Intra-seasonal variability and wavelet characteristics of lake evaporation in comparison with hydro-meteorological data at Lake Keban (Turkey)

This study focuses on the variability of lake evaporation and also the periodic relationships among hydro-meteorological variables. The monthly hydro-meteorological data of Lake Keban were investigated by wavelet transforms. The results show that the main periodicity is on an annual scale. This periodicity is weaker for precipitation and wind speed but higher for evaporation, temperature, runoff and relative humidity. In addition to this, the continuous wavelet figures show some weak periodicities on the almost 10-year scale level but they are not continuous over time. Also, strong events on a short-term monthly scale are seen for evaporation, precipitation and runoff in 1988. This event in 1988 may be explained by the 1988 La Nina event, which was one of the strongest on record. Also, the periodicities on the 2-8-month scales in the precipitation data can be interpreted as being connected with the strong El Nino events of 1982 and 1992.