|Social and Environmental Aspects of Desertification (UNU, 1980, 38 pages)|
Study Group on Climate and Desertification
Leader: Professor P.D. Tyson
The members of this study group are:
|Dr. T.G.J. Dyer||University of the Witwatersrand, Johannesburg, South Africa.|
|Dr. M.H. Glantz||National Center for Atmospheric Research, Boulder, Colorado, USA.|
|Mr. A.T. Grove||University of Cambridge, England.|
|Mr. D. Lee||Commonwealth Bureau of Meteorology, Melbourne, Australia.|
|Professor D. Sharon||Hebrew University of Jerusalem, Israel.|
|Professor H. Suzuki||University of Tokyo, Japan.|
|Professor P.D. Tyson||University of the Witwatersrand, Johannesburg, South Africa.|
The study group was formed in 1976 following the Ash. khabad meeting of the Working Group. The intention was to encourage research of various kinds relating to the general theme of climate and Desertification (including semi-arid areas). The meteorological and climatological framework into which the individual studies fall has been well developed by Hare in his background review on Climate and Desertification presented to the United Nations Conference on Desertification in Nairobi in 1977.
The work of the study group covers a wide field of interests including Quaternary lake-level fluctuations, coastal upwelling and deserts, the nature of desert rainfall, synchronization of Desertification in the world, estimation of the likelihood of extended drought conditions in southern Africa, climate and crop yields in semi-arid regions and monitoring rainfall deficiencies in semi-arid regions.
The projects are as follows:
Quaternary Lake Level Fluctuations: A.T. Grove In a paper in 1976 on late Quaternary lake level fluctuations in Africa, Street and Grove showed how much of Africa has experienced quasi-synchronous changes in lake levels over the last 30,000 years. This work is being extended to include global lake levels in the Late Quaternary.
Coastal Deserts: M.H. Glantz Research is being conducted on coastal upwelling of cold water and its influence on coastal deserts along with desertification.
Desert Rainfall Patterns: D. Sharon Two main investigations have been conducted. The first is concerned with the analysis of daily rainfall in a desert area and the determination of localized rainfall distribution or spottiness. The second is concerned with the mesoscale structure and life history of Negev storms.
World Patterns of Desertification: H. Suzuki The question of synchronization of Desertification is being considered. The extent to which the less advanced northward extension of the Equatorial Westerlies during the 1968 to 1973 period has had world-wide repercussions is under examination.
The Likelihood of Extended Droughts in the 1980s in Southern Africa: P.D. Tyson Maps to show the temporal and spatial variation of rainfall over the sub-continent from the midnineteenth century onwards have been prepared. The use of a simple model suggests that the decade from 1983 onwards may be one in which about seven to ten years will be drier than average.
Monitoring Rainfall Deficiencies: D. Lee In this study the decile values of rainfall are used to provide the basis of quasiforecasts of the probability that areas will be deficient in rainfall for specific periods.
Crop Yields and Climate: T.G.J. Dyer Linear multiple regression models in which combinations of mid season rainfall and temperature are taken as predictor variables are being formulated and used to predict end-season crop yields. Preliminary results suggest a surprisingly high proportion of crop-yield variance can be accounted for in this way.
The research findings of individuals in the study group have been presented at national and international conferences, and more than a dozen papers have been published in scientific journals.
Study Group on the Perception of Desertification
Leader: Dr. R.L. Heathcote
The members of this study group are:
|Mr. M. Butler||Adelaide College of Advanced Education, Adelaide, South Australia.|
|Dr. R.L. Heathcote||Flinders University of South Australia, Adelaide, South Australia.|
|Mr. S.P. Malhotra||Central Arid Zone Research Institute, Jodhpur, India.|
|Professor T.F. Saarinen||Department of Geography, Regional Development & Urban Planning, University of Arizona, Tucson, USA.|
|Mr. M.U.A. Tennakoon||Central Bank of Sri Lanka, Colombo, Sri Lanka.|
Since much of the work of this study group has been in the form of studies commissioned under the Natural Resources Programme of the United Nations University, and in view of the fact that work by other members is reported elsewhere in this publication, the main report of the study group is included in the United Nations University Session.
