Spatio-temporal patterns of sediment connectivity in vineyards : anthropogenic control and impacts on sediment yield

Abstract

<p>Vineyards are often considered to be among the agricultural lands most sensitive to erosion. To cope with soil degradation and associated downstream consequences (e.g. mudflows, alteration of water quality, transfer of pesticides to rivers) numerous French vineyards developed management strategies that consists in controlling runoff using diches and road networks to route eroded sediments in traps. In addition, vineyards regions such as Burgundy, commonly use plots backfilling to compensate for soil loss on sloping vineyards. In this study, evaluate the impact of these anthropogenic interventions on the sediment cascade by coupling soil erosion measurements and modelling on a small sub-catchment of the Mercurey wine region in burgundy.</p><p>We applied the SUM/ISUM method to measure erosion rates on a set of 7 selected vine plots in different contexts of slope, age and type of farming. These measurements were complemented by the monitoring of sediment traps and stream flow at the outlet of the catchment. The main objective was to quantify sediment fluxes at different spatial and temporal scales to identify the effect of management strategies (wall, diches, sediment traps and backfilling) on sediment connectivity and sediment transfers. Then, these results were compared to the WATEM/SEDEM model. Our objective was to relate the observed (actual) and modelled (potential) erosion and sediment transfer.</p><p>At the catchment and sub-catchment scale, both measurements and models show a low amount of sediment transfer, from 1.3 t.ha<sup>-1</sup>.yr<sup>-1</sup> at the sub-catchment scale (0.5 km²) to 0.1 t.ha<sup>-1</sup>.yr<sup>-1</sup> at the catchment scale (10 km²). These results demonstrate the efficiency of the runoff management system on sediment connectivity from plots to river. These observations were confirmed by the flood hysteresis analysis which suggests a local (channel or close) origin of sediments. On the other hand, large differences were observed from the comparison of the measured and modelled erosion rates at the plot scale, illustrating the effect of backfilling practices which tends to compensate part of long/medium term soil losses on hillslopes. In spite of erosion control strategies, the measured rates on vine plots remain higher than what can be tolerated for sustainable development of agriculture. Therefore, we suggest that the current erosion mitigation strategy should be complemented with other techniques that maintain soils on plots (e.g., grass strips on the interrows, mulching).</p>