The recent deluge of rain in Los Angeles served as a poignant reminder of just how damaging extensive paving can be, especially in an area close to a body of water.  The great expanses of sidewalks, streets and driveways prevent rainfall from being absorbed into the ground, which causes runoff—coursing streams of water that eventually will end up in the ocean.  Runoff is detrimental for two reasons: it carries whatever pollutants it picks up into the nearest body of water, harming aquatic life, and it means that rainwater is not being absorbed into the land where it can replenish depleted aquifers.

Recently, many companies and researchers have been developing pervious pavement, which is as strong and resilient as normal paving but which allows water to enter the ground.  There is a wide variety of options available that I would strongly encourage anyone replacing a driveway or walkway around their home to consider.  One type is a collection of gravel with sufficient space between each pebble to allow water to flow through at 480 inches per hour.  Another option is what’s called open pavement; it creates a latticework of cement with open earth in between where rain can collect and slowly percolate into the ground.  A third type is modular paving, which is installed like brickwork with spaces between the pieces to allow water to seep through.  Homes are a good starting place to improve rainwater absorption, but ultimately cities must adopt some type of pervious paving to remedy this problem.