CEP Field Survey & Data Collection 2 — Questions and Answers
Question 1: Which GPS error source is most effectively reduced by using Differential GPS (DGPS) correction?
- Multipath interference
- Satellite geometry error
- Selective availability and atmospheric delay (Correct answer)
- Receiver clock drift
Correct answer: Selective availability and atmospheric delay
DGPS uses a fixed base station with a known position to calculate and broadcast corrections that remove common-mode errors like atmospheric delay and, historically, selective availability.
Question 2: When conducting a wetland delineation field survey, which three-parameter approach is required under the 1987 U.S. Army Corps of Engineers Wetland Delineation Manual?
- Soils, slope, and hydrology
- Hydrology, hydric soils, and hydrophytic vegetation (Correct answer)
- Vegetation, wildlife, and water quality
- Topography, drainage, and land use
Correct answer: Hydrology, hydric soils, and hydrophytic vegetation
The 1987 Corps manual requires positive evidence of hydrology, hydric soils, and hydrophytic vegetation for an area to be classified as a jurisdictional wetland.
Question 3: A surveyor uses a Munsell color chart in the field primarily to:
- Classify vegetation density
- Identify soil horizon depth
- Describe soil color for profile documentation (Correct answer)
- Measure organic matter percentage
Correct answer: Describe soil color for profile documentation
The Munsell system standardizes soil color descriptions using hue, value, and chroma notation, enabling consistent comparison across surveys.
Question 4: Which sampling design best ensures every location in a study area has an equal probability of being selected?
- Purposive sampling
- Convenience sampling
- Simple random sampling (Correct answer)
- Judgment sampling
Correct answer: Simple random sampling
Simple random sampling assigns equal selection probability to all possible sample units, supporting unbiased statistical inference across the study area.
Question 5: Total dissolved solids (TDS) in a water sample are most accurately measured by:
- Turbidity meter
- Gravimetric filtration and evaporation (Correct answer)
- Dissolved oxygen probe
- pH electrode
Correct answer: Gravimetric filtration and evaporation
Gravimetric analysis filters a known water volume, evaporates it, and weighs the residue to obtain TDS in mg/L per Standard Methods.
Question 6: In a biological field inventory, a point count survey method is primarily used to assess:
- Soil macroinvertebrate diversity
- Bird species abundance and distribution (Correct answer)
- Aquatic plant biomass
- Reptile population density
Correct answer: Bird species abundance and distribution
Point count surveys station observers at fixed locations for timed periods to detect and record all birds seen or heard, providing abundance estimates.
Question 7: Chain-of-custody documentation for environmental field samples is required primarily to:
- Reduce laboratory processing time
- Establish legal defensibility and sample integrity (Correct answer)
- Estimate sample collection costs
- Determine sample volume requirements
Correct answer: Establish legal defensibility and sample integrity
Chain-of-custody forms track every person who handles a sample from collection through analysis, protecting data integrity for regulatory or legal proceedings.
CEP Field Survey & Data Collection 2
Which GPS error source is most effectively reduced by using Differential GPS (DGPS) correction?