Monitoring Land Use Land Cover Changes in West Africa

1
Monitoring Land Use / Land CoverChanges in West
Africa

• A Collaborative Program of the
• USGS EROS Data Center
• AGRHYMET Regional Center
• Sahel Institute
• With funding from the
• U.S. Agency for International Development

U.S. Geological Survey National Mapping
Division EROS Data Center
2
Sahel LU/LC Project Cooperators

• African Cooperators
• CILSS
• AGRHYMET
• INSAH
• National Government Agencies
• US Cooperators
• USAID
• USGS
• WRI

3
Sahel LU/LC National Cooperators

• Burkina
• Institut de lEnvironnement et de Recherches
  Agricoles
• Dir. des Etudes et de la Planification /
  Agriculture
• Chad
• Dir. de la Production Agricole
• Gambia
• Forestry Department
• National Environment Agency
• Guinea Bissau
• Dir. Générale de lEnvironnement
• Mali
• Institut Géographique du Mali
• Institut dEconomie Rurale
• Mauritania
• Direction de lElevage et de lAgriculture
• Centre National de lElevage et Recherche
  Vétérinaire
• Niger
• Dir. de lEnvironnement
• Institut Géographique National du Niger

4
Land Use and Land Cover Definitions

• Land cover refers to the attributes of a part of
  the Earths land surface, including biota, soil,
  topography, water, and human structures

• Land use refers to the purposes for which humans
  exploit the land cover

5
Why is it important to monitor changes in land
use and land cover?

• West Africas land resources are changing at a
  rapid pace at local to regional scales. The
  ecosystems on which West African societies depend
  are showing many signs of stress. A systematic
  understanding of changes in land use and land
  cover is critical to understanding ecosystem
  functioning and services, and human welfare. A
  spatially explicit study of land use and land
  cover changes will lead to a better understanding
  of the causes of change, and their consequences
  for the environment and society. Such
  understanding will improve land and water
  management decisions to ensure that ecosystems
  and changing landscapes are sustainably managed.

6
Remote Sensing A Definition

• Remote sensing is the science and art of
  acquiring information about the Earths surface
  without being in physical contact with it.

Image Courtesy of NASA SeaWiFs
7
Remote Sensing Advantages

• Synoptic perspective
• Unique vantage point
• Extra-visual information
• Historical and permanent record

8
Major Environmental Concerns in West Africa

• Rainfall has declined (Sahel)
• Natural resources degrading under increasing
  human pressure (agricultural expansion, wood
  cutting, etc.)
• Land Use and Land Cover changes occurring at
  unprecedented rates
• Forest cover diminishing by 2.9 million ha per
  year (SSA)
• Biodiversity has declined (flora and fauna)

9
Lake Chad A Time-Series Based on Landsat
Images  
10
An Essential Principle
Healthy Ecological Systems
Healthy Economic Sociological Systems
11
Changes in Land Use / Land Cover

• How are the natural and human landscapes changing?

• What are the rates and magnitudes of change?

• What are the causes of change?

• What impacts are the changes having?

12
Methodology Three Levels of Data Collection

• Satellite level

• Aerial level

• Ground level

13
Satellite Level Historical Imagery from the
Corona and Argon Satellite Programs Corona System
Overview Period of Operation
1959-1972 Number Missions 95 successful
121 total Orbit Near-polar Altitude
150 to 203 km Sensor Type Photographic
camera, 24 focal length Film Type
Kodak panchromatic film Nominal Photo
Scale 1305,000 Spectral Region
Visible Scan Angle 70 degrees Ground
Coverage 19.6 by 266 km Ground Resolution
1.5 to 8 meters
14
Corona Satellite Photography Jan. 1968
Full frame 20 X 266 km
Enlargement 8 X 8 km
0
500
Meters
15
Corona Satellite Photography Jan. 1968
Enlargement 2.4 X 2.4 km
Enlargement 1.2 X 1.2 km
16
Aerial Level Example from Aerial Survey, Mali
(Nov. 2000, Frame 100)
17
Aerial Level Example from Aerial Survey, Mali
(Nov. 2000, Frame 120)
18
Mali Case Study Land Use in the Cercle de
Kolokani, 1972
19
Mali Case Study Land Use in the Cercle de
Kolokani, 1999
20
Burkina Case Study Mare aux Hippopotames 1973
and 1999 (Landsat Images)
21
Burkina Case Study Mare aux Hippopotames in 1965
22
Burkina Case Study Mare aux Hippopotames in 1999
23

• Burkina Case Study Mare aux Hippopotames
• Primary Land Uses
• limited farming and settled pastoralism (1965)
• extensive farming and settled pastoralism (1999)
• Land Use / Land Cover Change
• agricultural area shows a 7-fold increase in 34
  years
• agricultural expansion rather than
  intensification is still the rule
• agricultural expansion has consumed most arable
  lands
• loss of nearly half of the natural vegetation in
  34 years
• high level of vegetation degradation in natural
  areas

