How Does a Wetland Work?

How Wetlands Work

In over 70 years of wetland conservation, Ducks Unlimited Canada (DUC) has become Canada’s leading experts on wetland habitats. DUC’s scientists constantly engage in environmental research to continue learning more about wetlands and the environmental issues affecting them.

Wetlands are among the most productive ecosystems found on Earth. They are spread all over the world. They support many different types of plant and animal species. They naturally filter our water. But how do wetlands ‘work’?

What is a wetland?

Wetlands are areas where the water meets the land. They are a transition between dry land areas and deeper water areas. As a result, some wetlands hold water year-round while others may only hold water for one or two months each spring.

In a wetland, the water table is either at or very near the soil surface. As a result, wetlands have plants and soils that are adapted to this ‘wet and dry’ environment.

Wetlands exist as part of a watershed, which is a landscape-level system through which water flows and moves.

What makes up a wetland?

In general, wetlands have three parts to them. The first is uplands, which are the dry land surrounding a wetland. Upland areas can have trees, grasses and many other types of vegetation in them.

The second part of a wetland is the riparian zone. This is a strip of land and vegetation between the higher uplands and the shallower, wet areas of a wetland. Riparian areas are heavily vegetated with trees, grasses, brush and other types of plants.

The third part of a wetland is the aquatic area. This is the wet area of the wetland. The aquatic area can be deep, with lots of open water, or it can be very shallow, with no open water at all. Rushes, cattail and many different wetland plants are found in the aquatic zone of a wetland..

diagram of a typical wetland

Strongly influenced by water, wetlands support natural vegetation and maintain soil structure that is distinct from the surrounding drier uplands. Wetlands occur in shallow basins, depressions, and along the shallow edges of many streams, deeper ponds, and lakes.

How does a wetland ‘work’?

This depends a great deal on how the water in a wetland interacts with the surrounding areas. This includes how the water flows in and out of a wetland and how deep the water is.

Wetlands receive water from a variety of sources:

groundwater
rain
water runoff from spring melts and precipitation
streams, rivers and lakes

Wetlands can be thought of as giant sponges. They absorb water from many different sources during wet periods, and they release it slowly into the surrounding areas during dry periods. In this way, wetlands can help to reduce flooding, ease the impact of drought and recharge groundwater supplies.

Water flowing into a wetland from higher ground must move through the upland and riparian areas. These areas are important, as they form ‘barriers’ that help to filter water as it passes through them. The plants and soils absorb chemicals, nutrients, sediments and other impurities from the water as it passes through.

Once the water is in the aquatic area, its levels may vary. Some wetlands, like fens and bogs, are very shallow, with little or no open water. Others, like marshes and swamps, have lots of open water. Some wetlands are permanently wet, while others are only wet at certain times of year.

The water level helps to determine the type of vegetation and wildlife found in a wetland. Wetlands with less open water tend to have more heavy vegetation, such as moss, in them. Wetlands with lots of open water are also vegetated, but they also attract a lot of wildlife.