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James S. Famiglietti - One of the best experts on this subject based on the ideXlab platform.
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Groundwater Storage Monitoring From Space
Comprehensive Remote Sensing, 2020Co-Authors: Jianli Chen, Clark R. Wilson, James S. Famiglietti, Bridget R ScanlonAbstract:Abstract As a major component of the global water cycle, Groundwater (underground water) includes water present beneath Earth’s surface within pore spaces in soil and deeper sediments and in fractured formations in the saturated zone. Groundwater plays a key role in connections between the global hydrological cycle and climate change and is a vital resource in many parts of the world. Groundwater Storage (GWS) change is mainly controlled by a balance between discharge (including extraction by pumping for agricultural and domestic consumption) and recharge through infiltration from soil or seepage from surface reservoirs. GWS change can be monitored by water level measurements in wells in combination with geological information describing the ability of the saturated zone to store and release water. However lack of adequate in situ observations has prevented accurate estimates of GWS change in most regions of the world. Only a few well-developed countries have both networks of measured wells, and sufficient knowledge of soil and rock material properties. Satellite gravity measurements from the Gravity Recovery and Climate Experiment (GRACE) satellites provide an alternative method for estimating GWS change. Since its launch in March 2002, GRACE has measured changes in Earth’s gravity on a monthly basis for over 13 years with an accuracy sufficient to detect a centimeter of water equivalent water Storage change at a spatial resolution of a few 100 km. This accuracy is comparable to or better than estimates from well level measurements, so GRACE provides a complementary spatial average when both measurement types are available. GRACE estimates of Storage change require that other causes of gravity change be removed, usually via hydrologic and similar geophysical models. GRACE gravity measurements have been successfully used in studies that span the globe, including Northwest India, California’s Central Valley, the High Plains Aquifer in the United States, the North China Plain, various regions in the Middle East, and Australia’s southern Murray–Darling Basin. This chapter starts with an overall introduction of global Groundwater Storage changes, observations and challenges (11.1), followed by a brief introduction to Groundwater and its role in the global water cycle (11.2), and in situ Groundwater observations and limitations (11.3). Detailed descriptions of Groundwater monitoring by satellite gravimetry and related data processing methods are described in 11.4, followed by in-depth discussions of major error sources and issues in GRACE-based Groundwater Storage estimation and how people should address them in 11.5. 11.6 provides a comprehensive review of the progress in Groundwater monitoring by GRACE satellite gravimetry using some case studies of regional long-term Groundwater Storage changes over the world. A summary is provided at the end in 11.7.
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Projecting Groundwater Storage changes in California’s Central Valley
Scientific Reports, 2018Co-Authors: Elias C. Massoud, Adam J. Purdy, Michelle E. Miro, James S. FamigliettiAbstract:Accurate and detailed knowledge of California’s Groundwater is of paramount importance for statewide water resources planning and management, and to sustain a multi-billion-dollar agriculture industry during prolonged droughts. In this study, we use water supply and demand information from California’s Department of Water Resources to develop an aggregate Groundwater Storage model for California’s Central Valley. The model is evaluated against 34 years of historic estimates of changes in Groundwater Storage derived from the United States Geological Survey’s Central Valley Hydrologic Model (USGS CVHM) and NASA’s Gravity Recovery and Climate Experiment (NASA GRACE) satellites. The calibrated model is then applied to predict future changes in Groundwater Storage for the years 2015–2050 under various precipitation scenarios from downscaled climate projections. We also discuss and project potential management strategies across different annual supply and demand variables and how they affect changes in Groundwater Storage. All simulations support the need for collective statewide management intervention to prevent continued depletion of Groundwater availability.
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projecting Groundwater Storage changes in california s central valley
Scientific Reports, 2018Co-Authors: Elias C. Massoud, Adam J. Purdy, Michelle E. Miro, James S. FamigliettiAbstract:Accurate and detailed knowledge of California’s Groundwater is of paramount importance for statewide water resources planning and management, and to sustain a multi-billion-dollar agriculture industry during prolonged droughts. In this study, we use water supply and demand information from California’s Department of Water Resources to develop an aggregate Groundwater Storage model for California’s Central Valley. The model is evaluated against 34 years of historic estimates of changes in Groundwater Storage derived from the United States Geological Survey’s Central Valley Hydrologic Model (USGS CVHM) and NASA’s Gravity Recovery and Climate Experiment (NASA GRACE) satellites. The calibrated model is then applied to predict future changes in Groundwater Storage for the years 2015–2050 under various precipitation scenarios from downscaled climate projections. We also discuss and project potential management strategies across different annual supply and demand variables and how they affect changes in Groundwater Storage. All simulations support the need for collective statewide management intervention to prevent continued depletion of Groundwater availability.
