No matter where you live, you are surrounded by infrastructure and systems designed to move rainwater into appropriate basins and reservoirs.
It is a similar issue to having a lack of vegetation, which is explained in more detail below.
Vegetation can help slow runoff and prevent flooding.
Most mountainous areas experience relatively consistent snowfall totals from year to year, but an unusually heavy winter of precipitation can spell bad news for low-lying areas around the mountains when spring hits.
The good news is that sustained winter precipitation provides a long lead time to prepare for potential flooding. These are just a few examples of common causes of floods, but there does not need to be an incredible weather event for you to experience flooding at your home.
This is part of what happened after Hurricane Katrina hit New Orleans in 2005.
Flash Floods Essay
Levees failed and made the flooding far worse than it would have been otherwise.
When there is a lack of vegetation, however, there is little to stop water from running off. While area residents likely welcome the rain, the lack of vegetation after the drought can cause flash flooding.
This does not always happen given that basins and reservoirs are close to empty, but it can occur in cases of extreme rains following long periods of drought.
When you have an urban drainage basin that is made of concrete, there is no ground for water to sink into.
So, when those drainage basins fill up, it is going to mean flooding for low-lying areas.