{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,12]],"date-time":"2026-03-12T11:57:18Z","timestamp":1773316638254,"version":"3.50.1"},"reference-count":62,"publisher":"MDPI AG","issue":"23","license":[{"start":{"date-parts":[[2019,11,23]],"date-time":"2019-11-23T00:00:00Z","timestamp":1574467200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>Accurate assessments of groundwater resources in major aquifers across the globe are crucial for sustainable management of freshwater reservoirs. Observations from the Gravity Recovery and Climate Experiment (GRACE) satellite have become invaluable as a means to identify regions groundwater change. While there is a large body of research that focuses on downscaling coarse (1\u00b0) GRACE products, few studies have attempted to spatially downscale GRACE to produce fine resolution (5 km) maps that are more useful to resource managers. This study trained a boosted regression tree model to statistically downscale GRACE total water storage anomaly to monthly 5 km groundwater level anomaly maps in the karstic upper Floridan aquifer (UFA) using multiple hydrologic datasets. Evaluation of spatial predictions with existing groundwater wells indicated satisfactory performance (R = 0.79, NSE = 0.61). Results demonstrate that groundwater levels were stable between 2002\u20132016 but varied seasonally. The data also highlights areas where groundwater pumping is exacerbating UFA water-level declines. While results demonstrate the applicability of machine learning based methods for spatial downscaling of GRACE data, future studies should account for preferential flowpaths (i.e., conduits, lineaments) in karstic systems.<\/jats:p>","DOI":"10.3390\/rs11232756","type":"journal-article","created":{"date-parts":[[2019,11,25]],"date-time":"2019-11-25T03:10:00Z","timestamp":1574651400000},"page":"2756","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":57,"title":["Spatial Downscaling of GRACE TWSA Data to Identify Spatiotemporal Groundwater Level Trends in the Upper Floridan Aquifer, Georgia, USA"],"prefix":"10.3390","volume":"11","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-0494-8002","authenticated-orcid":false,"given":"Adam M.","family":"Milewski","sequence":"first","affiliation":[{"name":"Department of Geology, University of Georgia, Athens, GA 30602, USA"}]},{"given":"Matthew B.","family":"Thomas","sequence":"additional","affiliation":[{"name":"Department of Geology, University of Georgia, Athens, GA 30602, USA"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0299-1413","authenticated-orcid":false,"given":"Wondwosen M.","family":"Seyoum","sequence":"additional","affiliation":[{"name":"Department of Geography, Geology, and the Environment, Illinois State University, Normal, IL 61761, USA"}]},{"given":"Todd C.","family":"Rasmussen","sequence":"additional","affiliation":[{"name":"Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA 30602, USA"}]}],"member":"1968","published-online":{"date-parts":[[2019,11,23]]},"reference":[{"key":"ref_1","unstructured":"UNESCO (2011). 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