Updated towgs84 parameters of JTSK CRS, the towgs84 values were calculated for area of Czech and Slovak Republic as it is described here: http://grass.fsv.cvut.cz/gwiki/%C4%8Ceskoslovensk%C3%BD_transforma%C4%8Dn%C3%AD_kl%C3%AD%C4%8D

UPDATE tbl_srs set parameters = '+proj=krovak +lat_0=49.5 +lon_0=24.83333333333333 +alpha=30.28813972222222 +k=0.9999 +x_0=0 +y_0=0 +ellps=bessel +towgs84=542.5,89.2,456.9,5.517,2.275,5.516,6.96 +pm=greenwich +units=m +no_defs' WHERE auth_id = '5513';

UPDATE tbl_srs set parameters = '+proj=krovak +lat_0=49.5 +lon_0=24.83333333333333 +alpha=30.28813972222222 +k=0.9999 +x_0=0 +y_0=0 +ellps=bessel +towgs84=542.5,89.2,456.9,5.517,2.275,5.516,6.96 +pm=greenwich +units=m +no_defs' WHERE auth_id = '5514';

UPDATE tbl_srs set parameters = '+proj=krovak +lat_0=49.5 +lon_0=42.5 +alpha=30.28813972222222 +k=0.9999 +x_0=0 +y_0=0 +ellps=bessel +towgs84=542.5,89.2,456.9,5.517,2.275,5.516,6.96 +pm=ferro +units=m +no_defs' WHERE auth_id = '5221';

UPDATE tbl_srs set parameters = '+proj=krovak +lat_0=49.5 +lon_0=42.5 +alpha=30.28813972222222 +k=0.9999 +x_0=0 +y_0=0 +ellps=bessel +towgs84=542.5,89.2,456.9,5.517,2.275,5.516,6.96 +pm=ferro +units=m +no_defs' WHERE auth_id = '2065';

UPDATE tbl_srs set parameters = '+proj=krovak +lat_0=49.5 +lon_0=24.83333333333333 +alpha=30.28813972222222 +k=0.9999 +x_0=0 +y_0=0 +ellps=bessel +towgs84=542.5,89.2,456.9,5.517,2.275,5.516,6.96 +pm=greenwich +units=m +no_defs' WHERE auth_id = '102067';