Exposure and sensitivity can be combined into potential impact,which can also be regarded as the emergy value of the potentialdamage and loss caused by an event.The energy system diagram of urban flooding vulnerability(Fig. 1) shows the different energy and material flows betweenecological and urban economic systems, and represents the basisof cause–effect relationships among the components of vulner-ability. The energy diagram consists of natural and agriculturalsystems and the urban system. Flows representing climatic events,economic inputs and urban responses interconnect system compo-nents. When an extreme climate event occurs, it brings rainfall overa short period of time. The amount of rainfall energy (J1) can poten-tially contribute to the exposure of this area to the extreme climateevent. Depending on the characteristics of land cover and soil prop-erties, a proportion of the rainfall will become runoff energy (J2),which can be regarded as the exposure of the area. J3 is the ratioof runoff (J2) to rainfall (J1), representing the intensity of expo-sure. The assets stored in natural and agriculture systems and theurban system can be regarded as the components of the sensitivityto vulnerability. J4 and J5 are the damages that result in the nat-ural and agricultural systems and the urban system, respectively.The larger the stored assets the more likely flood damage will occurfrom an extreme climate event. J6 is the summation of total dam-age to both natural and agricultural systems and the urban system.The interaction of the intensity of exposure (J3) and sensitivity (J6)will represent the potential impacts (J7). Higher potential impactis likely to result in higher vulnerability. At the same time, whenan extreme climate event occurs the urban system can adapt (J10)by attracting more energy from outside sources in response to theevent. Finally, vulnerability is assessed by dividing the emergy ofpotential impacts by the emergy of adaptive capacity (J11)