2. Framework of emergy evaluation for assessing urban vulnerability to flooding From a systems perspective, cause–effect relationships between exposure, sensitivity, and adaptive capacity for assessing vulnerability are linked through energy and material flows between natural and social systems (Huang, Chang, & Yeh, 2011).In this section, the concepts of exposure, sensitivity, and adaptive capacity are redefined from an ecological energetic viewpoint.Emergy evaluation and indices for vulnerability assessments arealso proposed