Calcular a superfície abaixo do nível do mar

BrunoDI_GIUSTO

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Bom dia a todos. <\/SPAN><\/P>Qual será o melhor método para calcular, a partir de um DEM e um shapefile com os polígonos das comunas, a superfície total de cada comuna que está abaixo do nível do mar, por favor? <\/SPAN><\/P>Agradeço antecipadamente pela ajuda!<\/SPAN><\/P><\/BODY><\/HTML>

BrunoDI_GIUSTO

1- raster calculator (in Spatial Analyst Tools/Map Algebra) with [original DEM] <= 0 which produce a new raster with two categories, one above sea level and another below sea level

2- Tabulate area (in Spatial Analyst Tools/Surface/Zonal/) which calculate the surface of each previous categories within the polygons of the shapefile.

3- in the table created, create a new field for the total surface of the two categories.

4- in the same table, create a new field for the percentage of submerged land with surface of submerged land / total surface. Click on properties on the percent field, then click percentage, then Numeric, then all frequencies are percentage, adjust the number of decimals.

5-Spatial join the table to the original table of the shapefiles of the communes. End