I am trying to simulate water quality parameters for an Agriculture watershed (Area approx 5000 km2). Is there any module to simulate the same using WEPP (Water Erosion Prediction Project) model.
Dear sir, you can refer to the research paper by Linda Pieri Using the Water Erosion Prediction Project (WEPP) Model to Simulate Field-Observed Runoff and Erosion in the Apennines Mountain Range, Italy, JOURNAL OF HYDROLOGY 336(1-2):84-97 · MARCH 2007. This will help you to solve your problem. Wish you all the best.
If you want to simulate sediment and nutrient transports of a large watershed, you may want to use a watershed-scale model that has capacity to appropriately simulate channel routing processes. You would better to check what kinds of channel routing mechanisms WEPP uses to describe routing processes. To my understanding, WEPP was not developed to simulate watershed-scale processes but field-scale ones.
My student used WEPP at field and watershed scales and found a very good result. You need to go over the WEPP manual and see if that is a model useful for you. It is a physically based model and better that the SWAT sediment routine.
The papers by my student are in our researchgate site under my profile.