Estimating the saline springs component in the solute and water balance of Lake Kinneret, Israel

The relatively high salinity of Lake Kinneret, Israel (190-350 ppm Cl-) is a result of the activity of saline springs located at the bottom of the lake. Their subsurface location inhibits direct monitoring of their fluxes. The objective of this work is to characterize the monthly ground water flow and salinity of the unmonitored saline springs over a long-term period, and to find a functional relationship between deriving variables and these monthly discharges. Results of the long-term evaluation of the unmonitored saline springs activity, are intended to help distinguish between two competing models (‘gravity driven flow’ (GFM) and ‘self potential’ models), which were proposed as the mechanism of the Lake Kinneret saline springs. The monthly solute and water balance of 32 consecutive years (1968-2001) was calculated, in which the contribution of the saline springs was considered as the residual. Error analyses were conducted for both the water and the solute residuals, and constraints were used to calculate a better, physically based time series representing the unmonitored saline springs activity. The calculated time-series of water and solute discharge from the springs were used to find the functional relationship with the lake level. It was found that there was an increase of water and solute fluxes to the lake at periods of high lake level. We concluded that the results are in agreement with the proposed GFM: high fluxes of ground water to the lake, and high leaching of solute are the result of rainy seasons, which usually cause high lake levels as well.