Systematic index frame for functional assessment of constructed wetlands

Constructed wetlands (CWs), a form of natural or ecological engineering, are used for wastewater clarification as well as water resource conservation and restoration around the world. To assess the ecological and environmental functions of CWs, this paper proposes a systematic index system using a rate-level method to reflect the subjective and objective value of the wetland as well as to quantify its functional capacity. The systematic index framework, consisting of hydrology and ecology, along with landscape, socio-economic and service factors, is developed using the DPSIR (Driving Force, Pressure, State-Impact and Respond) model. Information on wetlands in Taiwan including the construction, operational status, and water purification ability, together with questionnaires, is collected. The results indicate that hydrological conditions and the types of plants in wetlands are the major determinants of the success of constructed wetlands. According to questionnaires answered by experts, the functional assessment system is composed of six oriented components, 13 main indicators, and 29 sub-indicators. The six components are Protection of Water Resources, Landscape and Environmental Maintenance, Ecosystem Health, Cultural Assets, Social/Economic Services, and Operations and Management. This research will provide an assessment of the implementation of constructed wetland efficiency and multi-objective planning of constructed wetlands, and may serve as a reference for the government in amending the wetlands law in Taiwan.

► We develop a systematic index framework based on the DPSIR (Driving Force, Pressure, State-Impact and Respond) model. ► We examine causal relationships of factors via questionnaires and statistical analysis. ► The proposed index system enables decision makers to adopt procedures to prevent the degradation of constructed wetlands.