It is great that you are looking into making improvements to your home to prevent future losses!
Your homeowners policy can provide reimbursement for supplies that are used to prevent further damage to your property at the time of a loss, but it is the nature of a gravel driveway to lose gravel from shifting—so this option would not apply here, either.
The risk of flooding is great in many parts of the U.S. However, damage related to flooding is not covered by regular home insurance policies. For this reason, it’s wise to add on flood insurance, although it will cost extra. Explore your options to find a plan that suits your needs.