Charlotte, NC has an extremely wet climate and a combination type soil. Each aspect on its own already makes crawl space flooding likely; however, together, your crawl space is even more at risk.
Soil Conditions
Cecil soil is a combination type soil consisting of sandy-loam soil particles on the surface, as well clay-loam soil particles in the lower layers. Sand-based soils not only are smaller in size, but also, they are finer in texture. Although this means that water can drain and filter much more readily with sandy soils, they are still vulnerable to soil erosion by either wind or water—two weather conditions that are common in Charlotte, NC. Soil erosion can decrease the soil levels, making water accumulation more likely.
Clay-based soils are different in that they change size depending on their exposure to water. They swell to sizes twice their size when they absorb any water, but they shrink down to their original size during drier periods. Repeated shrink-swell cycles can cause the soil around it to shift, resulting in less stable soil. Water can then enter the soil with ease and build up in the ground.
Climate
The city of Charlotte, NC experiences an average of 43 inches of rain per year, with an average of four inches during the summer. Furthermore, Charlotte, NC also experiences about six to 15 days where the temperatures are below freezing. This is around the amount of days that this city has snowfall, give or take. Wind speeds also average at around 7.1 miles per hour.
As you can see, the soil will always be exposed to some sort of water, whether it be rain or melted snow. This can cause sandy soils to be eroded away and clay soils to weaken the stability of the soil. Additionally, since wind speeds are high enough to sweep sandy soil away, soil erosion is also always likely. With less soil comes more water, therefore, paving the way for water to collect inside your crawl space and for eventual flooding.