CREATE OR REPLACE VIEW water_z0 AS (
    SELECT geom FROM ne_110m_ocean
    UNION ALL
    SELECT geom FROM ne_110m_lakes
);

CREATE OR REPLACE VIEW water_z1 AS (
    SELECT geom FROM ne_110m_ocean
    UNION ALL
    SELECT geom FROM ne_110m_lakes
);

CREATE OR REPLACE VIEW water_z2 AS (
    SELECT geom FROM ne_50m_ocean
    UNION ALL
    SELECT geom FROM ne_110m_lakes
);

CREATE OR REPLACE VIEW water_z3 AS (
    SELECT geom FROM ne_50m_ocean
    UNION ALL
    SELECT geom FROM ne_110m_lakes
    UNION ALL
    SELECT geom FROM ne_110m_rivers_lake_centerlines
    WHERE featurecla = 'River'
);

CREATE OR REPLACE VIEW water_z4 AS (
    SELECT geom FROM ne_10m_ocean
    UNION ALL
    SELECT geom FROM ne_50m_lakes
    UNION ALL
    SELECT geom FROM ne_50m_rivers_lake_centerlines
    WHERE featurecla = 'River'
);

CREATE OR REPLACE VIEW water_z5 AS (
    SELECT geom FROM ne_10m_ocean
    UNION ALL
    SELECT geom FROM ne_10m_lakes
    UNION ALL
    SELECT geom FROM ne_10m_rivers_lake_centerlines
    WHERE featurecla = 'River'
);