Erosion & Sedimentation
in Brazil
G EO 3 5 2 – E nvi ronm ental G e o logy S e m inar
Jordan Du ff y, Be n R u kavina , Kr i ste n Un d e r wood
5 N ove mber 2 0 1 4
Geographic
Setting
 5th largest country
 Pop: 202+ M
 85% of the population
live in cities near the
ocean
http://en.wikipedia.org/wiki/Brazil
http://www.worldatlas.com/webimage/countrys/samerica/lgcolor/brcolor.htm
Topography
High point: 9,823 ft at
Pico da Neblina
Low point: sea level
(Atlantic Ocean)
4,655 miles coastline
Climate
NW – tropical
>2500 mm rainfall
25 °C avg
NE – arid
~500 mm
27 °C avg
S – subtropical to
temperate
~ 1000 to 2000 mm
17 to 22 °C avg
http://commons.wikimedia.org/wiki/Atlas_of_Brazil#mediaviewer/File:Brazil_temp_1977.jpg
Land Cover
NW – rainforests
NE – deserts
S – savannas grading to
temperate forests
Equatorial
Rainforests
Semi-arid deserts
Tropical savannas
Temperate forests
http://commons.wikimedia.org/wiki/Atlas_of_Brazil#mediaviewer/File:Brazil_veg_1977.jpg
Soils
Oxisols (38.7%)
Alfisols (20%)
Entisols (14.5%)
www.anuario.igeo.ufrj.br
Guerra et al, 2014, Soil Erosion and Conservation in Brazil.
Soil Erosion
Avg 15.4 T / hectare/ yr
Tolerable 2 T/ hectare /yr
Cultivation
Development (pop growth)
Forest clearing
Hectare = 10,000 m2 = 2.471 acres
Guerra et al, 2014, Soil Erosion and Conservation in Brazil.
www.anuario.igeo.ufrj.br
Suspended
Sediment
Flux
Suspended Sediment Yields
Paraiba do Sul
Doce
Uruguai
Parana
Parnaiba
Amazon @ Obidos
0
50
100
150
200
tons per year per km^2
Lima et al., 2005, Suspended Sediment fluxes in the large river basins of Brazil.
http://www.irtces.org/isi/isi_document/2013/201301_Sediment_fluxes_Brazil_Werneck.pdf
Overview
Agricultural Concerns
Coastal Erosion
Landslides
Source: Wikipedia.org
Agricultural Concern
Conventional Techniques Problems

Erosion



loss of topsoil and organic matter
potential loss of seeds and fertilizers
Compaction of subtillage soil

reduce infiltration (runoff)
Source: FAO.org
Conservation Agriculture
“Conservation agriculture (CA)
aims to achieve sustainable and
profitable agriculture and
subsequently aims at improved
livelihoods of farmers through the
application of the three CA
principles: minimal soil
disturbance, permanent soil cover
and crop rotations.” -FAO 2014
Source: FAO.org
Residue Bases Zero-Tillage
Source: FAO.org
Zero Tillage

No overturning or disturbing of soil



no compaction of underlying soils
does not loosen top soil
Existing plant residue left
Loss of soil and water conventional vs zero tilling. (Saturnino and Landers, 1997)
Source: FAO.org
Crop Rotation

Uses residues of previous crops




provides permanent cover
prevents further erosion
Recycle nutrients
Improve soil quality
Source: afrsweb.usda.gov
Crop Cover



Decreases erosion
Increases water
infiltration
protects from pest,
disease, and weeds
Source: FAO.org
Benefits






