Dear Syed: This is a good question. In our experience there are two possible answers: 1) There is not an unique interpolation method for all the possible life situation when runoff mapping is required, so we need to try several techniques and every time, with a Jackknife assessment, select the method with the best performance for the studied situation. 2) The interpolation method should follow the nature of the studied process, in such case, being runoff a stochastic process then optimal interpolation methods should be used. In this line you need to follow methods like Kolmogorov optimal interpolation, Gandin interpolation and Kriging. Being the last the most well known due to broadly distributed tools where this method is implemented, nevertheless, the method that generalize all stochastic ones is the Kolmogorov optimal interpolation. That is from the theoretical point of view, from the practice, from our experience, there is no method able to provide best performance than 40% Mean Absolute Relative Error due to the low density of hydrological monitoring networks that are not enough to support a better result. Also, the majority of discharge observations are heavily influenced by human presure introducing additional variability that can not be handled by the interpolation methods. My sugestion: Try to find an interpolation code for the Kolmogorov optimal interpolation, if there is not any then apply Kriging.

For more research see the following links. Best regards,

https://dl.sciencesocieties.org/publications/aj/abstracts/91/3/AJ0910030393

https://books.google.com.co/books?id=MkydCKWlm_QC&pg=PA311&lpg=PA311&dq=Kolmogorov+A.N.+Optimal+Interpolation&source=bl&ots=PanC4cXSCJ&sig=Sb9jmkIiQXXnCXfHNqLsIbXwEJI&hl=es&sa=X&redir_esc=y#v=onepage&q=Kolmogorov%20A.N.%20Optimal%20Interpolation&f=false

Article Development and application of optimally adaptive linear com...

Article Interpolation of monthly runoff along rivers applying empiri...

Sir, As you know main sources of surface runoff are Precipitation in terms of Snowfall and rainfall. Satellite data interpretation gives only idea of Terrain, Landuse/Landcover and soil type. so if you want to calculate surface runoff you need precipitation information as well as water discharge in the river outlet.

Dear people, I would recommend the use of a simplified hydrological model capable of deriving runoff from precipitation and evapotranspiration or whatever hydrological process you would like to consider as well as the time step and spatial extent. I guess the interpolation of precipitation and potential evapotranspiration is easier being two disperse variables. 

Hi

such a simple conceptual model is for instance GR2M, which proved very robust in many different kinds of climates.

I put an example of a paper on this topic, one about GR2M, and a second one about the Yates model, which needs no calibration and gave consistent results, compared to the Yates model.

Best

Gil

SCS-CN Method

In order to have better results, you will need some discharge measurements. Otherwise, everything else will be in the sphere of stochasticity or approach with great uncertainty...

Soil Conservation Service or SCS runoff curve number method is best method for calculating surface runoff.check this site.

Conference Paper Surface Water Management of water Scarcity Area Specially fo...