Aggregate breakdown and surface seal development influenced by rain intensity, slope gradient and soil particle size

Abstract

Abstract. Aggregate breakdown is an important process which controls infiltration rate (IR) and the availability of fine materials necessary for structural sealing under rainfall. The purpose of this study was to investigate the effects of different slope gradients, rain intensities and particle size distributions on aggregate breakdown and IR to describe the formation of surface seal. To address this issue, 60 experiments were carried out in a 35 × 30 × 10 cm detachment tray using a rainfall simulator. By sieving a sandy loam soil, two sub-samples with different maximum aggregate sizes of 2 mm (D max 2 mm) and 4.75 mm (D max 4.75 mm) were prepared. The soils were exposed to two different rain intensities (57 and 80 mm h −1 ) on several slopes (0.5, 2.5, 5, 10 and 20 %) each at three replicates. The result showed that for all slope gradients and rain intensities, the most fraction percentages in soils D max 2 and D max 4.75 mm were in the finest size classes of 0.02 and 0.043 mm, respectively. The soil containing finer aggregates exhibited higher transportability of pre-detached material than the soil containing larger aggregates. Also, IR increased with increasing slope gradient, rain intensity and aggregate size under unsteady state conditions because of less development of surface seal. However, under steady state conditions, no significant relationship was found between slope and IR. The findings of this study revealed the importance of rain intensity, slope steepness and soil aggregate size on aggregate breakdown and seal formation, which can control infiltration rate and the consequent runoff and erosion rates.

Effects of vegetation restoration on the aggregate stability and distribution of aggregate-associated organic carbon in a typical karst gorge region

“…Finally, the residue on the sieves was collected, dried at 60 • C, and weighed (Sainju et al, 2003). The total SOC and SOC associated with water-stable aggregates were determined through oxidation with potassium dichromate and external heating (Bao, 2005).…”

“…SOC is a binding substance imperative for the formation of aggregate structures (Cerdà, 2000;Wu et al, 2004). Land cover significantly affects SOC contents by influencing the input and output of the organic matter in soil and, therefore, the distribution and stability of soil aggregates (Powers, 2004;Luo et al, 2011;Arjmand et al, 2015). After vegetation restoration, the organic carbon contents, MWD, and GMD of the WSAs > 0.25 mm increased, and the PAD and D values decreased.…”

Impact of Raindrop Characteristics on the Selective Detachment and Transport of Aggregate Fragments in the Loess Plateau of China

“…46, 50.03, 72.02, 63.21, 66.63, and 44.47% of the total splash erosion. Arjmand Sajjadi and Mahmoodabadi (2015) performed raindrop splash experiments using rainfall intensities of 57 and 80 mm h -1 and showed that the transport of fine particles <0.043 mm was greater than the transport of larger particles under high rainfall intensity. This conclusion is consistent with the conclusion presented by Meyer et al (1980).…”

Soil Atterberg limits of different weathering profiles of the collapsing gullies in the hilly granitic region of southern China

“…PSD affects the movement and retention of water, solutes, heat, and air, and thus greatly affects soil properties (Arjmand Sajjadi et al, 2015 Fig. 3.…”