A prediction in ungauged basins is one of the challenging tasks for a hydrologist of this century. Even though the physically based hydrological models can be the more appropriate in ungauged basins but data requirement limit the use. Conceptual hydrological models are simple and easy to use. These models are needed to be calibrated to obtain the parameters of the model. Availability of data at all location in the basin limits the calibration of conceptual hydrological models. In this book a calibration methodology is presented for discharge series limited condition using upstream and downstream data.