Index: trunk/resources/data/validator/deprecated.mapcss
===================================================================
--- trunk/resources/data/validator/deprecated.mapcss	(revision 18405)
+++ trunk/resources/data/validator/deprecated.mapcss	(revision 18519)
@@ -2088,4 +2088,37 @@
 }
 
+/* #21630 */
+*[waterway=riverbank][!natural][!water],
+*[waterway=riverbank][natural=water][!water],
+*[waterway=riverbank][!natural][water=river],
+*[waterway=riverbank][natural=water][water=river] {
+  throwWarning: tr("{0} is deprecated", "{0.tag}");
+  suggestAlternative: "natural=water + water=river";
+  group: tr("deprecated tagging");
+  fixAdd: "natural=water";
+  fixAdd: "water=river";
+  fixRemove: "waterway";
+  assertMatch: "way waterway=riverbank";
+  assertMatch: "way waterway=riverbank natural=water";
+  assertMatch: "way waterway=riverbank water=river";
+  assertMatch: "way waterway=riverbank natural=water water=river";
+  assertNoMatch: "way waterway=riverbank natural=shingle";
+  assertNoMatch: "way waterway=riverbank water=lake";
+  assertNoMatch: "way waterway=riverbank natural=water water=lake";
+  assertNoMatch: "way waterway=riverbank natural=shingle water=river";
+}
+*[waterway=riverbank][natural][natural!=water],
+*[waterway=riverbank][water][water!=river] {
+  throwWarning: tr("{0} is deprecated", "{0.tag}");
+  suggestAlternative: "natural=water + water=river";
+  group: tr("deprecated tagging");
+  assertMatch: "way waterway=riverbank natural=shingle";
+  assertMatch: "way waterway=riverbank water=lake";
+  assertNoMatch: "way waterway=riverbank";
+  assertNoMatch: "way waterway=riverbank natural=water";
+  assertNoMatch: "way waterway=riverbank water=river";
+  assertNoMatch: "way waterway=riverbank natural=water water=river";
+}
+
 node[amenity=bench][capacity][!seats],
 way[amenity=bench][capacity][!seats] {