I like the ASLA blog The Dirt quite a bit. They cover a variety of topics and showcase different voices and viewpoints (I especially liked Rene Bihan’s “Nature is Dead” piece and the “Landscape Architects Must Fight For Public Health” editorial).

A recent entry, “Leveraging the Landscape to Manage Stormwater,” combines an article and a video animation to outline some of the stormwater challenges in paved environments.

It’s a nicely done video that clearly lays out, in simplified terms that anyone can understand, what the main challenges are with on-site stormwater management on developed sites. It demonstrates how three simple and increasingly popular solutions — green roofs, rain gardens, and pervious pavers — can help meet these challenges, using a campus as the example site.

I understand that it was a general video and not meant to address every scenario, however I do wish they had picked a more urban setting. The stormwater management challenges on a site like a campus are even more acute in an ultra urban environment, where land is more expensive and paving is everywhere. Green roofs and pervious paving still have extremely valuable applications in these settings, of course. Rain gardens are a harder sell, as they occupy highly valued land and tend to be maintenance intensive. 

One of the things most lacking in ultra urban environments is good quality, lightly compacted loam soil. Soil volume and quality, while often overlooked in site design, are can provide significant stormwater management through retention, detention, and filtration. It is also critical for mature tree growth, and mature trees themselves act as giant stormwater pumps and interceptors, preventing substantial quantities of rain from ever even hitting the ground.

With over 50% of the global population now living in cities, we need to focus on design solutions that are applicable for highly urbanized environments. Green infrastructure like trees and soil will be critical to making that effort an economic and ecological success.

Image: ASLA