Arid zones are not uniform.
There are at least four primary groups:
1. Hot, dry global zones bounding both sides of the tropics, as in North Africa and the middle East.
2. Cold, continental dry zones, as in central Asia and central Australia.
3 Cold, upland dry zones, blocked by high mountains, such as in central Anatolia.
4. Cold and dry polar zones, such as those in northern Canada and at the poles.
Common to all these are dryness, diurnal fluctuation in temperature, and the resulting stressful climate. This chapter, is primarily concerned with the first type – hot, dry zones.
Hot, dry arid zones are those areas where the average rate of evaporation is higher than the average annual rate of precipitation, where the annual rate of precipitation does not sufficiently support dry farming, where temperatures between day and night vary greatly, and where high degrees of solar energy radiation are experienced, especially during the summer.
The little rain which does fall in the arid zone is sparse, torrential, turbulent and brief.
Half of the world’s states have part or all of their territory within arid zones. The desert contains 15 per cent of the world’s population and more than one-third of the world’s land mass, Twenty two per cent of all potentially arable lands, or roughly 700 million hectares (ha), are in arid or semiarid zones (Table 1-2). Arid and semiarid areas contain most of the world’s oil reserves.
The arid zones are not homogeneous in their resources. The most dominant of their features is the stressful conditions of their climates. It is also true that most arid land has much uncultivable land.
Such land requires large investments in fertilizers, in watering, and in special treatments. Among all the arid-zone resources, the most available and reliable is solar energy, which technologically we are just beginning in be able to use.
In the past, the survival of civilization in arid zones depended primarily on man’s understanding the delicate environment and establishing an equilibrium between society and that environment. Disruption of this balance, led to the collapse of those societies.
In this delicate environment, only industries which can meet the established ecological planning goals and standards should be accepted. Land, water or air pollution industries must be prevented from being constructed in the region.
Potential of arid zone:
In hot dry regions there can be seven areas- solar radiation, wind energy, recreation, agriculture, mining, new settlements and air navigation of advantage for potential development. The year around cloud free sky and the corresponding high solar radiation provide potential for a variety of agricultural uses, such as food dehydration, grain drying and evaporation for desalination of water.
Grain drying for example nut of Araca catechu are dried at Bikaner a station in Thar desert by hot air, heated by solar energy. With technological improvements in irrigation, desalination and the use of brackish water, the hot arid areas offer new potential for food production.
Wind energy is an endlessly abundant resource. The intensity of solar radiation throughout the day and the extreme diurnal temperature produce active aerodynamics which support the use of wind energy at the local level at least.
The different forms of wind mills used throughout history and are known as: Persian sail windmill ‘Dutch’ windmill, Mediterranean sail windmill, American farm windmill, Flettner Rotor, Savonious Rotor, Jacobs Wind Plant, Darrieus Rotor, Smith-Putnam Wind Turbine, Venturi Shrouded Wind Generator, Enfield-Andreau Wind Turbine (1954), Hutter Wind Turbine (1961), Wind works 12 Footer (1973), Princeton Sailwing (1974), SST Wind Turbine (1974),Noah Wind Rotor (1974), and NASA 100 kw Wind Turbine (1975). Arid zones have much potential wind movement, which can be utilized by wind mills.
The cloud-free, rarely stormy skies of the hot, dry climates could provide an excellent location for air navigation centres, both military and civilian.
Finally, arid zones contain potential space for future settlements and large-scale development. The availability and low price of land, as well as the healthful climates, when contrasted to the existing congestion of urban settlements in non-arid zones, make the arid zones highly suitable for future tourism, recreational and health centres, as well as permanent settlements.
Policy for Arid-Zone Development:
Policy is the framework necessary to unify, diversified parties under one umbrella toward, common goal. A policy must be general as well as functional. Because arid zone development requires immense resources and effective planning and coordination, it is doubtful that the arid zone can be developed to meet its potential without a national policy.
Moreover, because of its delicate ate ecological equilibrium, the necessity for a coordinated policy becomes essential. The land’s mostly virgin and empty nature and public ship make such a policy feasible. And zone development may seem to be a national-local or regional endeavour, the policies for arid land development stem from four universal ems.
