Mapping mean annual groundwater recharge in the Nebraska Sand Hills, USA

Abstract

[2000][2001][2002][2003][2004][2005][2006][2007][2008][2009] period was estimated at a 1-km spatial resolution as the difference of mean annual precipitation (P) and evapotranspiration (ET). Monthly P values came from the PRISM dataset, while monthly ET values were derived from linear transformations of the MODIS daytime land-surface temperature values into pixel ET rates with the help of ancillary atmospheric data (air temperature, humidity, and global radiation). The study area receives about 73 mm of recharge (with an error bound of ±73 mm) annually, which is about 14 ± 14% of the regional mean annual P value of 533 mm. The largest recharge rates (about 200 ± 85 mm or 30 ± 12% of P) occur in the south-eastern part of the Sand Hills due to smoother terrain and more abundant precipitation (around 700 mm), while recharge is the smallest (about 40 ± 59 mm or 10 ± 14% of P) in the western part, where annual precipitation is only about 420 mm. Typically, lakes, wetlands, wet inter-dunal valleys, rivers, irrigated crops (except in the south-eastern region) and certain parts of afforested areas in the south-central portion of the study area act as discharge areas for groundwater.

Potential climate change effects on groundwater recharge in the High Plains Aquifer, USA

“…For the NHP, the recharge map of Szilagyi et al [2011] is not directly comparable to the map produced in this study due to different definitions of recharge, but in both cases there is a very strong west to east recharge gradient associated with the rainfall gradient. The recharge under annual and irrigated vegetation in the CHP and SHP is much greater than under perennial vegetation consistent with field measurements [McMahon et al, 2003;Scanlon et al, 2010aScanlon et al, , 2010b and highest recharge in the High Plains is in eastern Nebraska and eastern Kansas associated with irrigation on coarsetextured soils.…”

“…In the SHP, reported deep drainage under dryland agriculture ranges from 4.8 to 92 mm yr À1 with a median of 21 mm yr À1 [Scanlon et al, 2007] and from 18 to 97 mm yr À1 with a median of 41 mm yr À1 under irrigated agriculture [Scanlon et al, 2010a], this is an increase over native vegetation, which has negligible diffuse recharge [Scanlon et al, 2007]. A water balance approach was used to estimate recharge and discharge in the Nebraska Sand Hills based on gridded rainfall and ET data [Szilagyi et al, 2011], and this study found an average recharge rate of 72 mm yr À1 , which corresponded well with chloride-based estimates.…”

Vadose zone lag time and potential 21st century climate change effects on spatially distributed groundwater recharge in the semi-arid Nebraska Sand Hills

“…In the NSH, Holocene sand deposits overlie up to 300 m of Quaternary and/or Pliocene alluvial sand and silt (Wang et al, 2009) and coarse clastic sediments of the Miocene Ogallala Group, that all-together make up the thickest part of the High Plains aquifer (Loope et al, 1995). The High Plains aquifer is considered a vital source of water for irrigated agriculture in the central United States, leading the NSH to be regarded as one of its most important GR areas (Szilagyi et al, 2011b).…”

“…Groundwater recharge rates in the NSH can be large and have been estimated to be greater than 200 mm/yr in some locations (Szilagyi et al, 2011b). These high rates of GR, along with a large groundwater reservoir (High Plains aquifer), make the region economically as well as ecologically valuable, supplying water to major rivers, thousands of groundwater fed lakes and wetlands, and sub-irrigating meadows-responsible for a third of Nebraska's beef cattle industry (Gosselin et al, 2000).…”

“…Among the various hydrologic cycle components, GR is the leading variable determining groundwater resources availability and sustainability in semi-arid and arid environments (Crosbie et al, 2013;Szilagyi et al, 2011b). Of practical importance to groundwater modeling and water resource management are the effects of projected changes in potential groundwater recharge (GR p ) rates (deep drainage beneath the root zone) on multi-decadal to century time scales, because regions with deep water tables and/or experiencing low GR p rates with fine-textured soils can have vadose zone lag times that exceed a century (McMahon et al, 2006;Scanlon et al, 2010).…”