THE RESPONSE OF THE SEDIMENTOLOGICAL REGIME IN LAKE-KINNERET TO LOWERLAKE LEVELS

The surface level of Lake Kinneret is regulated to remain between -209 m and -213 m msl. During the stratified period, soluble reactive phos phorus (SRP), ammonium (NH4+) and dissolved sulphide (H2S) accumulate in the hypolimnion. The concentration of these solutes, which are dire ct and indirect products of the decomposition of organic matter, incre ase considerably in summers with lower lake levels. A numerical model describing depth-averaged hypolimnion and epilimnion current velocitie s for high and low lake levels was adapted for Lake Kinneret. Simulate d hypolimnetic currents were shown to be stronger for low lake levels as a result of the fact that low lake levels are characterized by a th inner hypolimnion while the thickness of the epilimnion remains unchan ged. We suggest that the stronger hypolimnetic currents have the follo wing consequences: 1. turbulence is induced, 2. the enhanced turbulenc e results in higher resuspension, 3. because SO4= is available to bact eria on resuspended particles, mineralization rates are enhanced, and 4. focusing of fine sediments and associated organic matter to the pel agic zone is enhanced.