Distr.: LIMITED
ECA/NRD/CART.9/ETH.3 October 1996
Original: ENGLISH
Ninth United Nations Regional Cartographic Conference for Africa Addis Ababa, Ethiopia
11-15 November 1996
ASSESSMENT OF HUMAN IMPACT ON THE PHYSICAL
ENVIRONMENT USING REMOTE SENSING AND GIS TECHNIQUES
IN ETHIOPIA
ASSESSMENT OF HUMAN IMPACT ON THE PHYSICAL ENVIRONMENT
USING REMOTE SENSING AND GIS TECHNIQUES
IN ETHIOPIA
An overview report of Case Studies of the Sheraro-Humera and Tana-Beles Areas
A PAPER TO BE PRESENTED TO THE NINTH UN REGIONAL CARTOGRAPHIC CONFERENCE FOR AFRICA
11-15 NOV. 1996, ADDIS ABEBA
BY
DEGELO SENDABO
ETHIOPIAN MAPPING AUTHORITY
September, 1996
ASSESSMENT OF HUMAN IMPACT ON THE PHYSICAL ENVIRONMENT USING REMOTE SENSING AND GIS
TECHNIQUES IN ETHIOPIA
Case Studies of the Sheraro-Humera and Tana-Beles Areas
BY
DEGELO SENDABO
ETHIOPIAN MAPPING AUTHORITY I. GENERAL BACKGROUND
Rapidly growing human population, extension of arable land and similar human and natural factors have become the main factors causing decertification, deforestation and degradation of soil and for ecological and environmental changes. Additionally, the Sahara Desert is extending southward following the general trends of the above mentioned phenomena. Northern Ethiopia is within the Sahelian region of Africa, where decertification, drought, and environmental changes are rapidly creating a problem and the Sheraro-Humera and Tana-Beles areas are at the border of this Sahelian region. The areas were covered by dense forests and are still the area of the upper reaches of many rivers and streams which provide water for rivers like Tekeze and Blue Nile.
At present, many development projects, especially in farming, are taking place. Furthermore, resettlement programs have taken, place particularly in the Tana-Beles area. Because of such and similar activities, the areas experience environmental impact including degradation of soil, depletion of natural forest and reduction of the wild life in number and type.
To overcome the mentioned and similar problems, remotely sensed data, especially that from satellites, with integration of geographic information systcms(GIS). can play an important role.
The multi-temporal data from aerial photographs, maps, space photographs and satellite images using analogue and digital data processing systems and techniques help in the analysis of the past and present conditions and in the formulation of future plans for optimum use of natural resources.
The data, mainly employed in the studies are multi-temporal and multi-spectral remotely sensed
images and photographs.
II. DESCRIPTION AND ANALYSTS OF RESKARCH PROBLEMS.
There are multiple factors that created an environmental impact on the Sheraro-Humera and Tana- Beles areas. These include an increase in human population, which
leads to an extension of arable land resulting in the reduction of forest land and causes erosion, soil degradation, decrease in rainfall, increase in temperature which, in turn, affect the drainage system in one way or another. From this one can understand that the ecological system of a given area is a chain in which without one link the others may not exist or survive. The researches undertaken, therefore, answers the following questions.
- What are the main factors for sparse settlement and lower human population distribution in the previous times in the study area?
- What was the natural environment generally and vegetation, soil and drainage system specifically before human settlement like previously?
- What are the attraction or pull factors for human population in the areas?
- What changes appeared in the ecological system of the areas?
- What is the extent of the effect both with respect to time and space?
- How can remotely sensed data processing and geographic information systems help in studying and analyzing the environmental problems?
'■* What will be the future prospect of the areas?
- What measures should be taken for the protection of the environment as a whole?
■r Who will be responsible for the environmental protection and maintaing of the ecological balance?
- What other areas with similar problems and /or susceptible to similar problems can learn from
the research? .
III. THEORIES AND HYPOTHESES
The following theories and hypotheses were taken into consideration before starting the research on the Sheraro-Humera and Tana-Betes areas.
- The natural environment of the Sheraro-Humera and Tana-Beles areas is badly affected due to human and natural impacts.
- The dynamic growth of human population and global climatic changes gave rise to the need for more arable land and grazing area thus resulting in erosion, soil degradation and depletion of natural forest of the study area.
