Rain garden design for stormwater management in Chiang Mai, Thailand: A Research-through-Design Study

Conventional stormwater management may cause long term environmental issues. Fortunately, Water Sensitive Urban Design (WSUD) can manage stormwater more sustainably. However, the design examples of WSUD elements, such as rain gardens within the geographical and cultural context of Thailand are lacking. This study investigated the patterns of rain garden design suitable for urban areas in Chiang Mai and developed examples of rain garden design processes and prototypes in an urban context for Chiang Mai.  
This research used the Research by design Method (RDM), which has great potential in bridging the gap between research and application. The researchers selected the site at the Faculty of Agriculture, Chiang Mai University. They designed 2 schematics of rain gardens with local Lanna plants. Then, they compared stormwater capacity with the existing site via the Natural Resources and Conservation Service (NRCS) Curve Number Method. The design results were evaluated by stakeholders and design experts to bridge the gaps between international standards and local contexts.   
We found that 1) the west side of the site was most appropriate to develop the pilot project. 2) Both design schematics performed better than the original site. 3) Stakeholders and design experts see the potential of the site, but had concerns regarding its actual performance, maintenance, scale, and safety. This paper offers and provides an example of the rain garden design process which can be used as a baseline for future designs of rain garden and water sensitive urban designs.