WSP00978 - Laserfiche WebLink

Home Browse Search

~ N l\j OJ , .."..... ~ -., ;; , . . ~ '. . i': , t- ~ . ',' SEGREGATION OF SALINITY SOURCES This work dicl not involve sny new c1ata collection activity, but relied almost entirely on data "Which have been collectecl by the various governmental agencies. Dats were obtainecl from the Soil Conservation Service, the Water and Power Resources Service, various state agencies ancl regional councils of governments for 208 studies. Topographic maps ancl aerial photographs were utilized to estimate canal and lateral lengths as well as to provide an incli- cation of cropping patterns and fielcl sizes. Automobile trips were macle to the various areas to collect data from local organizations ancl to discuss the agricultural problems and practices with farmers and local administrators. Nevertheless, much of the c1ata is incomplete and estimates of existing condi- tions were made based on c1ata collected elsewhere, and the author's experience and judgment. . State and fecleral water recorcls ancl existing reports were utilizecl to . establish a basic water and selt buclgets for each.area including stream flow. <..< < quality ancl quantity, qualitative ancl temporal distribution of individual d.iversions ancl groundwater quality. Then, within the structure of the area- wide budgets, canal by cenal water and salt buclgets were c1evelopecl for each canal and the collective laterals uncler each canal. Existing seepage losses were made using existing seepage test data, if available, or extrapolated from other canals or areas. Equilibrium grounclwater con centrations were estimated from well c1ata ancl base flow "Water quslity records from drains ancl streams in . the areas for each canal. It was assumed throughout this study that grouncl- water concentrations woulcl not change as a result of the projects, and this assumption has been reasonably vslidated by investigations in several areas in the basin (Skogerboe et al., 1979a; King ancl Hanks, 1975; and Bliesner et al., 1977) . I.~ Wetted perimeters and canal capacities were established from state engi- neers' records ancl other data sources relative to the inlet capacity. Utiliz- ing aerial photographs ancl other data sources, the flow capacity at the end of each canal was estimatecl or measurecl. The wettecl perimeter and flow were then assumecl to vary linearly throughout the length of the canal. Average seepage volumes were computed and multiplied by the average number of estimatecl or known days of annual operation at the various selectecl water levels. The equilibrium concentrations of the groundwater were multipliecl by the total annual seepage volume to obtain an estimatecl mass emission of salt from each canal ancl the aggregate laterals under that canal. Annual existing aggregated on-farm mass emissions of salt which included estimated head c1itch and taUwater c1itch seepsge losses were calculated from Soil Conservation Service data, Water ancl Power Resources Service c1ata, or other publishecl rasults. The amount of time water "Was generally available was estimsted by publishecl water records or by conveTsation with farmers and local ditch company officials. The incliviclual buclgets were aggregatecl ancl compared to the areawide water ancl salt flows. If the results appearecl to be unreasonable, the inclividual buclgets were re-examined ancl re-computed if necessary. The results were 49 . ..>1 !", '<.'.-.-