Bouajila Essifi, Mohamed Ouessar, Mohamed Moussa

& Houcine Khatteli

Institut des Regions Arides (IRA),

Medenine - TUNISIA

UN/Iran Workshop on the Use of Space

Technology for Dust Storm and Drought

Monitoring in the Middle East Region

5-9 Nov. 2016, Tehran – Iran.

TUNISIA: The dry prone areas cover almost more than 4/5 of the total area where desertification related problems are of major importance. Long: 7° - 12°E, Lat: 32° - 38°N Area: 164 000 km² Climate Heterogeneity: 2 opposite climate domains: Mediterranean (temperate humid), Sahara (arid tropical) Coastline spans: 1300 km, 75% suffers from aridity and drought, Annual rainfall: Northwest: 500-1500 mm, South:150 mm. A strong variability: After 1900: 20 Droughts and 14 Floods,

ARID & SEMIARID TUNISIA

Quantitative Degradation Qualitative Degradation

Reduction of Area Biodiversity Loss

Droughts / Erosion Croplands / Overgrazing

Edaphic / Climatic Contrainsts Anthropogenic Impact

Precarious climate tightly linked to aridity.

Area affected by drought are facing increased risk of food and

water shortage

Steppic rangelands with sparse vegetation

Overexploitation Favorising Desertification Processes

Extensive Livestock

Dry Farming

Overgrazing

Desertification

Drought is a complex natural phenomenon of climate (Wilhite, 2005):

Its impacts depend on meteorological conditions, land surface and

ecosystem type, and socioeconomic circumstances.

Preparedness for drought forms an important part of national

environmental policies,

TUNISIA, has limited institutional and technical capacity to prepare for

a drought and to mitigate its impacts,

Insufficient readily available information on drought onset and

development for agencies and for the general public.

Arid

Zones

Observatories

On September 25th 2015, countries adopted a set of goals to end poverty,

protect the planet, and ensure prosperity for all as part of a new

Sustainable Development Agenda. Each goal has specific targets to be

achieved over the next 15 years.

#UNCCD: What is Desertification…

Desertification… Some alarming key issues…

Desertification… Some alarming key issues…

Desertification… Some alarming key issues…

Desertification… Some alarming key issues…

Desertification… Some alarming key issues…

The Institut des Regions Arides (IRA), created in 1976 (40th anniversary),

has been assigned the main mandates of:

Conducting research

on natural resources

management and

combating

desertification

Contributing to

capacity building in

drylands related

topics

Providing expertise

and assistance for

development

agencies operating

in the dry areas.

A specific program on desertification surveillance by combining Remote

Sensing and GIS tools to field investigation.

Natural resources and desertification surveillance at

different spatial and resolution

scales

Socio-economic

interactions between local

population and their

environmental landscapes

Monitoring of wildlife and endangered

animal species

Geomatic-based tools for decision making in drylands

assessment and

development

• 2003-2006: “Desertification Observatories” funded by the Swiss Cooperation, OSS and ROSELT: www.oss-online.fr/indicateurs-écologiques-du-roseltoss-désertification-et-biodiversité--des-écosystèmes-circum

• 2005-2010: “A Surveillance System for Assessing and Monitoring of Desertification (DESURVEY)” funded by the EU: www.noveltis.com/desurvey/

• 2007-2010: LADA “Land Degradation in Drylands” funded by FAO: www.fao.org/lada/

• 2007-2011: “Desertification Mitigation and Remediation of Land” (DESIRE) funded by the EU: www.desire-project.eu

• 2011-2014: “Water harvesting and Agricultural techniques in Dry lands: an Integrated and Sustainable model in MAghreb Regions” (WADISMAR) funded by the EU: www.wadismar.eu

Satellite Remote Sensing Coupled to Climate/Topography Data

OBJECTIVES

• Identification and assessment of degradation processes in affected

areas,

• Monitoring of degradation and recovery processes,

• Performance evaluation of mitigation programmes,

• Early warning of disturbance,

Low Cost, Replicable, Multi-scale

Available Information Sources:

Remote Sensing datasets from Satellites and Aircrafts, Terrestrial

Observation Systems

Environmental Change is defined by its landscape consequences, and it is these

consequences that have to be detected and quantified using space data.

Environmental Change can only be inferred from remote measurements of the spatial

and temporal dynamics of landscape attributes (Graetz, 1996).

Biological Productivity, Soil Resources, Efficiency of Water & Energy Use

Consistency with Desertification Process

Sufficiently large time window for observation steps (i.e. 5 year

integration periods) to avoid impact of exceptional situations,

Sufficiently long time intervals between assessment steps (i.e., 10

years) to allow for recordable changes in landscape functions,

Applicable to both natural and agricultural landscapes (annual averages

vs. seasonal peaks of landscape functions),

Forecasting Capacities

To assess land degradation in Southern Tunisia natural regions using

RS times-series (Landsat, AVHRR, MODIS…) and/or higher resolution for

hotspots (SPOT, GEOEYE, IKONOS...),

To develop a surveillance system that can de used to monitor and

diagnose desertification, vulnerability of eco-agricultural systems

relative to desertification (‘vulnerability’ is land degradation).