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Downscaling GRACE Remote Sensing Datasets to High-Resolution Groundwater Storage Change Maps of California’s Central Valley
Remote Sensing, 2018Co-Authors: Michelle E. Miro, James S. FamigliettiAbstract:NASA’s Gravity Recovery and Climate Experiment (GRACE) has already proven to be a powerful data source for regional Groundwater assessments in many areas around the world. However, the applicability of GRACE data products to more localized studies and their utility to water management authorities have been constrained by their limited spatial resolution (~200,000 km2). Researchers have begun to address these shortcomings with data assimilation approaches that integrate GRACE-derived total water Storage estimates into complex regional models, producing higher-resolution estimates of hydrologic variables (~2500 km2). Here we take those approaches one step further by developing an empirically based model capable of downscaling GRACE data to a high-resolution (~16 km2) dataset of Groundwater Storage changes over a portion of California’s Central Valley. The model utilizes an artificial neural network to generate a series of high-resolution maps of Groundwater Storage change from 2002 to 2010 using GRACE estimates of variations in total water Storage and a series of widely available hydrologic variables (PRISM precipitation and temperature data, digital elevation model (DEM)-derived slope, and Natural Resources Conservation Service (NRCS) soil type). The neural network downscaling model is able to accurately reproduce local Groundwater behavior, with acceptable Nash-Sutcliffe efficiency (NSE) values for calibration and validation (ranging from 0.2445 to 0.9577 and 0.0391 to 0.7511, respectively). Ultimately, the model generates maps of local Groundwater Storage change at a 100-fold higher resolution than GRACE gridded data products without the use of computationally intensive physical models. The model’s simulated maps have the potential for application to local Groundwater management initiatives in the region.
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downscaling grace remote sensing datasets to high resolution Groundwater Storage change maps of california s central valley
Remote Sensing, 2018Co-Authors: Michelle E. Miro, James S. FamigliettiAbstract:NASA’s Gravity Recovery and Climate Experiment (GRACE) has already proven to be a powerful data source for regional Groundwater assessments in many areas around the world. However, the applicability of GRACE data products to more localized studies and their utility to water management authorities have been constrained by their limited spatial resolution (~200,000 km2). Researchers have begun to address these shortcomings with data assimilation approaches that integrate GRACE-derived total water Storage estimates into complex regional models, producing higher-resolution estimates of hydrologic variables (~2500 km2). Here we take those approaches one step further by developing an empirically based model capable of downscaling GRACE data to a high-resolution (~16 km2) dataset of Groundwater Storage changes over a portion of California’s Central Valley. The model utilizes an artificial neural network to generate a series of high-resolution maps of Groundwater Storage change from 2002 to 2010 using GRACE estimates of variations in total water Storage and a series of widely available hydrologic variables (PRISM precipitation and temperature data, digital elevation model (DEM)-derived slope, and Natural Resources Conservation Service (NRCS) soil type). The neural network downscaling model is able to accurately reproduce local Groundwater behavior, with acceptable Nash-Sutcliffe efficiency (NSE) values for calibration and validation (ranging from 0.2445 to 0.9577 and 0.0391 to 0.7511, respectively). Ultimately, the model generates maps of local Groundwater Storage change at a 100-fold higher resolution than GRACE gridded data products without the use of computationally intensive physical models. The model’s simulated maps have the potential for application to local Groundwater management initiatives in the region.
Matthew Rodell - One of the best experts on this subject based on the ideXlab platform.
