ASR Recovery Initiation Index
For water systems utilizing aquifer storage and recovery (ASR) for water storage, the ASR Recovery Initiation Index is a spreadsheet-based tool that can help managers decide when to initiate recovery (i.e., pumping of water stored in the aquifer). This Microsoft Excel model incorporates and weights 10 variables related to current water supply, projected future demand, current hydrological conditions, and future climate projections (temperature and precipitation) at 1- and 3-month time intervals; these variables are optimized for the original basin used to generate the model, but can be adjusted and customized based on the user’s own watershed and location. The variables are used to generate a daily index value, which after being smoothed against a 30-day running average, can be used to evaluate whether current and projected water supply can meet demand, and if found insufficient, to prompt managers to begin aquifer recovery to meet water supply needs. By generating a daily numerical comparison of water supply and demand trends in light of climate projections, this index allows water managers to better evaluate how and when additional water supply sources may be needed, helping to maximize water system efficiency. This index can be used by utilities at various stages of water resources planning. For example, it can be used to inform and justify current aquifer management decisions, or can serve as a useful example for water systems that rely on multiple water sources or that are trying to develop a water supply decision framework.
Example in use: The ASR Recovery Initiation Index was originally developed by the Peace River Manasota Regional Water Supply Authority in Florida. During high flow periods, the Authority captures and stores water from the Peace River in several underground aquifers, in addition to two surface reservoirs. This stored water is used to for water supply during low-flow periods and/or during high tides, when the water at the Authority’s river intake station is too brackish to pump. However, utilizing stored aquifer water presents many management challenges. For example, the water must be extensively treated, can cause algal blooms in surface reservoirs, and must be pumped at a rate that avoids depletion of underground reserves until the onset of the next wet season. To minimize operational costs and mitigate negative consequences of aquifer pumping, the Authority worked collaboratively with other partners to develop the ASR Recovery Initiation Index. The index functions as a decision support tool to help the Authority decide when to initiate aquifer recovery each season, helping prevent early withdrawals that can increase utility costs, water quality problems, and vulnerability to future water shortages.
Phase of Adaptation: Assessment, Implementation
Water utility managers, planners, engineers