WSP06479 - Laserfiche WebLink

Home Browse Search

Gcn::?'7Q All Inde~ 3tatlons tnat are usea as a basis for determining the stream flow in relation to normal for tne Water Resources Review were In~luded in the group of representative gag- ing stations for whIch data are shown on plate 1. The monthly distribution of discharge varies with changes In topography, geology, and geographical location. Ground-water storage In the sand-hill regIon of Nebraska regulates the discharge of streams that flow frOM that regIon Bufficiently to produce unusually uniform dlschsrge within each year Bnd from one year to another. At several gagIng stations In other parts of the MIssouri River Sasin, the monthly distrIbu- tion of discharge Is greatly affected by sto~age In reservoirs and by diversions. Irri~ation D~v~lopment Figur~s 2, 3, and 4 show the g~n~ral amount and rate of d~velopment of irrigation by drainage basins and by States (or parts of States that are not entirely wIthin the MissourI River BasIn). Acreages ..erel ob- tained from reports of the Bureau of the Census:2/ those for 1889, 1899, and 1909 were computed, and those for 1919, 1929, and 19JB were taken directly. Acreages were reported only by counties and States for the years 1889, 1899, and 1909j hence the figures of irrIgated acreage by counties frequently had to be subdivided among different drainage basIns before the total acreagea by drainage basin~ ~ould be obtained. The subdivisIon was based in part on acreages irrigated dur- ing 1902 and reported by drainage bBslns. On the whole, figures 2 to 4 probably ahow the rate and extent of development of irrigation fairly accurately. The amount of irrigation is a rough index of the approximate amount of depletion of stream flow that may be expected in the different drainage basins and States. . In general, the irrigated acreages in- cr~~sed rapidly in most parta of the Missouri River Basin until about 1909. Since that time the total irrigated acreage has in- creased slowly in nearly all parts of the ba~ln. Although man, ac~es of new land have been irrigated since 1909. the new irrigated area3 have been partly offset by the with- drawal of land from irrigation. Stora~e Development The expansion of reservoir capacity in the Missouri River Basin by decades from 1900 to 1947 is shown on figure 5. The reservoir- capacity development in the Missouri River Basin area of the States of Colorado, Montara, NebraSka, and Wyoming is also shown for comparative purposes. The development of storage reservoirs in the other Missouri River Basin States was omitted because of the relatively insignificant storage amounts. The base data used in preparation of figure 5 were obtained from the report by ]t U.S. Bur. Census. Irrigation of agricultural lands, Censuses of 1900, 1910, 1920. 1930, and 1940; Bull. 16, Irrigation in the United States 1902; Agriculture by irrigation in the western part of the United States 1890. < 5 Harbeck3/ and include only reservoirs or more than 5,000 acre-feet usable capacity. Storage-capacity development data are good indicators of the degree of utilization of surface-water resources. A continual incr6ase in the reservoir capacity of an ar~a where irrigation is extensive from decade to decade indicates an increase in the usage of surface waters; after appropriations of the natural unregulated flow of a particular stream have exhausted the supply, the only possible means of satisfying 8dditio~al use requirements is through the storage of flood flows and nonirrigation-season runoff. Areas which show no appreciable increase in storage capacity with time are probably developed to nearly 100-percent utilization of the water reso~rcee. The portIon of the State of Colorado lying within the Missouri River Basin is an example of such an area. No discernible increase in storage capacity has occurred since 1920; additional water supplies must be found through transbasin diversions or from gro.~d water. The States of Montana, Nebraska. and Wyoming, which have not used a3 high a percentage of the surface-wa~er supplies of the areas within the Missouri River Basin as the State of Colorado, show a continual expansion of re- servoir cspacity and will probably do so in th~ immed1ate future. ." RUNOFF Runoff, as the term is used in this re- port, i9 the flow that would occur naturslly in Q surface stream.j/ Total runoff from a basin differs from volume of discharge from that basin by the net amount of water diverted to or from the basin, the net lo~ses resulting from artificial storage of water, and the net change in storage during tho period of comparison. Underground flow from one surface-drainage baain to another is included 85 part of the runofr of the basin in which it appears as surface flow. Birdwood and Blue Creeks and Loup River at the edges of th~ ssnd-hill region of north- western Nebraska are examples of streams that have relatively high runoff because of seepage from a ground-water reservoir that has been recharged partly by precipitation on areas outside their surface-drainage basins. Isolated large sprin~s such as Hot Springs near Thermopolis, Wyo., Hot Springs near Hot Springs, 3. Dak., Big Springs nBar Lewiston, Mont., and Mammoth Hot Springs at Mammoth, Mont., have not been shown 8S localized areas of high runoff on the runoff maps t~at accompany this report. .': .. :-: ...~..- ~arbeck, G. E., Jr., Reservoirs in the Unite States, U. S. Geol. Survey Circ. 23, March 1948. . 4/Runofr, in the general aense, may be def1ned a9 the portion of precip1tat10n that becomes surface water in streams, lakes, and reservoirs through direct precipitation on water surfaces, surface flow, or underground move:r::ent. I