WSP06068 - Laserfiche WebLink

Home Browse Search

0:51 ,'HE IMPACTS OF IMPROVING :FFICIENCY OF IRRIGATION SYSTEMS IN WATER AVAilABILITY IN THE OWER SOUTH PLATTE RIVER BASIN SUMMARY The impacts on overall water supply resulting; ~om different water management strategies for con- Jllctive use of surface .Jnd ground waters ....ere :udied [or a gO-mile section of the South Platte lver, roughly between Balzac and Julesburg. A com- Jter simulation study was conducted usin~ data for l~ 10 years between 1952 and 1961. A drQught period \ the early 'SOs i~ included. lOlQ .~,-..~ - - - - ---- 1" - -.- -..,-.-. ~1-~--'" :: .~ I f J~1,,5.g ~tI$lIH '~r _.:J ~ " ' I stOll"I~1'( .... I I '.'(,l'S . ..j "'I .:.:: ::.::::: :...:: '.'/(' i::>.:: .1.(-.: .::":.::::' ( :.::.::.: ....:........., 'i~' :::L::-: ::.....,::j :i:~T:.cu ~I ".~..'..'".. 'v roLOlAroJ ../: ~'udv Mn The management strategies considered included: lining some of the cnnals to improve conveyance ficiency; 2) improving water use efficiency on e farm; J) pumping with relaxed restrictions; and, ~ combination of all these strategies. The study indicates that the most effective stra- gy by f~r to alleviate the serious consequences of a ought on irrigated agriculture is to fully use the 0und water reservoir capacity of the stream-aquifer stem. Under increased pumping the stream and the j...... ! aquifer quickly r~ilcll n new equilibrium and after two years ther~ is no indication of a continued mining condition in tile nquifer. This sLrategy 15 not only very effective ill tll~ sl,ort term but also quite safe In the long term. Improving farm irrlgation efficiency from its curr~nt average 41 p~rcent to 75 percent docs not improve substantially the overall water use eUici- ency in the reach of the river studied. That Is, the volume of water annually passing downstream out of Colorado is reduced very little, and the junior priority water rights continue to be short of water, JUSt as nOl.'. The degree of irrig.1tion need satisfac- tion on individual farms served by priority rights is h.c reased. --/ Lining of candls having seepage losses exceeding 25 percent is likewise uf little benefit to the over- all '-later use efficiency in the study reach. No additional water is made available to Junior priority right uwners nor is water made available for new beneficial uses. However, the irrigation water requirement, is more nearly satisfied for irrigators served by the lined canals. Neither of tbe two improved efficf.ency strate- gies enables the full irrigation water requirement to be met. However. it can be met by allowing in- creased pumping or by a combination of increased pumping with efficiency lmprovements. In this case the overall efficiency of water use in the study reach of the river is improved and less ~ater is "lost" downstream out of the state. INTRODUCTION The objective of the lower South Platte River Basin study 1s to assess the benefits that could be renlized from improvements in irrigation system efficiencies and changes in management strategies on the overall water use effectiveness of the system, particularly under drou~ht conditions. For example, .