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In this paper, we analyse how the performance and calibration of a distributed event-based soil erosion model at the hillslope scale is affected by different simplifications on the parameterizations used to compute the production of suspended sediment by rainfall and runoff. Six modelling scenarios of different complexity are used to evaluate the temporal variability of the sedimentograph at the outlet of a 60 m long cultivated hillslope. The six scenarios are calibrated within the generalized likelihood uncertainty estimation framework in order to account for parameter uncertainty, and their performance is evaluated against experimental data registered during five storm events. The Nash-Sutcliffe efficiency, percent bias and coverage performance ratios show that the sedimentary response of the hillslope in terms of mass flux of eroded soil can be efficiently captured by a model structure including only two soil erodibility parameters, which control the rainfall and runoff production of suspended sediment. Increasing the number of parameters makes the calibration process more complex without increasing in a noticeable manner the predictive capability of the model. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

[Display omitted] • Parameterization of runoff models is challenging in agricultural catchments. • Knowledge on using soil surface state for model parameterization was synthetized. • A comprehensive field survey was performed on a 1045 ha agricultural catchment. • A simple framework for soil surface state is proposed and evaluated for common crops. • A software is provided to derive runoff model inputs from rainfall and crop types. The detrimental impacts of surface runoff and soil erosion, particularly in cultivated areas, call for the use of distributed runoff and soil erosion models with a view to supporting adapted catchment management strategies. However, runoff model parameterization remains challenging in agricultural catchments due to the high spatial and seasonal variability of soil properties. Data acquisition is demanding and may not always be feasible. Therefore, model parameterization in such environments have been the subject of numerous research efforts. The combined analysis of land use management and soil surface state was proposed in literature to address this issue and demonstrated its potential for runoff analysis and modelling. However, these research findings were related to specific rainfall sequences and/or soil surface state. In this study, existing knowledge on soil surface state and its application to runoff model parameterization were synthetized and included in an easy-to-use parameterization software (PREMACHE), providing a framework for modelers lacking of means and/or data for modelling complex agricultural catchments. To develop and evaluate the software, a dataset was acquired over 9 years on more than 110 plots in a 1045 ha agricultural catchment, including crop types, soil surface state, rainfall and runoff time series. Soil surface state dynamics was modeled based on crop types and daily rainfall. It was evaluated in the experimental catchment and validated in a nearby catchment. Soil hydrodynamic properties (e.g. infiltration capacity) were deduced from this framework and literature data at a daily time step, for each plots. Moreover, runoff events were measured when the modeled infiltration capacity was low, indicating that the parametrization adequately captured its temporal dynamics. The software developed in this study, as well as setup values deduced from the monitoring campaigns are provided with the manuscript for application in other ungauged catchments and explore their impact on agricultural catchment hydrological dynamics. [ABSTRACT FROM AUTHOR]

Purpose: Understanding hydro-sedimentary dynamics at the catchment scale requires high temporal resolution data on suspended sediments such as their origin, in addition to the common measurements of sediment concentrations and discharges. Some rapid and low-cost fingerprinting methods based on spectroscopy have recently been developed. We investigated how visible spectra could be used to predict the proportion of various source materials in suspended sediment samples, paying particular attention to the potential alteration of spectrocolorimetric signatures between soils and suspended sediments during transport. Materials and methods: The 22-km Galabre catchment, France, is composed of black marls, limestones, molasses, undifferentiated deposits and gypsum. Forty-eight source materials were sampled and 328 suspended sediment samples were collected at the outlet during 23 runoff events. Measurements were taken with a diffuse reflectance spectrophotometer on dried samples. As the erosion processes are particle size selective, five particle size fractions of source material were measured in order to assess the potential alteration of the fingerprint signatures. As the biogeochemical processes occurring in the river could also affect the signatures, source materials were immersed in the river for durations ranging from 1 to 63 days and subsequently measured. Finally, partial least-squares regression models were constructed on 81 artificial laboratory mixtures to predict the proportions of source materials. Results and discussion: The spectrocolorimetric measurements discriminated the primary source materials but not the Quaternary deposits. As the gypsum was not conservative, only the black marls, molasses and limestones were used in the fingerprinting procedure. The construction of the partial least-squares regression models led to a median absolute error of 1.1%. This error increased to 3.9% when the models were applied to source samples with: (1) different particle sizes; (2) different durations spent in the river; or (3) different origins than those used for their construction. The effect of particle size on the fingerprinting procedure was larger than the effect of biogeochemical reactions or the spatial variability of the spectrocolorimetric signatures. Half of the 23 runoff events analysed exhibited huge variations in the source proportions from one sediment sample to another. Conclusions: The spectrocolorimetric fingerprinting approach was able to quantify routinely the proportion of primary source materials in all suspended sediment samples collected during runoff events. The high temporal resolution of the predicted proportions revealed that only analysing three or four suspended sediment samples during a runoff event could lead to a misunderstanding of the hydro-sedimentary processes for more than half of the investigated runoff events. [ABSTRACT FROM AUTHOR]

[Display omitted] • MUSLE is able to predict sedimentary response and mitigation measures in burnt areas. • High-severity fire increase soil erosion and sediment load at the basin scale. • Emergency stabilization and soil erosion barriers are effective to reduce soil erosion. • SWAT model may be a post-fire management decision tool. The present paper contributes to bridging the gaps in modelling post-fire impact and mitigation measures on soil erosion. The specific aims were to predict the effects of forest fires and post-fire mitigation measures on runoff and specific sediment yield (SSY) in a river basin (Celone, S-E Italy). The Soil and Water Assessment Tool model, calibrated with field observations, was used to evaluate runoff and SSY for the current land use (baseline) and six post-fire scenarios. From 1990 to 2011, at the basin scale, the average annual SSY was 5.60 t ha- 1yr−1 (SD = 3.47 t ha-1yr−1). 20% of the total drainage area showed a critical value of SSY (>10 t ha−1 yr−1). The effects of different fire-severity levels were predicted for one year after the fire, acting on a limited area (2.3% of the total basin area). At the basin scale, the post-fire effect on surface runoff was negligible for all scenarios (<0.4%), and the impact on SSY increased from 5.86 t ha−1 yr−1 up to 12.05 t ha−1 yr−1. At the subbasin scale, the post-fire logging scenario showed the highest increase of soil loss (SSY increased from 9.48 t ha−1 yr−1 to 57.40 t ha−1 yr−1). Post-fire mitigation treatments like straw mulching and erosion barriers effectively reduced soil erosion in high- and moderate-severity fires (19.12 t ha-1yr−1 and 20.93 t ha−1 yr−1, respectively). At the hydrological response unit level, the SSY estimated for the forest in the baseline ranged from 1.18 t ha- 1yr−1 to 2.04 t ha−1 yr−1. SSY increased more than one order of magnitude for the high-severity fire scenarios and ranged from 4.33 to 6.74 t ha−1 yr−1 in the very low-severity fire scenario, underlining the scale effect from the HRU to the basin scale. [ABSTRACT FROM AUTHOR]