Paper 1 · rainfall analysis techniques
A rainfall dispersion graph plots each year's total rainfall as a point against time for 30 years of records at a station. If the points are tightly clustered close to the long-term mean line, what does this indicate about the station's rainfall?
ARainfall at the station is unreliable, varying greatly from year to year.
BRainfall at the station is reliable, varying little from year to year.
CRainfall at the station is increasing steadily over time.
DRainfall at the station is decreasing steadily over time.
Explanation: Tight clustering of yearly totals close to the mean means low year-to-year variability, which is what 'reliable' rainfall means; a wide scatter around the mean would instead indicate unreliable rainfall.
Derived from ZIMSEC Geography Paper 1, November 2004, Q2