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long term non anthropogenic Groundwater Storage changes simulated by three global scale hydrological models
Scientific Reports, 2019Co-Authors: Matthew Rodell, Bailing Li, Justin Sheffield, Eric F Wood, E SutanudjajaAbstract:This study examined long-term, natural (i.e., excluding anthropogenic impacts) variability of Groundwater Storage worldwide. Groundwater Storage changes were estimated by forcing three global-scale hydrological models with three 50+ year meteorological datasets. Evaluation using in situ Groundwater observations from the U.S. and terrestrial water Storage derived from the Gravity Recovery and Climate Experiment (GRACE) satellites showed that these models reasonably represented inter-annual variability of water Storage, as indicated by correlations greater than 0.5 in most regions. Empirical orthogonal function analysis revealed influences of the El Nino Southern Oscillation (ENSO) on global Groundwater Storage. Simulated Groundwater Storage, including its global average, exhibited trends generally consistent with that of precipitation. Global total (natural) Groundwater Storage decreased over the past 5–7 decades with modeled rates ranging from 0.01 to 2.18 mm year−1. This large range can be attributed in part to Groundwater’s low frequency (inter-decadal) variability, which complicates identification of real long-term trends even within a 50+ year time series. Results indicate that non-anthropogenic variability in Groundwater Storage is substantial, making knowledge of it fundamental to quantifying direct human impacts on Groundwater Storage.
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Groundwater Storage Variations in India
Springer Hydrogeology, 2018Co-Authors: Soumendra N. Bhanja, Abhijit Mukherjee, Matthew RodellAbstract:In recent years, intense abstraction of Groundwater has led to depletion in Groundwater Storage (GWS) in India, the second most populous country in the world. In this chapter, we demonstrate our work on estimating Groundwater Storage over India by using data from the Gravity Recovery and Climate Experiment (GRACE) satellite mission to study long-term (2003–2014) change in GWS over India. Rapid depletion of GWS is observed in the Indus–Ganges River basin in the northern and eastern parts of the Indian subcontinent at rates of about −1.25 ± 0.14 (−12.56 ± 1.37 km3/year) and −1.05 ± 0.35 cm/year (−13.12 ± 4.36 km3/year), respectively. The fertile alluvial plains of this semiarid basin support huge areas of irrigated agriculture, leading to depletion of GWS. On the other hand, the southern and western parts exhibit Groundwater replenishment.
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Groundwater Storage changes present status from grace observations
Surveys in Geophysics, 2016Co-Authors: Jianli Chen, James S Famigliett, Bridget R Scanlon, Matthew RodellAbstract:Satellite gravity measurements from the Gravity Recovery and Climate Experiment (GRACE) provide quantitative measurement of terrestrial water Storage (TWS) changes with unprecedented accuracy. Combining GRACE-observed TWS changes and independent estimates of water change in soil and snow and surface reservoirs offers a means for estimating Groundwater Storage change. Since its launch in March 2002, GRACE time-variable gravity data have been successfully used to quantify long-term Groundwater Storage changes in different regions over the world, including northwest India, the High Plains Aquifer and the Central Valley in the USA, the North China Plain, Middle East, and southern Murray–Darling Basin in Australia, where Groundwater Storage has been significantly depleted in recent years (or decades). It is difficult to rely on in situ Groundwater measurements for accurate quantification of large, regional-scale Groundwater Storage changes, especially at long timescales due to inadequate spatial and temporal coverage of in situ data and uncertainties in Storage coefficients. The now nearly 13 years of GRACE gravity data provide a successful and unique complementary tool for monitoring and measuring Groundwater changes on a global and regional basis. Despite the successful applications of GRACE in studying global Groundwater Storage change, there are still some major challenges limiting the application and interpretation of GRACE data. In this paper, we present an overview of GRACE applications in Groundwater studies and discuss if and how the main challenges to using GRACE data can be addressed.
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uncertainty in global Groundwater Storage estimates in a total Groundwater stress framework
Water Resources Research, 2015Co-Authors: Alexandra S Richey, Sean Swenson, James S. Famiglietti, Brian F Thomas, Minhui Lo, Matthew RodellAbstract:Groundwater resilience is defined and quantified with remote sensing from GRACETimescales of aquifer depletion are assessed as a Total Groundwater Stress ratioThe volume of usable global Groundwater Storage is found to be largely unknown.
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estimating Groundwater Storage changes in the mississippi river basin usa using grace
Hydrogeology Journal, 2007Co-Authors: Matthew Rodell, James S. Famiglietti, Jianli Chen, Hiroko Kato, Joe Nigro, Clark R. WilsonAbstract:Based on satellite observations of Earth’s time variable gravity field from the Gravity Recovery and Climate Experiment (GRACE), it is possible to derive variations in terrestrial water Storage, which includes Groundwater, soil moisture, and snow. Given auxiliary information on the latter two, one can estimate Groundwater Storage variations. GRACE may be the only hope for Groundwater depletion assessments in data-poor regions of the world. In this study, soil moisture and snow were simulated by the Global Land Data Assimilation System (GLDAS) and used to isolate Groundwater Storage anomalies from GRACE water Storage data for the Mississippi River basin and its four major sub-basins. Results were evaluated using water level records from 58 wells set in the unconfined aquifers of the basin. Uncertainty in the technique was also assessed. The GRACE-GLDAS estimates compared favorably with the well based time series for the Mississippi River basin and the two sub-basins that are larger than 900,000 km2. The technique performed poorly for the two sub-basins that have areas of approximately 500,000 km2. Continuing enhancement of the GRACE processing methods is likely to improve the skill of the technique in the future, while also increasing the temporal resolution.
