Consider a pension fund with a liability structure that requires it to meet cash flow obligations starting in 5 years, totaling $1 million per year for a period of 10 years. The fund has identified a fixed income portfolio that can provide predictable cash flows, but it must ensure that the assets align with these future liabilities to mitigate the risk of cash flow shortfalls.

In this context, discuss the concept of cash flow matching as a liability-driven investment strategy. Specifically, evaluate the advantages and challenges associated with implementing a cash flow matching strategy for this pension fund. In your response, provide a detailed analysis of how cash flow matching can be effectively designed and the key factors that must be considered in its execution.