Floods and Droughts in Our Future – A Local Perspective

by Brian T. Lynch, MSW

There is a front-page article in the Star-Ledger today about how climate changes are creating increased flood risks in New Jersey. In ten of the last twenty-one years, extreme flooding events have occurred, and major flooding is expected to increase two to five times more often in the next 75 years. So, the Governor is issuing emergency rules for new construction to avoid future flood damage. Criteria for flood zones in New Jersey are being raised two feet, for one example. How we deal with stormwater now is already a crisis, not to mention a serious environmental threat to our streams and rivers that must carry extra water out to sea.

The irony is that climate scientists say we can expect longer dry periods between heavier rain events. That may mean we could rapidly cycle between floods and dry conditions. It’s enough to drive you to drink!

And drink we must. Our bodies are 60% water, and our brain contains 75% water. Maybe that’s why our brains are sometimes called wetware. On average, we use 101.5 gallons of water a day per person, which works out to 148,000 gallons of water a year for an average household.

Rain is the source of all the freshwater for life above the sea. We who live around here get plenty. If you’re lucky enough to own a house on a ¼ acre lot in Mine Hill, 9,000 gallons of pure water land on your property for every inch of rain that falls from the sky. We just got 1.2” of rain yesterday.





Mine Hill averages 51.5 “ of rain a year or 1.8 million gallons per acre. That’s three times more than an average household needs. Most of it runs off your property, into the street, down a storm drain, then into a stream or river. The more rain that falls in any given event, the quicker it washes out to sea. That means that the harder it rains, the less water that sticks around for our use and the plants and animals around us. It also means the ecology of our streams and wetlands is under greater stress. Mitigating residential and commercial flooding without addressing the increased volume of water in our river systems could make matters worse for our ecosystems.

Here's the thing we need to keep in mind. All the water we use is either stored in lakes and reservoirs on the surface or in underground aquifers. Once the reservoirs are full, all that extra rainwater from a deluge rushes out to the ocean. It’s lost water.

The aquifers below us are replenished when rainwater seeps deep underground from lakes bottoms, riverbeds, wetlands, and land not covered by buildings, roads, sidewalks, driveways, or other impervious surfaces. It takes a long time for water to reach the aquifers. The more impervious surface area we create, the less water reaches our aquifers. Also, the harder it rains the faster the water spills into storm drains and out to sea.

The keys to refilling our aquifers are to slow down the speed of the water traveling over the land and maximize the amount of open shaded space. I say “shaded” space because evaporation is the biggest source of water loss. Most of the water used to irrigate a farmer's field evaporates before it has a chance to seep underground. The same is true for our unshaded lawns.

So, what might we do on a local level to secure our water sources going forward?

First, we need to preserve as much open space as possible. We should encourage redevelopment over new development. We need to slow down the water as it runs over the land. We can do that by planting more trees and vegetation in places where it has been removed. We can restore vegetation buffer zones along lakes and rivers to slow the inflow of rainwater. We can build better detention and retention basins and upgrade the ones we already have. Modern retention basin designs allow for more water to seep into the ground. They minimize evaporation loss and create more habitat for wildlife.

 

It would also be great if we could increase the capacities of our reservoirs in anticipation of climate changes, but land availability in New Jersey is limited. Better personal water conservation habits and less lawn watering are the alternatives.

We can also advocate for laws and regulations that minimize or reduce impervious cover on new construction or renovations. Porous blacktop can replace conventional blacktop for driveways and parking lots to prevent most runoff. Pavers can replace concrete sidewalks and patios. Rain barrels and landscaping techniques can be used to limit the amount of water that runs off our property and into the street. Nearly half of all the flood water that damages residential and commercial property comes from impervious surface runoff. If everyone limited runoff from their property, it would greatly reduce flooding in flood-prone areas.