Interannual to multidecadal climate forcings on groundwater resources of the U.S. West Coast

Analyses of infrequent (quasi-decadal) large groundwater recharge events in the northern Great Basin: Their importance for groundwater availability, use, and management

“…The higher‐frequency events identified in the precipitation spectrum are not present in the groundwater spectrum suggesting that these precipitation events have less effect on groundwater levels. This is consistent with the findings of several studies [ Dickinson et al ., ; Velasco et al ., ] which showed that low‐frequency signals tend to be better preserved in the groundwater level record than high‐frequency signals because of damping in the unsaturated zone which is related to soil texture, depth to water, and mean and period of the infiltration flux. This also implies that the quasi‐decadal groundwater recharge events are highly important in supplying large amounts of recharge to the groundwater system.…”

“…There has been a considerable amount of research linking climatic variability and forcing to hydrologic responses in arid and semiarid regions such as the western U.S. [ Brekke et al ., ; Earman and Dettinger , ; Gurdak and Qi , ; Hanson et al ., ; Nayak et al ., ; Pool , ; Small , ]. While much effort is spent to assess and predict changes in surface water resources, storage, and availability, little has been done to understand how climatic events and changes affect groundwater resources, specifically long‐term availability, use, and sustainability [ Gurdak et al ., ; Meixner et al ., ; Velasco et al ., ]. Many studies link climate variability to changing groundwater levels [ Gurdak et al ., ; Hanson et al ., ; Kuss and Gurdak , ; Scanlon et al ., ; Whittemore et al ., ], but few quantify the amount of groundwater storage gained during climate‐induced large recharge events.…”

Understanding the potential of climate teleconnections to project future groundwater drought

“…Such periodic teleconnection signals have been detected in rainfall (Luković et al 2014), evapotranspiration (Tabari et al 2014), air temperature (Faust et al 2016), and river flow (Su et al 2018;Dixon, et al 2011); however these periodicities are often weak when compared to the finer-scaled (daily to seasonal) variability that is typical of hydrometeorological processes (Meinke et al 2005). By contrast, groundwater systems are expected to be particularly susceptible to inter-annual teleconnection influence, given their sensitivity to long-term changes in rainfall and evapotranspiration (Bloomfield & Marchant 2013;Forootan et al 2018;Van Loon 2015;Folland et al 2015), and their ability to filter fine-scale variability in recharge signals (Dickinson et al 2014;Velasco et al 2015;Townley 1995). Consequently, recent studies have focused on the detection of long-term periodic cycles in groundwater levels in Europe (e.g.…”

“…These latter methods include Fourier transform, (Nakken, 1999, Pasquini et al 2006, singular spectrum analysis (SSA) (Kuss & Gurdak 2014;Neves et al 2019) and wavelet transformations (Fritier et al 2012;Holman et al 2011;Tremblay et al 2011). The wavelet transform (WT) has been shown to be particularly skilful at detecting inter-annual periodic behaviour in noisy hydrogeological datasets; detecting the influence of the NAO, ENSO and Atlantic Multidecadal Oscillation (AMO) on North American groundwater levels (Kuss & Gurdak 2014;Velasco et al 2015), and the NAO, East Atlantic pattern (EA) and Scandinavian pattern on European groundwater level variability (Holman et al 2011;Neves et al 2019). However, in order to enhance inter-annual periodicity detection, many studies have used data processing methods that remove or supress variability at the higher end of the frequency spectrum (e.g.…”

Filtering of Period Infiltration in a Layered Vadose Zone: 1. Approximation of Damping and Time Lags

“…[16] and [17]. The period of the forcings may be representative of irrigation cycles or seasonal or annual climatic variability identified through time series analysis of atmospheric or hydrologic data (e.g., Hanson et al, 2004; Gurdak et al, 2007; Dickinson et al, 2014; Velasco et al, 2017). The fine soil is a silty clay and the coarse soil is a sandy loam, which have differing soil hydrologic parameters (Table 1) that produce complex flow and water content responses at the layer boundary.…”