The uses of water resources depend on the hydrological behavior of rivers and river basins. When the use of water are planned, the risk of future hydrological behavior of the rivers and basins must be assumed. The hydrological behavior of flow and precipitation depends on the climate, which tends to be stationary (the characteristics of the variable do not vary with time). However, with the development of society, non-stationary processes are observed due to one or more of the following factors:
• Land use change;
• Hydraulic works;
• Variability or climate change.