An Innovative Approach to Measuring Resilience Based on Post-Earthquake Water Demand

The quantity and quality of water supply is always a significant concern following an earthquake. Water for drinking and cooking is vital, and it is also needed for firefighting, medical systems, and post-earthquake reconstruction. The concept of “water resilience” has previously been used to measure how well a water system withstands disaster and how long it takes to recover to an acceptable level. However, although there are data for short- and medium-term water demand, community factors and water demand have been neglected in measuring resilience. This approach takes the changes in post-earthquake water demand into account to give a more accurate, dynamic evaluation of water supply resilience. As the water demand increases after the earthquake, the proposed resilience measurement evaluates the gap between post-earthquake water system functionality and water demand. As such, the proposed method calculates resilience values that are lower than the traditional method which compares the post-earthquake system functionality with business as usual functionality (or water demand). The demand-based resilience measure therefore places more emphasis on earthquake preparation planning to ensure the preparation measures (such as resourcefulness and redundancy) meet the post-earthquake water demand. The proposed measure in this paper was developed based on a review of previous research and the method was verified for the case of Christchurch following the 2011 earthquake.