Rapid assessment of wetland ecosystem services (RAWES) in wetland offsetting for urban developments: an example from Valenzuela City, Philippines

Abstract

Environmental offsets provide a mechanism for mitigating the impact of urbanization and development on the environment. The Rapid Assessment for Wetland Ecosystem Services (RAWES), initially developed as a qualitative assessment tool for gathering monitoring data for Ramsar Convention-related reporting, was used in this study as a less resource-intensive alternative for wetland characterization in an infrastructure development project in Valenzuela City, Philippines. Offsetting assures that the negative environmental effects from development are balanced with environmental gains. However, a crucial factor in the offsetting process is in identifying the offset sites, which should be ecologically similar or better in character compared to the impact site. Benchmarking and characterization of impact sites are therefore conducted to ensure that a ‘no net loss’ of wetlands and biodiversity occurs once offset sites are identified, and development plans are implemented. A framework for applying the RAWES as a wetland characterization tool for environmental offsetting was presented that focused on the identification of ecological services provided by the existing wetland that could be lost or diminished when the development occurs. To assess the RAWES as a tool for rapid wetland assessment for environmental offsetting, the study used four evaluation criteria from previous work of Fennessy, Jacobs, and Kentula (2007), namely, if the method: (1) can be used to measure condition, (2) is truly rapid, (3) includes a site visit, and (4) can be verified. The results demonstrated the use of the RAWES approach in determining the ecological character of an urban wetland in support of developing an offset site conservation and management plan. The use of the RAWES provided the best solution for the ecological site assessment of the impacted urban wetland as a basis for offsetting that met project-based requirements of a rapid, low-resource, flexible, and science-based characterization of ecological conditions.