Calibrating APEX model for predicting surface runoff and sediment loss in a watershed - a case study in Shivalik region of India

The process-based model needs to be calibrated before its applications to derive a reliable estimate. A process-based agricultural policy/environmental eXtender (APEX) model was utilised to assess surface runoff and soil loss of a micro-watershed belongs to the Shivalik region of Himachal Pradesh, India. The model was performed exceptionally well for surface runoff (r2 - 0.81) and sediment yield (r2 - 0.81) with the Nash- Sutcliffe Efficiency assessments of 0.71 for surface runoff and 0.70 for sediment yield. The average annual soil loss is 23.42 t ha-1yr-1 from the watershed. The study revealed that the soil erosion in the Shivalik region increases and identified scrubland as the significant source for generating soil erosion in the watershed. Also, the APEX model could predict surface runoff and soil loss in the Shivalik region. The comprehensive information generated from the study will help to generate a sustainable land use plan in the Shivalik region.