Field Survey & Data Collection Flashcards

Which of the following is classified as a PRIMARY hydrology indicator under the Corps of Engineers wetland methodology?

Answer: Surface water present within or ponding the area

Surface water present within or ponding the area is a primary hydrology indicator because it directly demonstrates inundation without requiring inference from secondary evidence.

A wetland observation well (piezometer) installed at a survey site is used primarily to:

Answer: Monitor the depth and duration of seasonal water table fluctuations

Observation wells record water table depth over time and are used to confirm whether hydrology criteria (saturation within 12 inches for ≥5–12.5% of the growing season) are met.

During a field survey, 'oxidized rhizospheres' are best described as:

Answer: Orange or reddish iron oxide coatings lining root channels in otherwise reduced soil

Oxidized rhizospheres form when plants pump oxygen through their roots into anaerobic soil, causing localized iron oxidation that appears as orange or red coatings around root channels.

In most temperate US regions, the optimal time to conduct a wetland hydrology field survey is:

Answer: During the wet season (late winter/early spring) when indicators are most visible

Late winter and early spring represent the peak hydrology period in temperate regions, when water table levels are highest and inundation/saturation indicators are most easily observed.

'Drift lines' as a secondary wetland hydrology indicator are best described as:

Answer: Rows of dead plant material and debris deposited at the high-water mark as floodwaters recede

Drift lines are accumulations of organic debris, leaves, and fine sediment deposited in lines along vegetation or ground surface at the elevation reached by receding floodwaters.

Under the three-parameter approach, wetland hydrology criteria are generally satisfied when the soil is saturated or inundated:

Answer: Within 12 inches of the surface for a continuous or cumulative period equivalent to 5–12.5% of the growing season

The Corps criteria require water within 12 inches of the surface for at least 5% (some supplements use up to 12.5%) of the growing season, which reflects the minimum duration needed to create wetland conditions.

Which secondary hydrology indicator is typically most useful in a forested bottomland hardwood wetland?

Answer: Water-stained leaves on the forest floor

Water-stained leaves accumulate on the forest floor and develop distinctive dark staining from prolonged inundation, making them a reliable secondary indicator in forested wetlands where other evidence may be seasonal.