Seminary on Brazil
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Seminary on Brazil's land use such as Methodological courses in GIS at SahelTech


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This article is a summary of “Land use change detection for environmental management: using multi-temporal, satellite data in the Apodi Valley of northeastern Brazil” wrote by Mukesh Singh Boori and Venerando Eustáquio Amaro. In fact, we try disengaging its importance for our country “Mali in Africa” especially all scientific methods used by its experiment authors. We have been not trying to confiscate this article’s properties but we are instead showing GIS’ and Remote Sensing’s utilities to people who are interested about this subject in the other hand we try to make political decision maker paying attention about the high quality of this scientific methods for revolving environmental problems caused by agriculture extension. Please to cite the original note such as: Boori, M.S. & Amaro, V.E. (2010)-Land use change detection for environmental management: using multi-temporal satellite data in the Apodi Valley of northeastern Brazil, Applied GIS, 6(2), 1-15.
COULIBALY A.B, Student in Geography Information Systems and Management of Natural Resources at SahelTech from 2010 to 2012 under the late Professor KONATE D,responsibility President of SahelTech in Mali.



Publié par
Publié le 17 mai 2013
Nombre de lectures 45
Langue English

A People-A Purpose-A Faith

Scientia, Virtus, Labore

Applied GIS
Theme of seminary

Land use change detection for environmental management: Using multi-
temporal, satellite data in the Apodi Valley of northeastern Brazil

Wrote by
1Mukesh Singh Boori
Venerando Eustáquio Amaro
Geo-processing Laboratory, Geodynamic & Geophysics Division,
Department of Geology, Center of Exact Sciences and Earth,
Federal University of Rio Grande do Norte,
Brazil (2010)

Summarized and presented by
Amadou Bina Coulibaly

Managed by
Pr Dialla Konate

th thFrom March, 6 to April 6 2012
Bamako/Mali Contents
I) Abstract, objectives and methodology of the survey
II) Problems expressed in this study: what’s advice for our country Mali?
III) Scientific methods and variables used in this survey: Do all of these variables
have a sense in Mali?
IV) Plan of the survey
V) Role of images in the survey
VI) How this study can be used to improve the management of the environment,
of the human and natural resources?
VII) Conclusions of this survey
VIII) Can we lead the same survey in Mali?
IX) Arguments from this survey permitting to convince a Malian’s authority of
the interest of GIS
X) Comment about GIS’ utility

