ADDING AREA TO CULVERTS

[ErnestDankwah]

Hello, I have delineated watershed from DEM for some culverts. I would like to add the area of each watershed to its respective culvert and I would really appreciate any help I can get. The culverts are point shapefiles and the watershed are from the DEM. Since these are two different Layers, I am finding it hard to add the area drained by each culvert (which is in the DEM)to its respective culvert.

I have 1435 culvert points shapefile and there are 1409 watershed areas I need to add to the culvert shapefile.

Also, I have a land cover data classified into two classes (pervious and impervious) that I would like to add as another attribute of the culverts point shapefile. I would like to determine percent of watershed that is impervious as attributes of each culvert.

Can anybody please give me clues as to how to proceed?

Thank you.

[MarkBoucher]

If you have a flow accumulation (fac) raster, (which you likely have if you've deliniated the watershed) you could extract the value from the fac raster to the points. Then you'd need to multiply the fac value by the grid area (100sf for a 10'x10' grid) to get the watershed area.

With the Spatial Analyst function \Extraction\Extract Values to Points you could use the culvert point feature class (fc) and fac raster to create a new point fc that has the same fields as the culvert point fc plus a "RASTERVALU" field. After creating the new point fc you can join it with the culvert point fc using the Object ID or someother unique field (or by location) and transfer the RASTERVALU to your culvert point fc while multiplying if by a factor to get the area.

Hope this makes sense.