There has been lots of rain lately – that means more flooding! We don’t have to tell you that flooding can cause lots of problems such as property damage, loss of power, inability to access properties (think about fire truck, ambulances, etc.), injury, and in some cases even death. Fortunately, we can do something about it, but it takes a basic understanding about why flooding occurs in the first place.
Flooding is primarily caused by intense rainfall over developed (paved) land. Other flood contributors are tide, changes in sea level, land subsidence, wind, compounding storm systems (hurricane / nor’easter), condition of drainage systems, and depletion of existing trees and forests.
Basic nuisance flooding and dangerous flash flooding come from precipitation running off of developed land and having no where to go if all the normal pipes and tributaries are either already filled / saturated with water or are obstructed by trash and debris. Flooding also occurs when the amount of precipitation is coming down so hard and fast within a given period of time that the existing drainage systems cannot move the water downstream fast enough. This is perhaps the most recurring problem for us in at least the last decade.
What can be done about it? Mother Nature would tell you to return everything to a forested condition. In this scenario, rainwater would then soak into the ground and the trees would pump it back up and release it into the air through evapotranspiration. Obviously, we can’t all live in a forest, and most land use requires some form of tree clearing. Given the constraints of development, we otherwise generally try to capture the rainwater and slowly release it back into the drainage system. If we can’t capture it, we will at least try to slow it down or reduce paved areas on the development site to allow it to soak into the ground. Designing properties to capture, to store, and to clean water have been the name of the game for modern-day land development. At WPL, we work toward this on every project. In fact, we use several strategies to handle rainwater in ways that uniquely integrate with the rest of a property’s development. Some of these strategies include incorporation with the following:
Bioswale and Bioretention Gardens
Centralized Stormwater Parks
Green Roof Design
Permeable Parking Lot Retrofits
Storm Pipe Daylighting
Not every strategy is applicable to every project site, but rather the site and its context reveals opportunities when you know to look for them. For example, when we were planning the site for the Bow Creek Recreation Center in Virginia Beach, we kept looking for the “Bow Creek” which had been buried and piped under the old recreation center site. Given the need to allow for more stormwater storage, it became apparent that the pipe needed to be daylighted and opened up as a more natural water body. This not only provided a massive storage device for the Rec Center and its neighboring sites during large rainstorm events, but it also became a central amenity to the property. The “creek” was essentially restored and flooding has been greatly reduced for those around the project site.
This was one great example among many others. We often find ourselves on different projects making minor revisions such as parking lot renovations to put in structural soils and tree islands. Sometimes the small changes on an existing site can make a big impact – usually for more than just stormwater management. What issues are you facing on your property? Do you have some ideas on how to solve your flooding? Let us help you return back to a functional and sustainable property, and perhaps we can all look forward to a break from the rain!
Mike Fox, ASLA