Most people feel that real estate Business is risk Free, but i want to make it clear that every Investment/ business is not risk free rather thier level of risk differs. And this flood issue have made real estate Business more risky than we thought, though thier are some certain areas that is always save during flood so this are the areas that we are supposed to be looking for and not swampy areas. But in all I would admit with what you said about diversification even though your first choice of investment is to invest into real estate but we should not forget to look into other business/ Investment to avoid one particular point of failure.