Paper 1 · November 2004 · rainfall analysis techniques
A geographer has annual rainfall totals for 20 weather stations scattered across a 1 000 km² area, plus a topographical map of the area. Which technique is most appropriate for showing how annual rainfall varies across the whole area?
ARanking the 20 stations from wettest to driest and listing them in a table beside the map.
BPlotting each station's total at its correct location and drawing isohyets to interpolate rainfall values between them.
CPlotting each station's total at its correct location and joining them with contour lines of equal elevation, which actually represent height above sea level rather than rainfall.
DCalculating one average rainfall figure for the whole area and shading the entire map a single colour.
Explanation
Isohyets are lines of equal rainfall interpolated between plotted station values, producing an isohyetal map that shows spatial rainfall distribution; contour lines instead show equal elevation, a single average discards all spatial variation, and a ranked table shows no spatial pattern at all.
Derived from ZIMSEC Geography Paper 1, November 2004, Q2