Perhaps you should try some spelling variations:
irrigation schemes » irrigation systems
irrigation scheme » irrigation systems
syria irrigation » africa irrigation, drip irrigation, surge irrigation
side irrigation » saline irrigation, scale irrigation, under irrigation
support syria » support social, support agri

You may be able to get more results by adjusting your search query.

• The words AND, OR and NOT may confuse the search; try adding quotes: "(( support syria irrigation schemes. ) OR ( supply side irrigation scheme. ))~".
• Adding a wildcard symbol may retrieve word variants: (( support syria irrigation schemes. ) OR ( supply side irrigation scheme. ))*.