DEMO: Dike water deficit (drought) monitoring using GIS and remote Sensing data

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Demo of an open source GIS publication showing dike water deficit on a detail level.

LINK: http://www.you-rs.com/droogtemonitor/

How does it work and what can you see

Every summer the Dutch national weather institute will calculate the current rainfall deficit. This means in a dry year there is more rainfall evaporated than fallen (negative number). these numbers can vary over the country.

A dike however is a 3D structure above the surrounding area: it's evaporation area is larger than the rainfall area. On a slope this can be a factor 1.3 higher. So a dike will evaporate more thus have a larger deficit.

Have a look at this documentary (English) that shows you what happens with dry dikes: they have to be kept wet or they will shrink!

The application will calculate the corrected rainfall deficit based on a KM mesh rainfall deficit (rainfall minus evapo(transpi)ration) and will apply a levee slope correction amplification). In addition the calculated deficit is started on march 1 (national count starts on april 1st) because droughts frequently start in early spring.

The method can also be used to review historic events. based on available data also the expremely dry year 1997 was calculated. 

just zoom in - klick on a dot (levee point) and the graph will show in gray the dutch standard line and in Red the calculated local line for that point on the levee. 

Do you see how much it can vary!!? leave a comment below and let me know what you think about this GIS application. Stefan J. Flos

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