Margaret Zimmer

2020 Hellman Fellow

margaret.zimmer@ucsc.edu

Assistant Professor; Earth and Planetary Sciences
UC Santa Cruz

Project Title: Quantification of groundwater recharge in non-perennial rivers

Project Description: Arid and semi-arid regions cover approximately 40% of Earth’s land surface and groundwater is often the primary source of freshwater in these landscapes. Understanding the major mechanisms of groundwater recharge are critically important for the sustainability of aquifers to help meet our global freshwater demands. A critical and major pathway of natural aquifer recharge is the infiltration of surface water through riverbeds. While non-perennial rivers (i.e. rivers that annually dry down at some point in time or space) account for >50% of our river networks in California as well as globally, currently most of our understanding of groundwater recharge in rivers stems from studies in perennial river systems (i.e. rivers that flow year round). The Hellman Fellowship will support members of our lab in the collection of river network-scale field observations that will allow us to address current knowledge gaps regarding how, when, and where flow in non-perennial river networks can recharge societally valuable groundwater reservoirs.