The energy system diagram we proposed illustrates how the three components of vulnerability are inter-related and interacted via energy and resource flows. Values for these components can be calculated and compared using common emergy units to analyze the interface of natural and urban systems.
2.2. Evaluation of exposure, sensitivity, and adaptive capacity to map the spatial dimensions of urban flooding vulnerability,the Spatial Analyst Toolbox of ArcGIS 9.3 (ESRI, 2008) can be used to calculate the spatial distribution of exposure, sensitivity, and adaptive capacity of the study area. The study design and methods for calculating exposure, sensitivity, and adaptive capacity as they relate to ecological-energetic flows are described below.