Communicating with higher has always the most effective part for me when managing scarce resources.  The other options are important and generally need to be understood before talking to higher, but much of managing scarce resources (especially time) comes from truly understanding your higher headquarter’s intent and priorities.  If you go to higher with a good plan, resourced as much as possible with internal and lateral resources, and then articulate what your shortfalls are and the impact of not receiving them, you have the best chance of getting what you need (even if it may not be what you want).  Additionally, you may learn that you have been out of sync and that your plan isn’t nested with their priorities and have time to adjust before committing resources on the wrong things.