The hydrology of Lake Bosumtwi, a climate-sensitive lake in Ghana, West Africa
Lake Bosumtwi, lying in a million-year-old meteor crater, is hydrologically closed in spite of the wet, humid climate in this part of Ghana. To understand this geographical enigma, a water-balance model that describes both the historical lake-level record and the full range of lake levels observed in terrace deposits around the lake was developed. The water-balance model shows that the reception of rainfall by and evaporation from the lake surface are the dominant constituents of the water balance. Prior to 1969, the average rainfall of 1550 mm year−1 was generally equal to lake evaporation, and the average annual rise of 30 cm year−1 was produced mostly by runoff from the small watershed around the lake. Since 1969, with a decreased rainfall of 1380 mm year−1, the combination of rainfall and runoff has nearly equaled lake evaporation, resulting in a nearly steady lake level. Long-term simulations show that stochastic climatic variations very similar to those observed in this century could produce the full range of lake levels observed in terrace deposits. The low salinity of about 1‰ suggests that dissolved solutes were removed by lake overflow in the recent geological past.
Read full paper https://doi.org/10.1016/0022-1694(95)02982-6