Lake Kinneret (The Sea of Galilee): the effects of diversion of external salinity sources and the probable chemical composition of the internal salinity sources

This paper investigates the chemical variations and evolution of Lake Kinne ret (LK), the Sea of Galilee after the diversion of onshore saline springs through the Salinity Diversion Channel (SDC) which reduced the salinity of the lake water. The mass-balance approach enables to determine the average chemical composition of the unknown internal lake sources of salinity that in addition to other known sources, contribute salts and control the chemis try of the lake water. This study reveals, for the first time, the average chemical composition of the internal lake salinity sources. Mass balances s how that the water discharge of the lake internal sources is 61 x 10(6) m(3 ) year(-1) and that these sources contribute 72,000 tons of chloride, annua lly. The SDC operation caused a long term decrease in the concentrations of Cl, Mg, Na, K, Ca, SO4 and Br in lake water. Concomitantly, the ionic rati os of Na/Cl, Mg/Cl. Ca/Cl, K/Cl and SO4/Cl have increased and Br/Cl ratio h as decreased. The average chemical composition of the lake internal sources , is characterized by Na/Cl and Mg/Cl ionic ratios which closely resemble t hose measured in the two well known submerged saline springs, of Fulyia a a nd Fulyia b, and in water of a deep observation well, located north of the lake (referred to as KIN-8). The decrease in Br/Cl ionic ratio from greater than or equal to 3.58 X 10(-3) prior to the SDC operation, to 3.29(+/-0.11 )X 10(-3) in mid 1990s implies that the major internal sources of Cl and Br to the lake are characterized by Br/Cl ratios less than or equal to 3.29 X 10(-3). Br/Cl ionic ratios somewhat lower than 3.29 X 10(-3) were found on ly in Fulyia a and Fulyia b springs and in KIN-8 water. It is therefore sug gested that Fulyia Like water is the internal saline source which supplies most of the Na, Cl and Br to the lake. Sulphate, however, is contributed to the lake mainly (over 80%) through freshwater streams. Calcium and alkalin ity originate mainly from freshwater sources, including internal lake flow of groundwater, lower in salinity but saturated with CaCO3. Thus, internal sources of solutes are mostly composed of the saline end member of Fulyia l ike water and of fresher groundwater. These conclusions have practical impl ications for lake water management. (C) 1999 Elsevier Science B.V. All righ ts reserved.