Wilfried Brutsaert - One of the best experts on this subject based on the ideXlab platform.
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The estimation of Groundwater Storage changes at climatic time scales from low streamflow observations
2020Co-Authors: Wilfried BrutsaertAbstract:During periods of no precipitation or artificial inputs, the water flow observed in a river can be assumed to result primarily from drainage of Groundwater from the upstream riparian aquifers in the catchment. Groundwater Storage in a basin goes through various high and low phases during any given year depending on the antecedent precipitation inputs over the region; hence, an objective way to track the long term evolution of this Storage over many years is to monitor its lowest level each year, that is, when it reaches "rock bottom", or the non-depleted reserve, which is available for the next year. Because the Groundwater drainage into the river system is directly related to the water stored in the upstream aquifers, observations of the trends of the annual lowest flows can serve to deduce quantitative estimates of the basin-scale Groundwater Storage trends over the period of the streamflow record. The proposed method was implemented and validated with streamflow and Groundwater level observations in two basins in Illinois, and then applied with streamflow data in a large basin in Mongolia, where it could be compared with other measures of a changing hydrologic cycle.
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Groundwater Storage trends in the loess plateau of china estimated from streamflow records
Journal of Hydrology, 2015Co-Authors: Lu Zhang, Lei Cheng, Xiaoping Zhang, Tim Cowan, Wilfried BrutsaertAbstract:Summary The catchments in the Loess Plateau in China have experienced significant land use change since the 1950s with a great number of soil conservation measures such as revegetation being implemented. Such soil conservation measures and climate variability have had considerable impacts on annual streamflow from these catchments. However, much less is known about changes in Groundwater Storage as the period of direct Groundwater Storage measurements is too short to reliably infer Groundwater Storage trends. For this study, annual values of Groundwater Storage from 38 catchments in the Loess Plateau were estimated from daily streamflow records based on Groundwater flow theory. It was found that over the period of record (viz. 1955–2010), statistically significant ( p
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Long-term annual Groundwater Storage trends in Australian catchments
Advances in Water Resources, 2014Co-Authors: Lu Zhang, R. E. Crosbie, Wilfried Brutsaert, Nick PotterAbstract:The period of direct Groundwater Storage measurements is often too short to allow reliable inferences of Groundwater Storage trends at catchment scales. However, as Groundwater Storage sustains low flows in catchments during dry periods, Groundwater Storage can also be estimated indirectly from daily streamflow based on hydraulic Groundwater theory; this idea was applied herein to 17 selected Australian catchments to examine their long-term (half a century or longer) Groundwater Storage trends. On average, over past 45. years, Groundwater Storage exhibited negative trends in all the selected catchments, except in the Katherine River catchment located in the Northern Territory. These negative trends persisted over longer periods, close to 100. years in some catchments and the strongest decreasing trend of 0.241. mm per year was observed in the Barron River catchment in New South Wales. However, Groundwater Storage exhibited different trends over the different shorter periods. Thus, while during the period of 1997-2007, 15 out of the 17 catchments showed negative trends in Groundwater Storage, during the period of 1980-2000, 12 out of the 17 catchments exhibited positive trends in Groundwater Storage; this underscores the fact that record lengths of one or even two decades are inadequate to derive meaningful trends. Strong consistencies in the trends exist across most catchments, indicating that Groundwater Storage is affected by large-scale climate factors.
