The Chehalis Washington Home Depot and Kmart are installing flood barriers to prevent flood damage as reported by Carly Nairn of the Lewis County Washington Chronicle this January 2, 2010.
This is response to the 2007 flood that put the Home Depot under 18 inches of water costing millions of dollars.
There will be greater real dollar costs above and beyond the direct costs in installing these barriers — Costs to Chehalis and costs to their up and downstream neighbors.
These structures are here now and certainly have the right to protect their businesses and their protection will provide an initial direct benefit to Lewis County. However there is no free lunch.
- The presence of these large structures including their parking lots will cause future flooding
The Home Depot store manager Brian Sperber, as noted in the above mentioned article recognized that stores such as Home Depot are in floodplain and that they contributed to increase flooding in 2007.
- Down and upstream communities will have to deal with increased depths, greater velocity, less time to prepare… The downstream communities of Centralia, Rochester Oakville, and Elma along with unincorporated lands will have increase costs. As will upstream communities.
Our climate is warming, bringing increased winter rain amounts and increases in intensities within the Chehalis River valley. Summers will be dryer. As a direct result of these structures natural floodplain storage benefits will be reduced. In the summer the ground water table will be lower and in the winter the flood heights and flood duration will be greater. There will be decreases in farm productivity and an increase need for flood protection. And there are a host of other effects – increased sediment, forest fire risks, less productive lands….,
Impact on sports and commercial fishing will be felt. As water spills over onto the floodplain it seeps into the ground where it is processed. Pollutants are filtered and eaten by small plants and animals as the water works its way back into the river and on to the ocean.
These stores are here and the community is benefiting. However new development should be located off the floodplain. And, compensating approaches should be installed to mitigate the adverse impacts of these structures such encouraging wet gardens, installing vegetated detention areas, replacing parking areas with impermeable surfaces ….
We must look for new approaches to floodplain management.
