Climate change and Urban Vulnerability in Africa

Assessing vulnerability of urban systems, population and goods in relation to natural and

man-made disasters in Africa

1

“Training on the job” Course on Hazards, Risk and (Bayesian) multi-risk assessement

Napoli, 24.10.2011 – 11.11.2011

22/04/2023

Module 3.5: Desertification, Case Studies

Iavazzo, Topa, Terracciano

AREAS AT RISK FROM DESERTIFICATION

(Waugh, 1995)

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DESERTIFICATIONIN AFRICA

Source: UN - United Nations

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DESERTIFICATIONIN WEST AFRICA

St. Louis

Ouagadougou

Douala

Source: UN - United Nations

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DESERTIFICATIONIN EAST AFRICA

Addis Ababa

Dar Es Salaam

Source: UN - United Nations

ESAs model was developed in Mediterranean habitat. The application of this methodology in west Africa sub-Saharan areas needs a readjustment for some parameters to adapt the classes

and weigh of indices to different habitat conditions.

The readjustment of vegetation index was made starting from classification of the dominant natural vegetation and agricultural crops in sub-Saharan west Africa, and subsequently

weighing indices in relation to the four sub-indices.

Mediterranenan area Sub-Saharan west Africa

Class Vegetation 1 Mixed Mediterranean macchia/evergreen forest 2 Mediterranean macchia 3 Permanent grassland 4 Annual grassland 5 Deciduous forest 6 Pine forest 7 Evergreen forest except pine forest 8 Evergreen perennial agricultural crops 9 Deciduous perennial agricultural crops 10 Annual winter agricultural crops 11 Annual summer agricultural crops 12 Bare land

Class Vegetation1 Tropical rain forest2 Woodland savanna3 Grassland savanna4 Steppe5 Semidesert6 Annual agricoltural crops7 Perennial agricoltural crops8 Bare areas

MEDALUS METHODOLOGY

7

Fire Risk

Erosion Protection

Drought Resistance

Plant Cover

VQIVegetation Quality Index

Mean Annual Rainfall

Aspect

Aridity Index

CQIClimate Quality Index

Soil Texture

Rock Fragment

Slope Gradient

Soil Depth

Parent Material

Drainage

SQISoil Quality Index

Land Use Type

Land Use Intensity

Policy

MQIManagement Quality Index

ESAI

MEDALUS METHODOLOGY

(Kosmas et al., 1999)

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100 km

CASE STUDY: BURKINA FASO

50 km

STUDY AREA:OUAGADOUGOU REGION

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LAND COVER MAP

FAO, 2009

VQIREFERENCE DATA

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Vegetation Types Index

Very Low

Bare land, semidesert, perennial agricultural crops, annual agricultural crops (cotton, maize)

1.0

Low Evergreen forest, Annual agricultural crops (cereals) 1.2

Moderate Sparse vegetation 1.4

High Steppe 1.6

Very High Savannah 2.0

VQIVEGETATION QUALITY INDEX

FIRE RISK

100 km

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EROSION PROTECTION

VQIVEGETATION QUALITY INDEX

Vegetation Types Index

Very high Evergreen forest 1.0

High Savannah 1.2

Moderate Steppe, Sparse vegetation 1.4

Low Perennial agricultural crops, Annual agricultural crops 1.6

Very Low Semidesert – Bare areas 2.0

100 km

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DROUGHT RESISTANCE

VQIVEGETATION QUALITY INDEX

Vegetation Types Index

Very high Evergreen forest 1.0

High Savannah 1.2

Moderate Perennial agricultural trees 1.4

Low Steppe, Sparse vegetation 1.6

Very Low Annual agricultural crops 2.0

100 km

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PLANT COVER

VQIVEGETATION QUALITY INDEX

Plant Cover % Index

High > 40% 1.0

Low 10 - 40% 1.8

Very Low < 10% 2.0100 km

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VQIVEGETATION QUALITY INDEX

Non affectedPotential

Fragile 1Fragile 2

Fragile 3

Critical 1Critical 2

Critical 3

100 km

Urban area

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Zone AI Index

Arid 0.01 < AI < 0.2 1.0

Semi-arid 0.2 < AI < 0.5 1.7

Sub-humid 0.5 < AI < 0.75 2.0

100 km

CQICLIMATE QUALITY INDEX

AI = P/ETP = 0.5

P: mean annual rainfallETP: potential evapotranspiration (calculated by method of Thornthwaite)

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PEDOLOGICAL MAP

O.R.S.T.O.M., 1973 – 1/500000

PEDOLOGICAL MAP

O.R.S.T.O.M., 1976 – 1/500000

PEDOLOGICAL MAP

I.R.A.T., 1985 – 1/1000000

GEOLOGICAL MAP

D.G.M., 1976 – 1/1000000

DOMINANT SOILS

FAO, 2001

SQIREFERENCE DATA

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Texture Index

Good Loamy, Sandy Clay Loam, Clay Loam 1.0

Moderate Sandy Clay, Silt Loam 1.2

Poor Silt, Clay, Silt Clay 1.6

Very Poor Sandy 2.0

TEXTURE

SQISOIL QUALITY INDEX

100 km

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RF cover (%) Index

Very Stony > 60 1.0

Stony 20 - 60 1.3

Bare < 20 2.0

ROCKFRAGMENTS

SQISOIL QUALITY INDEX

100 km

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Slope (%) Index

Flat < 6 1.0

Gentle 6 – 18 1.2

Steep 18 - 35 1.5

Very Steep > 35 2.0

SLOPE

SQISOIL QUALITY INDEX

100 km

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Depth (cm) Index

Very Deep > 100 1.0

Deep 75 – 100 1.4

Moderate 40 – 75 1.6

Shallow 15 – 40 1.8

Very Shallow < 15 2.0

SOILDEPTH

SQISOIL QUALITY INDEX

100 km

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Parent Material Index

Good Schists, Basic & Ultra Basic Rocks, Conglomerates 1.0

Moderate Limestone, Granite, Sandstone 1.4

Poor Marl, Pyroclastics 2.0

PARENTMATERIAL

SQISOIL QUALITY INDEX

100 km

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Index

Well Drained 1.0

Moderately Drained 1.4

Imperfectly Drained 1.6

Poorly Drained 2.0

DRAINAGE

SQISOIL QUALITY INDEX

100 km

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Non affectedPotential

Fragile 1Fragile 2

Fragile 3

Critical 1Critical 2

Critical 3

100 km

SQISOIL QUALITY INDEX

Urban area

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Land Use Intensity ESAS Index

Low LLUI 1.0

Medium MLUI 1.5

High HLUI 2.0

CROPLAND AREAS

100 km

MQIMANAGEMENT QUALITY INDEX

LAND USE

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MQIMANAGEMENT QUALITY INDEX

Stocking rate ESAS Index

Low ASR< SSR 1.0

Medium ASR=SSR to 1.5*SSR 1.5

High ASR>1.5*SSR 2.0

PASTURE AREAS

100 km

LAND USE

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Degree of Enforcement Index

High Complete: > 75% of the area under protection 1.0

Moderate Partial: 25 - 75% of the area under protection 1.5

Low Incomplete: < 25% of the area under protection 2.0

POLICY

100 km

MQIMANAGEMENT QUALITY INDEX

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Non affectedPotential

Fragile 1Fragile 2

Fragile 3

Critical 1Critical 2

Critical 3

100 km

MQIMANAGEMENT QUALITY INDEX

Urban area

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MEDALUS METHODOLOGY

100 km

Non affected

Potential

Fragile 1

Fragile 2

Critical 1

Critical 2

Critical 3

Urban area

Fragile 3