Effects of area threshold values and stream burn-in process on runoff and sediment yield using QSWAT model

Abstract

ABSTRACT In the present study, efforts have been made to identify the effects of stream burn in process on runoff and sediment yield in hydrological modelling exercise. Twelve separate QSWAT model of Upper Tapi River Sub Basin were developed using stream burn in and without burn in process at 25, 50, 100, 200, 300 and 400 km2 area threshold values (ATVs). The model performance was evaluated using R 2, Nash–Sutcliffe model efficiency, and percentage bias values at different ATVs. Results showed that for un-calibrated model flow was less affected by the burn in process while significant difference were seen in sediment load values when computed using burn in process. The average difference in sediment load is around 13t/ha between burn in and without burn in process for un-calibrated model. The surface runoff and sediment load was also affected by ATV. Surface runoff and sediment load was decreased when ATV was increased from 25 to 400 km2 for uncalibrated model in both the processes. After calibration, variations have been seen in flow and sediment when computed from both burn in and without burn in process at ATVs more than 100 km2. The model performance is improved when burn in process is used for both un-calibrated and calibrated model.