4.7 Wetlands in Landscapes

Wetlands can be generally classified based on geologic/ hydrologic conditions and vegetation. Classes include marine, estuarine, riverine, lacustrine and palustrine. Terrestrial systems include riverine (associated with rivers), lacustrine (associated with topographic depressions, that are like a lake), and palustrine (includes most inland wetlands and a subset of estuarine and intertidal systems) as shown in Figure 51.

Wetlands that are well connected to groundwater commonly occur at groundwater discharge sites associated with local, intermediate and regional groundwater systems (e.g., Figure 10). In addition, they can also occur on slopes associated with spring discharge (Figure 43), in topographic lows in recharge areas, and low-relief depression dominated landscapes.

Wetland systems illustrated in Figure 51 show wetlands in sites with large topographic relief. However, many wetlands occur in areas with low topographic relief and cover large areas. Often wetlands form in topographic settings where the water table intersects the land surface for all or part of the year. For example, in North America large expanses of wetlands occur in low relief regions including the boreal reaches of Canada, and the interior and coastal plains of Canada, the United States and Mexico (Figure 52). Mitsch and Gosselink (2000) and Fretwell and others (1996) provide additional examples of wetland landscape settings and groundwater flow systems.