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annual drought flow and Groundwater Storage trends in the eastern half of the united states during the past two third century
Theoretical and Applied Climatology, 2010Co-Authors: Wilfried BrutsaertAbstract:Low flow drainage from a river system, in the absence of precipitation or snowmelt, derives directly from the water stored in the upstream aquifers in the basin; therefore, observations of the trends of the annual lowest flows can serve to deduce quantitative estimates of the evolution of the basin-scale Groundwater Storage over the period of the streamflow record. Application of this method has allowed for the first time to determine the magnitudes of the trends in Groundwater Storage over the past two-third century in some 41 large prototypical basins in the United States east of the Rocky Mountains. It was found that during the period 1940–2007 Groundwater Storage has generally been increasing in most areas; these positive trends were especially pronounced in the Ohio and Upper Mississippi Water Resources Regions, but they were weaker in most other regions. Notable exceptions are the northern New England and especially the South Atlantic-Gulf regions, which saw prolonged declines in Groundwater levels over this nearly 70-year long period. These observed long-term trends are generally in agreement with previous studies regarding trends of other components of the water cycle, such as precipitation, total runoff, and terrestrial evaporation. Over the most recent 20 years, from 1988 through 2007, except for the Ohio and the Souris-Red-Rainy regions, most regions have experienced declining average Groundwater levels to varying degrees, with maximal values of the order of −0.2 mm a−1.
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Recent Low-Flow and Groundwater Storage Changes in Upland Watersheds of the Kanto Region, Japan
Journal of Hydrologic Engineering, 2009Co-Authors: Michiaki Sugita, Wilfried BrutsaertAbstract:Annual trends in baseflow and Groundwater Storage over the past 40 years are deduced from stream flow observations in four upland catchments in the northern parts of the Kanto region. The analysis is based on the assumption that baseflow is an exponential decay function of time, which yields a linear relationship between Storage and baseflow. These catchments are part of the water supply system for the Greater Tokyo metropolitan area, and Groundwater constitutes an integral component of their Storage capacity. Although the data exhibit great variability from year to year, no evidence was found that any persistent or systematic changes in low streamflow regime and in Groundwater Storage have taken place in this region over the period of record.
Bridget R Scanlon - One of the best experts on this subject based on the ideXlab platform.
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Groundwater Storage Monitoring From Space
Comprehensive Remote Sensing, 2020Co-Authors: Jianli Chen, Clark R. Wilson, James S. Famiglietti, Bridget R ScanlonAbstract:Abstract As a major component of the global water cycle, Groundwater (underground water) includes water present beneath Earth’s surface within pore spaces in soil and deeper sediments and in fractured formations in the saturated zone. Groundwater plays a key role in connections between the global hydrological cycle and climate change and is a vital resource in many parts of the world. Groundwater Storage (GWS) change is mainly controlled by a balance between discharge (including extraction by pumping for agricultural and domestic consumption) and recharge through infiltration from soil or seepage from surface reservoirs. GWS change can be monitored by water level measurements in wells in combination with geological information describing the ability of the saturated zone to store and release water. However lack of adequate in situ observations has prevented accurate estimates of GWS change in most regions of the world. Only a few well-developed countries have both networks of measured wells, and sufficient knowledge of soil and rock material properties. Satellite gravity measurements from the Gravity Recovery and Climate Experiment (GRACE) satellites provide an alternative method for estimating GWS change. Since its launch in March 2002, GRACE has measured changes in Earth’s gravity on a monthly basis for over 13 years with an accuracy sufficient to detect a centimeter of water equivalent water Storage change at a spatial resolution of a few 100 km. This accuracy is comparable to or better than estimates from well level measurements, so GRACE provides a complementary spatial average when both measurement types are available. GRACE estimates of Storage change require that other causes of gravity change be removed, usually via hydrologic and similar geophysical models. GRACE gravity measurements have been successfully used in studies that span the globe, including Northwest India, California’s Central Valley, the High Plains Aquifer in the United States, the North China Plain, various regions in the Middle East, and Australia’s southern Murray–Darling Basin. This chapter starts with an overall introduction of global Groundwater Storage changes, observations and challenges (11.1), followed by a brief introduction to Groundwater and its role in the global water cycle (11.2), and in situ Groundwater observations and limitations (11.3). Detailed descriptions of Groundwater monitoring by satellite gravimetry and related data processing methods are described in 11.4, followed by in-depth discussions of major error sources and issues in GRACE-based Groundwater Storage estimation and how people should address them in 11.5. 11.6 provides a comprehensive review of the progress in Groundwater monitoring by GRACE satellite gravimetry using some case studies of regional long-term Groundwater Storage changes over the world. A summary is provided at the end in 11.7.
