Areal estimation of rainfall (fact sheets 5&6)

Question 1

six methods of areal estimation of rainfall

Answer 1

1. arithmetic mean
2. thiessen polygons
3. hyposometric curve
4. isohyetal method
5. rainfall radar
6. mathmatical surface

Question 2

using the arithmetic mean for areal estimation of rainfall

Answer 2

assumes uniform distribution of rain gauge and flat terrain is needed

Question 3

if there isn’t uniform distribution of rain gauges use…

Answer 3

thiessen polygons

Question 4

thiessen polygon method

Answer 4

joining the bisectors at mid-points between the gauges, the individual gauge catches are then weighted by the proportion of the catchment that their polygon occupies

Question 5

hypsometric curve

Answer 5

used to estimate the catchment-average rainfall that is explicitly altitude weighted

Question 6

isohyetal method

Answer 6

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