added layers variable to 2nd script

02_process_data.R

@@ -1,4 +1,5 @@
 # load libraries
+library(nhdplusTools)
 library(sf)
 
 # reload extent data so you don't need to run the download data script again
@@ -26,6 +27,10 @@ extent <- list(longitude_max = max(extent$longitude),
 # load and crop hydrologic data
 data <- list(NULL)
 sf_use_s2(FALSE)
+layers <- c("NHDArea",
+          "NHDFlowline",
+          "NHDWaterbody",
+          "NHDPlusLandSea")
 for (layer in layers){
 data[[layer]] <- st_crop(st_read(paste0(nhdplusTools_data_dir(),"/data.gpkg"), layer = layer), y = extent_bbox)
 }