Laserfiche WebLink
<br /> <br />INTERACTION OF GROUND WATER <br />AND STREAMS <br /> <br />Streams interact with ground water in all <br />types of landscapes (see Box B), The interaction <br />takes place in three basic ways: streams gain <br />water from inflow of ground water through the <br />streambed (gaining stream, Figure 8A), they lose <br />water to ground water by outflow through the <br />streambed (losing stream, Figure 9A), or they do <br />both, gaining in some reaches and losing in other <br />reaches, For ground water to discharge into a <br />stream channel, the altitude of the water table in <br />the vicinity of the stream must be higher than the <br />altitude of the stream-water surface, Conversely, <br /> <br />A <br /> <br />GAINING STREAM <br /> <br />Flow direction <br /> <br /> <br /> <br />- ----~-- <br /> <br />------- <br /> <br />if ~/ <br />r // <br />UnSll\urate~J2.!'.!'-- I <br />.;:-,-----.::- <br />Water table <br />'" <br /> <br />- <br /> <br />- <br /> <br />, <br /> <br />t <br /> <br />------- <br /> <br />---- <br />Shallow aquifer <br /> <br />B <br /> <br />70 <br /> <br />__________ 60 <br /> <br />60 <br /> <br />Water-table contour <br /> <br />Ground-water flow line <br /> <br />50 <br /> <br />50 <br /> <br />40 <br /> <br /> <br />40 <br /> <br />30 <br /> <br />30 <br /> <br />E <br />. <br />~ <br />Vi <br /> <br />20 <br /> <br /> <br />20 <br /> <br />Figure 8, Gaining streams receive water from tIle <br />grollnd-water system (A), This can be determined <br />from water-table contollr maps becallse the contollr <br />lines point in the IIpstream direction where they cross <br />the stream (8), <br /> <br />for surface water to seep to ground water, the <br />altitude of the water table in the vicinity of the <br />stream must be lower than the altitude of the <br />stream-water surface, Contours of water-table <br />elevation indicate gaining streams by pointing in <br />an upstream direction (Figure 8B), and they indi- <br />cate losing streams by pointing in a downstream <br />direction (Figure 9B) in the immediate vicinity of <br />the stream, <br />Losing streams can be connected to the <br />ground-water system by a continuous saturated <br />zone (Figure 9A) or can be disconnected from <br /> <br />A <br /> <br />LOSING STREAM <br /> <br />Flow direction <br /> <br /> <br />1fr <br />r <br /> <br />, <br />, <br />, <br />/ <br />, <br />/ <br /> <br />Water table .- <br />___________L----- II' <br />--- <br />~ <br /> <br />Unsaturated <br />'....._____ lone <br />" ----------- <br />--- <br />'--- <br /> <br />~ <br /> <br /> <br />B <br /> <br />100 <br /> <br />~ <br /> <br /> <br />b\e contour <br />\Natef-ta <br /> <br />90 <br /> <br />80- <br /> <br />___Ground-water flow line <br /> <br />70- <br /> <br />Figure 9. Losing streams lose water to the grollnd- <br />water system (A), This can be determined from water- <br />table contollr maps becallse the cOIltollr lines point <br />in the downstream direction where tlley cross the <br />stream (B), <br /> <br />9 <br />