I wanna know how is going to be my watershed in 20 years, i have demands between (1992-2005), i changed my annual activty level with the population and the growth as 0.56%,but as i have the data only for these years ...i'm not projecting for twenty years.

Go to main menu and access years and time steps through the General menu and set the "time horizon" by inserting your starting year for analysis as "Current account Year" and Last Year as "last Year of Scenario" to cover the whole duration of your study.
Use Growth function to project the population for the other years based on the value of previous years e.g. 'Growth(0.0056)"

Usaste la funcion de growthfrom en el expression builder? con la tasa de crecimiento, el año inicial, y el valor inicial, esta funcion proyecta tambien la poblacion hacia el futuro.