Surface Processes and Soil Effects of Slopewash, Schemes and Mind Maps of Construction

Download Surface Processes and Soil Effects of Slopewash and more Schemes and Mind Maps Construction in PDF only on Docsity! Lecture  3:  Surface  Processes  and  Soil   Effects  of  slopewash   × Process  where  run  off  on  the  surface  of  the  hillslope  shifts  sediment  and   soil  material  downslope     Horton’s  model  of  overland  flow   × Hortonian  flow  occurs  when  precipitation  exceeds  infiltration  à  requires   high  intensity  rainfall  event  or  water  repellant  soil,  short  bursts  of  runoff   after  high  intensity  rainfall     × Belt  of  no  erosion,  active  erosion  and  deposition  of  material                           × Belt  of  active  erosion  in  mid  slope  –  ridges  would  sink     × Colluvium  =  base  of  slope  accumulation,  concave  profile,  sheet  wash  à   steep,  thin   × Alluvium  =  material  which  has  been  transported  and  deposited  by  a   stream,  valley  floor,  flat,  channelized  flow     Rainsplash     × Erosion  and  transport  by  rain  splash  à  impact  and  momentum  of  rain   drops  on  the  surface  –  only  affects  soft  surfaces  with  loose  particles  à   creates  divets  à  net  downslope  movement     × In  Hortons  ‘no  erosion’  zone  à  rain  splash  erosion   × Deposition  on  slopes  à  micro  terrace  and  litter  dams     × Vegetation  modifies  pattern  of  parallel  rills  (construction  sites)  –  once   vegetation  is  introduced  these  paths  converge  and  diverge  à  greater   sinuosity     × Saltation  à  jumping  –  transport  of  particles,  big  enough  to  be  lifted  (bed   load)   × Suspended  load  (small  enough  to  be  moved  until  velocity  slows  and  they   settle)   × Floating  load                       Bushfire   × Recovery  (litter  dam,  traps  sediment  and  ponds  water)   × Establishment  (dam  traps  bed  load,  floating  load  erosion  below  dam   × Stability  (dam  full,  micro  terrace  formed     Effects  of  slopewash  on  soil  formation   × Moving  material  around  and  sorting  material     × On  slope  deposition  of  coarse  material  in  fundamentally  important  –  a   mechanism  for  coarser  topsoil  formation     Effects  of  slopewash  and  bioturbation  on  soil  formation   × Bioturbation  introduces  soil  from  depth  to  the  surface   × Surfacewash  sorts  surface  materials   × Bioturbation  buries  and  mixes  sorted,  coarse  wash  deposits   × These  processes  result  in  TEXTURE  CONTRAST  SOILS  =  coarse  topsoil   (biomantle)  over  finer  subsoil     Lecture  4:  Saprolite