Study on the evapotranspiration effects on the daily discharge variations

Abstract

It is a well known phenomena that the discharge varies as time in a day time by evapotranspiration suction. This phenomena can be observed in a small upper mountainous basin at low flow stage. The precise observations were taken place in two basins having area 0.18km² and 0.060km². Each basin shows discharge variations clearly. Numerical simulations based on Richards's equation taking acount of evapotranspiration were carried out and the calculated discharge rate were compared with the observational one. The simulation model can explain simple decrease phenomena, but for complex stage as discharge recovery, the model is not sufficient to explain the phenomena.