In Turkey, the population growth and industrial development have caused a scarcity in energy. Turkey has a great hydroelectric energy potential. However, this potential is evaluated only to a certain extent. The major step in the determination of hydroelectric potential is to estimate the river runoff, which is one of the most important hydrological variables used in most of the water resources applications. Reliable estimation of runoff from land surface into streams and rivers is difficult and time consuming for ungauged basins. However, Remote Sensing (RS) and Geographic Information System (GIS) technologies can augment to a great extent the conventional methods used in rainfall-runoff studies. These techniques can be used to estimate the spatial variation of the hydrological parameters, which are useful as input to the rain-fall-runoff models.