I'm a fairly novice GIS user and know just enough to get in trouble in a lot of cases. I am trying to look at the connection between several measured parameters at a few hundred stations along several rivers and the landuse patterns in the areas drained in ArcGIS 10. I have created basic watershed analysis layers (flow directions, flow accumulation, catchments, etc) for the entire area of interest. Is there a way to easily sum up the land usage for the area drained by each station (i.e. get the number of cells of each type of land use along with the total cells drained) so that I could use that for further analysis? If so, how would be the easiest way to implement that so I don't have to do it individually for each station? I would assume there would be a way to script it, but I don't know anything about scripting in ArcGIS 10. Thanks so much!
Recompute the flow accumulation by setting the input ("rainfall area") to 1 within the cells of a given land use and 0 elsewhere. Extract the values at the stations (one operation via the "extract values to points" tool). Multiply these results by the squared cellsize to estimate the areas. Repeat for each land type. Join the results on the station identifiers. When finished, the percentages are computed in the usual way by renormalizing the areas for each station to sum to 100%.