1) Abstract, objectives and methodology of the survey
This study is a contribution about land use and land cover in the Apodi Valley in the
semiarid region of northeastern Brazil, with geographic coordinates range from a latitude
04°55'46".77 to 05°13'39".41 south and from longitude 37°01'30".79 to 37°22'42".42 east. It
tried evaluating land use and land cover changes between 1986-2009 into using satellite
imagery data for 1986, 1989, 1996, 2001, and 2009. In fact, the maximum likelihood
supervised classification, and post classification change detection technique in remote sensing
and GIS (Geography Information System) were also used in this study. For performing the
classification results on satellite images, using ancillary data, visual interpretation and expert
knowledge of the area through GIS were done in order to map land cover in the so-called
This present survey wants to be a contribution to the survey and to the elaboration of
map of land use in northeastern in Brazil by using satellite images in the goal to contribute to
the best natural resource management. For that to make; it aims to:
 Provide a recent perspective of different land-cover types,
 Monitor 1986-2009 land-cover changes using supervised classification,
 And describe problems and make brief suggestions for improved management of
natural resources.
Firstly, the methodology research of this survey is consisted to select general and
special books or articles which have already analyzed the similar themes as Coppin, P.
(2004) about Digital change detection methods in ecosystem monitoring published in the
International Journal of Remote Sensing; Aboel Ghar, M., Shalaby, A. & Tateishi, R. (2004)
on Agricultural land monitoring in the Egyptian Nile Delta using Landsat data in the
International Journal of Environmental Studies and Lins, K.S. & Kleckner, R.L. (1996) about
Land cover mapping: An overview and history of the concepts, in Scott, J.M., Tear, T.H. &
Davis, F. (eds.) concerning Gap analysis: a landscape approach to biodiversity planning,
Bethesda, MD, American Society for Photogrammetry and Remote Sensing. This fact allows
theirs to specify what they’ve to do for getting their objectives. Thus, in this study they try
explaining insufficient you’ll probably find when you’re working with satellite data or images
in extracting information from this. For completing data research to improve image quality,
they apply some methods as supervised classifications; post-classification that Remote
Sensing’s or Geography Information System’s (GIS) software as Envi, Idrisi, ArcGis and
MapInfo offers us. 2) Problems expressed in this study: what’s advice for our country Mali?
For many countries in the world agriculture was an important engine for economic
development, and the livelihood of rural populations and the welfare of entire countries
critically depend on agricultural productivity. At the same time, agricultural practices have
enormous consequences for natural systems and threaten the natural resource in many regions.
This fact was consented in northeaster Brazil about 25 years by a multitude of problems as
major disturbances, both natural and manmade-drought, civil disturbances leading to
migration, large population increases and globalization. Each of these has had implications for
land use requirements, with subsequent impacts on natural vegetation cover, biodiversity
socio-economic stability and food security. Thus, in this survey they want to resolve this
problem even reduce its ampler by using satellites data and making map which exposes the
evolution of each phenomenon and its impact each other on northeastern Brazil’s land.
Besides this survey is fundamentally significance for Mali, so given the importance of
agriculture for sustainable development in this country, it is paramount to make map of land
use and land cover to monitor and assess the natural and economic impacts of environmental
change by using satellite images. Another importance of this survey for Mali is to allow
political and administrative authorities being able to detect very quickly the problem and to
make real decisions at any times while supervising environmental evolutions. This fact
diminishes the economic wasting.
3) Scientific methods and variables used in this survey: Do all of these variables
have a sense in Mali?
As we said at the beginning, methodology research was done on general and special
articles. So the main method in this study has consisted to analyze satellite data for the study
area with Remote Sensing’s software as Envi by applying the maximum likelihood supervised
classification, and post classification. In this logical, they proceed by using orbital images of
Landsat TM, ETM+, Spot 4-HRVIR, IKONOS and CBERS 2B satellite data. Then for
secondary data collecting they used SB-24-XB-IV, SB-24-XDI, XDI-SB-24-1-2 and MI-897-