Study Group on Pastoralism and Desertification
Leader: Dr. Douglas L. Johnson
The members of this study group are:
|Dr. E. Bernus||ORSTOM, Paris, France.|
|Dr. J.S. Birks||University of Durham, England.|
|Dr. D. Campbell||University of Nairobi, Kenya.|
|Dr. D. Chatty||University of Damascus, Syria.|
|Professor R.J Harrison Church||London School of Economics, England.|
|Dr. W. Fricke||Heidelberg University, Federal Republic of Germany|
|Dr. D.L. Johnson||Clark University, Worcester, USA.|
|Dr. M.M. Khogali||University of Khartoum, Sudan.|
|Dr. A. Schmueli||Tel Aviv University, Israel.|
|Professor B.W. Spooner||University of Pennsylvania, Philadelphia, USA.|
Dr. Johnson reported that the focus of this study group was the response of traditional pastoral nomadic systems to change and the implications of this response for desertification processes. Several recent studies emphasized the ability of traditional pastoralists to assess the carrying capacity of grass and water at their disposal and maintain rotational grazing that avoids environmental deterioration. Whilst some of this balance may have been an inadvertent byproduct of pastoral nomadic mobility, the result has been a dynamic equilibrium in most drylands until the early twentieth century. Even in terms of off-take rates from traditional rangelands, the record has been one of consider able productivity.
There seems little doubt that the picture of traditional rangeland users as
rational and productive exploiters of dryland Pesources is well-founded.
However, the systems that are adaptive under one set of socio-economic
circumstances may be less successful when conditions change. Herein lies the
current focus of the study group's investigation, which has concentrated on two
types of adaptation to change:
(1) situations where livelihoods change and population concentration occurs, and
(2) instances where dispersed resource-use strategies are maintained.
In the first case, pastoral nomads are increasingly responding to change by opting out of the nomadic way of life through sedentarization or by introducing technology in ways that encourage local concentrations of people and flocks. In both instances the result is excessive pressure on local environments, leading to accelerated environmental degradation. Characteristically, the sedentarization of nomadic groups leads to rings of deteriorated vegetation close to the settlement, as fuelwood collection increases and grazing pressure is locally intensified. In other instances, introduction of concentrated inputs such as wells results in serious local disruption when land-use control mechanisms are not introduced simultaneously.
Two types of change affect pastoralists attempting to retain a dispersed and mobile pattern of land use. The expansion of dry-farm agriculturists, the conversion of dry-season pasture to alternative land uses, and the loss of control over open rangeland as a result of nationalization and the collapse of traditional tribal authority, have put traditional nomadic communities under significant stress. All of these processes have one common feature: they remove critical resources from traditional patterns of use and control. The amount of land alienated to alternative use is less important than its critical role within the traditional pastoral system. The alternative land-use systems and development projects may be productive in at least the short term, but the adverse social and environmental consequences are frequently experienced in pastoral areas and populations far removed from project boundaries.
The second type of change concentrates on using traditional pastoral systems as the basis for new rangeland development. Few examples of this type of concern have yet come to light, although Syrian pastoral co-operatives offer some indication of movement in this direction. By restoring local control over rangeland resources and retaining modified mobility patterns, some of the worst aspects of rangeland deterioration can be avoided and desertification potentially reversed.
The projects are as follows:
Sedentarization and Desertification: A. Schmueli
Dr. Schmueli has studied Bedouin sedentarization in the Judaean Desert for the last 20 years and has more recently investigated the relationships between sedentarization and desertification in the Sinai and Negev deserts.
Migrant Studies: J.S. Birks
Previous investigations focused on migrants to Mecca in the Sahelian-Sudanic zone and socio-economic change among pastoralists in Oman. His current activity is participation in the International Migration Project which is examining labour migration in the Persian Gulf.
Pastoral Adaption to Modern Market Systems: D. Chatty
After initial studies in the Bika Valley, Lebanon, including transportation technology, Dr. Chatty has begun an investigation of pastoralism in northern Syria, as well as the development of pastoral co-operatives in the Homs-Hama area.
Resource Competition between Pastoralists and Sedentary
Farmers: D. Campbell
Dr. Campbell is presently examining competition between the Masai and adjacent agriculturalists. Response of pastoral nomads to drought in Maradi, Niger, from 1968 to 1973 was the focus of an earlier study.
Pastoral Development and Drought in Northern Nigeria: W. Fricke The final report of this investigation is about to be published
Nomadic Pastoralism and Desertification: M.M. Khogali and E. Bernus
Dr. Khogali is involved with the SwanseaKhartoum Research Project which includes a pastoral component as well as a more general examination of this theme in the Sudan.
Dr. Bernus is carrying out a study in the Tuareg area of Niger.
Sahelian Drought Recovery: J. Sutter
Dr. Sutter has worked for three years on a pastoral development project in Niger concentrating particularly on nomadic recovery and also on changing terms of trade between nomadic and settled populations.
Well Development: R.J. Harrison Church
Dr. Harrison Church is examining well development policy in West Africa.
