@article{fdi:010053463,
  title = {{I}mpact of slope gradient on soil surface features and infiltration on steep slopes in northern {L}aos},
  author = {{R}ibolzi, {O}livier and {P}atin, {J}. and {B}resson, {L}.{M}. and {L}atsachack, {K}.{O}. and {M}ouche, {E}. and {S}engtaheuanghoung, {O}. and {S}ilvera, {N}orbert and {T}hi{\'e}baux, {J}ean-{P}ierre and {V}alentin, {C}hristian},
  editor = {},
  language = {{ENG}},
  abstract = {{I}t was recently demonstrated that, infiltration into mountain-tilled soils with highly stable microaggregates, increases with increasing slope gradient. {I}n this work we investigate the processes that underpin this phenomenon by means of field experiments and modelling. {T}he study area is located in northern {L}aos. {R}ainfall simulations were conducted in two 1-m(2) plots using a portable field simulator. {T}he drop size distribution and kinetic energy were similar to that occurring on the occasion of tropical downpours. {S}oils exhibited a clay loam texture and very similar organic matter contents across experimental plots, but differed greatly in slope gradient (30% and 75%). {R}unoff water samples were collected at intervals ranging from 1 to 3 min, depending on the runoff intensity. {P}lots microtopography was measured before and after rainfall simulations using an automatic surface roughness meter on a 1-cm grid. {H}igh-resolution bulk density images were obtained from soil slices using a standard {X}-ray generator. {F}inal infiltration rates of 6 and 21 mm h(-1); soil detachment of 667 and 310 g m(-2); surface lowering due to soil loss of 0.82 and 0.38 mm; surface lowering due to compaction of 1.21 and 0.90 mm; percentage area with sieving crust of 36% and 90%; percentage area with erosion crust of 63% and 0%; were obtained for the 30% and 75% slopes, respectively. {T}hree main conclusions can be drawn from this work: (1) high intensity rainfall can rapidly transform soil surface features of steep bare soil; (2) on steeper slopes, the micro-relief tends to form micro-terraces much more pervious and less erodible than the ripple-like roughness that formed on gentler slopes; and (3) there was a more pronounced lowering of the soil surface due to compaction and denser microlayers on gentler slopes. {T}he latter conclusion confirms the hypothesis that higher effective rainfall intensity is responsible for the formation of less permeable erosion crusts under 30% slope gradients while more permeable structural crusts develop under 75% slope gradients. {T}he runoff results were modelled with the {G}reen and {A}mpt model which accounts for time evolution of soil hydraulic conductivity. {T}his modelling shows that soil is undoubtedly non homogeneous, evolves with time and that infiltration kinetics is slower and soil permeability greater for the 75% slope.},
  keywords = {{I}nfiltration ; {R}unoff generation ; {S}teep slopes ; {H}illslope processes ; {R}ainfall simulation ; {LAOS}},
  booktitle = {},
  journal = {{G}eomorphology},
  volume = {127},
  numero = {1-2},
  pages = {53--63},
  ISSN = {0169-555{X}},
  year = {2011},
  DOI = {10.1016/j.geomorph.2010.12.004},
  URL = {https://www.documentation.ird.fr/hor/fdi:010053463},
}