Why does new "Development "cause stormwater problems?

[raccoon]

In my Nextdoor, someone posted:

“ Get ready, Cityname, for the
stormwater flow that will result from all those new homes!“

Why does stormwater flow result from new homes?

[Raven]

1. Because building results in less permeable areas which means that the

rainwater is not absorbed by the ground soil and thus becomes runoff that ends up in your basement or worse.

[hunter]

2. Undeveloped land soaks up rainwater and slows down its movement.

Rooftops, concrete, and asphalt don't. The water runs right off.

[AleksS]

3. This is a pretty good overview:

https://www.njstormwater.org/bmp_manual/NJ_SWBMP_1%20print.pdf

“ Runoff Quantity
Development can dramatically alter the hydrologic response of an area and, ultimately, an entire watershed. Prior to development, native vegetation can either directly intercept precipitation or evapotranspirate that portion that has infiltrated into the ground back into the atmosphere. Development can remove this beneficial vegetation and replace it with turf grass lawns and impervious roofs, driveways, parking lots, and roads, thereby reducing the site’s pre-developed evapotranspiration and infiltration rates. In addition, clearing and grading can remove surface depressions that store rainfall.

Construction activities may also compact the soil and diminish its infiltration rate, resulting in increased rates and volumes of stormwater runoff from the development site.

Impervious areas directly connected to gutters, channels, and storm sewers can transport runoff more quickly than natural, vegetated conveyances. This shortening of the transport or travel time quickens the rainfall-runoff response of the site, causing flow in downstream waterways to peak faster and higher than under natural or predeveloped site conditions. These increases can create new and aggravate existing downstream flooding and erosion problems and can increase the quantity of sediment and other pollutants in the waterways.

Filtration of runoff and removal of pollutants by natural surface and channel vegetation is eliminated by storm sewers that discharge runoff directly into waterways. Increases in impervious area can also decrease

opportunities for infiltration and reduce stream base flow and groundwater recharge. Reduced base flows and increased peak flows produce greater fluctuations between normal and storm flow rates, which can increase channel erosion and adversely impact aquatic organisms and habitats. Reduced base flows can negatively impact the hydrology of adjacent wetlands and the health of biological communities that depend on these base flows”


There’s more but it might be a long read.

[raccoon]

4. Thanks, all of you. Nt