18-Geom-A7 Geospatial Information Systems · December 2015
Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
National Exams — December 2015 — 04-Geom-A7 Geospatial Information Systems. Closed-book; an approved Casio or Sharp calculator is permitted. Format: twelve short-answer questions of varying value totalling 100 marks; all questions constitute a complete exam and are solved in full below. Datum and coordinate conventions follow the Canadian spatial reference framework — NAD83(CSRS) horizontally and CGVD2013 vertically.
Reference texts: P. A. Longley, M. F. Goodchild, D. J. Maguire & D. W. Rhind, Geographic Information Systems and Science (4th ed., Wiley, 2015); P. Bolstad, GIS Fundamentals: A First Text on Geographic Information Systems (6th ed., XanEdu, 2019); P. A. Burrough, R. A. McDonnell & C. D. Lloyd, Principles of Geographical Information Systems (3rd ed., Oxford, 2015); M. Worboys & M. Duckham, GIS: A Computing Perspective (2nd ed., CRC, 2004); J. P. Snyder, Map Projections — A Working Manual (USGS PP 1395); ISO 19115 Geographic information — Metadata.
Question text not reproduced: the examination questions are © Engineers and Geoscientists BC. Open the official past paper (linked at the top of this page) to read the question, then follow the worked solution below.
(a) Retail store site selection. This is a suitability analysis combining demand, competition and accessibility. Assemble the layers — population/census demographics (income, age), road network, existing competitor and own-store locations, candidate parcels with zoning, and traffic counts. Then: (1) define criteria — target market density, a minimum drive-time catchment, distance from competitors, adequate parcel size and correct commercial zoning; (2) run service-area/drive-time network analysis around candidate sites to measure the population reachable within, say, 10 minutes; (3) use buffers and overlay to exclude parcels too close to an existing store or in the wrong zone; (4) apply demographic overlay to sum the spending power in each catchment; (5) combine the weighted criteria in a suitability model (weighted overlay / multi-criteria evaluation) to rank the candidate parcels; and (6) map the top-ranked sites for the business decision. The GIS quantifies market potential and accessibility that intuition alone cannot. (b) Properties affected by a floodplain. This is a point/polygon-in-polygon overlay problem. Obtain the floodplain (flood-hazard) polygon — from a hydraulic study, a flood-inundation model over a DEM, or a mapped regulatory floodplain — in the same datum/projection as the parcel fabric. Then: (1) overlay the floodplain polygon on the parcel layer with a spatial intersect/select-by-location to identify every parcel that falls within or intersects the floodplain; (2) optionally compute the proportion of each parcel inundated and, using a DEM, which flood depth/return-period zone it lies in; (3) join the attributes to extract owners, addresses and assessed values of the affected parcels; and (4) produce a map and a report/notification list. The result is an objective, repeatable determination of exactly which properties the floodplain affects — the kind of overlay query that is the classic justification for a GIS.
