This is the fourth article in the Greenwich Sustainability Committee’s “One Water” weekly series.
It may feel counterintuitive to think of soil to improve our water supply, but soil plays a critical role in our watershed. Because the soil is largely invisible we tend to think of it as simply the place where plants grow. In fact, soil is a living matrix that absorbs, filters and stores our water. Soil holds the landscape together in the presence of water.
Our water is absorbed through the soil where it is filtered to create clean streams, rivers, lakes, aquifers, wells, and in our case, Long Island Sound. Water filters through the land in a process called soil infiltration. Healthy soil is essentially made by living organisms into a sponge that absorbs water and stores it as a reservoir for plant life to draw on, and to make nutrients available to the plants. Within this soil sponge plants grow stronger, stay green longer, cool and protect the land from erosion.
In school we all learned about the water cycle, the dominant paradigm for understanding how water regenerates the Earth’s water system. After all, we only have the water that is here on Earth – there is none falling from space to replenish what is used. We depend on the water cycle to circulate our supply, cleaning it in the process. It is a closed system.
This large water cycle paradigm views evaporation as a loss to the system. However, a new paradigm, where evaporation is understood as the source of all precipitation is called the small water cycle. Although it is called the small water cycle, it is actually more important to local precipitation patterns than the large water cycle. Up to two thirds of precipitation on land actually comes from the small water cycle. It is the small water cycle that is interrupted by human activity, and it is therefore the small water cycle that can be influenced by how we use the land.
When we understand how the small water cycle affects regional weather patterns we can better understand the importance of holding water on the land. When soil holds water deeply, the water is filtered and cleaned. It can then be preserved in our groundwater supply and collect in underground reservoirs called aquifers. When water can’t fully penetrate the soil, excess water runs across the surface of the landscape taking contaminants and sediment with it and often causing floods. And, of course, when water isn’t held by the soil, droughts become more frequent. According to the National Climate Assessment, Connecticut has had a 71 percent increase of rain in the heaviest weather events, the highest in the country along with the rest of the Northeast. This cycle of heavy rain followed by drought is directly related to our soil’s inability to absorb and hold water, carrying enormous costs for homeowners and municipalities alike.
As we outlined in our previous article, runoff has negative consequences for the quality of our water supply….