The Agrihood Design: Valuation of Ecosystem Services for NbS Visions in Peri-urban Housing Estate Development, Bangkok, Thailand

Abstract

Nature-based Solution (NbS) designs increasingly are being implemented to reduce environmental impacts of urban development and enhance community resiliency to disruptions ranging from floods to climate change to Covid-19. But, the question remains, how do we assess the ecosystem service benefits provided by competing NbS designs in order to optimize such benefits? As such, the objective of this study was to develop and trial an assessment approach for the valuation of ecosystem services in a peri-urban area of Bangkok, Thailand. In our evaluations we considered the ecosystem service benefits of: i) water yield; ii) sediment yield; iii) nutrient yield; iv) carbon sequestration; v) urban heat island mitigation; vi) crop production; vii) habitat quality; and viii) aesthetics. Our ecosystem services valuation approach was tested using three case studies in peri-urban Bangkok, Khlong Luang, Pathum Thani: i) an existing new single detached housing development in the area; ii) an area in its currently undeveloped, open and scrub forest state; and iii) the same area as (ii), but theoretically developed using an Agrihood design concept. The valuation approach included a combination of mathematical modeling for the water, sediment, and nutrient yield ecosystem services and an empirical, data-driven approach for urban cooling, carbon sequestering, crop production, habitat quality, and aesthetics. While the existing housing development design was meant to be relatively green and nature-oriented, the Agrihood design outperformed it in every ecosystem service category, including habitat quality and aesthetics. The Agrihood design also had lower sediment and nutrient yields and mean concentrations as compared to current (natural) conditions at the site, which is attributed to the inclusion of constructed wetlands in the design for the main drainage canal. This work represents a good preliminary step in establishing a local scale ecosystem services valuation framework for urban areas in a tropical climate, but additional refinements to the indicator determinations are needed.