Strategies to Improve Urban Hydrology

Sourced from Earth & Space Science News

More than half of the world’s population lives in cities, and the trend of urban migration is expected to continue for the foreseeable future. As city populations swell, the “built environment” expands; paved surfaces, buildings, and other urban infrastructure replace forests, grasslands, wetlands, and agriculture. From a hydrologic perspective, this transformation results in a large-scale transition from a water-penetrable (pervious) surface to water-impenetrable (impervious) cover.

The loss of natural land cover leads to a host of urban water issues, including increased risks of flooding and pollution and reduced groundwater recharge. As these problems have grown, many cities have attempted to improve urban hydrology through green infrastructure initiatives that aim to improve stormwater management. Rain gardens, green roofs, disconnected downspouts, permeable pavement, and soil amendments have all been implemented to improve water capture and soil infiltration at the scale of individual parcels. Despite their proven effectiveness, however, adoption rates remain low in many cities, in part because homeowners lack the necessary incentive to renovate their properties but also because of uncertainty about which practices best address surface runoff and subsurface hydrology.

Here Voter and Loheide explore green practices to identify which strategies most effectively alter surface runoff, deep drainage, and evapotranspiration at the scale of a residential parcel. The authors developed 96 different simulations that compared the effects of different hydrologic interventions. The simulated conditions were based on on-the-ground conditions in Madison, Wis.

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