2 topographic sheets. After that, Digital image processing was performed using the ER
Mapper 7.1 software, which involved geo-coding using the UTM (Universal Translator
Mercator) cartographic projection zone 24S-Datum SAD-69 with the Root Mean Square
(RMS) error being less than 1.0 meters. At the ending of this step, a Global Position System
(GPS) with an accuracy of 10 meters was used to map and collect the coordinates of
important land use features during pre- and post-classification field visits to the study area in order to prepare land-use and land-cover maps. The area was classified into fifteen main
classes and each class reflects and introduces one phenomenon as below:
1. Wetland: Land whose soil is saturated with moisture either permanently or
seasonally, so such areas are covered either partially or completely by shallow pools of water.
2. Agriculture: Areas cultivated with annual crops, vegetables, or fruit
3. Forest (CAATINGA): Small trees and shrub vegetation area except for savanna
4. Exposed soil: Land areas of exposed soil surface influenced by human impacts
and/or natural causes, containing sparse vegetation with very low plant cover due to
overgrazing and woodcutting
5. Fixed dunes: Vegetation has developed on dunes so that it forms a more or less
complete cover of the substrate
6. Industry: Shrimp, salt and other economic activities
7. Pond: Permanent or temporary water body
8. Mangroves: Small trees and shrubs grow near the saline coast line and river
9. Mobile dunes: Dunes without vegetation
10. Ocean & river: The Apodi River and its mouth to the Atlantic Ocean
11. Petroleum: Oil and natural gas
12. Salt: Transitional areas between land and water, occurring along the intertidal
shore of estuaries and sounds where salinity ranges from near ocean strength to near fresh in
the river area
13. Shrimp: Aquaculture sites that cultivate marine shrimp or prawns for human
14. Stabilized pond: Permanent water bodies for industrial purposes
15. Urban: Includes construction activities along the coastal dunes (summer resorts)
as well as sporadic houses of the Bedouins within the local villages and some governmental
buildings in the main cities of Mossoro, Areia Branca and Grossos.
With these methods they were able to determine exactly changes by percentage of
every class and then to locate in map during four intervals: 1986-1989, 1989-1996, 1996-
2001, and 2001-2009.
All of these variables above constitute an interest thing for the world’s land use and
land cover study but there some of its which get a sense for our country Mali, among those we
can notice variables of agriculture, of wetland, of exposed soil, of fixed dunes, of mobile
dunes, of pond and of urban. Generally, agriculture is livelihood in Mali and particularly rural people’s occupations about 80 percent. Thus, this study can help Malian’s people to increase
their agriculture productivity, to improve annual crops outputs and to reduce environmental
deterioration. Concerning wetland, in Mali it is the reason of agriculture existed and it is very
important too. Indeed, with fluvial law, Niger’s river is the main river which waters
agriculture area in Mali. That means you need to follow the variation of annual pluviometer
and satellite images allow us to do it. Exposed soil joins agriculture which is very extensive in
Mali. This fact means you have to practice more wood cutting for making crops area. With
this survey, we can avoid damage as dryness and drought. Mobile dunes and fixed dunes both
of these exist in Mali particularly to the northern. Thus, by using Remote Sensing’s and GIS’
data we get the opportunity to follow the evolution of dunes, and its impacts on the
agricultural area and to know exactly how to do? Where you have to do? And when that is
better to do to regenerate forest even vegetation by planting trees?
4) Plan of the survey
It is structured as following:
1. Introduction
2. Study area
3. Methods
3.1 Data sets
3.1.1 Image classification
3.1.2 Land use change-detection maps
4. Results and discussion
4.1 Major problems in the Apodi Valley region’s eco-environment
4.2 Suggestions for local eco-environmental management
5. Conclusion
5) Role of images in the survey
The images or pictures even figures in this study constitute the supports. These explain
exactly what was written. Indeed, methods used in this survey were ended by dividing study
area to fifteen classes. Every class has colored by a specify color and has been taught us about
one phenomenon. Thus, we can see exactly which is very important and then making a
comparison between different phenomena in space and in time on different dates in Apodi
Valley region of northeastern Brazil. Example: the first image locates the study area in Brazil, in the world and the last one
is about variables or classes found by classification’s methods. Here is the role that image are
in this survey. Cf. to figures below:

6) How this study can be used to improve the management of the environment, of
the human and natural resources?
Remind that this survey is about land use change detection for environmental
management in the Apodi Valley region of northeast Brazil. Indeed, their authors used some
methods such as supervised classification, post-classification etc. on the satellites data on
different years for 1986, 1989, 1996, 2001, and 2009. This fact allows theirs to attain the
objectives that they fixed at the beginning. Therefore, with these Scientifics methods, it becomes possible to make regional survey on a variety of themes and identification of
features such as landforms on the one hand and to study also dynamic themes like water,
agriculture, land degradation, urban development on the other hand which are encompassed
under natural and human-induced effects. It also permits easy acquisition of data over
inaccessible areas. Thus, the remote sensing and GIS constitute today dynamics tools for
environmental studies. This fact is very economical and very faster.
7) Conclusions of this survey
The study concluded by showing the results of every class or variable and the reason
of its increasing and decreasing. Indeed, for a total area of 1372.8 square kilometer (km²),
forest area was 692.9 km² (50.54%) in 1986; 677.3km²(49, 4%) in 1989; 623.9 km² (49.9%)
in 1996; 616.5km²(45.4%) in 2001 and 724.3km²(52.84) in 2009. So we notice that the rate of
forest decreased from 1989 to 2001. This fact explains by human pressures with urban
development. But it starts to increase in 2009 because governmental political about protection
rules of environment. Then agricultural area was 234.20 km² (17.1%) in 1986;
192.6km²(14.0) in 1989; 244.62 km² (19.58%) in 1996, 242.3(17.8) in 2001 and 189.51 km²
(13.8%) in 2009. So the agricultural area is initially increased from 1986 to 1996, but it then
decreased from 2009. The urban area covered 18.74 km² (1.36%) In 1986, but by 2009 it had
increased to approximately 53.50 km² (3.88%). This fact explains why agricultural area has
been decreasing. It could be also one of the reasons of political motivations to preserve
environment. The wetland area was 151.83 km² (11.05%) in 1986, but it decreased to 3.51%.
that’s due to varying precipitation and temperature. Then salt area was 149.2km²(10.9%) in
1986 and still decreasing to 10.0% in 2009. So it is approximately stable but, due to market
demand, it has been slowly replaced by shrimp farms since 2001. This one represented
10.5km²(0.8%) in 2009. Fixed dunes have continuously decreased to (1.6%) from 1986 to
(0.9%) 2009 and mobile dunes have continuously increased to 0.7% from 1986 to 0.9 %
(2009), which is an indication of climate change in the area. Industry first appeared in 1996
with approximately 0.6 km² (0.04%), and it then continuously increased to reach 3.3 km²
(0.2%) by 2009. Then, we have to notice that the biggest change occurred in the petroleum
area; it was 1.1 km² (0.1%) in 1986, it is now 77.9 km² (5.7%) and it is still continuously
increasing. Ocean & river area was 53.3(3.9%) in 1986 and still increasing to 4.9% 2009.
Exposed soil, mangroves, ponds and stabilized pond are sometimes decreased and increasing
too. In summary, and about percentage terms, we note that the dominance of agriculture and
forests changed little between 1986 and 1989, but between 1989 and 1996 reclamation
accelerated and the construction of new agrarian communities began. Then, between 1996 and 2001, because the whole infrastructure of the Apodi Valley regional area was now completed
impressive rates of change were observed. Around 43.8% of the land (other than forests and
agriculture) in 1996 was developed to other classes by 2001. Due to the remarkable change
which occurred during this period, areas of no-change represented 87.0%, and the changed
area represented 13.0%. Finally, from 2001 to 2009, changes in land cover also took place,
but at an even faster rate of change than in the 1996-2001 periods. By 2009 shrimp farms and
stabilized ponds had appeared as new classes, and land degradation had increased. So the
unchanged area represented 56.1% (729.3 km²) of the total area, whereas the changed area
represented 43.9% (643.6 km²) of the total area.
Over the last 25 years unprecedented land cover and land use changes have occurred
within the Apodi Valley region. These changes are due to the development projects of the
agricultural, industrial and tourist kinds. It has been also both human and natural even socio-
economic impacts. A high rate of population increase, economic development and
globalization on one side, and natural hazards such as floods, landslides, drought and climate
change on the other have continuously and are still eroding northeast Brazil’s natural
ecosystems and resources. Brief the development of agricultural area and industry makes the
concentration of population around these areas. This fact produces on it turn environmental
degradations. Finally, we need remote sensing’s and GIS’ data such as tools to solve this
problem. This problem needs also to be seriously studied, through a multi-dimensional
approach that includes socio-economic considerations, in order to preserve the newly
reclaimed land and increase food production.
8) Can we lead the same survey in Mali?
By following the Scientifics methods used in this study and according to our reality
the same survey can be led here. Indeed, Mali is the south part of Africa and it is crossed by
Niger’s river with a lot of potentialities such as arable area, pasture, and fishing. These
resources are threatened by natural and human pressures such as urban development and
constitute the reason of many conflicts in Mali. Thus, the satellite data can be used in an
operational information system in Mali for different applications of which geology, forestry,
the follow-up to long term of the soil utilization, agriculture etc. which allow us to improve
management of natural resources.
9) Arguments from this survey permitting to convince a Malian’s authority of the
interest of GIS
Since the end of sixties, the intertropical area of the world in general and of Africa
particularly has been undergone a process of visible desertification under the shape of the