To establish the relationships between degradation processes, natural

ecosystem dynamics, and human activities.

To contribute to strengthen the necessary scientific knowledge for the

future orientation of the sustainable Development Strategy at national

level.

Geostatistics

LC/LU Classification

RS TIME-SERIES

Assessment / SPACE Modelling / TIME

Change Maps of

Land Processes MONITORING

CHARACTERIZATION OF DEGRADATION/DESERTIFICATION HOT SPOTS

DESERTIFICATION SYNDROME:

Description of Archetypical, Co-evolutionary Patterns of Human–Nature

Interactions

ASSESSMENT

Field Data Ancillary Data

OBJECTIVES

• Change analysis of vegetation before and after the protection in

1994,

• Mapping and assessment:

• Degradation before protection

• Vegetation recovery processes after protection,

• The natural park was created in 1994,

• Stretching over an area of 5750 ha – 37 km to the south of

Tataouine city.

• A steppic ecosystem in a pastoral landscape.

VEGETATION CHANGE ANALYSIS : NATURAL PARK WADI DEKOUK

(1984-2010)

VEGETATION CHANGE ANALYSIS : NATURAL PARK WADI DEKOUK

(1984-2010)

1- Landsat TM images,

2- Classification Method:

Iterative Self-Organizing

Unsupervised classifier

(ISOCLUST) under IDRISI

Selva®.

3- Change detection using

Land Change Modeler (LCM)

under IDRISI Selva®.

VEGETATION CHANGE ANALYSIS : NATURAL PARK WADI DEKOUK

(1984-2010)

METHODOLOGY

VEGETATION CHANGE ANALYSIS : NATURAL PARK WADI DEKOUK

(1984-2010)

Gains by category Losses by category Net change by

category

Ha % Change Ha % Change Ha

Sparse Vegetation/Bare

Soil

865 42,70 -835 -41,86 29

Psammophetic Vegetation 271 18,44 -650 -35,18 -379

Psammo-Halophyte

Vegetation

171 22,83 -127 -18,04 44

Halophyte Vegetation 501 52,97 -193 -30,27 308

Sandy Bare Soil 372 100,0 -374 -100,0 -2

• Gains, losses persistence maps between 1984 (before protection) and

2010 (following protection) were derived for the different land cover

categories: steppic, psammophetic, halophyte vegetation, and sand

accumulation, etc.

• The biggest change in terms of gains, losses and persistance was

recorded in the class of Sparse Vegetation/bare Soil,

• The Psammophetic Vegetation class has known the highest negative

change.

• The principal positive change was attribued to the Halophyte

Vegetation.

VEGETATION CHANGE ANALYSIS : NATURAL PARK WADI DEKOUK

(1984-2010)

RESULTS

2dRUE Application, (DESURVEY Project)

Input Data: NDVI monthly

images (1998-2008)

Source: SPOT

VEGETATION NDVI data,

(VITO, 2005):

http://free.vgt.vito.be

1 km Decadal NDVI data.

http://free.vgt.vito.be/http://free.vgt.vito.be/

Land actively degrading along the last 10 years is very scarce: 7000 sq.km.

Land static with no trend in long or short term is very abundant: 1000000 sq.km.

Hypothesis: Active degradation took place before the analysis period,

Static land is already very degraded,

Typology of hydrological years from 1969 to

2012 (Beni-Khedache Station):

Percentage of normality (mm):

PN = (Pi/Pm)*100

With Pi (mm): annual rainfall

Pm: average rainfall of years (1969 à 2012),

Based on year classification:

Humid: PN [ 110;+∞ ],

Normal: PN [ 80;110],

Moderately Dry: PN [ 55;80],

Very Dry: PN [0;55]

Bring out results that may explain:

Desertification syndrome concept: Exploitation - Regional/Local

Analysis,

Retrospective evaluation of the effects of changing socio-

economic boundary conditions on development and current

state of natural resources in Southern Tunisia.

Changes correlated with agro-meteorological conditions:

Climatic hazards: aeolian erosion, drought, etc.

Socioeconomic transformations: flocks density, dry farming, etc.

Results seems to confirm the "new paradigm" of arid ecosystems:

In desequilibrium or ‘event driven’ In equilibrium disturbed by human impact

DESERTIFICATION/DEGRADATION

Irreversible/permanent - Reversible/Temporary.

Overexploitation/mismanagement - Loss of biological potential.

Drought - Anthropogenic role.

Thank You!