Soil samples were discriminated according to catchment substrate (i.e. carbonate and silicate) 87Sr/86Sr ratios of suspended sediment varied depending on hydrological conditions Different particle size fractions were modelled for different flood intensities (i.e. < 2 mm and < 2 μm) Carbonate soils dominated two less intense flood events (63%) whereas silicate soils dominated a higher intensity flood (72%) Field drainage systems likely enhance the hillslope to river connectivity, particularly for the finest particles