Laserfiche WebLink
<br />The predevelopment water budget and a <br />water budget for average developed conditions in <br />the southern High Plains aquifer during 1960-80 <br />are shown in Figure lIB. Comparison of these <br />water budgets shows that, due to irrigation <br />return flow, recharge to the High Plains aquifer <br />increased more than twentyfold from an estimated <br />24 million cubic feet per day during predevelop- <br />ment to about 510 million cubic feet per day <br />during 1960-80. This increase in recharge (about <br />486 million cubic feet per day) together with <br />the decrease in storage (about 330 million cubic <br />feet per day) accounts for over 98 percent of the <br />total pumpage (about 830 million cubic feet per <br /> <br />Figure 11. The effects of ground-water <br />withdrawals on the southern High Plains <br />aquifer. <br /> <br />Schematic cross section (A) of the <br />southern High Plains aquifer illustrating <br />that ground-water withdrawal in the middle <br />of the southern High Plains aquifer has a <br />negligible short-term effect on the discharge <br />at the boundaries of the aquifer. (Modified <br />from Lohman, 1972.) (B) Water budgets of <br />the southern High Plains aquifer (all flows <br />in million cubic feet per day) before develop- <br />ment and during development. (Modified <br />from Johnston, 1989; data from Luckey <br />and others, 1986). <br /> <br />A <br /> <br />West <br /> <br /> <br />day). Less than 2 percent of the pumpage is <br />accounted for by decreases in natural discharge <br />(about 14 million cubic feet per day). <br />A long delay between pumping and its <br />effects on natural discharge from the High Plains <br />aquifer is caused by the large distance between <br />many of the pumping wells and the location of the <br />springs and seeps that discharge from the ground- <br />water system. The southern High Plains is perhaps <br />the best known example of significant, long-term <br />nonequilibrium for a regional ground-water <br />system in the United States. That is, water levels <br />continue to decline without reaching a new <br />balance (equilibrium) between recharge to and <br />discharge from the ground-water system. <br /> <br />East <br /> <br />~W~t~L~I: <br />High Plains <br />aquifer <br />I!i.'l:~'.'."',.",; <br />~1i. . ~ r ",.". _ ',. <br />~ -' ~ <br />" ~' <br />~; ,"' <br />~1"~'P <br />III j!~ ~ .~~. <br /> <br /> <br />Vertical scale greatly exaggerated <br /> <br />B <br /> <br />System before development <br /> <br />System during development <br /> <br />Natural <br />recharge <br />24 <br /> <br />Recharge <br />and irrigation <br />return flow Pumpage <br />510 830 <br /> <br />Decrease <br />in storage <br />330 <br /> <br /> <br /> <br />Natural <br />discharge <br />24 <br /> <br />Natural <br />discharge <br />10 <br /> <br />p.~...M <br /> <br />28 <br />