--- a/wamos.sql	Wed May 30 15:58:02 2018 +0200
+++ b/wamos.sql	Wed May 30 16:39:26 2018 +0200
@@ -61,6 +61,10 @@
        -- TODO: add real waterway area attributes (DRC 2.1.3)
        );
 
+CREATE TABLE wamos.reference_water_levels (
+       reference_water_level varchar(20) PRIMARY KEY
+       );
+
 CREATE TABLE wamos.gauges (
        location isrs PRIMARY KEY,
        dummy_attrib varchar,
@@ -68,6 +72,13 @@
        -- TODO: add real gauge attributes (DRC 2.1.4)
        );
 
+CREATE TABLE wamos.gauges_reference_water_levels (
+       gauge_id isrs REFERENCES gauges,
+       reference_water_level varchar(20) REFERENCES reference_water_levels,
+       PRIMARY KEY (gauge_id, reference_water_level),
+       value int NOT NULL
+       );
+
 --
 -- Bottlenecks
 --