1. how can i assess the surface water potential by WEAP ?
2. what are the major inputs(data) for this purpose for to quantify the
surface water potential ?

Hi I am hoping you are doing great, I am doing the same study as yours, please share your email so we can discuss, I am sure you have completed yours by now.

Temesgen and others who may be interested-

To complete a surface water potential assessment, you would likely need to build a rainfall-runoff hydrology model using WEAP. For more information, please see the Hydrology and Calibration chapters of the tutorial, as well as our YouTube video lesson series: https://www.youtube.com/watch?v=vn6MRbOTVA4&list=PLoJ3pxCzMP1uQRaimYV-wxJRRuIMNzdVU&index=12

The main data inputs would be land cover and climate. These inputs can be generated by the catchment delineation mode in WEAP, which is covered by the YouTube videos. However, you will need to calibrate your rainfall runoff model to match observed streamflows. The video series additionally looks at calibration.

Apologies for not getting back to you originally.