Agricultural managed aquifer recharge (Ag?MAR) initiatives have been piloted in California to mitigate the effects of unsustainable groundwater withdrawals. These initiatives rely on capturing wet?year water and spreading it on large areas of irrigated agricultural lands to enhance recharge to aquifers. This webinar includes two parts, considering Ag-MAR projects at regional and local scales. In the first part, we highlight the necessity of taking an integrated approach to evaluate Ag-MAR projects for planning purposes. We show the use of Integrated Water Flow Model (IWFM) to evaluate how Ag?MAR projects can affect streamflows, diversions, pumping, and unsaturated zone flows in the Tulare county. We further show the sensitivity of three different spatial patterns of Ag?MAR, each chosen based on different thresholds of soil suitability on the hydrologic system. This part ends with showing how regional Ag-MAR projects can cause waterlogging in the root zone.
The second part of the seminar examines the on-site application of Ag-MAR projects within the Tulare Irrigation District, which is a 70,000-acre agricultural irrigation District located in the Tulare county. The District has historically been operated as a conjunctive use district, relying on surface water to meet agricultural demands when available, and in years when surface water is not able to meet agricultural demand, landowners turn to groundwater pumping. The District has utilized a distribution system of 300-miles of unlined canals and 1,300 acres of recharge basins to manage wet year supplies for groundwater recharge. To comply with the Sustainable Groundwater Management Act, the District is working to enhance its groundwater recharge capabilities through various projects and management actions. We show in this part how some of the most promising projects such as pricing incentives for surface water applications, on-farm recharge, and groundwater recharge enhancement tools such as SkyTEM, TowTEM, and the use of an online application called the Groundwater Recharge Assessment Tool (GRAT) could be applied to achieve successful Ag-MAR projects.