuously recycles the Earth’s water supply through a dynamic process that has existed for millions of years. This water cycle (or hydrologic cycle) moves rainfall from the atmosphere to land, through surface and groundwater systems, to the ocean, and back into the atmosphere. The water cycle is made up of several basic components: evaporation (and transpiration), condensation, precipitation, infiltration, groundwater recharge, and runoff.
Anyone who has looked at local rivers and streams during a storm can see the effects of runoff. Soil that washes off construction sites; trash, cigarette butts, and other litter that has washed from parking lots; antifreeze and oil that has dripped from cars and trucks; fertilizers and pesticides from golf courses, fields, and lawns; nutrients from agricultural operations; grit and salt from de-icing roadways: all this and more can be flushed directly into waterways when it rains.
The more we alter the landscape, the more we affect the natural cycle and its ability to deal with runoff. When we grade and cut and pave and build, we’re not only causing more polluted water to move into waterways more quickly, we’re making less water available for absorption into the ground. Believe it or not, that can affect stream flow and the aquifers we depend on for drinking water in many parts of the state.
Putting Nature to Work
In the natural cycle, the majority of precipitation falls into the ocean, but some hits the ground. Of the precipitation that falls on land, some is quickly absorbed by the soil; some is used by plants and trees; and some infiltrates into the ground. The rest flows over land surfaces as runoff, oftentimes dissolving materials or sweeping them along with its flow.
Forests, fields, and other vegetated areas slow the flow of this polluted runoff, filter out sediments, and trap pollutants or break them down in roots. Conversely, buildings, roads, parking areas, and exposed bedrock increase the volume and speed of runoff because these hard surfaces prevent water from absorbing into the ground and offer little resistance to slow down the flow.