The hydrologic outcome of a Low Impact Development (LID) site including superposition with streamflow peaks

Abstract

Hydrology plays a key role in mitigating environmental impacts with Stormwater Management (SWM). Site-level Low Impact Development (LID) is a promising approach but impeded by a lack of experience, performance metrics and comprehensive analysis. This study investigated the hydrologic performance of a small LID site (0.15 km²) including superposition with high flows of the receiving stream by monitoring precipitation, discharge and streamflow for 30 months. The results (73% event capture, 66–87% volume reduction, 39 L/ha/s peak discharge, 4.5% streamflow amplification) implied that site-level LID provides an alternative to conventional SWM even for unfavourable conditions. Weak performance related to underground storage, antecedent conditions, storm characteristics and freezing periods occurred seasonally; and a minimum storm capture volume could not be observed, but a maximum retention capacity. Future LID site designs should consider these characteristics and limitations, together with a differentiated analysis of a set of metrics for deducing environmental implications.

Keywords:

• Stormwater runoff
• urban hydrology
• design
• rainfall-runoff analysis
• environmental impact
• source control

Acknowledgements

Ernst+CO Engineering Company carried out the HEC-RAS simulations and the association Regiowasser e.V. Freiburg provided ideal support. We thank Gottfried Bleyer from the federal institute of viticulture Freiburg (WBI), Bernhard Paul from AHK Company, Jürgen Bolder from the city of Freiburg and Erik Henkel from badenova AG for kindly providing data and site documentation. Till Volkmann provided a blueprint for the correction of precipitation data and the contribution of field data by Franziska Opferkuch and Daniel Badillo is greatly acknowledged. The authors would like to thank all anonymous reviewers for their helpful comments that have greatly improved this manuscript.

Funding

This work was supported by badenova AG and Co. KG (innovation fund for the protection of climate and water) and the city of Freiburg [grant number 2009-09].

Additional information

Funding

Funding

This work was supported by badenova AG and Co. KG (innovation fund for the protection of climate and water) and the city of Freiburg [grant number 2009-09].