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Groundwater Storage changes present status from grace observations
Surveys in Geophysics, 2016Co-Authors: Jianli Chen, James S Famigliett, Bridget R Scanlon, Matthew RodellAbstract:Satellite gravity measurements from the Gravity Recovery and Climate Experiment (GRACE) provide quantitative measurement of terrestrial water Storage (TWS) changes with unprecedented accuracy. Combining GRACE-observed TWS changes and independent estimates of water change in soil and snow and surface reservoirs offers a means for estimating Groundwater Storage change. Since its launch in March 2002, GRACE time-variable gravity data have been successfully used to quantify long-term Groundwater Storage changes in different regions over the world, including northwest India, the High Plains Aquifer and the Central Valley in the USA, the North China Plain, Middle East, and southern Murray–Darling Basin in Australia, where Groundwater Storage has been significantly depleted in recent years (or decades). It is difficult to rely on in situ Groundwater measurements for accurate quantification of large, regional-scale Groundwater Storage changes, especially at long timescales due to inadequate spatial and temporal coverage of in situ data and uncertainties in Storage coefficients. The now nearly 13 years of GRACE gravity data provide a successful and unique complementary tool for monitoring and measuring Groundwater changes on a global and regional basis. Despite the successful applications of GRACE in studying global Groundwater Storage change, there are still some major challenges limiting the application and interpretation of GRACE data. In this paper, we present an overview of GRACE applications in Groundwater studies and discuss if and how the main challenges to using GRACE data can be addressed.
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Use of GRACE Satellites to Assess Trends in Groundwater Storage Globally
2014Co-Authors: Bridget R Scanlon, Di Long, Laurent LonguevergneAbstract:GRACE satellite data have proved invaluable in providing data on spatiotemporal variability in water Storage at a global scale. While estimates of total water Storage are relatively straightforward in large scale basins, disaggregating the Groundwater Storage component is complicated because of uncertainties in other components of the water budget. In this presentation we will discuss results of GRACE analysis on Groundwater Storage in different systems, ranging from simple unconfined aquifers with little surface water interactions (e.g. High Plains aquifer) to more complicated unconfined/confined aquifers with combined surface water and Groundwater based irrigation (U.S. Central Valley and N India) systems. We will discuss different approaches for estimating changes in Groundwater Storage, uncertainties in these approaches, and comparisons of Storage estimates from GRACE with those based on regional water level monitoring data and regional Groundwater models. This analysis should advance applications of GRACE data in assessing changes in Groundwater Storage and highlight important factors to constrain uncertainties in Storage estimates.
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ground referencing grace satellite estimates of Groundwater Storage changes in the california central valley usa
Water Resources Research, 2012Co-Authors: Bridget R Scanlon, Laurent Longuevergne, Di LongAbstract:There is increasing interest in using Gravity Recovery and Climate Experiment (GRACE) satellite data to remotely monitor Groundwater Storage variations; however, comparisons with ground-based well data are limited but necessary to validate satellite data processing, especially when the study area is close to or below the GRACE footprint. The Central Valley is a heavily irrigated region with large-scale Groundwater depletion during droughts. Here we compare updated estimates of Groundwater Storage changes in the California Central Valley using GRACE satellites with Storage changes from Groundwater level data. A new processing approach was applied that optimally uses available GRACE and water balance component data to extract changes in Groundwater Storage. GRACE satellites show that Groundwater depletion totaled ∼31.0 ± 3.0 km3 for Groupe de Recherche de Geodesie Spatiale (GRGS) satellite data during the drought from October 2006 through March 2010. Groundwater Storage changes from GRACE agreed with those from well data for the overlap period (April 2006 through September 2009) (27 km3 for both). General correspondence between GRACE and Groundwater level data validates the methodology and increases confidence in use of GRACE satellites to monitor Groundwater Storage changes.
