Efforts to improve urban stormwater management rely primarily on engineered stormwater control measures (SCMs). The majority of publicly available information about how to choose and design catchment-appropriate green and gray stormwater infrastructure is based on hydrologic models, design handbooks, and worksheet calculators that provide rule-of-thumb design guidelines. However, these engineering approaches frequently overlook the role of ecohydrology. It is often difficult to predict how choosing any one SCM design will affect localized site hydrology, and equally challenging to confirm that an installed SCM has met both design criteria and catchment-scale hydrology goals. Answers to these questions are limited by the constraints of performing fully replicated and controlled catchment-scale experiments in urban systems. Additionally, the handbook guidelines are based on how each design model is expected to perform, instead of measurements that describe how designs actually do perform within the urban mosaic. The International BMP Database contains a large compilation of SCM case studies with information about structural design, hydrologic activity and water quality performance of more than three dozen structural types. In an effort to understand the implications of structural design choices on hydrologic performance, we treat hydrologic performance data from the International BMP database as repeated measures in a natural (uncontrolled) experimental design and attempt to focus on the fixed effects of structural behavior by treating site, environmental and temporal variables as random factors in a linear mixed effects model.
Results/Conclusions
Integrating this information with previous research from natural and agricultural ecohydrology, the case study estimates also indicate structural design alternatives that drive performance by affecting trade-offs between specific hydrologic loss pathways. This information is intended to help differentiate between structural effects on local ecohydrology and environmental effects from the surrounding site or climate. The structural alternatives are presented within a decision tree framework to allow visualization of how structural design features affect green infrastructure performance while holding site and environmental variables constant.