On 4-5-6 February 2008, 32 mms of rain fell on the 1,300 sq km Stour
catchment area in 48 hours, a total of 42 million tonnes.
About 20% became surface runoff, causing an increase in the river flow
rate (highlighted), estimated at transporting an extra 8.4 million
tonnes in 6 days. A peak of 3.4 million tonnes was reached on the third
day after the rain.
About 80% soaked into the ground, causing the groundwater level to rise
by an average of 2.56 cms. This stored rainwater would return to the river
by seepage over a period of months or years, or be reduced by evaporation
or transpiration during the remaining summer.
In the floodplains, the groundwater rose by 55 cms before seepage
caused it to return to its previous value in about 7 days.
 |
On 9th and 10th July 2008, 47 mms of rain fell on the 1,300 sq km Stour
catchment area in 24 hours, a total of 61 million tonnes.
About 17% became surface runoff, causing an increase in the river flow
rate (highlighted), estimated at transporting an extra 10 million
tonnes in 5 days. A peak of 4 million tonnes was reached on the second
day after the rain.
About 83% soaked into the ground, causing the groundwater level to rise
by an average of 3.9 cms. This stored rainwater would return to the river
by seepage over a period of months or years, or be reduced by evaporation
or transpiration during the remaining summer.
In the floodplains, the groundwater rose by 80 cms before seepage
caused it to return to its previous value in about 7 days.
 |