Tucson, as with the rest of Arizona, is situated on old land, plates that have survived numerous pole shifts without fracturing. As improbable as may seem, the hardened soil, which creates flash floods in the desert, will give this desert area water problems both during the shift and during the almost perpetually rainy years afterwards. Tucson is surrounded by mountains, which will run rainwater into the lowlands. With rising sea levels pushing back on the rivers, rivers will empty more slowly, and thus flash floods can become lakes. Ensure that your survival sites are situated with this taken into consideration, not in a flash flood runoff.
Where Arizona is beyond the reach of tidal waves, and on high enough ground that it will be above water after the existing poles melt, it will be in the traffic lanes that carry refugees from Texas and Mexico. Mexico will carry refugees from Central America, which will be devastated, and from Mexico City itself. Texas will find itself on mud-strewn flats, with water-weary survivors looking for dry ground. Without fertile agriculture, Tucson and its vicinity will find that stores of food become wealth, quickly plundered from the weak. This does not have a happy solution.