|Authors: ||O. Starry, J. Lea-Cox, A. Ristvey, S. Cohan|
|Keywords: ||soil moisture sensor, green roof, stormwater management, evapotranspiration|
Green roof systems are being installed worldwide for various environmental benefits, primarily to reduce stormwater runoff associated with impervious roofs in dense urban environments.
To effectively quantify the stormwater retention and efficiency of green roofs at any scale, we need to be able to resolve two important issues: (1) Monitoring of green roofs is both resource-intensive and expensive; (2) Green roofs have both physical and biotic components, both of which can be highly variable across space and time.
To address these challenges, we have installed and tested a commercially-available sensor network system (Decagon Devices, Inc.) that resolves the issue of being able to cost-effectively measure the performance of green roofs over time.
This sensor network was deployed in 16 experimental greenroof platforms at the University of Maryland (UMCP) with four replicate platforms planted with three Sedum species (S. album, S. kamtschaticum, and S. sexangulare) or left unplanted.
Real-time microclimatic data was also collected from a suite of environmental sensors, in addition to replicated soil moisture and temperature sensor data (Echo-TM, Decagon Devices) from each of the platforms (n=4 sensors per platform). These data were used to parameterize a greenroof water balance model, which is focused on predicting rates of evapotranspiration (ET) and the system capacity for mitigating stormwater runoff at any specific time.
These monitoring capabilities and model predictions will help improve our understanding of the underlying mechanisms that are responsible for greenroof stormwater retention efficiency.
Only with a clear understanding of how much stormwater green roof systems can retain in different climatic scenarios, will we be able to consider or refine policies regarding permitting and incentives for this type of roof construction.
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