This page describes the join of ccm21.catchments with the clc

CookBook Eda

First an example for Britany

building a table of clc only for Britany

After several trial neither --- ST_Crosses --- nor --- ST_Contains --- did work, the example with ST_Intersects provides a surface that is larger than britany, but ST_Crosses missed the area near the coasts as the geom had to be fully within Britany.

-- extraction of a clc table for Britany
DROP TABLE IF EXISTS clc.clc00_v2_Bretagne;
CREATE TABLE clc.clc00_v2_Bretagne AS
SELECT * FROM clc.clc00_v2_europe where gid IN (
SELECT gid FROM  clc.clc00_v2_europe clc JOIN
    (SELECT the_geom FROM france.region where code_reg='53') as sub
    ON ST_Intersects(sub.the_geom,clc.the_geom));
    
ALTER TABLE clc.clc00_v2_Bretagne ADD CONSTRAINT c_pk_gid PRIMARY KEY  (gid);
alter table clc.clc00_v2_Bretagne add CONSTRAINT enforce_dims_the_geom CHECK (ndims(the_geom) = 2);
alter table clc.clc00_v2_Bretagne add  CONSTRAINT enforce_geotype_the_geom CHECK (geometrytype(the_geom) = 'MULTIPOLYGON'::text OR the_geom IS NULL);
alter table clc.clc00_v2_Bretagne add  CONSTRAINT enforce_srid_the_geom CHECK (srid(the_geom) = 3035);
CREATE INDEX indexclc00_v2_Bretagne ON clc.clc00_v2_Bretagne
  USING GIST ( the_geom GIST_GEOMETRY_OPS ); 

-- run this only once
INSERT INTO geometry_columns(f_table_catalog, f_table_schema, f_table_name, f_geometry_column, coord_dimension, srid, "type")
SELECT '', 'clc', 'clc00_v2_Bretagne', 'the_geom', ST_CoordDim(the_geom), ST_SRID(the_geom), GeometryType(the_geom)
FROM clc.clc00_v2_europe LIMIT 1;

Cutting the surface according to the catchments area

Note this one took a long time to run on my computer, one hour for Britany... It uses --- ST_Intersects --- to reduce the search list and -- ST_Multi(ST_Intersection()) to cut along the primary catchments borders.

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--DECOUPAGE DES SURFACES
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DROP TABLE IF EXISTS clc.clipped_bretagne;
CREATE TABLE clc.clipped_bretagne AS
SELECT intersected.clcgid, intersected.gid, code_00,the_geom
FROM (SELECT clc.gid as clcgid, c.gid,code_00, ST_Multi(ST_Intersection(clc.the_geom, c.the_geom)) the_geom
        FROM  clc.clc00_v2_europe clc INNER JOIN ccm21.catchments c
        ON  ST_Intersects (c.the_geom,clc.the_geom)
        WHERE c.wso_id IN (SELECT wso_id FROM france.wso WHERE area='Bretagne')
       -- AND substring(code_00 from 1 for 1)='1'
       )  AS intersected; --1h12 min
ALTER TABLE clc.clipped_bretagne ADD column id serial PRIMARY KEY;
alter table clc.clipped_bretagne add CONSTRAINT enforce_dims_the_geom CHECK (ndims(the_geom) = 2);
alter table clc.clipped_bretagne add  CONSTRAINT enforce_geotype_the_geom CHECK (geometrytype(the_geom) = 'MULTIPOLYGON'::text OR the_geom IS NULL);
alter table clc.clipped_bretagne add  CONSTRAINT enforce_srid_the_geom CHECK (srid(the_geom) = 3035);
CREATE INDEX indexclc00clipped_bretagne ON clc.clipped_bretagne
  USING GIST ( the_geom GIST_GEOMETRY_OPS ); 
  -- les limites sont bien meilleures
-- Here to analyse the structure of data in the created table
SELECT ST_AsText(the_geom) from clc.clipped_bretagne limit 20;

The final file is effectively cut ....