24

• Burkina Case Study Mare aux Hippopotames -
  continued
• Driving Factors
• rainfall has declined, but is not a major factor
• population shift massive migration and
  resettlement from central Burkina
• agriculture establishment of cotton production
  expansion of cropland
• adoption of technology introduction of modern
  farming tools
• Recommendation A need for agricultural
  transformation
• Must develop a profitable cash crop with reliable
  markets
• Must adopt improved, affordable technologies that
  benefit both cash and food crops
• Must be training programs that equip young
  farmers with literacy and management skills to
  function as commercial farmers

25
Sahel Land Use / Land Cover Phase 2 Goals

• Develop a Sahel / West African regional land use
  / land cover monitoring framework in partnership
  with AGRHYMET and INSAH
• Construct complete satellite image archives of
  the Sahel / West Africa and transfer to AGRHYMET
  (Years 1965, 1984, 2000)
• Stratify Sahel / West African landscapes
  geographically according to ecological regions
• Characterize and quantify land use / land cover
  change using aerial photos, Corona, Landsat, and
  MODIS, spanning the period 1942 to 2000
• Understand and document long-term biophysical
  changes and relationships to human activities
• Provide information to CILSS food security and
  natural resource management programs
• Work with CILSS regional and national
  environmental policy-makers to provide a better
  understanding of the changing natural resource
  base, implications for social and economic
  well-being, and implications for the future
• Construct geographic models that project and
  predict lu / lc trends to 2050 under various
  what if scenarios of population growth,
  economic activity, climatic conditions, and
  social factors
• Interpret lu / lc change in terms of
  biogeochemical cycling, with special emphasis on
  carbon sequestration in soils and vegetation
• Prepare a plan to extend this framework to the
  rest of West Africa

26
Landsat scene locations and coverage for Years
1984 and 2000
Sahel / West Africa Landsat ETM coverage
27
Ecological Regions Example at Continental Scale
28
Produce Ecological Regions Map for Sahel / West
Africa
Area to be mapped
29
Example of Landsat 7 Image from November 2000
30
Example of Stratification into Ecological
Regions, Mali-Burkina
GR
BH
GM
BH
MS
31
Les Sahel / West Africa Landsat Coverage and
Ecological Regions
32
Workshop on the Stratification of Ecological
Regions AGRHYMET / Niamey, April 2 11, 2001
33
Detailed view of Landsat TM Mosaic over Senegal
and Mauritania (Baseline image for stratification
into ecological regions)
34
(No Transcript)
35
Sahel / West Africa Sample Frames and Ecological
Regions
36
Ecological Regions of Senegal Showing the 20 X 20
km Sample Frames
37
Acquire and Prepare Imagery over the Sahel / West
Africa from four time periods
Aerial photos 1942 or 1955
Corona 1965 - 1968
Landsat TM 1984 - 1985
Landsat ETM 1999 - 2000
38
Locate 10 X 10 km sample frames and
prepare Imagery for analysis
Aerial photos 1942 or 1955
Corona 1965 - 1968
Landsat TM 1984 - 1985
Landsat ETM 1999 - 2000
39
Example of Sample Frame in the Senegal River
Valley
Corona 1965
Landsat TM 1992
20 X 20 km
20 X 20 km
Note Target dates for mapping land use / land
cover will be 1965, 1984, and 2000.
Where available, photos from 1942 or 1955 will
also be used.
40
Aerial and Ground Verification of Change of a
Sample Frame, Senegal River Valley
41
.
Example of Sample Frame in the Saloum
Agricultural Region
Corona 1968
Landsat TM 1992
20 X 20 km
20 X 20 km
Note Target dates for mapping land use / land
cover will be 1965, 1985, and 2000.
Where available, photos from 1942 or 1955 will
also be used.
42
.
Example of LU / LC in a Sample Frame Saloum
Agricultural Region, Senegal
Land Use / Land Cover in 1992
Land Use / Land Cover in 1968
20 X 20 km
20 X 20 km
Note Target dates for mapping land use / land
cover will be 1965, 1985, and 2000.
Where available, photos from 1942 or 1955 will
also be used.
43
Produce Statistics on Land Use / Land Cover
Trends for Each Area Frame Example from the
Dinfara Frame, Mali
44
Land Use / Land Cover Trends for Sanambele (22.1
sq. km.)
Percent of Total Area
Year
Source Analysis of Corona and Landsat imagery
45
Produce Statistics on Land Use / Land Cover
Trends for Each Ecological Region and Each
Country Senegal Example
46
West African Landscapes The Gorgol, Mauritania
Corona 1966
Landsat 1999
47
Expected Benefits

• Improved understanding of the biophysical aspects
  of lu / lc change over the past 50 years
• Improved understanding of desertification,
  including
• Changes in land performance
• Changes in ecosystem type
• Impact on ecosystem services
• Identification of environmental success including
  positive NRM impact
• Improved understanding of the socioeconomic
  driving factors of change
• Increased public awareness of environmental
  issues and land resource changes
• Work with CILSS regional and national
  environmental policy-makers to provide a better
  understanding of the changing natural resource
  base, implications for social and economic
  well-being, and implications for the future
• Improved understanding of future options based on
  geographic models that project and predict lu /
  lc trends to 2050 under various what if
  scenarios of population growth, economic
  activity, climatic conditions, and social factors
• Provide linkages between lu/lc trends and
  biogeochemical cycling, with special emphasis on
  carbon system dynamics in soils and vegetation