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Difficulties in Assessing Reliability of Groundwater Storage Changes from GRACE Satellite Data
2011Co-Authors: Gil Strassberg, Clark R. Wilson, Bridget R Scanlon, Laurent Longuevergne, Di LongAbstract:There is increasing interest in use of GRACE satellite data to monitor changes in Groundwater Storage. The objective of this study was to assess the reliability of Storage change estimates from GRACE using comparisons with ground-based data. Groundwater basins with large signals from Groundwater depletion due to irrigation were selected and include the High Plains and Central Valley aquifers in the US. The High Plains aquifer is the most straightforward because it is large (450,000 km2), and has only two Storage components (soil moisture and Groundwater). The aquifer is unconfined; therefore, converting water level changes to water Storage is relatively straightforward. Good correlations were found between Groundwater Storage change estimated from GRACE and ground-based data from 2002 through 2007. The Central Valley aquifer is much more difficult to analyze because it is much smaller (52,000 km2), and has a large number of Storage components (snow, surface water, soil moisture, and Groundwater) with different spatial distributions. The aquifer varies from unconfined to confined; therefore, Storage coefficients vary by orders of magnitude. Processing the larger river basins that include the Central Valley increases the area to 154,000 km2. Snow data are available from SNODAS and surface water reservoirs are monitored directly. Groundwater levels are monitored; however, it is difficult to determine which wells are penetrating unconfined, semiconfined, or confined portions of the aquifer, increasing uncertainties in water Storage estimates from water level data. Groundwater depletion was generally restricted to the 2006 through 2009 drought and depletion from GRACE (25 - 26 km3) compared favorably with estimates ground-based data (23 km3). Improving estimates of Groundwater Storage changes will require quantification of inputs and outputs to aquifers, incorporating irrigation into land surface models to provide reliable data on soil moisture Storage changes, and improved estimates of Groundwater Storage from water level or potentiometric surface data. While some suggest that satellite data may replace ground-based monitoring, reliable estimates of Groundwater Storage from GRACE require strong integration of satellite and ground-based data and modeling analyses.
Clark R. Wilson - One of the best experts on this subject based on the ideXlab platform.
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Groundwater Storage Monitoring From Space
Comprehensive Remote Sensing, 2020Co-Authors: Jianli Chen, Clark R. Wilson, James S. Famiglietti, Bridget R ScanlonAbstract:Abstract As a major component of the global water cycle, Groundwater (underground water) includes water present beneath Earth’s surface within pore spaces in soil and deeper sediments and in fractured formations in the saturated zone. Groundwater plays a key role in connections between the global hydrological cycle and climate change and is a vital resource in many parts of the world. Groundwater Storage (GWS) change is mainly controlled by a balance between discharge (including extraction by pumping for agricultural and domestic consumption) and recharge through infiltration from soil or seepage from surface reservoirs. GWS change can be monitored by water level measurements in wells in combination with geological information describing the ability of the saturated zone to store and release water. However lack of adequate in situ observations has prevented accurate estimates of GWS change in most regions of the world. Only a few well-developed countries have both networks of measured wells, and sufficient knowledge of soil and rock material properties. Satellite gravity measurements from the Gravity Recovery and Climate Experiment (GRACE) satellites provide an alternative method for estimating GWS change. Since its launch in March 2002, GRACE has measured changes in Earth’s gravity on a monthly basis for over 13 years with an accuracy sufficient to detect a centimeter of water equivalent water Storage change at a spatial resolution of a few 100 km. This accuracy is comparable to or better than estimates from well level measurements, so GRACE provides a complementary spatial average when both measurement types are available. GRACE estimates of Storage change require that other causes of gravity change be removed, usually via hydrologic and similar geophysical models. GRACE gravity measurements have been successfully used in studies that span the globe, including Northwest India, California’s Central Valley, the High Plains Aquifer in the United States, the North China Plain, various regions in the Middle East, and Australia’s southern Murray–Darling Basin. This chapter starts with an overall introduction of global Groundwater Storage changes, observations and challenges (11.1), followed by a brief introduction to Groundwater and its role in the global water cycle (11.2), and in situ Groundwater observations and limitations (11.3). Detailed descriptions of Groundwater monitoring by satellite gravimetry and related data processing methods are described in 11.4, followed by in-depth discussions of major error sources and issues in GRACE-based Groundwater Storage estimation and how people should address them in 11.5. 11.6 provides a comprehensive review of the progress in Groundwater monitoring by GRACE satellite gravimetry using some case studies of regional long-term Groundwater Storage changes over the world. A summary is provided at the end in 11.7.
