GIS For Engineering (Knowledge) 5

Question 1

What is the primary use of Positional Dilution of Precision (PDOP) in GIS engineering GPS surveys?

Accepted Answer

Indicating the quality of GPS satellite geometry affecting positional accuracy

Answer

PDOP measures how satellite geometry affects GPS accuracy; a low PDOP (below 4) indicates well-spaced satellites and more reliable positional measurements.

Question 2

In GIS-based floodplain analysis for engineering design, which federal dataset defines base flood elevations in the US?

Accepted Answer

FEMA Flood Insurance Rate Maps (FIRM)

Answer

FEMA's Flood Insurance Rate Maps define the 100-year floodplain boundaries and Base Flood Elevations used by engineers for site design and regulatory compliance.

Question 3

What is 'conflation' in the context of GIS engineering data management?

Accepted Answer

Merging and aligning two datasets of the same area to create an improved combined dataset

Answer

Conflation aligns features from two overlapping datasets and transfers attributes, used to update older engineering basemaps with more accurate survey data.

Question 4

Which map projection preserves area and is most appropriate when an engineering study requires accurate acreage calculations across a large region?

Accepted Answer

Albers Equal-Area Conic

Answer

The Albers Equal-Area Conic projection preserves area relationships across wide extents, making it the standard choice for US-wide area measurement studies.

Question 5

In an engineering GIS workflow, what is the purpose of 'edge matching' when working with adjacent map sheets?

Accepted Answer

Ensuring that features align correctly and attributes match across tile boundaries

Answer

Edge matching aligns vector features (roads, pipes, parcels) that cross boundaries between adjacent map tiles or data sources to eliminate positional and attribute discrepancies.

GIS - Geographic Information System Practice Test

GIS - Geographic Information System Practice Test

GIS For Engineering (Knowledge) 5