Study Group on Desertification in Extremely Arid Environments
Leader: Professor Wolfgang Meckelein
The members of this study group are:
|Dr. W. Achtnich||University of Hohenheim, FederaI Republic of Germany.|
|Dr. J.W. Allan||University of London, England.|
|Professor E. Ehlers||University of Marburg, Federal Republic of Germany.|
|Mr. O.A.H. Ghonaim||University of Alexandria, Egypt.|
|Professor I. Kobori||University of Tokyo, Japan.|
|Professor W. Meckelein||University of Stuttgart, Federal Republic of Germany.|
|Mr. C. Nesson||University of Bordeaux, France.|
|Professor W. Ritter||University of Regensburg, Austria.|
|Dr. E. Wehmeier||University of Stuttgart, Federal Republic of Germany.|
Until recently, attention has been given almost exclusively to desertification problems in the marginal zones of arid lands, yet desertification has been increasingly reported from within the deserts proper; that is from the extremely arid areas. Deterioration or shrinkage and abandonment of the cultivated areas have been observed in isolated small and large oases and across oasis regions. The reasons for this are manifold and relate to the field of physical geography as well as that of social and economic geography.
To limit the scope of the work and objectives of the study group, it was recommended that research should mainly concentrate on relationships between desertification within oases and utilization of water resources. It was considered that, eventually, another item might be the threat caused by shifting sand. Problems of water supply may be connected for example with natural or artificial lowering of the groundwater table, but a surplus of water may also have disastrous effects, causing a rise in the groundwater table and a salinity hazard in the soils.
Such phenomena of desertification are increasing and have contributed to a profound crisis of oases, most evident in the deserts of North Africa and the Middle East. A detailed analysis of causes and effects of desertification within oases is therefore extremely important. In North Africa alone, more than two million oasis dwellers are affected, not to speak of the 38 million Egyptians in the Nile Valley oasis and 500,000 nomads in the Sahara desert who are also dependent on oases. These figures underline the importance of the work in progress, which is significant because it has a direct bearing not only on the oases themselves but also on the utilization of resources in the surrounding extremely arid areas. A number of case studies have been initiated to tackle the problems mentioned above. They have been care. fully selected according to the following criteria: - first, all the important countries affected should be represented; - second, the case-studies should cover as many different aspects as possible. Both human and natural aspects of desertification have been examined.
The projects are as follows:
Desertification in the Oasis Regions of Gourara and Touat, with Special Reference to Water Storage and to Water Salinization, and also to Problems of Moving Sand: Wolfgang Meckelein, in collaboration with Mrs. A. Kirchner Field studies were carried out in the spring of 1978. Water samples were brought to Stuttgart and analyzed there. It appears that soil salinization is favoured not by water shortage but by bad irrigation and drainage techniques. In the area of Gourara, moving sands are also causing the abandonment of cultivated land. Here the formation of dunes close to the oases seems to be induced by man himself, in that artificial obstacles designed to protect against shifting sand lead to the formation of larger dunes which then endanger the oases.
Desertification In and Around the Aoulef Oases: Iwao Kobori
The paper deals with the Tidikelt area, one of the older oasis regions in the Western Sahara. Professor Kobori has worked there intensively and has also published some of his results.
Desertification in the Oued Righ, Northeastern Algeria: Claude Nesson
A publication will give examples of desertification from the oases of Oued Righ. Areas will probably be mapped to show where desertification has occurred already and those in which the process is presently active. Relationships will be documented between the phenomena of desertification and the withdrawal of groundwater, resulting in important lowering of the groundwater table and in harmful physical and cultural consequences. As a contribution towards remedial programmes, this case-study will offer a deeper insight into the dangers inherent in certain kinds of human interference, and demonstrate the possibilities of preventing and solving such problems in new reclamation projects.
Desertification Phenomena in the Northern Oases of the Nefzaoua Region, South Tunisia: E. Wehmeier A detailed description and explanation of the present water situation in the area is given. Two generations of aerial photographs (1949, 1969),, as well as two field trips (1975, 1977) and data from the Tunisian Service de l'Eau, have helped to establish deeper understanding of the connections between groundwater extraction and fluctuations in the irrigated area.
Changes in the Oases of Southern Libya: J.A. Allan Data have been established on relationships between the development of water resources and the desertification processes in the west and east of southern Libya.
Surplus of Water as a Main Cause of Desertification in the Siwa Oases:
Field studies were carried out in 1974, 1976 and 1977. The results so far show that increasing salinization is caused by rising groundwater. The high groundwater level itself results from a number of newly drilled wells, the water of which is only partly used or not at all. On the other hand, the abandonment of peripheral irrigated lands frees formerly-used spring water, and this also contributed to the water surplus.
Desertification Phenomena in a New Desert Reclamation
Project: Wolfgang Meckelein This study aims to find out why this new desert reclamation project, established with modern techniques, suffers from soil salinization and moving sand. One publication on this project appeared in 1977.
