Flood mapper’s guide

“We need to prepare for a food in Tandale! Use this guide to help get the food prone areas mapped.”

Flood mappers: Using the aerial image as a contextual backdrop layer, you will need to create a set of polygon areas representing expected food depth in the area covered by the provided dataset. The food layer you generate should have the following properties:

Name Tandale_floods.shp
Type polygon
Required attribute depth
Attribute type decimal
Attribute length 10 (with 3 decimal places)
Notes When capturing your floods, ensure that your flood polygons do not overlap.

You try:


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Capture the food areas using the tandale_imagery base map and make a quick determination as to what depth each should be set to (use your best guess if you are not sure). Use the depth scheme in the table below:

Not flooded Low flood Medium flood High flood
0 0.1 (i.e. 10cm) 0.8 (i.e. 80cm) 1.5 (i.e. 1.5 m)

Plan the digitising work so that each team member captures a diferent section of the study area. When all of the team are fnished, share the data to one team member who should then combine the data into one layer.
Once your layer is fnalised, stop editing and use the InaSAFE keywords wizard to defne appropriate keywords for the layer you have created. When you have received all the exposure and aggregation datasets, run an analysis for each of these scenarios:

  • Flood on roads aggregated by wards
  • Flood on buildings aggregated by wards
  • Flood on people aggregated by wards