Topic
- Precipitation (Meteorology) 34
- Watersheds 33
- Drainage 26
- Climate 25
- Canals 24
- Sewage 24
- Population 22
- International regimes 21
- Foreign relations 20
- Pipelines 20
- World Bank 20
- Political parties 19
- Reclamation of land 18
- Water--Purification 18
- Atatürk Dam (Turkey) 17
- Elections 15
- Drinking water 14
- Reservoirs 14
- Banks and banking 13
- Investments, Foreign 13