Inferring time‐varying recharge from inverse analysis of long‐term water levels

Abstract

[1] Water levels in aquifers typically vary in response to time-varying rates of recharge, suggesting the possibility of inferring time-varying recharge rates on the basis of longterm water level records. Presumably, in the southwestern United States (Arizona, Nevada, New Mexico, southern California, and southern Utah), rates of mountain front recharge to alluvial aquifers depend on variations in precipitation rates due to known climate cycles such as the El Niño-Southern Oscillation index and the Pacific Decadal Oscillation. This investigation examined the inverse application of a one-dimensional analytical model for periodic flow described by Lloyd R. Townley in 1995 to estimate periodic recharge variations on the basis of variations in long-term water level records using southwest aquifers as the case study. Time-varying water level records at various locations along the flow line were obtained by simulation of forward models of synthetic basins with applied sinusoidal recharge of either a single period or composite of multiple periods of length similar to known climate cycles. Periodic water level components, reconstructed using singular spectrum analysis (SSA), were used to calibrate the analytical model to estimate each recharge component. The results demonstrated that periodic recharge estimates were most accurate in basins with nearly uniform transmissivity and the accuracy of the recharge estimates depends on monitoring well location. A case study of the San Pedro Basin, Arizona, is presented as an example of calibrating the analytical model to real data.

Spatio-temporal impact of climate change on the groundwater system

“…A majority of the current studies assessing the impact of climate change on the groundwater system estimate the impact on the annual or seasonal average spatially distributed recharge, e.g. : Dickinson et al (2004), Scibek and Allen (2006), Scibek et al (2007), Serrat-Capdevila et al (2007) and Woldeamlak et al (2007). Woldeamlak et al (2007) stated that climate change impact studies based on steady-state groundwater simulation have limitations in representing boundary conditions and can only be used for assessing sensitivities.…”

Identificação de respostas não estacionárias dos níveis de água subterrânea aos padrões de teleconexão oceano-atmosfera no Atlântico Norte, utilizando a coerência de onduletas

“…The soil, unsaturated, and saturated zones of aquifers can filter or remove much of the high-frequency signals and noise (Dickinson et al 2004), producing a buffering effect which provides resilience to water resources and associated ecosystems under short-term climate extremes. However, recent studies 2006;Gurdak et al 2007;Holman et al 2009) have indicated that groundwater-level fluctuations are affected by relatively low frequency (interannual to multidecadal) atmospheric and ocean circulation systems such as the North Atlantic Oscillation (NAO), which are known to affect weather and river flows (Jones and Banner 2003;Qian and Saunders 2003;Barker et al 2004;Schroder and Rosbjerg 2004;Hannaford and Marsh 2008).…”

“…However, recent studies 2006;Gurdak et al 2007;Holman et al 2009) have indicated that groundwater-level fluctuations are affected by relatively low frequency (interannual to multidecadal) atmospheric and ocean circulation systems such as the North Atlantic Oscillation (NAO), which are known to affect weather and river flows (Jones and Banner 2003;Qian and Saunders 2003;Barker et al 2004;Schroder and Rosbjerg 2004;Hannaford and Marsh 2008). Milly et al (2008) assert that stationarity should no longer serve as the central assumption in water resource risk assessment and planning largely because of climate change and natural low-frequency climate variability such as from the NAO, Pacific Decadal Oscillation (PDO; Mantua and Hare 2002), or Atlantic Multidecadal Oscillation (AMO; Enfield et al 2001). …”

Climate Variability and Groundwater Response: A Case Study in Burkina Faso (West Africa)

“…The similarity between inter-annual groundwater variation and the moving average of rainfall over several years reflects, in some way, a slow and long-term response of the groundwater. The slow response of underground system has been reported by several authors who argue that the rainfall signal is filtered and lagged through the soil and undergound system [5,70]. The aquifer reacts as a low-pass filter that smoothed out the high frequency fluctuations of the rainfall signal [71].…”

“…In addition to creating a long term response to climate variability, differences in local hydrodynamic parameters may induce different responses of the groundwater level in space [70,74]. A strong heterogeneity of hydrodynamic parameters due to a difference in the nature of the rock or In addition to creating a long term response to climate variability, differences in local hydrodynamic parameters may induce different responses of the groundwater level in space [70,74]. A strong heterogeneity of hydrodynamic parameters due to a difference in the nature of the rock or in the fault lines within the catchment can justify the difference in behavior between upstream and downstream areas.…”