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Long-term Groundwater Storage change in Victoria, Australia from satellite gravity and in situ observations
Global and Planetary Change, 2016Co-Authors: J L Chen, Clark R. Wilson, Bridget Scanlon, Byron D. Tapley, Andreas GüntnerAbstract:Analysis based on satellite gravity measurements from the Gravity Recovery and Climate Experiment (GRACE) and land surface models indicates that Groundwater Storage in Victoria, Australia had been declining steadily, until a trend reversal around early 2010, attributed to two wetter seasons in 2010 and 2011. In situ Groundwater level measurements (from a network of 1395 bores in Victoria) also indicate a steady Groundwater depletion since the early 1990's, and show remarkable agreement with GRACE estimates for the 10-year period (2003-2012) in common with the GRACE mission. Groundwater depletion rates for 2005 to 2009 are relatively large as indicated by both GRACE estimates (8.0±1.7km3/yr) and in situ measurements (8.3±3.4km3/yr). Over the same period (2005-2009), GRACE measurements capture significant Groundwater depletion in a wider region covering much of the southern Murray-Darling Basin, and the total Groundwater depletion rate in this region is about 17.2±4.7km3/yr. Annual Groundwater Storage changes are strongly correlated with precipitation anomalies, but only about one-fifth of anomalous precipitation contributes to Groundwater recharge. The strong correlation suggests that this Groundwater depletion is primarily related to drought with related Groundwater pumping for agricultural and domestic consumption. The remarkable agreement between GRACE estimates and in situ measurements demonstrates the great potential of satellite gravity observations in combination with land surface model estimates to quantify changes in regional Groundwater resources, especially when in situ measurements are limited or unavailable. This study shows the importance of reducing leakage bias in GRACE observations and the effectiveness of the forward modeling iterative method used.
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Difficulties in Assessing Reliability of Groundwater Storage Changes from GRACE Satellite Data
2011Co-Authors: Gil Strassberg, Clark R. Wilson, Bridget R Scanlon, Laurent Longuevergne, Di LongAbstract:There is increasing interest in use of GRACE satellite data to monitor changes in Groundwater Storage. The objective of this study was to assess the reliability of Storage change estimates from GRACE using comparisons with ground-based data. Groundwater basins with large signals from Groundwater depletion due to irrigation were selected and include the High Plains and Central Valley aquifers in the US. The High Plains aquifer is the most straightforward because it is large (450,000 km2), and has only two Storage components (soil moisture and Groundwater). The aquifer is unconfined; therefore, converting water level changes to water Storage is relatively straightforward. Good correlations were found between Groundwater Storage change estimated from GRACE and ground-based data from 2002 through 2007. The Central Valley aquifer is much more difficult to analyze because it is much smaller (52,000 km2), and has a large number of Storage components (snow, surface water, soil moisture, and Groundwater) with different spatial distributions. The aquifer varies from unconfined to confined; therefore, Storage coefficients vary by orders of magnitude. Processing the larger river basins that include the Central Valley increases the area to 154,000 km2. Snow data are available from SNODAS and surface water reservoirs are monitored directly. Groundwater levels are monitored; however, it is difficult to determine which wells are penetrating unconfined, semiconfined, or confined portions of the aquifer, increasing uncertainties in water Storage estimates from water level data. Groundwater depletion was generally restricted to the 2006 through 2009 drought and depletion from GRACE (25 - 26 km3) compared favorably with estimates ground-based data (23 km3). Improving estimates of Groundwater Storage changes will require quantification of inputs and outputs to aquifers, incorporating irrigation into land surface models to provide reliable data on soil moisture Storage changes, and improved estimates of Groundwater Storage from water level or potentiometric surface data. While some suggest that satellite data may replace ground-based monitoring, reliable estimates of Groundwater Storage from GRACE require strong integration of satellite and ground-based data and modeling analyses.
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estimating Groundwater Storage changes in the mississippi river basin usa using grace
Hydrogeology Journal, 2007Co-Authors: Matthew Rodell, James S. Famiglietti, Jianli Chen, Hiroko Kato, Joe Nigro, Clark R. WilsonAbstract:Based on satellite observations of Earth’s time variable gravity field from the Gravity Recovery and Climate Experiment (GRACE), it is possible to derive variations in terrestrial water Storage, which includes Groundwater, soil moisture, and snow. Given auxiliary information on the latter two, one can estimate Groundwater Storage variations. GRACE may be the only hope for Groundwater depletion assessments in data-poor regions of the world. In this study, soil moisture and snow were simulated by the Global Land Data Assimilation System (GLDAS) and used to isolate Groundwater Storage anomalies from GRACE water Storage data for the Mississippi River basin and its four major sub-basins. Results were evaluated using water level records from 58 wells set in the unconfined aquifers of the basin. Uncertainty in the technique was also assessed. The GRACE-GLDAS estimates compared favorably with the well based time series for the Mississippi River basin and the two sub-basins that are larger than 900,000 km2. The technique performed poorly for the two sub-basins that have areas of approximately 500,000 km2. Continuing enhancement of the GRACE processing methods is likely to improve the skill of the technique in the future, while also increasing the temporal resolution.
