Lab 6: Isarithmic Mapping

This week, we learned about israithmic mapping and interpolation. We created an annual precipitation map, shown above, with data from the Parameter-elevation Relationships on Independent Slopes Model (PRISM) Group at Oregon State University published by the USDA, Natural Resources Conservation Service, National Geospatial Management Center in September 2012. The metadata explains how the precipitation data was derived and interpolated. The raster dataset derived the annual precipitation in inches using point data from a 30-year climate period from 1981-2010. PRISM uses an underlying grid like the digital elevation model (DEM) or a 30-year climatological average to get estimates of precipitation and temperature. 

I learned how to apply the Hillshade function to create a 3D depiction of the terrain surface on top of the annual precipitation raster dataset. I also learned about using Hypsometric Tints to make elevation zones more distinct so that viewers can see the differences in depth. It is implemented in the map by being place over a hillshaded layer with varying amounts of transparency to accurately show the various elevations. This way, you can more clearly see the mountain ranges located to the west side of the state and that the eastern part of the state appears to be mostly flat in comparison. This can help the map reader understand how precipitation values are relevant to elevation variations throughout the state. I also used the Contour List tool to create contour lines that overlayed the hypsometric tints. I entered 10 contour values manually to match the hypsometric steps from 10 to 180. The contours help enhance the terrain features. Where the contours are close together, it represents steeper terrain and higher elevations.