Water layer river mapping bug fixes (#1182)

This PR is a bugfix for the `water` layer.

* `waterway=stream`, `waterway=river`, `waterway=canal`, `waterway=ditch`, and `waterway=drain` are all linear features, not area features.  Thus, these objects are being unnecessarily mapped into the `osm_water_polygon` polygon table, and this PR removes these unneeded mappings.
* The combination `natural=water` + `water=river` is the most popular tagging for river areas.  However, the current mapping causes rivers tagged in this way to be rendered in the vector tiles as a `lake`.  This PR adds a check for the `water=river` tag and tags both variants of river areas as `class=river`.

`natural=water` + `water=river` river mapping:
![image](https://user-images.githubusercontent.com/3254090/129825551-388491de-549e-4843-80cc-01dba358c360.png)

`waterway=riverbank` river mapping:
![image](https://user-images.githubusercontent.com/3254090/129825618-4239eae7-a2bc-4a82-9931-fda2c02c2b40.png)


Lake mapping for a `natural=water` (with no other tagging):
![image](https://user-images.githubusercontent.com/3254090/129825554-9394b3d3-988a-4e92-a9f8-b198c695ec37.png)

layers/water/mapping.yaml

@@ -75,6 +75,9 @@ tables:
     - name: waterway
       key: waterway
       type: string
+    - name: water
+      key: water
+      type: string
     - name: is_intermittent
       key: intermittent
       type: bool
@@ -95,11 +98,8 @@ tables:
       - bay
       - spring
       waterway:
-      - river
       - riverbank
-      - stream
-      - canal
-      - drain
-      - ditch
       - dock
+      water:
+      - river
     type: polygon

layers/water/water.sql

@@ -1,8 +1,9 @@
-CREATE OR REPLACE FUNCTION water_class(waterway text) RETURNS text AS
+CREATE OR REPLACE FUNCTION water_class(waterway text, water text) RETURNS text AS
 $$
 SELECT CASE
+           WHEN waterway='riverbank' THEN 'river'
            %%FIELD_MAPPING: class %%
-           ELSE 'river'
+           ELSE 'lake'
            END;
 $$ LANGUAGE SQL IMMUTABLE
                 PARALLEL SAFE;
@@ -314,7 +315,7 @@ FROM osm_ocean_polygon_gen_z6
 UNION ALL
 -- etldoc:  osm_water_polygon_gen_z6 ->  water_z6
 SELECT geometry,
-       water_class(waterway) AS class,
+       water_class(waterway, water) AS class,
        is_intermittent,
        NULL::boolean AS is_bridge,
        NULL::boolean AS is_tunnel
@@ -334,7 +335,7 @@ FROM osm_ocean_polygon_gen_z7
 UNION ALL
 -- etldoc:  osm_water_polygon_gen_z7 ->  water_z7
 SELECT geometry,
-       water_class(waterway) AS class,
+       water_class(waterway, water) AS class,
        is_intermittent,
        NULL::boolean AS is_bridge,
        NULL::boolean AS is_tunnel
@@ -354,7 +355,7 @@ FROM osm_ocean_polygon_gen_z8
 UNION ALL
 -- etldoc:  osm_water_polygon_gen_z8 ->  water_z8
 SELECT geometry,
-       water_class(waterway) AS class,
+       water_class(waterway, water) AS class,
        is_intermittent,
        NULL::boolean AS is_bridge,
        NULL::boolean AS is_tunnel
@@ -374,7 +375,7 @@ FROM osm_ocean_polygon_gen_z9
 UNION ALL
 -- etldoc:  osm_water_polygon_gen_z9 ->  water_z9
 SELECT geometry,
-       water_class(waterway) AS class,
+       water_class(waterway, water) AS class,
        is_intermittent,
        NULL::boolean AS is_bridge,
        NULL::boolean AS is_tunnel
@@ -394,7 +395,7 @@ FROM osm_ocean_polygon_gen_z10
 UNION ALL
 -- etldoc:  osm_water_polygon_gen_z10 ->  water_z10
 SELECT geometry,
-       water_class(waterway) AS class,
+       water_class(waterway, water) AS class,
        is_intermittent,
        NULL::boolean AS is_bridge,
        NULL::boolean AS is_tunnel
@@ -414,7 +415,7 @@ FROM osm_ocean_polygon_gen_z11
 UNION ALL
 -- etldoc:  osm_water_polygon_gen_z11 ->  water_z11
 SELECT geometry,
-       water_class(waterway) AS class,
+       water_class(waterway, water) AS class,
        is_intermittent,
        NULL::boolean AS is_bridge,
        NULL::boolean AS is_tunnel
@@ -434,7 +435,7 @@ FROM osm_ocean_polygon_union
 UNION ALL
 -- etldoc:  osm_water_polygon ->  water_z12
 SELECT geometry,
-       water_class(waterway) AS class,
+       water_class(waterway, water) AS class,
        is_intermittent,
        is_bridge,
        is_tunnel

layers/water/water.yaml

@@ -12,14 +12,18 @@ layer:
     class:
       description: |
           All water polygons from [OpenStreetMapData](http://osmdata.openstreetmap.de/) have the class `ocean`.
-          Water bodies with the [`waterway`](http://wiki.openstreetmap.org/wiki/Key:waterway) tag are classified as `lake`, `dock`, or `river`.
+          Water bodies with the [`waterway=riverbank`](http://wiki.openstreetmap.org/wiki/Tag:waterway=riverbank) 
+          or [`water=river`](http://wiki.openstreetmap.org/wiki/Tag:water=river) tag are classified as river.  Wet and dry docks
+          tagged [`waterway=dock`](http://wiki.openstreetmap.org/wiki/Tag:waterway=dock) are classified as a `dock`.
           All other water bodies are classified as `lake`.
       values:
-        lake:
-          waterway: ['', 'lake']
         dock:
           waterway: 'dock'
         river:
+          water: 'river'
+          waterway: 'riverbank'
+        lake:
+          waterway: ''
         ocean:
     intermittent:
       description: |