Radioisotopes for the estimation of the water balance of lakes and reservoirs

The water balance of Lake Chala, on the borders of Kenya and Tanzania, was estimated by labelling the lake in 1964 with tritium. On the basis of measurements up to 1968 the estimated average annual subsurface inflow and outflow were 12.83x106 m3 and 8.57x106 m3 respectively. An additional sampling in September 1977 resulted in the revised estimates of 8.39x106 m3 and 4.14x106 m3 for the inflow and outflow respectively as average annual values during the period 1964 to 1977. (author)