Exploring calibration strategies of the SEDD model in two olive orchard catchments

- The model was calibrated in two olive orchards with different environmental characteristics and soil management.
- Different model parameterization strategies under different runoff conditions are proposed.
- Temporal variability of the sediment delivery ratio (SDR) at the event and annual scale was evaluated.
- The model allowed the identification of areas within the watersheds most prone to soil losses.

To optimize soil conservation strategies in catchments, it is required an accurate diagnosis of the areas contributing to soil erosion by using models such as SEDD (Sediment Delivery Distributed model). In this study, different calibration strategies of the SEDD model were explored to adapt its use in two olive catchments with different environmental features and managements. A data series of rainfall-runoff-sediment load, collected in the catchments for 6 years was used: i) to evaluate calibration strategies for different management and flow conditions through the analysis of the C and R factors, and ii) to describe the temporal patterns of sediment delivery ratio (SDR) at the event and annual scales. Different results and calibration approaches were derived from contrasting soil features and sediment dynamics in the catchments. A good model performance with simple calibration procedure was obtained for the catchment with clayey soil and a very active gully, whereas the model parameterisation was adapted to event features in the catchment with sandy soil where the importance of concentrated flow was minor.Mean annual values of SDR at the watershed scale (SDRw) were 110.1% for the catchment with clayey soil and 64.1% for that with sandy soils. SDRw values greater than 100% occurred in very humid years with precipitations 30% above the mean annual values. At the event scale, similar behaviours of SDR were observed. SDR > 100% were associated with the gully exporting sediments out from the clayey catchment, whereas this was done by rills and an ephemeral gully in the sandy catchment.