Throughout history, people have found it desirable to construct cities along streams. There are many obvious advantages (water, transportation access, etc.) but there is a major disadvantage: The flow of water in streams is never constant, and the high amount of water flowing in streams often leads to flooding.

From a geological perspective, floods are a natural consequence of changes in the flow of streams. They are part of the water cycle. Streams receive most of their water from precipitation, and the amount of precipitation falling in any given drainage basin varies from day to day, year to year and century to century.

As development continued,  floodplains were filled and opportunities for flood storage were lost. At the same time, additional stormwater runoff was being generated because of the impervious surfaces reated by development. Most recently, we are seeing an increase in the intensity of storms, dumping enormous volumes of water in a short period of time. With more water and fewer places for it to go, we experience flooding.

Flooding is not a new problem. It has been a topic of concern  -- and studies -- in Westchester County for more than a century