Five-century record of climate and groundwater recharge variability in southern California

Abstract

Modifications to the rates of water flowing from the surface to groundwater (groundwater recharge) due to climate variability are the most difficult to assess because of the lack of direct long-term observations. Here, we analyze the chloride salt distribution below the surface soil on a plateau near Los Angeles to reconstruct the amount of recharge that occurred in the last five centuries. Over this time interval, periods of major high and low recharge with different duration follow each other and this cyclicity is consistent with long-term atmospheric forcing patterns, such as the Pacific Decadal Oscillation. This study determines the range and the natural variability of recharge to groundwater, which sustains local freshwater flow system, and helps forecast future availability of groundwater resource in southern California, where water scarcity is critical to both local and global populations.

Groundwater response to climate variability in Mediterranean type climate zones with comparisons of California (USA) and Portugal

“…Today, over 2 billion people rely on groundwater as their primary source of freshwater (Kundzewicz and Döll 2009) and 1.7 billion people live in water-stressed areas (Gleeson et al 2012). Aquifers in semiarid regions, including the Mediterranean (Giorgi 2006;Stigter et al 2014) and the southwestern US (Barco et al 2010;Manna et al 2019), are particularly vulnerable to climate change (Navarra and Tubiana 2013; Cui et al 2020) and natural climate variability (Taylor et al 2013;Cui et al 2017). Moreover, two thirds of the world's population inhabit coastal areas (United Nations 2016) making coastal aquifers in semiarid areas more susceptible to excessive anthropogenic activities such as overabstraction and population inflation from tourism.…”

Groundwater pollution: Occurrence, detection, and remediation of organic and inorganic pollutants

“…Climate change has also considerably increased the vulnerability of groundwater resources to pollution. While it is difficult to ascertain the changes in groundwater recharge accurately, analysis of historical records helps determine the changes (Manna, Walton, Cherry, & Parker, 2019). The authors performed an analysis of the last five centuries of data on the subsurface distribution of chloride salt on a plateau near Los Angeles to reconstruct the amount of recharge.…”

Resilient California Water Portfolios Require Infrastructure Investment Partnerships That Are Viable for All Partners

“…Exacerbating these complexities, atmospheric rivers deliver a large fraction of the state's annual precipitation during a few short events (Dettinger et al., 2011; Gershunov et al., 2017), introducing strong interdependencies between floods and droughts. This makes it critical to resolve daily scale dynamics (Hanak, Jezdimirovic, et al., 2018; Kocis & Dahlke, 2017; Malek et al., 2022; Zeff et al., 2021), while simultaneously multi‐decadal simulations are needed to properly evaluate the impacts of long‐term infrastructure investments, the slow dynamics of groundwater storage change (Manna et al., 2019), and the deep uncertainties in climatic, economic, and regulatory changes. Lastly, it is critical that planning models resolve a wide range of spatial scales and system actors in order to evaluate how water moves through statewide infrastructure networks in response to local actions by individual water utilities, irrigation districts, and water storage districts (hereafter referred to collectively as “water districts”; Zeff et al., 2021).…”