Water resource responses to climate in the water-energy-food nexus of the Pajaro Valley Watershed, CA

Abstract

Climate variability and change are major factors that affect groundwater resources on a global scale. However, it is still poorly understood how components of the hydrologic system respond to these signals of climate variability. The crucial role of groundwater in the water-energy-food nexus underscores the need to better understand how climate will affect groundwater in the future. This need is especially urgent in coastal agricultural regions where groundwater is the primary source of water. This thesis quantifies the response of hydrologic processes and human interaction to interannual to multidecadal climate variability in coastal aquifers, specifically the El Nino Southern Oscillation (2-7 year cycle) and Pacific Decadal Oscillation (15-30 year cycle), in Pajaro Valley, California, located in California's coastal aquifer system. I examined whether climate signals were present in long-term records o f precipitation, streamflow, groundwater levels, recharge, and pumping using Singular Spectrum Analysis. I quantified the response of these variables to modes of climate variability by performing lag correlations. These analyses illustrate the extent to which the Pajaro Valley watershed responds to climatic and anthropogenic forcings. The findings from my research can aid water managers in creating sustainable groundwater management practices in areas that are highly groundwater dependent and experiencing the negative effects o f groundwater overdraft.