For example, wetlands in the northern United States tend to accumulate a greater depth of peat than wetlands of a similar type in the southeastern U.S., due to higher rates of decomposition in the latter. Precipitation has a substantial effect on wetland hydrology, particularly the water balance in the wetland. Also of significance is the timing or pattern of rainfall in the region, including the proportion of annual rainfall occurring during the growing season. Rainfall patterns can affect frequency and duration of flooding, as well as the dominant type of vegetation in a wetland. Geomorphology Geomorphology, referring to landforms and landscape relief, plays a major role in wetland hydrology and ecology within a particular climatic region.
Geomorphology encompasses the shape, size and location of wetlands in the landscape.
The morphology of individual basins or wetlands, for example, influences flooding depth as well as hydroperiod, which refers to frequency and duration of flooding. Geomorphology of the surrounding landscape exerts a strong influence on surface and groundwater connections between the wetland and adjacent terrestrial and aquatic ecosystems. Another example of geomorphological influence on wetland function is the location of the wetland in the landscape, especially the landscape position relative to aquatic ecosystems such as rivers and lakes. Landscape position of a wetland may have a significant effect on regional water quality, by controlling the type and extent of wetland interaction with surface and groundwater flows in the watershed. Certain types of depressional wetlands also are effectively isolated from direct interaction with groundwater in the surrounding area.