Here comes the big bad flood!

Since the mid-1900s, scientists’ ability to predict the arrival of extremely wet or dry weather has improved for many reasons.

1 Satellite photographs Satellite images show weather systems developing long before they make landfall - often giving weather forecasters several days’ notice of heavy rain arriving.

2. Soil moisture monitoringIf soil is wet from previous storms then new rain cannot soak in and will flow fast over the land to the river - making the flooding even worse.

2. Soil moisture monitoringData can be sent from the monitoring equipment by radio - keeping scientists up to date with what’s happening. Photo

courtesy of www.campbellsci.co.uk

3. MappingMaps show how steep the land is. This gives scientists an idea of how quickly rain will flow downhill. Geology maps show what rocks are present - and if water can soak in.

4. Hydrograph calculationsOnce they know how much rain is coming, how steep slopes are and how wet soils already are, scientists can compute hydrographs to show how high the river level is likely to get.

Flood warnings in the UK are issued by the Environment Agency, who employ many of the UK’s top river scientists

Visit their web site and look at flood warnings at http://www.environment-agency.gov.uk/subjects/flood/floodwarning/

The Environment Agency works closely with the UK’s weather experts, such as the Hadley Centre and the Met Office

Visit the Met Office and look at weather warnings at http://www.metoffice.gov.uk/