Erosion
Run-off
Fertilizers
Replanting
Fuel
Pond/River
recharge
Source: FAO.org
CA Summary Video - FAO
http://www.youtube.com/watch?feature=player_embedded&v=03JcYzx
369Y
Source:http://www.crossover.tractebel-engineering-gdfsuez.com
Coastal Erosion
Coastal
Erosion
• 4,655 miles coastline
• 400 municipalities
• 23 % of population
Nicolodi & Zaboni, 2008
Main drivers postulated:
• Sea Level Rise (records unclear)
• Changes in wave energy (magnitude, direction)
• Balance of Sediment supply from rivers
• Urbanization / engineering interventions
Est. 1955 Near Sao Paulo - 3.4 mm / yr
Nicolodi & Zaboni, 2008, Ministry of the Environment, Erosion in Brazilian Coastline: An Overview,
https://www.pices.int/publications/presentations/Climate_Change_2008/Climate_Change_2008_S3_1/S3_1_Nicolodi.pdf
Nicolodi & Zaboni, 2008, Ministry of the Environment, Erosion in Brazilian Coastline: An Overview,
https://www.pices.int/publications/presentations/Climate_Change_2008/Climate_Change_2008_S3_1/S3_1_Nicolodi.pdf
Nicolodi & Zaboni, 2008, Ministry of the Environment, Erosion in Brazilian Coastline: An Overview,
https://www.pices.int/publications/presentations/Climate_Change_2008/Climate_Change_2008_S3_1/S3_1_Nicolodi.pdf
Source: BBC
Landslides
Increasing Rainfall
Source: Foxnews
April 2010
•
11.5” in 24 hours
•
Rio average yearly
rainfall: 46.3”
•
300 landslides
•
Cristo Redentor cut off
•
Favela Moro do
Bumba: Built on landfill
•
Government warned of
risk
•
Over 250 dead
•
Al Jazeera Video
Source: Vladimir Platanow EBC
Source: Dailymail.co.uk
January 2011

12” in hours

Over 900 dead

Majority of deaths in
poverty stricken areas

NPR: Inattention to
favelas “more manmade
than natural”
Source: BBC
Urban Landslide Hazards in
Niterói city (Smyth et al)
Niterói city, part of Rio





Hot and humid
Intense precipitation events
Annual precipitation: 47”
Topographic constraints
Thin superficial organic material layer over weather rock
 1. argilaceous soils such as kaolinite and oxides of iron and aluminum, esp. gibsites
 2. potassium feldspars, <10% clay element present
Urban Landslide Hazards
Increase in vulnerability
 Concentration of people and
activities in limited space
 Number of people and activities
 Proximity to human made
hazards
Favela Vulnerability
Low income housing built on marginal lands avoided by other
classes
 Hillsides
 Low construction standards
 Favelas vs high-rise apartments in clay-rich regolith
Patterns of landslide occurrence (with intense precipitation)




Loss of vegetation cover
Undercutting of slopes
Loading of regolith
Deforestation
 Causes rise in water table?
 Antecedent physical conditions
 Favelas generally built here
High risk areas: boulder slope
 Largest, densest favelas located
Future Planning
Municipal authorities should require a more effective planning strategy
 Utilize environmental information on vulnerability
Use GIS to generate hazard risk map based on evaluation of data
 Land cover, land use type, field research
References
http://en.wikipedia.org/wiki/User:Desmanthus4food/Perennial_rice
http://www.fao.org/docrep/006/y4690e/y4690e0a.htm
http://afrsweb.usda.gov/SP2UserFiles/Place/60100500/csr/ResearchPubs/reeves/reeves_
96c.pdf
http://www.theguardian.com/world/2011/jan/15/brazilian-landslides-sri-lankaaustralia
http://www.bbc.co.uk/news/world-12205677
http://pt.wikipedia.org/wiki/Morro_do_Bumba#mediaviewer/File:Morro_do_Bumba.jpg
http://www.gearthblog.com/blog/archives/2011/02/08/DigitalGlobe-Coverage-ofMudslides-in-Brazil_25Jan2011.pdf
http://www.theguardian.com/world/gallery/2010/apr/07/landslides-flooding-rio-dejaneiro
http://www.nytimes.com/2011/01/17/world/americas/17brazil.html?pagewanted=all
http://latimesblogs.latimes.com/laplaza/2010/04/rio-mudslides-update.html
http://www.scirp.org/journal/PaperInformation.aspx?PaperID=29084
http://www.cnn.com/2012/06/14/world/americas/rio-climate-change-c40/index.html
Smyth et al. (2000) Urban landslide hazards: incidence and causative factor in Niteroi, Rio
de Janeiro State, Brazil. Elsevier Science Ltd.