Our second post will be about watersheds. One thing to always consider during a natural disaster, such as hurricanes, is not the direct hit of the storm, but as it makes landfall and moves across the state. Here's why flooding becomes more of an issue than the power of wind.
A watershed is the collective area of water and land, from a higher elevation to a lower one. A great way to understand a watershed is to use your palm as a guide. Cup you hand, with your palm facing upwards. Your fingertips represent mountains and your wrist represents the ocean. Here on the east coast of the U.S., our waters will flow from the mountains to the sea (west to east). The lines on your palm represent all the waterways (including rivers, streams, and creeks) that flow down to the Atlantic Ocean.
For centuries, since the beginning of our settlement here, people have naturally gravitated towards water sources. We build our homes close to a water source, we make sure our farms have sufficient water, and we visit and vacation near water. Because of this, more people live along rivers, streams, tributaries, and in a floodplain.
If we live in the mountains or the middle of the state (in NC it's the Piedmont), our river levels will rise during periods of rain. If we live along the coast, our rivers will rise due to our daily tides. This is how a normal watershed works. After a rainfall or after high tide, the water levels will recede, by either flowing downstream or by being absorbed into tree roots or the ground. During storm events and natural disasters is when we run into major problems.
When a hurricane comes ashore, it brings with it heavy rain and storm surges, or an excess of water. Along the coastal areas, this storm surge will add to a normal tide, flooding low-lying areas and overwashing barrier islands. Once the storm moves inland, it will inundate the watershed. When this much water falls over a short period of time, there is nowhere for the water to go but over the banks of the rivers and onto roads.
With extreme flooding conditions, caution is the key. Although it may look shallow, you have no idea how deep the water really is. Underneath that water could be boulders, sinkholes, or uneven payment that is invisible while driving. There's no way around it and you certainly can't trust going through it. For a natural watershed to work properly, we have to give it time to absorb the excess water, either through the ground or flowing out to sea. This could take days or weeks and the damage to our roads and homes can be costly. This is the price we pay for settling near water sources.