Hydrographs

The average rainfall over the Stour catchment area is 860mm. The figures are higher in the north and west of the area and lower in the middle and south. Sturminster Newton records an average of 807mm.
Occasionally rainfall occurs with a greater intensity as a result of the passage of a depression.
Records kept since the 19th century show that there have periodically been times of higher rainfall which resulted in floods.

link to historic rainfall figures

The River Stour has a history of flooding and major floods were recorded as far back as 1756.
Recent major floods occurred in 1960, 1966, 1974 and twice in 1979. In the past decade flooding seems to be occurring with greater regularity. There were minor floods in 1990, 1992 and 1994/5 with larger floods occurring in 1999 and 2000.

1. At what time of year were historic rainfall amounts recorded?

Look at the hydrograph for the River Stour at Hammoon in 1999.

link to hydrograph for the River Stour, Hammoon 1999

2. Why is Hammoon a good location to monitor the flow of the River Stour?
3. Describe the pattern of flow of the River Stour at Hammoon in 1999.
4. How high was the peak flow in December?

The hydrograph for the month of December shows the fluctuations in discharge on the River Stour.

link to hydrograph for the River Stour, December 1999

The floods just before Christmas in 1999 were the third highest since flow records began in 1967.

5. What are the similarities between the flow of the River Stour in 1979 and 1999?