Investigating the Water Budget and Subsurface Hydrology of Two Rain Gardens in Calgary, Alberta

Urban development incorporates impervious surfaces that prevent stormwater from infiltrating into the soil. Rain gardens are a form of low impact development technology that mitigate some of these effects by promoting natural stormwater infiltration. Rain gardens have extensively been researched in warm and humid climates; however, less is known about these features in cold and semi-arid climates. This study used water budget and subsurface monitoring techniques to investigate how two rain gardens performed as stormwater management tools in Calgary, Alberta. The Highland Park and Cambrian Heights rain gardens were monitored from May to October in 2023 and 2024, using data from natural precipitation as well as five large simulated rainfall events to evaluate each garden’s performance. Water budgets were developed for both sites across individual precipitation events and entire monitoring seasons, with both gardens having a 100% stormwater runoff removal efficiency over the study period. Over the monitoring seasons, 51–57% of stormwater seeped into the native soil beneath and around the garden at Highland Park, and 69–75% at Cambrian Heights. Relatively high infiltration rates of 21 mm hr-1 at Highland Park and 304 mm hr-1 at Cambrian Heights helped to facilitate this performance, indicating the importance of subsurface geology on rain garden performance. Water in the shallow subsurface (~1 m depth) was observed to flow approximately 2 m laterally away from each garden, with no observations of lateral flow reaching 3 m. Groundwater monitoring wells at Highland Park also demonstrated that mounding of the water table extended out at least 1.5 m from the edge of the garden, and confirmed that some infiltrating water induced recharge to the water table. Overall, this study showed rain gardens to be effective stormwater management tools and helped to provide guidance on their implementation in Calgary, Alberta and the surrounding region.

Name thesis:degree_name

Master of Science (MSc)

Discipline thesis:degree_discipline

Geoscience

Grantor

Science

Year dc:date.issued

2025

Author dc:creator

• Ilg, Dan Jacob

Advisor dc:contributor.advisor

• Cey, Edwin

Committee members dc:contributor.committeemember

• Hayashi, Masaki
• He, Jennifer

Statement dc:rights

• Unless otherwise indicated, this material is protected by copyright and has been made available with authorization from the copyright owner. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.

Language dc:language.iso

en

DOI

https://dx.doi.org/10.11575/PRISM/50082

OAI identifier oai:identifier

oai:ucalgary.scholaris.ca:1880/122489