Comparison of seasonal terrestrial water storage variations from GRACE with groundwater‐level measurements from the High Plains Aquifer (USA)

Abstract

[1] This study presents the first comparison of seasonal groundwater storage (GWS) variations derived from GRACE satellite data with groundwater-level measurements in the High Plains Aquifer, USA (450,000 km 2 ). Correlation between seasonal GRACE terrestrial water storage (TWS) and the sum of GWS estimated from field measurements (2,700 wells) and soil moisture (SM) simulated by a land surface model is high (R = 0.82). Correlation between GRACE-derived and measured GWS is also significant (R = 0.58). Seasonal GRACE-derived TWS and GWS changes were detectable (! uncertainty) in 7 and 5 out of 9 monitored periods respectively whereas maximum changes (between winter/spring and summer/fall) in TWS and GWS were detectable in all 5 monitored periods. These results show the potential for GRACE to monitor GWS changes in semiarid regions where irrigation pumpage causes large seasonal GWS variations. Citation: Strassberg, G., B. R.Scanlon, and M. Rodell (2007), Comparison of seasonal terrestrial water storage variations from GRACE with groundwater-level measurements from the High Plains Aquifer (USA), Geophys. Res. Lett., 34, L14402,

Estimating soil moisture storage change using quasi-terrestrial water balance method

“…The drastic drop in surface runoff in this semi-arid region is attributed to over-exploitation of surface and subsurface water resources Fan et al, 2010). Strassberg et al (2007) also noted that surface water storage accounts for less than 1% of total water storage in the semi-arid high-plains of US. In the heavily irrigated North Indian Region, Rodell et al (2009) assumed that surface water contribution to total water storage is negligible.…”

“…ETWatch has also been independently validated for HRB using GRACE (Gravity Recovery and Climate Experiment) and lysimeter measurement data with negligible degree of bias and uncertainty (Moiwo et al, 2011). The error biases in the water balance equation and ETWatch are expected to improve at higher time-scales (Strassberg et al, 2007;Wu et al, 2008b;Moiwo et al, 2009). There is a significant correlation between precipitation and ET.…”

“…In this study, water storage change is defined after Strassberg et al (2007) as the difference in storage between any two successive periods. Note that all the storage change terms here are treated as averages in both time and space (Yeh et al, 1998).…”

“…The uncertainty analysis approach discussed by Strassberg et al (2007) is adopted in this study. Based on the analysis, RMSE between the measured and estimated monthly soil moisture storage is 21.35 mm-which is less than 10% of the average value of measured soil moisture for [2003][2004][2005][2006].…”

“…In especially semi-arid regions where surface water resources are limited, water balance for the terrestrial component of the hydrologic cycle is mainly driven by changes in soil moisture and groundwater; generally quantified as (Strassberg et al, 2007;Swenson et al, 2006;Moiwo et al, 2009;Rodell et al, 2009):…”