Bouajila ESSIFI
Environmental Remote Sensing, Ph.D. Candidate
INSTITUT DES REGIONS ARIDES (IRA)
TUNISIA
« Desertification and Drought Monitoring
in Arid Tunisia based on Remote Sensing Imagery »
Research Undertaken & Case-Studies
EU COST Action September 2015, Antalya – Turkey
Bouajila ESSIFI
INSTITUT DES REGIONS ARIDES (IRA),
TUNISIA
TUNISIA…Arid and Semiarid regions:
The dry prone areas cover almost more than 4/5 the total area where
desertification related problems are of major importance.
R EMAD A SMA RD H IBA TAT AOU I N E SU DTAT OU I N E NO R DG HO MR ASSE NBI R L AH MAR T U N I S I A i n N O R T H AF R I C A
Longitude: 7° and 12° E
Latitude: 32° and 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,
G E O G R AP H I C & C L I M AT I C C H AR A C T E R I S T I C S
The INSTITUT DES RÉGIONS ARIDES (IRA), created in 1976, has been assigned
the main mandates of:
G E O - I N F O R M AT I C R E L AT E D AC T I V I T I E S O F I R A
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.
G E O - I N F O R M AT I C R E L AT E D AC T I V I T I E S O F I R A
A specific program on desertification surveillance by combining RS
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
I R A – I N T E R N AT I O N A L C O O P E R AT I O N P R O J E C T S
• 2003-2006: “Desertification Observatories” funded by the Swiss Cooperation in
collaboration with OSS and ROSELT
• 2005-2010: “A Surveillance System for Assessing and Monitoring of Desertification
(DeSURVEY)” funded by the EU
I R A – I N T E R N AT I O N A L C O O P E R AT I O N P R O J E C T S
• 2007-2010: LADA “Land Degradation in Drylands” funded by FAO
I R A – I N T E R N AT I O N A L C O O P E R AT I O N P R O J E C T S
• 2007-2011: “Desertification Mitigation and Remediation of Land” (DESIRE) funded by the
EU
I R A – I N T E R N AT I O N A L C O O P E R AT I O N P R O J E C T S
N AT I O N A L C E N T E R S F O R S PAC E T E C H N O L O G Y
1988: CNCT, The National Remote Sensing Center
Develeop capacities at national level,
Coordinate and execute national programs on space technology,
Provide technical advisory services related to space infromation, training and education
opportunities in Space technology,
Enhance the regional and internatinal cooperation.
1990: CRTEAN, The North African States Regional Center for Remote
Sensing
Promote RS, GIS, mapping and their applied activities,
Ensure a useful and efficient complementarity in the above fields for the
benfit of its member statesand associated members.
Drought is a complex natural phenomenon of climate (Wilhite, 2005):
A period of lower than average rainfall,
Linked to a deficit of water resources availability covering a large geographic
area and which extends over a relatively significant period (Rossi, 2000).
Droughts impacts depend on meteorological conditions, land surface and ecosystem
type, and social and economic circumstances.
D R O U G H T M O N I T O R I N G : A H I G H P R I O R I T Y F O R T U N I S I A
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.
P R O B L E M AT I C R AT I O N A L E
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.
Degraded soil resources and water resources.
ARID TUNISIA: B I O P H Y S I C AL AS P E C T S
Steppic rangelands with sparse vegetation
ARID TUNISIA: B I O P H Y S I C AL AS P E C T S
Overexploitation Favorising Desertification Processes
Extensive Livestock
Dry Farming
Overgrazing
Desertification
E AR T H O B S E R VAT I O N S : AN AS S E T
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. -R.D. Graetz (1996)
Detection and Monitoring must be based on
Landscape Functions that are Associated with Land
Degradation Status
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
S AT E L L I T E O B S E R VAT I O N S
S AT E L L I T E O B S E R VAT I O N S
A S P E C T S O F T H E A D O P T E D A P P R A O C H
GIS Socioeconomic Data Fieldwork
Synoptic - Repetitive - Selective
RS Times-Series
Inventory Assessment Surveillance
Knowledge – Modelling – Management
LU/LC Classification
STABILITY
Synthesis in terms of Tendencies
AMELIORATION DEGRADATION
Discriminate Hotspots of Change
O V E R AL L O B J E C T I V E S
To assess land degradation in Southern Tunisia natural regions (1984 to 2010) using RS times-
series (Landsat, AVHRR, MODIS…) and 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 contribute to strengthen the necessary scientific knowledge for the future orientation of the
sustainable Development Strategy at national level.
