Estimating irrigation water use and withdrawal of ground water on the High Plains, U.S.A.

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Vol.2, No.8, pp. 127-129, 1983 0273~l77/83/08012703$01.50/0lrintcd in Great Britain. All rights reserved. Copyright CUSIARESTIMATING IRRIGATION WATERUSE AND WITHDRAWAL OF GROUNDWATER ON THE HIGH PLAINS, U.S.A.James R. WrayU.S. Geological Survey, 521 National Center, Reston, VA 22092,U.S. A.ABSTRACTIn four decades following the Dust Bowl days of the 1930s, extensive areas of dry farmingand rangeland on the semiarid U.S. High Plains were transformed into a vast region ofirrigated oases, producing meat and grain for much of the world. The agricultural economyhas experienced such rapid growth in part because of the availability of ground water andbecause of development of new irrigation technology to use that water for agriculture.However, more water is being used than is being replaced. To estimate both the volume ofwater withdrawn and the regional scope of the problem a technique has been developed thatcombines multispectral data from Earthorbiting satellite with known pumpage data for thesame growing season. The location and extent of irrigated croplandsome with differentcrops watered at different timesis inventoried using computerassisted analysis of thedata from Landsat. The amount of water used is estimated by multiplying and summingsurface area of irrigated agriculture and the average measured pumpage from sampled sites.Published findings to date are cited in the Selected References. All suggest transfer-ability of a promising technology to the study of land transformation processes elsewhere.Water used for irrigating cropland has regularly accounted for approximately half of thewater used in the United States. Even so, the daily total of water used for irrigationincreased 2.6 times, from 269 billion liters in 1940 to 623 billion liters projected for1985. In the same period, however, the amount of irrigation water taken from ground watersources increased 4.0 times, from ~42billion liters in 1940, to a projected 170 billionliters in 1985. Stated another way, 50 percent of the water for irrigation came fromground sources in 1940. By 1985, it is expected that 70 percent will come from groundsources. In the High Plains region, transformations from surface water use to groundwater use are even more dramatic. So are the problems.As a result of increased pumpage, the water table has declined at an everincreasingrate. In the western fourth of the State of Kansas, for example, water level declineprior to 1950 was very small. Since then, however, large areas report total declines of38 meters, while several smaller areas report declines of 16 meters or more. Meanwhile,the increased pumpage also increased energy use at a time when energy supplies weredecreasing and their costs increasing. The threat to the regional economy is great indeed.The evaluation and quantification of these problems (the first steps toward a solution)introduce another problem: how to derive better estimates of water usage, and groundwater withdrawn, in a given growing season over an area as large as 455,000 squarekilometers. See Figure 1.To deal with these problems, many water management programs have been established by localjurisdictions throughout the High Plains region. Because the primary aquifer is regionalin scope, and is not bound by jurisdictional boundaries, the U.S. Geological Surveyinitiated a study of the entire aquifer region. Some preliminary reports are listed inthe Selected References. Still underway, this project promises findings of interest tothose studying land transformation processes from space and ground observations.This study also provides one of the most promising nearoperational applications of Earthobservation by satellite used in combination with ground observations. For the 1978 and1980 crop years, multispectral data from more than 38 nominal Landsat scenes were examined(figure 1), some at different times throughout the growing season. From these, one billiondata elements called pixels, each 0.46 hectare in size, were classified by computerassisted techniques into land cover categories. Ground water pumpage was sampled atrandomly selected sites in 15 counties throughout the aquifer region. The total waterused was estimated by multiplying and summing the surface area of irrigated agricultureand the average measured pumpage from the sampled sites area. Products of the studyinclude maps of irrigated cropland and other land covers, estimates of water use byJASR 2/81 127128 J.R. Wray1minute latitude/longitude cells throughout the entire region, development of a regionalhydrological model, and a procedure manual that adds the tools of Earth observation fromspace to those already used by local water resources organizations. Because the primaryproducts are not available yet in their intended final form, comparable advances in tech-nology are illustrated with some examples from other resource problems in other regions.These not only suggest the applicability of the technology to the study of transformationof agricultural lands, but also demonstrate that such applications are not limited toagricultural lands.SOUTHDAKOTA IWYo~~1 38 ~ -~/L__._.y__..