Dear NatCap community,
I’m experiencing some difficulties in calibrating the SDR model to balance estimates of sediment export between measured values at the mouth of the full watershed (Whole WS dataset) and observations for 2 sub-basins (Sub WS dataset).
I am able to get similar values between the SDR model and the observations at the scale of the whole watershed but in this case the sediment exportation value of the sub-watersheds estimated by the SDR model were skyrocketing compared to the reality (Sub WS dataset).
Here is the sediment exportation results from my best run (SDR_75, SDR_76 in attachment):
SDR model whole WS: 187306tn/an VS reality: 187862tn/an
SDR model Sub catchment 1: 252tn/an VS Sub WS dataset 1: 111tn/an
SDR model Sub catchment 2: 5020tn/an VS Sub WS dataset 2: 300tn/an
I tried adjusting many of the calibration parameters according to Hamel and all. (2015) (P and C values in my biophysical table, Threshold flow acc, K parameter, IC0 parameter and even max SDR). However, the result of my simulation never works at both scales (whole WS and sub-watersheds).
Do you have any recommendation on which parameters or datasets I should adjust to help me get better results? Or would someone have an explanation about the gap between the watershed and his sub catchments?
Thank you in advance
Hamel, P., Chaplin-Kramer, R., Sim, S., & Mueller, C. (2015). A new approach to modeling the sediment retention service (InVEST 3.0): Case study of the Cape Fear catchment, North Carolina, USA. Science of the Total Environment, 524, 166-177.