18-Geom-A7 Geospatial Information Systems · May 2017
Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
National Exams — May 2017 — 04-Geom-A7 Geospatial Information Systems. Closed-book; any non-communicating calculator permitted. Format: fifteen questions of varied value totalling 100 marks; fifteen questions constitute a complete paper and all fifteen are solved in full below. Most answers are required in essay form. 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); H. Samet, The Design and Analysis of Spatial Data Structures (Addison-Wesley, 1990); 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 buffer is a zone drawn around a feature at a specified distance — a circle around a point, a corridor around a line, or an outward (or inward) band around a polygon. In proximity analysis, which answers "what is near what," the buffer is the tool that makes "near" explicit: the analyst sets the threshold distance, generates the buffer, and then uses it in a spatial (select-by-location) or overlay operation to identify all features that fall within (or beyond) that distance of the source feature. For example, buffering streams by 100 m and selecting parcels that intersect the buffer finds every property inside a riparian setback; buffering a proposed well and intersecting it with land use flags affected areas; buffering roads by 300 m identifies land too close for a school (as in Question 4). Buffers can use a fixed distance, a variable distance driven by an attribute (e.g., wider buffers for busier roads), or multiple ring distances to grade proximity. The output — the buffer polygon plus the features selected against it — turns a vague notion of closeness into a precise, mappable, analysable zone, and is a building block of site selection, impact assessment and service-area studies.
