Just imagine your pool is a concrete boat hull. Kind of tricky to calculate but when the amount of water displaced is greater than the weight of the pool shell, then you have lift and it can float. The depth of water displaced is equal to the level of the water table minus the level of the water in the pool. Knowing the shape of the pool you can roughly calculate the volume and therefore the weight of the displaced water. Of course, the big unknown is the level of the water table. The weight of water is about 62.5 pounds per cubic foot. I know this doesn't help you much but if the area is relatively dry then you should be OK. Saturated ground or standing water, NO.
Al