- Remote sensing techniques with integration of a geographic information system help in analyzing the multi-temporal changes which are useful in forecasting the future aspect of a given
area.
- Studies undertaken using conventional methods concerning the environmental systems are likely to be biased because they do not use multi-temporal and multi-spectral remotely sensed data
Using remote sensing and geographic information systems and techniques some modeling can be made for possible solutions to overcome the national environmental problems.
IV. OBJECTIVE
Based on the briefly stated conditions of the Sheraro-Humera and Tana-Beles areas the main objectives of the research are>
- to assess the past environmental condition of the study area;
- to analyze the present conditions of the environmental problems;
- to forecast the future prospect based on the past and present situations;
- to establish/build some models based on remote sensing and geographic information systems to overcome environmental problems of the country especially that of areas with dense forest and semi arid climates.
- to develop a database system for environmental management and monitoring.
V. METHODS AND APPROACHES.
Different methods and approaches have been applied in the studies. The major ones are:
- Digital image processing of the remotely sensed satellite data/images using ERDAS Imagine, (Earth Resources Development Analysis system) ARCINFO, MAPINFO and other relevant software as the main tools for the digital data processing and analysis. The digital image processing included different steps such as preprocessing, enhancement, training area selection, evaluation of the sample signatures, evaluation of the training samples, rectification, accuracy assessment, tabular and graphic data presentations and output map production.
- Analogue data interpretation from aerial photographs and satellite images on media such as film and paper was carried out using the available optical instruments like Bauch and Lamb Zoom Transfer Scope, Procom-2 and the likes.
- Digital to analogue conversion to produce films and paper prints was done using a film wqter and photolaboratory facilities.
- Digitizing vector information or data from the existing or newly interpreted topographic and
thematic maps;
- Reference was made to different studies on similar subject or related fields .
- Ground truth data collection was done in the study areas for data compilation, assessing additional information and to compare the expected and actual conditions of the area in the same seasons as that of data acquisition.
- Different multi-temporal and multi-spectral data or image, thematic and topographic maps and attribute data of the study area are applied in the studies.
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- Data compilation, organization and integration.
- Integrating the attribute data with the maps and establishing of database system.
- Data analysis for a research report.
VI. RESULTS AND FINDINGS
Among the findings and results of the research the following are the major ones.
- Thematic maps supported by topographic information of the areas showing the land use/ cover, soil degradation and drainage system.
- Analysis of the level of soil degradation, forest depletion in relation to human and natural
factors.
- Technical research report and modeling techniques on the application of remote sensing and geographic information systems on environmental studies.
- Comments on natural environmental impacts in the areas and recommendations on protection
and conservation of the natural environment.
- Proposal for further and detailed studies using similar and/or advanced remote sensing and geographic information system techniques in different areas susceptible to environmental
problems.
- Presentation of the data and derived information in terms of maps, tables, graphs, images and,
etc.
REFERENCES
1. Carlos R. Valenzuela (1990), Introduction to Geographic Information System. ITC, Enschede 2. Colwel, Robert N. M™'"' "f ^mote Sensing 2nd ED Vol. 1983. The Sheridan Press, Falls
Church
3. I.n r P (19861 Applied Remote Sensing Longman. Scientific & Technical, New York.
4. Mather. Paul M (1986) Computer processing & Remotely Sensed Images: an Introduction, John Willy & Sons, New York.
5. Nigusu Jobre (1994), EMA's Experience in the Production of 1:50000 Scale Photomaps using Stereo SPOT Images and GPS Survey, Geo-Information Bulletin of Ethiopia, EMA, Addis
Abeba.
6. OWolabi E.A.(1994) Challenges of Informatics Development and Exploitation in Africa, Regional Office for Science and Technology in Africa, VOL. 29 NO.l, Nairobi.
7. Paulo D. and Claudo V. eds. (1992) Resettlement and Rural Development in Ethiopia, Franco
Angeli, Milanojtaly.
8. Phil O'Keefe and Ben Wisner (1977), Landuse and Development, IA1, London, UK.
9. Sabins, Floyd F(1986), Remote Sensing Principles and Interpretation , 2nd Ed. WH Freeman and Company, New York.
NOTE:
This is an overview of the case studies. If there is an interest on the original material contact the
Ethiopian Mapping Authority.
