OCR Text |
Show humidity data collected in the vicinity of Great Salt Lake to estimate evaporation using the eddy flux technique. Their results indicated evaporation from Great Salt Lake was greater than predicted in earlier studies. Precipitation on the surface of Great Salt Lake constitutes a major inflow to the lake. Research on the distribution of precipitation over the lake at this time has not progressed much beyond the preparation of isohyetal maps, by E. L. Peck, which include the Great Salt Lake regions. Several water budget analyses have been performed on Great Salt Lake with the goal of better defining the magnitude of the components which contribute to lake inflow and outflow. Peck and Dickson ( 1965) used a water budget analysis in which monthly precipitation, surface inflow, and change in storage of the lake were assumed to be known from basic data. Unknown quantities were evaporation and groundwater inflow. Although no specific estimates of groundwater inflow or evaporation were made, the study concluded that groundwater contributes significantly to the lake with the exact amount being related to the amount of evaporation. Palmer ( 1966) proposed a yearly water budget for the years 1930- 1963. The average annual inflow to the lake was estimated at 1,690,000 acre- feet ( excluding precipitation) with 6 percent of the inflow contributed by groundwater. Steed ( 1972) prepared a water budget analysis for 1944- 1970 in which monthly terms were used. Average annual inflows were found to be 1,756,000 acre- feet of surface flow, 206,000 acre- feet of groundwater, and 685,000 acre- feet of precipitation. Outflows included 2,493,000 acre- feet of evaporation and 151,000 . acre- feet of evapotranspiration. The chemical makeup of the dissolved mineral inflow to Great Salt Lake and the makeup of Great Salt Lake brine has been investigated mainly by the USGS and Utah Geological and Mineralogical Survey ( UGMS). Hahl and Mitchell ( 1963) present a compilation of data collected from July 1959 through June 1962 to aid in the definition of the chemical composition of streams, drains, and springs discharging into Great Salt Lake and, additionally, to define the chemical composition of the lake brine. Hahl and Langford ( 1964) is a continuation of the above study and reports on conclusions drawn from the above data. During the 1964 water year more detailed data were obtained on surface inflow at sites closer to the lakeshore. Hahl ( 1968) used these data to estimate the salt inflow at the lakeshore for water years 1960, 1961, and 1964. The data for 1960 and 1961 were collected during low inflow and low lake stage years. ; The fact that data for high flow years were not included may affect the estimate of salt inflow to the lake Which Hahl obtained. . Using data on the brine concentration within the lake from 1963- 1966, Hahl and Handy ( 1969) concluded that four types of brine coexist in the lake. The northern arm ( north of the railroad causeway) was found to contain a typical concentrated brine, while the brine in the southern arm was divided into three distinct concentration categories or zones, namely: 1( 1) from the surface to a depth of about 16 feet; ( 2) ' below 16 feet and assumed to originate from flow from the northern arm through the causeway; and ( 3) below 16 feet and assumed to originate from groundwater inflow. The four brine types ( that of the north- em arm and the three zones in the southern arm) are illustrated by Figure 8. North Arm m £ 2 10- j e o i> o a " s 20- 30- % South Arm isewayl ** Algal Reefs - 10 - 20 Verticle Exaggeration X 2300 Figure 8. The four brine zones within Great Salt Lake ( after Hahl and Handy, 1969). 30 |