Since your town was impacted in a negative way by the flooding the demand for home improvement items will be high. When demand is high and supply is low it can drive up prices. Most stores would definitely take advantage of this supply and demand case because they could turn a bigger profit. That would be a motivating reason for some people or companies.
As for me personally, I would not raise prices in my business because I feel that is taking advantage of people in a bad situation. You know that they are going to need to supplies to help them fix flood damage and they will have no option but to buy the needed materials. However, if you raise prices it could backfire on you and they may go somewhere else to get the materials needed instead of shopping with you.