Open spaces and green infrastructure can make a valuable contribution to managing surface water runoff and flooding.
Blue infrastructure such as ponds, lakes, and rivers do help store water, but additional stormwater management is gained with green areas such as parks and fields within the floodplain that will temporarily store stormwater and aid with infiltration.
“if you wait until it floods, it will be too late”
Floods occur when runoff from rain or snowmelt exceeds the capacity of rivers, stream channels or lakes and overflows onto adjacent land. Floods can also be caused by storm surges. Flood risks and impacts can be worsened by new development, clearing and increased impervious surface cover in upstream areas, which causes increased runoff during storm events.
Orange County has experienced flooding events impacting residential, business and agriculture communities. Flooding damage cost hundreds of millions of dollars. Area reports of sewage backing up into homes and streets where families needed to be evacuated and structures condemned. Throughout history, floods have claimed uncounted human lives and devastated property, even destroying cities. Yet people continue to settle and build in floodplains, increasing the risk of property damage and loss of life.
Open space preservation is a strategy that reduces flood risk by restricting development in flood-prone greenspaces. These greenspaces might exist in naturally low-lying areas and river floodplains, thereby making them more prone to flooding. Restricting development in flood prone open spaces can keep homes out of harm’s way from floodwaters and provide for the natural process of absorption and filtering of water.
Communities need to work together in flood control and preventing water contamination from entering a larger watershed across municipal boundaries by way of streams and groundwater from runoff from roads and construction sites as well as aging wastewater infrastructure. As the amount of imperviousness increases in a watershed, the velocity and volume of stormwater runoff increases, which can have several environmental impacts: increased flooding downstream, erosion, and pollutant loads in receiving waters; decreased groundwater recharge and level of water table; altered stream beds and flows; and impaired aquatic habitat.
Preserving open space and creating parks and greenways are key tools to limit imperviousness and create riparian buffers in a watershed, which can be the most cost-effective means for reducing and managing stormwater runoff and protecting water quality.
Sources:
http://waterauthority.orangecountygov.com/watersheds.html
Floodplain Construction Requirements in NYS – NYS Dept. of Environmental Conservation