How you can identified the risks at various stages of the project?

The "risks" shouldn't vary during a project or suddenly appear out of nowhere. By definition, any project is a risk. You take risks in order to generate profit. Your "risk" should be identified at the beginning of the project and hopefully it is a financial risk rather than say, a code or OSHA violation or substituting wood for steel... Financial risk is defined in your project pro forma. Job site risks that put people in danger are illegal and should be avoided. Risks taken to violate the code and fool construction inspectors are also ill-advised in that at any time during the construction process, you will be obliged to correct defects and illegal construction whether the inspector passed it or missed it.