Decreasing contamination of runoff: Runoff and stormwater management

Vegetative groundcover such as turfgrass (a) has a much greater absorptive capability than less-permeable groundcover like asphalt (b), and can ‘soften’ the impact of storms by slowly releasing runoff and allowing more to infiltrate down into the ground. Impervious areas, in contrast, concentrate rainfall into fast-moving, high-volume flows that have greater ability to carry pollutants and cause erosion. Such runoff is often directed into storm drains, which may be directly connected to rivers, lakes, and streams. Image courtesy Chris Murray

By Christopher Murray, PhD

The issue is not that it rains, but rather what is put in the path of that rain. In areas with healthy terrestrial ecosystems, when rainwater falls it is absorbed by the soil and the organisms that live in and on it. Some of this water is used in the biological processes of the ecosystem, but most eventually makes its way out as groundwater or runoff. This takes time, and passage through these abiotic and biotic systems slows down the water, filtering it and ‘softening’ its impact. Where humans have developed the land and introduced paving, roofing, and otherwise waterproof large spaces, a runoff problem has been created. Rainfall is concentrated into fast-moving, high-volume torrents immediately carried to the stormwater management system. Little is absorbed in the process, and this water not only has the ability to carry more pollution (faster flows can carry larger debris farther), but it is also a powerful force for erosion—especially where new development is taking place and soil is bare.

Read the full article: Turf Fertilization: Decreasing contamination of runoff

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