TY - JOUR
T1 - Groundwater Loss and Aquifer System Compaction in San Joaquin Valley During 2012–2015 Drought
AU - Ojha, Chandrakanta
AU - Werth, Susanna
AU - Shirzaei, Manoochehr
N1 - Funding Information:
We thank D. Argus, an anonymous reviewer, and the Editor for constructive comments and suggestions. This study was funded by the National Aeronautics and Space Administration grant NNX17AD98G. ALOS PALSAR©JAXA/METI, accessed through ASF DAAC. The GPS data used in this study were provided by the Nevada Geodetic Laboratory (http:// geodesy.unr.edu/). Groundwater level data were obtained from the California Department of Water Resources (https://gis.water.ca.gov/app/gicima/). U.S. Geological Survey provides extensometer data. All results are present in the paper and its supporting information. Additional data related to this paper may be requested from the authors.
Publisher Copyright:
©2019. The Authors.
PY - 2019/3
Y1 - 2019/3
N2 - California's millennium drought of 2012–2015 severely impacted the Central Valley aquifer system and caused permanent loss of groundwater and aquifer storage capacity. To quantify these impacts within the southern San Joaquin Valley, we analyze various complementary measurements, including gravity changes from Gravity Recovery and Climate Experiment (GRACE) satellites; vertical land motion from Global Positioning System, interferometric synthetic aperture radar, and extensometer; and groundwater level records. The interferometric data set acquired by the Sentinel-1 satellite only spans the period January 2015 and October 2017, while the other data sets span the entire drought period. Using GRACE observations, we find an average groundwater loss of 6.1 ± 2.3 km3/year as a lower bound estimate for the San Joaquin Valley, amounting to a total volume of 24.2 ± 9.3 km3 lost during the period October 2011 to September 2015. This is consistent with the total volume of 29.25 ± 8.7 km3, estimated using only Global Positioning System deformation data. Our results highlight the advantage of using vertical land motion data to evaluate groundwater loss and thus fill the gaps between GRACE and GRACE-Follow-On missions and complement their estimates. We further determine that 0.4–3.25% of the aquifer system storage capacity is permanently lost during this drought period. Comparing groundwater level and vertical land motion data following September 2015, we determine an equilibration time of 0.5–1.5 years for groundwater levels within aquitard and aquifer units, during which residual compaction of aquitard and land subsidence continues beyond the drought period. We suggest that such studies can advance the knowledge of evolving groundwater resources, enabling managers and decision makers to better assess water demand and supply during and in-between drought periods.
AB - California's millennium drought of 2012–2015 severely impacted the Central Valley aquifer system and caused permanent loss of groundwater and aquifer storage capacity. To quantify these impacts within the southern San Joaquin Valley, we analyze various complementary measurements, including gravity changes from Gravity Recovery and Climate Experiment (GRACE) satellites; vertical land motion from Global Positioning System, interferometric synthetic aperture radar, and extensometer; and groundwater level records. The interferometric data set acquired by the Sentinel-1 satellite only spans the period January 2015 and October 2017, while the other data sets span the entire drought period. Using GRACE observations, we find an average groundwater loss of 6.1 ± 2.3 km3/year as a lower bound estimate for the San Joaquin Valley, amounting to a total volume of 24.2 ± 9.3 km3 lost during the period October 2011 to September 2015. This is consistent with the total volume of 29.25 ± 8.7 km3, estimated using only Global Positioning System deformation data. Our results highlight the advantage of using vertical land motion data to evaluate groundwater loss and thus fill the gaps between GRACE and GRACE-Follow-On missions and complement their estimates. We further determine that 0.4–3.25% of the aquifer system storage capacity is permanently lost during this drought period. Comparing groundwater level and vertical land motion data following September 2015, we determine an equilibration time of 0.5–1.5 years for groundwater levels within aquitard and aquifer units, during which residual compaction of aquitard and land subsidence continues beyond the drought period. We suggest that such studies can advance the knowledge of evolving groundwater resources, enabling managers and decision makers to better assess water demand and supply during and in-between drought periods.
KW - Drought
KW - GPS
KW - GRACE
KW - Groundwater depletion
KW - Groundwater levels
KW - InSAR
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U2 - 10.1029/2018JB016083
DO - 10.1029/2018JB016083
M3 - Article
AN - SCOPUS:85064488906
SN - 2169-9313
VL - 124
SP - 3127
EP - 3143
JO - Journal of Geophysical Research: Solid Earth
JF - Journal of Geophysical Research: Solid Earth
IS - 3
ER -