Water balance of Lake Chala and its relation to groundwater from tritium and stable isotope data

Artificially injected tritium was used to estimate the water balance of Lake Chala, Kenya, which has no surface inflow or outflow. Over 5 years mean annual subsurface inflow and outflow are estimated to be 12.5 × 106m3 and 8.2 × 106m3 respectively. It is concluded that environmental tritium cannot be used for such a balance estimation. The relation of the lake to springs in the area was studied on the basis of the deuterium and oxygen-18 content of the waters. The data indicate that none of the springs derives a major component of its discharge from the lake. Tritium concentrations of two springs point to a high probability of partial recharge by lake water.