Two links you might find useful if you want to know the real history of waterfall and what to do instead (from the father and the son).

The Rise and Fall of Waterfall: http://www.youtube.com/watch?v=X1c2–sP3o0

Improving Software Economics: Top 10 Principles of Achieving Agility at Scale: http://soft.doit.com.cn/subject/IBM090818/Royce_SoftwareEconomics_whitepaper3.pdf