Perhaps you should try some spelling variations:
sanitation schemes » sanitation systems, sanitation access, irrigation schemes
irrigation scheme » irrigation systems
chain irrigation » change irrigation, basin irrigation, chain integration
city sanitation » site sanitation, security sanitation, water sanitation
supply city » supply cote, supply costs

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( supply chain irrigation scheme. ) or ( supply city sanitation schemes. ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( supply chain irrigation scheme. ) OR ( supply city sanitation schemes. )).
• Adding a wildcard symbol may retrieve word variants: (( supply chain irrigation scheme. ) or ( supply city sanitation schemes. ))*.