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w w w::. w > <! o ~ 60 Co e-- ::; SO o ~ ~ e-- E 40 e-- " ~ 30 Figure 2.8. 100 + + + T + + + + 90 ++ + + + + ++ + + + + 80 + ++ ++ + + 70 -t4- + ++ + + + + ++ + -+ ++ + T + + .... + + + + + + 20 ++ I _, + +++ ] +*~i; I ~:[ + , ++ ++-- ~ ,.Jet +' I -t-P+ .r ! t++I, +.It, + 1ij".t~":yl'.' .". .:+.. I .1." -I .. 1 ;I~I!; -'"-, '.. -11'1, + i ~'t:*' '-' T + .t ~- --- + + + + ++ + + ., + --l-+ + +T + + +- ., .. + + + ,+J "iJ-+ ++ -t + + + + + + ++ ++ T + + ., T + + ++ . + t + -~ -+- """+ ., + -+ + .f !- ., -t!:.t-" ++ +' +- .. -t -r 10 .1 Ii' 2S I 30 ~ 5 10 15 JRAH1AGE FL01.I (CFS! Salt outflow plotted as a function of drainage flow for 35 drains in the Grand Valley, Colorado, subbasin. (U.S. Bureau of Reclamation Grand Valley Salinity Control Project data.) Table 2.4. Trends in changes of soil salt loading with river water type and leaching fraction. (After Swarez and Rhoades 1977,) Type of river water Changes in salt loading Rivers undersaturated with Carn) , Net rerroval of earn) from solution nnder law leaching (LF ~ 0.1) Net dissolution of Carn) nnder high leaching (LF ~ 0.4) Lost earn3 by precipitation in the soil root zone under low leaching, and by precipitation in the river channel (after remixing the drainage water with undiverted river water) lmder high leaching. The total amounts of precipitation and the river compositions were uneffected by irrigation mmagement. Rivers saturated with earn). Rivers saturated with CaC03 and nearing saturation with gypsum. Lost substantially rrore salts by precipitation under low versus high leaching. LF ~ O. L LF ~ 0.4, Precipitation of salts was relatively constant through successive valleys. Initial valleys showed no gypsum precipitation, but subsequent valleys showed sharp rise in gypsum precipitation. -~-_._-----_._--_._----_._-----_._--~_..._.. --------....--- ~_. --.---...-.--.----.--... 15