Did Araoian Oases Run Dry?: W. Ritter
A number of important oases in central and eastern Saudi Arabia owe their existence to fossil (?Pleistocene) groundwater issuing from karst springs. Observations in Ghatghat, Aflaj, Wadi Miyah, Yabrin and Bahrain show that during historical times there existed either higher-located aquifers and springs, or even higher-yielding ones than today. In some of these areas irrigation is practiced today only by flooding, and deep wells need to be drilled. These observations are backed by aerial photographs which show remnants of settlements and fields, tells, qanats, and groups of burial mounds. It remains open to debate whether the reason for the abandonment of settlements and oases was a gradual diminution of the fossil water resources or socioeconomic factors.
Protective Measures Against Desertifications in Irrigation Agriculture as Exemplified in Al-Hassa Oasis: W. Achtnich During several years on a pilot farm in the Al-Hassa area, the opportunity was taken to carry out studies into the prevention of Desertification by different methods of stabilizing the soil. This work is incomplete.
Oases of Bam in Central Iran: E. Ehlers
This study aims to depict economic and social-geographical structural changes due to land reform and the installation of pumps. The problems studied include: traditional aspects of the rural structure; effects of land reform such as decrease in cultivated areas, out-migration and the growing of specialized crops; and the installation of pumps and its consequences, including lowering of the groundwater table, concentration of irrigation agriculture in the hands of former landlords and increased social disparities.
It is proposed to publish the various case-studies in a single volume to be ready on the occasion of the International Geographical Congress in Tokyo in 1980. The volume will be furnished with an introduction on the general problems of Desertification in extremely arid environments and contain a concluding chapter dealing with the results and consequences of the various research activities.
Study Group on Wind Action and Desertification
Leader: Dr. Monique Mainguet
The members of this study group are staff of the Laboratoire de Geographie Physique Zonale (LGPZ), Reims University, France, as follows:
J.Y. Le Merrer,
Dr. Mainguet reported that this group had been carrying out studies of aeolian processes in the Sahel and adjacent arid regions, and that the work had involved mapping and systematically classifying dune types, determining the palaeoclimatic inheritance in present landscapes, studying external processes, principally wind action and mechanisms of wind erosion, and formulating measures to reduce the desertification hazards resulting from drought stress and land use respectively. In particular, with the support of the French Direction Générale a la Recherche Scientifique et Technique (DGRST) over the last three years, the study group has been engaged in a country-wide study of wind action in Niger Republic in relation to natural and human factors, part of the findings of which were used in the Niger Case Study for the Nairobi Desertification Conference.
The projects are as follows:
Bibliography on Aeolian Phenomena and Measures to Combat Wind Erosion: M. Mainguet, M. Callot and L. Canon A bibliography of 4,500 items, on aeolian phenomena in the Sahel region and measures to prevent wind erosion, has been completed for publication.
Mapping of Soil Degradation from LANDSAT Imagery: M. Mainguet and L. Canon Mapping of soil degradation from LANDSAT imagery has been carried out in collaboration with FAO and UNEP. The mapping, at a scale of 1:5 m, has been in Chad, Central African Empire, northern Niger, Upper Volta and eastern Mali.
Agricultural Development in the Mayahi Region, Niger: M. Mainguet, L. Canon and M C. Chemin The above-named, with support from staff of LPGZ, have collaborated with the Groupement d'Etudes et de Recherches pour le Développement de l'Agronomie Tropicale (GERDAT), the Institut de Recherches Agronomiques Tropicales et des Cultures Vivrieres (I RAT) and the Universities of Strasbourg and Bordeaux in a project for the development of this agricultural region. The study has involved mapping landforms and their dynamic status as a measure of the inherent stability of landscapes under development.
Sand Encroachment in Oases of Southern Morocco: M. Mainguet At the request of FAO, Dr. Mainguet took part in a project on problems of sand encroachment in oases along the Wadis Draa and Ziz. This work is described in a contributed paper under Physical Aspects of Desertification in this publication.
Field Studies of Aeolian Processes: M. Mainguet, L. Canon, A.M. Chapelle and M.C. Chemin Wind and rainfall records (1965 to 1975) of principal stations in Niger have been analysed. In the Niger Sahara, a quantitive analysis of sand found at the extremities of tracts affected by dominant wind currents has been completed by Dr. Mainguet. An investigation into the dynamics of ergs and dunes has been conducted on the Erg of FachiBilma (Chad-Niger) by Dr. Mainguet and Y. Callot. With L. Canon, Dr. Mainguet has produced a map of the extent of reactivation of sand mantles in relation to external dynamics and land development in the region of Eghazer and Azaouak, Niger, which was used in the Niger Case Study for the UN Desertification Conference. The installation of sand traps is planned in Upper Volta, to further the study of the aeolian processes involved in desertification.
Long-distance Wind Transport of Sand as Detected by Satellite Imagery: M. Mainguet, L. Canon, and M.C. Chemin Satellite imagery has been used to identify vast trans-Saharan arcs within which wind action is concentrated, and along which sectors of predominant erosion, transport and deposition can be distinguished.