Artificial recharge of groundwater consists of infiltrating surface water through a variety of means, such as spreading basins, to recharge subsurface aquifers. Some of the applications of artificial recharge include groundwater storage, natural purification, and replenishment of groundwater levels. Tucson Water manages the Central Avra Valley Storage and Recovery Project (CAVSARP), which includes 11 recharge basins, and the Southern Avra Valley Storage Recovery Project, which has 9 recharge basins. CAVSARP and SAVSARP are a set of intermittent multi-basin systems responsible for the recharge of the Central Arizona Project (CAP) water originating from the Colorado River. One of the biggest impediments to infiltration in recharge basins is the clogging layer that forms on the basin surface due to suspended solids in surface water and anaerobic conditions. In an intermittent recharge system, the recharge period is terminated before clogging has drastically reduced infiltration rates. The dry period then allows the recovery and maintenance of the system to restore infiltration capacities. The purpose of this study is to create an empirically based model of the effects of maintenance on the infiltration rates of CAVSARP and SAVSARP. A simple model was used to compare how infiltration rates vary over time with respect to antecedent wet/dry conditions and maintenance periods. The main hypothesis for this study is that the model could be calibrated and automated, using data over the past 20 years, to provide a better indication of when maintenance should occur for each individual basin.
1Tucson Water, City of Tucson, Arizona