Input for hydrological downscaling

What local data do I need to perform a hydrological downscaling?

The hydrological simulation of the upstream catchment area can be improved by performing a calibration against measured discharge in the location of interest. Input of local data is a time series of daily values:

1985-01-30 3.06
1985-01-31 3.2
1985-02-01 10
1985-02-02 39.9
1985-02-03 46.2
1985-02-04 23.5
1985-02-05 16.5

The length of the historical time series should be 5 years or longer. Further the start of the time series should be located after the starting point given by the SUDPLAN climate scenarios (presently 1960). A few missing daily values is acceptable, but all discharge variations of the upstream catchment area must be represented to achieve an accurate calibration.