Perhaps you should try some spelling variations:
"flood management activity." » "flood management activities.", "flood management facility.", "flood management authority.", "land management activity.", "fund management activity.", "flood management _ctivity."
"chain management contracts." » "cash management contracts."
"firm management water." » "firm management data.", "firm management based.", "firm management areas.", "fire management water.", "city management water.", "care management water."
"firm management case." » "fire management case.", "city management case.", "care management case."
"case management a." » "cash management a.", "waste management a.", "change management a.", "case management _."
"farm management how." » "cash management how.", "bank management how.", "data management how.", "farm management from.", "farm management _."

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

• If you are trying to use Boolean operators, they must be ALL CAPS: (((((((("risk management control.") OR ("chain management contracts."))) OR ("flood management activity."))) OR ((((("firm management water.") OR ("firm management case."))) OR ((("case management a.") OR ("farm management how."))))))) OR ("reform management tools."))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((((((\"risk management control.\") or (\"chain management contracts.\"))) or (\"flood management activity.\"))) or (((((\"firm management water.\") OR (\"firm management case.\"))) or (((\"case management a.\") or (\"farm management how.\"))))))) or (\"reform management tools.\"))~".
• Removing quotes may allow a broader search: (((((((( risk management control. ) or ( chain management contracts. ))) or ( flood management activity. ))) or ((((( firm management water. ) OR ( firm management case. ))) or ((( case management a. ) or ( farm management how. ))))))) or ( reform management tools. ))~.
• Adding a wildcard symbol may retrieve word variants: (((((((("risk management control.") or ("chain management contracts."))) or ("flood management activity."))) or ((((("firm management water.") OR ("firm management case."))) or ((("case management a.") or ("farm management how."))))))) or ("reform management tools."))*.