Op-Ed by NATHAN INKS
A number of heavy rainfall events this past spring caused flooding for many Metro Detroit communities. An increase in the frequency of heavy precipitation events combined with continued development and expansion of suburban areas has made flooding in local communities more common in recent years. Even if the region sees a decline in the frequency of heavy rainfall events, communities are likely to continue to suffer from damaging flooding if they do not take a proactive approach to urban water management.
Since the 1800s Michigan has lost around 40% of its wetlands; most of these losses have been along the Lower Peninsula’s eastern coastline, with Macomb and Wayne counties seeing the highest losses at over 90%. Wetlands provide natural flood control and filter out pollution. When wetlands are replaced with impermeable surfaces such as concrete and asphalt, the result is an increase in flooding and polluted storm runoff entering lakes, rivers, and streams.
Although Michigan has a wetland mitigation program with a goal of no net loss of wetlands, the sheer amount of urbanization that has taken place has left too much water with nowhere to go during rain events, even if the state maintains its current wetland acreage. Local governments need to start taking proactive steps to ensure that rainwater and runoff is being properly managed. Fortunately, there are a number of innovations that local governments and developers can utilize.
Bioswales, gently sloped troughs filled with plants and rocks, can be used to slow the flow of runoff and absorb pollutants in the process. Instead of being carried into storm sewers, polluted water is absorbed by the plants, and the pollutants are naturally broken down over time. Bioswales can be effectively used in place of or in addition to storm sewers along freeways and near residential developments.
Similarly, rain gardens can be installed in parking lots and on rooftops to absorb and filter rainwater. Rain gardens differ from bioswales in that they are not sloped; however, the two can be combined so that a bioswale leads into a rain garden.
Vegetation is not the only tool available. Pervious concrete and porous asphalt – although more expensive at the outset – are increasingly popular alternatives to traditional pavement that developers are turning to. By utilizing such permeable pavement materials, stormwater is able to drain back into the ground, recharging aquifers and other groundwater stores while pollutants are filtered out in the process. In the long run these solutions save municipalities and developers money, as they allow for increased land utilization and require less ancillary work to fit in with existing infrastructure.
As the Metro Detroit area continues to grow – especially in Oakland and Macomb counties – developers and municipal leaders need to take a proactive approach to rainwater management. The “pave, pipe, and pump” approach has failed, resulting in flooded basements and roads, and although we cannot undo the destruction to the region’s wetlands that has taken place over the past two centuries, we can change our infrastructure and land use to deal with rainwater in a manageable and environmentally friendly way. The time for municipal and county governments to take proactive steps – by utilizing bioswales, rain gardens, and permeable pavement and encouraging and assisting developers in doing the same – is now.