__ 3 33 ~ P~ /34 I 70COtO~~I 28I KANSAS ~ i3 33 73 6 OKLAHOMANEW MEXICOI ~ 133$I TEXASL~~~ ~~100 7 300 MILES0 1(10 200 300 400 KILOMETEI1SFigure l.Location of the High Plains aquifer (shaded area) in the U.S.A., and index tonominal Landsat scenes used to inventory cropland, 1978 and 1980 (Heimes and Luckey, U.S.Geological Survey, 1980).SELECTED REFERENCESR. DeAngelis, Irrigated Cropland, 1979, Hockley and Lamb Counties,Texas, U.S. GeologicalSurvey OpenFile Report 800168, scale 1:250,000, 1980.L.J. Gaydos, G.P. Thelin, W. Donovan, F.J. Heimes, H. Jones, A. Morse, and C. Koch, OneBillion Pixels: An Analysis and Reduction of Landsat Data for the High PlainsHydrological Model [abs.], American Society of Photogrammetry and American Congress onSurveying and Mapping, Denver, Colorado, March 1982, Proceedings, ASP TechnicalPapers, p. 562, 1982.Lst ifll2lt log Lrr 1 ga~i on hit or Use 129E.D. Gutentag and J.B. Weeks, Water Table in the High Plains Aquifer in 1978 in Parts ofColorado, Kansas, Nebraska, Oklahoma, South Dakota, Texas, and Wyoming, U.S.Geological Survey Hydrologic Investigations Atlas, HA643, scale 1:2,500,000 and text,1980.F.J. Helmes and R.R. Luckey, Evaluating Methods for Determining Water Use in the HighPlains in Parts of Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota,Texas, and Wyoming, 1979, U.S. Geological Survey WaterResources Investigation 80111,1980.F.J. Heimes and R.R. Luckey, Method for Estimating Historical Irrigation Requirements fromGround Water in the High Plains in Parts of Colorado, Knasas, Nebraska, New Mexico,Oklahoma, South Dakota, Texas, and Wyoming, U.S. Geological Survey, Water ResourcesInvestigations 8040, 1982.F.J. Heimes and G.P. Thelin, Development and Applications of LandsatDerived IrrigatedCropland Maps for WaterUse Determination in the High Plains [abs.], Missouri RiverBasin Commission on Identifying Irrigated Lands Using Remote Sensing Techniques,Proceedings, Sioux Falls, South Dakota, 1979.H. Johnson, Irrigated Cropland, 1978, Chase, Dundy, and Perkins Counties, Nebraska,U.S. Geological Survey OpenFile Report 800641, scale 1:250,000, 1980a.H. Johnson, Irrigated Cropland, 1978, Cheyenne and Sherman Counties, Kansas,U.S. Geological Survey OpenFile Report 800640, scale 1:250,000, 198Db.T. Johnson, Irrigated Cropland, 1978, Laramie County, Wyoming, U.S. Geological SurveyOpenFile Report 800638, scale 1:250,000, 198Dm.T. Johnson, Irrigated Cropland, 1978, Kit Carson, Phillips, and Yuma Counties, Colorado,U.S. Geological Survey OpenFile Report 800639, scale 1:250,000, 198Db.P. Jonas and B. Wright, Irrigated Cropland, 1978, Cherry County, Nebraska, U.S. GeologicalSurvey OpenFile Report 791626, scale 1:250,000, 1980a.P. Jonas and B. Wright, Irrigated Cropland, 1978, Todd County, South Dakota,U.S. Geological Survey OpenFile Report 791627, scale 1:250,000, 198Db.E.A. Martinko, J. Poracsky, E.R. Kipp, H. Krieger, and K. Gunn, Crop Phenology andLandsatBased Irrigated Lands Inventory in the High PlainsFinal Report, NationalAeronautics and Space Administration Grant No. NAG257, The University of Kansas SpaceTechnology Center, Remote Sensing Program; and Appendices volume, 1981.G.P. Thelin, T.L. Johnson, and R.A. Johnson, Mapping Irrigated Cropland on the High PlainsUsing Landsat, in Satellite Hydrology, Proceedings of the William T. Pecora MemorialSymposium on Remote Sensing, 5th, July 1979, Sioux Falls, South Dakota Minneapolis,Minnesota, American Water Resources Association, p. 715721, 1981.G.P. Thelin, R.R. Luckey, W. Donovan, and L.J. Gaydos, Use of Landsat Digital Data Withina Hydrologic Model for the High Plains Aquifer, Presentation at the Pecora VIISymposium, Sioux Falls, South Dakota October 1821, 1981.J.B. Weeks, Plan of Study for the High Plains Regional AquiferSystem Analysis in Parts ofColorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Texas, and Wyoming,U.S. Geological Survey WaterResources Investigation 7870, 1980.J.B. Weeks and E.D. Gutentag, Bedrock Geology, Altitude of Base, and 1980 SaturatedThickness of the High Plains Aquifer in Parts of Colorado, Kansas, Nebraska, NewMexico, Oklahoma, South Dakota, Texas, and Wyoming, U.S. Geological SurveyHydrological Atlas, HA648, scale 1:2,500,000 and text, 1981.B. Wright, Irrigated Cropland 1978, Curry County, New Mexico, U.S. Geological SurveyOpenFile Report 800169, scale 1:250,000, l980a.B. Wright, Irrigated Cropland, 1978, Texas County, Oklahoma, U.S. Geological SurveyOpenFile Report 800170, scale 1:250,000, 198Db.U.S. Geological Survey, A Manual for Using Landsat Data and Land Use and Land Cover Mapsfor Water Use Inventories in the High Plains, U.S. Geological Survey OpenFile Report,(in press).

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