The Shropshire Hills Area of Outstanding Natural Beauty (AONB)

Playing with data and plotting in R again. Took ages, but I learnt a lot!

The Shropshire Hills AONB and the hills of South Shropshire.

Data

OpenStreetMap via osmdata package in R.
- downloaded Shropshire Hills AONB boundary
- Peaks within the bounding box
- Places - towns only.

Tools

R with osmdata and ggplot2 packages.

What did I learn?

How to combine multiple layers in a plot
How to create a key for at least some of those layers - tried manual as well as auto.
How to label a points layer

What would I like to change?

Main thing is, I’d like to subset the hills to just within the AONB boundary, but the boundary is multiple line features, not a single polygon. So can I or would I need to, polygonise the lines in R?
Layout isn’t great…
Would look good with a hillshade or height layer behind it, but haven’t started looking at raster yet!!!

Process

Based on tutorial at https://jcoliver.github.io/learn-r/017-open-street-map.html

In the R notebook, but need to either include it, or summarise it here.

OpenStreetMap data in R

For Day 15 of the 30DayMapChallenge 2023.

Based on tutorial at: https://jcoliver.github.io/learn-r/017-open-street-map.html

Load required packages

library(osmdata)

Data (c) OpenStreetMap contributors, ODbL 1.0. https://www.openstreetmap.org/copyright

library(ggplot2)
theme_set(theme_bw())
library(ggspatial)
library(ggtext)
library(sf)

Linking to GEOS 3.13.1, GDAL 3.11.4, PROJ 9.7.0; sf_use_s2() is TRUE

Finding out what is available

Want to know what tags there are within certain features.

available_tags(feature = "boundary")

# A tibble: 26 × 2
   Key      Value             
   <chr>    <chr>             
 1 boundary aboriginal_lands  
 2 boundary administrative    
 3 boundary border_zone       
 4 boundary census            
 5 boundary disputed          
 6 boundary forest            
 7 boundary forest_compartment
 8 boundary hazard            
 9 boundary health            
10 boundary historic          
# ℹ 16 more rows

So what am I going to map???

boundary = protected_area = Shropshire Hills AONB
natural = peak

Define bounding box (bb)

# Use bounding box for Shropshire Hills AONB
aonbb <- getbb("Shropshire Hills AONB")
# print the matrix to the console to check.
aonbb

        min       max
x -3.235556 -2.502348
y 52.344255 52.689255

Download data

Download data layers

Download the following layers:

Shropshire Hills AONB boundary
Peaks (hills) within the bounding box
Places - just towns so not too many

q1 <- opq('Shropshire Hills AONB') %>%
    add_osm_feature(key = 'boundary',
                    value = c("protected_area"))
aonb_boundary <- osmdata_sf(q1)

q2 <- opq('Shropshire Hills AONB') %>%
    add_osm_feature(key = 'natural',
                    value = c("peak"))
peaks <- osmdata_sf(q2)

q3 <- opq('Shropshire Hills AONB') %>%
    add_osm_feature(key = 'place',
                    value = c("town"))
places <- osmdata_sf(q3)

Subset peaks so only have those peaks within the AONB boundary

Not so easy, because the boundary is a line class, not a polygon feature…

Plotting downloaded layers

aonb_plot <- ggplot() +
  geom_sf(data = aonb_boundary$osm_lines,
          aes(colour = "Shropshire Hills AONB"))+
  geom_sf(data = peaks$osm_points,
          aes(colour = "Hills"))+
  geom_sf(data = places$osm_points,
          colour = "blue")+
  coord_sf(crs = st_crs(27700), xlim = c(315000, 374000), ylim = c(270000, 315000),
           datum = st_crs(27700), expand = FALSE)+
  geom_sf_label(data = places$osm_points,   # Controls labels - in this case place names.
                aes(label = name), # field for the labels
                label.padding = unit(0.7, "mm"), # padding around the text - ie the white bit
                size = 2,  # size of text - no idea what the units are!
                fill = "white")+
  labs(x = NULL, y = NULL, color = "Key",
       caption = "Data copyright: OpenStreetMap Contributors 2023.") +
  ggtitle("The Shropshire Hills Area of Outstanding Natural Beauty (AONB)", 
          subtitle = "#30DayMapChallenge, Day 15: OpenStreetMap. Clare Gordon, November 2023.")+ 
  theme_grey(base_size = 9) +   # if don't set a theme, don't get coordinate grid...
  theme(plot.title.position = "plot",
        plot.title = ggtext::element_textbox_simple(face = "bold"),
        legend.position = c(0.63, 0.9),
        plot.margin = unit(c(0.5, 0.5, 0.5, 0.5), "cm"),
        panel.grid = element_line(color = "white", linewidth = 0.4, linetype = 2))
# print the plot
aonb_plot

Export the result…

ggsave("ShropshireAONB.png", device = png, bg = "white", width = 16, units = "cm", dpi = 300)

Saving 16 x 12.7 cm image