How does the rate of runoff change after development?

After development, the rate of runoff typically increases due to several key factors associated with urbanization. In developed areas, natural landscapes are often altered, leading to the replacement of permeable surfaces like soil and vegetation with impervious surfaces such as roads, rooftops, and parking lots. These impervious surfaces prevent water from infiltrating into the ground, which significantly reduces the natural absorption that would typically occur in undeveloped areas.

As a result, precipitation is more likely to flow over these hard surfaces and enter storm drains or waterways as surface runoff rather than soaking into the ground. In addition, the increased volume and speed of runoff can lead to higher peak flows, which can exacerbate flooding and erosion issues downstream. Furthermore, development may also affect the natural drainage pathways, allowing for even more rapid runoff into nearby water bodies.

This change in runoff dynamics is critical for stormwater management because it necessitates the implementation of effective stormwater control measures to mitigate the impact of increased runoff on local watersheds and ecosystems. Understanding this increase is vital for designing infrastructures, such as detention basins, green roofs, and permeable pavements, which aim to manage and reduce the effects of altered runoff patterns.