Bilans hydrologique et isotopiques (18O et 2H) du lac Massoko, Tanzanie. Quantification des échanges lac–eaux souterraines

This paper deals with the study of Lake Massoko (9°20′00S–33°45′20E, Tanzania), a maar lake of the East-African Rift. Although some water flux of the hydrologic balance of this lake are easily quantified, only the net flux between the Lake and groundwater can be appreciated. Overpassing this limit requires the establishment of stable isotopic (¹⁸O and ²H) budgets. This approach is discussed with a special attention on the atmospheric vapour estimation. Results allow to estimate the underground outflow at 60 % and underground inflow at 25 %, with regard of the total water input. This confirms the importance of the groundwater circulation in volcanic lakes of the East African Rift.