Controlling Soil Erosion

When water and land wrestle, the water always wins.

Martha’s Vineyard Island Blue Pages

are as much a fact of Island life as summer sunshine. When rain hits the Island, it either sinks into the ground or runs rapidly over land, picking up pollutants and soil before draining into our Bay. Meanwhile, waves and tides are eroding banks and beaches. The best way to control both rain runoff and wave action is to take advantage of native vegetation.

In natural landscapes, most rain soaks slowly into the ground and gradually drains to nearby surface waters. But as more land is cleared for development and more solid surfaces such as roofs, roads, parking areas, and driveways are built, more water is carried straight into storm drains and on into the Bay.

Runoff damages the Bay’s water in many ways. As runoff is swept towards the Bay, it carries a wide variety of pollutants such as metals, paints, oil, grease, lawn fertilizers, detergents, animal waste, and litter. It also carries soil sediments that can smother eelgrass beds, which are prime spawning grounds for shellfish and fish as well as other aquatic habitats.

We can’t control wind and rain but we can

and erosion using the land’s natural minimize the damage...

We can’t control the wind minimize the damage caused by runoff vegetation. Native species of shrubs, trees, and some grasses slow runoff, hold soil particles in place, help maintain the soil’s capacity to absorb water, and absorb wave energy on the shoreline. The roots of plants also help filter pollutants from the water before it enters the Bay.

Natural wetlands such as salt marshes, swamps, and bogs are especially good at slowing down the flow of runoff and filtering pollutants. Our coastal wetlands also defend against flooding and storm damage. The salt marshes surrounding the Island act like sponges, absorbing and containing floodwaters and buffering upland areas from waves. This is why we must preserve our wetlands.

You can help increase runoff absorption on your land by decreasing the size of paved surfaces and adding more native plants and shrubs to your landscape. Minimize road runoff by installing catch basins that detain and filter water.

Many paving surfaces provide the durability of concrete while allowing rainwater to soak into the ground. Bricks and flat stones, for instance, make an attractive, durable driveway and, if placed on well-drained soil or on a sand or gravel bed, allow rainwater to filter into the ground. Wood decks, usually installed for their functional good looks, can serve as a form of porous pavement. Redwood, cedar, and mahogany, for example, are as durable as most paving surfaces. The space between deck boards allows rainwater to drain directly onto the soil surface and soak into the ground.

Coastal erosion caused by wind and wave energy is a natural geological process. It is the primary source of our sand beaches and dunes. We can, however, inadvertently accelerate erosion by clearing shorefront areas, altering marshes, and building too close to the shoreline.

For controlling coastal erosion, scientists recommend natural vegetative solutions rather than hard structures like sea walls, jetties, and rock bulkheads. Although these structures were built to protect against erosion, they often have the opposite effect. Natural environments like salt marshes, beaches, dunes, and vegetated banks are more effective in dissipating wave action and thus protect against accelerated erosion. When enjoying the beach, look for dune grass. It protects our beaches. It traps sand and holds the beach in place—which is why it is never a good idea to walk or drive over it.

The key to success is using the right types of plants. Plants with strong root systems help stabilize banks while salttolerant plants work best on dunes. Only a few plants can thrive on the coast, and each one has its place in the shoreline environment. Plants that help absorb surface runoff and stabilize coastal banks include beach plum, bayberry, rosa rugosa, poison ivy, sassafrass, Virginia creeper, bearberry, and prickypear cactus.

Reduce your use of imper-

• vious surfaces. Use spaced paving stones, gravel, or crushed shells instead of concrete, and groundcover instead of grass.

• trees and shrubs, and plant new ones to encourage rainwater to filter into the soil.

Preserve established

• and pesticides.

Avoid chemical fertilizers

• waste.

Pick up litter and animal

Keep your car in good

• shape to avoid leakage.

Install gravel trenches along

• your driveways and patios to collect water and allow it to filter into the soil.

• etation.

Landscape with native veg-

See the Landscaping chapter.

• your neighbors to do the same.

Increase the greenery on your property and encourage

• in designing a shoreline vegetation plan. (See the Resources chapter.)

Contact the Master Gardeners’ Helpline for assistance

• mayor these questions:

Become an Activist! Ask your commissioner or town

• “What are you doing to encourage the use of less asphalt and more pervious surfaces for paving?”

• “What are you doing to reduce the runoff rate along the roadside and filter the pollutants?”

• “What are you doing to eliminate invasive species in municipal plantings?”

• Gardening at the Shore from the Garden Club of LBI. (See the Resources chapter.)

Purchase a copy of

The knobbed whelk (Busyconcarica), the state shell of New Jersey, is a type of very large sea snail. This whelk alternates between deep and shallow water. During the shallow water phase, knobbed whelks live near the shore on mud flats. On these flats, this marine gastropod preys on oysters, clams, and other marine bivalves.

The knobbed whelk, which is yellowish grey, can be found on all the beaches and bays of New Jersey. It is large, solid, and pear-shaped, coiling from left to right.