Mainstreaming Rain Gardens into Chiang Rai's Sustainable Development Agenda: A Desk-Based Policy Framework

Abstract

Urban flooding and wetland degradation remain persistent challenges for secondary cities in Northern Thailand, including Chiang Rai. Conventional drainage and flood-control measures are limited in their ability to manage high-intensity rainfall while also supporting biodiversity and community well-being. This paper develops a desk-based policy framework to mainstream rain gardens as a nature-based solution (NbS) within Chiang Rai's sustainable development goals. Drawing on international literature on Japanese rain garden design and global low-impact development (LID) practices, the study adapts technical principles such as infiltration media layers, micro-topographic water retention, and plant zoning for potential use in tropical northern Thailand. Secondary data, including urban planning documents, national climate adaptation strategies, and open-source geospatial datasets, are synthesized to identify opportunities for integrating local governance. The framework proposes three pathways: (i) regulatory measures, like adding rain garden credits into urban building codes and stormwater management guidelines; (ii) incentive mechanisms, such as fee reductions or recognition schemes for schools and community institutions that implement rain gardens; and (iii) educational programs, positioning rain gardens as living laboratories within schools and public spaces to enhance environmental literacy. While the analysis is conceptual and does not rely on primary field data, it illustrates how Japanese-inspired rain gardens can offer multifunctional benefits, such as flood mitigation, water quality improvement, urban cooling, and cultural-ecological value, if incorporated into Chiang Rai's policies and education systems. The paper concludes by presenting rain gardens as scalable, culturally adaptable NbS that align with Thailand's commitments to the Sustainable Development Goals (SDGs 6, 11, 13, and 15) and provide a practical pathway for resilient urban futures in the Mekong borderlands.