  In this paper as show that hydrological contributions in the colombian
electrical system during the period between 2004 and 2016 have a periodic
dynamic, with fundamental periods that are repeated every three years and that
tend to oscillate around a long term average, in this context, such
contributions can be characterized by mean reversion stochastic processes with
periodic functional tendency. The objective of this paper is modeling and
forecast the dynamic behavioral of hydrological contributions in the colombian
electric system. A description of climate and hydrology in Colombia is carried
out, as well as an analysis of periodicity and distributional properties of the
data. A Gaussian estimation is performed, which allows to find all the constant
and functional parameters from the historical data with daily frequency. The
forecasts of the hydrological contributions are graphically illustrated for a
period of three years and two alternatives to construct forecast fringes are
proposed.