To establish the relationships between degradation processes, natural dynamics ecosystem,
and human activities.
M E T H O D O L O G Y & S T U D Y F L O W C H AR T
Decadal Image
Classification:
LANDSAT
Data Preprocessing: Radiometric & Atmospheric Calibrations of LANDSAT
- MODIS - AVHRR
Image Enhancement:
Photo-interpretation
Geostatistics:
TimeStats
Accuracy Assessment Ancillary Data
Ground Truth
GIS Integration:
Change Detection
Land Cover / Land Use Maps
Analysis & Discussion of Results – Conclusion
Bibliographical Review
Geostatistics
Landcover Classification
LANDSAT TIME-SERIES
Assessment / SPACE Modelling / TIME
Change-maps
of
Land Processes
Map of MONITORING
CHARACTERIZATION OF DEGRADATION/DESERTIFICATION HOTSPOTS
DESERTIFICATION SYNDROME:
DESCRIPTION OF ARCHETYPICAL, CO-EVOLUTIONNARY PATTERNS OF
HUMAN–NATURE INTERACTIONS
Map of ASSESSMENT
M E T H O D O L O G Y & S T U D Y F L O W C H AR T ( C o n t i n u e d … )
L AN D C O N D I T I O N I N T H E M AG H R E B ( 1 9 9 8 - 2 0 0 8 )
DEL BARRIO et al. (2010) 2dRUE APPLICATION, (DeSurvey Project)
Input Data: NDVI
monthly images (1998-
2008)
Source: SPOT
VEGETATION NDVI data,
(VITO, 2005):
http://free.vgt.vito.be
Dekadal NDVI data is
obtained in a geographic
projection with spatial
resolution of 0.00892857
degrees
L AN D C O N D I T I O N I N T H E M AG H R E B ( 1 9 9 8 - 2 0 0 8 )
DEL BARRIO et al. (2010) 2dRUE APPLICATION, (DeSurvey Project)
Hypothesis:
Active degradation took
place before the analysis
period, and a reason for so
much static land is that it is
already very degraded,
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.
L C L U I N S O U T H E R N T U N I S I A ( 1 9 8 4 - 2 0 11 )
MOURTALA et al. (2013) - AFROMAISON PROJECT
Typology of hydrological years from 1969 to
2012 (Beni-Khedache Station):
Pourcentage of normality (mm):
PN = (Pi/Pm)*100
With Pi (mm): annual rainfall et 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]
L C L U I N S O U T H E R N T U N I S I A ( 1 9 8 4 - 2 0 11 )
MOURTALA et al. (2013) - AFROMAISON PROJECT
L C L U I N S O U T H E R N T U N I S I A ( 1 9 8 4 - 2 0 11 )
MOURTALA et al. (2013) - AFROMAISON PROJECT
L C L U I N S O U T H E R N T U N I S I A ( 1 9 8 4 - 2 0 11 )
MOURTALA et al. (2013) - AFROMAISON PROJECT
L C L U I N S O U T H E R N T U N I S I A ( 1 9 8 4 - 2 0 11 )
MOURTALA et al. (2013) - AFROMAISON PROJECT
L C L U I N S O U T H E R N T U N I S I A ( 1 9 8 4 - 2 0 11 )
MOURTALA et al. (2013) - AFROMAISON PROJECT
L C L U I N S O U T H E R N T U N I S I A ( 1 9 8 4 - 2 0 11 )
MOURTALA et al. (2013) - AFROMAISON PROJECT
D R O U G H T M O N I T O R I N G : O N G O I N G Q U E S T
Perspectives:
Data acquisition and processing,
Statistical modelling,
LC-LU mapping.
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.
Bouajila Essifi
Eremology & Combating Desertification Lab.
Institut des Regions Arides (IRA)
Medenine 4119 – Tunisia
Email: [email protected]
THANK YOU