It was Hurricane Matthew’s long trip up the coast that made it more destructive than many storms: Since it didn’t make landfall in Florida but hugged the coast as it moved up to South Carolina and then North Carolina, part of the system was always over water, and a cycle of evaporation and condensation from the ocean kept supplying more energy to the hurricane.
As the bands of rain soaked our state for hours and hours, the flowing water created erosion that exposed roots and vegetation, and the water soaked into the soil, softening the land subsurface and making it easier for the accompanying winds to uproot trees. The rainfall that washed away the soil also eroded away roads and destabilized culverts and other human-built structures.
So how can we avoid these damaging effects of a hurricane or a thunderstorm? Proper drainage helps to prevent ponding of water that produces the gradual infiltration to the subsurface and destabilizes the vegetation and structures and causes soil erosion. Erosion is also determined by the speed of the flowing water: Steep slopes and embankments should be landscaped in a way to reduce this fast flow of water. Having vegetation on slopes greatly reduces soil erosion.
The process of rebuilding and healing will take weeks to months. But the few inches of rainfall that Matthew brought to the Midlands has helped increase the levels of water in the ponds, lakes, streams and rivers. Some of this water will reach the water table and help us weather future droughts.
USC Professor of Earth and Ocean Sciences