20. Rain Gardening

Interpretive Intent: Long before the invention of pavement, storm drains or holding basins, nature itself managed the adverse effects of seasonal monsoons. Native plants and soils absorbed rain and run-off, then filtered out contaminants to create fresh supplies of clean groundwater. This natural process still works so well that a similar system now called a biofilter is incorporated into this garden. Like natural ecosystems, biofilters curb flooding and remove pollutants from storm run-off.

Exhibit Design: The biofilter you see here is filled with small gravel and planted with native and other grasses. Dormant in late summer when water is scarce, these plants come alive during spring rains or whenever water is plentiful.

To the untrained eye, this exhibits looks only like a lush landscape but in reality it’s that and so much more. Gravel filters out sediments and creates air pockets that encourage the growth of roots and friendly soil microbes. These tiny organisms break down and devour organic pollutants–especially hydrocarbons like the oil and grease that collect in parking lots.

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