What is the annual average rainfall for the basin?? Unless you mention this how anybody can even guess the answer, other than the local or regional experts!!
Evapotranspiration mostly depends on temperature and incoming short-wave radiation. I do not know the climatic conditions of the area, nor the vegetation present, but if it is a choice between the two numbers you suggested, I would go for 383 mm/year, because 32 mm seems extremely low.