These four well-known universal needs are caused by population growth, increased food consumption, the shortage of energy resources and in. leasing consumption of space for the expansion of settlements, especially the urban type.
The world’s population is growing faster now than in any other period story, and a large portion of this growth is in regions considered to be semiarid. The arid-zone developing countries such as India, Iran, Egypt and co have also been facing serious population growth in the recent decade land has the definite potential for absorbing population growth.
The periodic famines throughout the world in developing countries are, unfortunately, well known. Food shortage crises associated with rapid population growth make the arid and semiarid zone an attractive; for mass food production technology perfects the effective use of i houses and drip irrigation using desalinated and brackish water for of season crops and for year round cultivation,
World consumption of natural resources, especially minerals, is rapidly increasing. A reasonable portion of these resources, such as oil, which has not yet been depleted exists in arid and semiarid lands. World energy crises have accelerated the search for alternative energy sources. Solar radiation is already technologically and economically feasible, at least on a small scale, for house heating and cooling and even cooking.
Space for future settlement expansion, especially urban expansion, is available in arid zones. The development of arid zones seems unavoidable. In fact, urban planners, developers and decision makers are already involved in such development on a large scale in India, Iran, the Middle East, the Southwestern United States, Mexico, South America and Australia.
The conditions result from socioeconomic, political and other forces rather than from climatic conditions only are:
1. Coexistence of traditional agriculture of many types and mi livestock.
2. To resettle the nomads.
3. Low income per capita and a simple standard of living as a way of life.
4. Exploitation (and eventually depletion) of natural resources for economic benefit (of the public or private sectors) without any socioeconomic comprehensive plan after such exploitation ends.
5. Little or no research except in a few countries.
6. Haphazard planning coming mostly after catastrophic events such as drought; no comprehensive multifaceted planning and development.
Many facts of new national and international economic, social, and political developments since the end of World War II have brought about dynamic changes which have influenced the arid zone.
1. There is the research, planning and development effort initiated by the United Nations and its various agencies in the arid zone, especially in the developing countries of Asia, Africa and South America.
2. Many of the arid zone countries who were colonized (such as in the Middle East and North Africa) have become independent. The new political situation has led to the formulation of national planning policies and a native effort to implement them and has generated considerable construction.
3. The intensification of transportation development (especially air transportation) and the increased seasonal recreation of the middle class in developed countries have accelerated tourism in some developing arid zone countries especially those with ancient archaeological sites, such as India, Egypt, Israel and Iran and those which serve as seasonal recreational centres.
4. The development of the world economy has increased the dependency among nations, but has also supported the new economic concept that development in general (and that of the mineral industries in particular) may not depend only on local materials but also on imported resources, e.g., in Israel.
5. The accelerated advancement of new technology has benefited agriculture and other areas of development in the arid zone. Drip irrigation greenhouse agriculture, and new modes of transportation are among those developments.
6. The improvements in political, economic and especially health management in many of the developing arid regions have responded in national population growth. Urban growth has been accelerated by the non-orderly urbanization movement which is creating pressing needs for planning d for improvement.
All in all, the recent four decades of development have seen an evolution of new trends in arid zone construction throughout the world.
The study of these trends reveals the following:
The arid zones development potential is not primarily in agriculture because the land and the scarce water pose problems. Rather, the potential is r heterogeneous land uses with agriculture being only one possibility.
Since the 1973 world fuel crises, the world’s attention has focused on e importance of world oil reserves found mostly in the arid zones of the Middle East, Iran and North Africa. Also, increasing research has been focused on the possible uses of solar energy on both household and industrial levels. In the arid-zone solar energy is the freest and most readily available energy. Wind energy is also available in many arid regions.
Recreation and tourism:
This new trend has accelerated immensely in both developed countries such as the South-western United States and developing countries such as India, Egypt, Israel and Iran. Although these trends are global, the arid zone’s warmth throughout most of the year has provided good seasonal vacations for resident of cold climates.
Recreation and tourism are usually associated with high standards of services such as hotels, restaurants and transportation, New job opportunities and economic growth result from tourism,
The growth of settlements in arid zones, both of established and new ones, is noticeable. Many new cities have been built in the arid zones of Iran, Pakistan, Israel, Egypt and Australia. For aria zone panning and building, the lessons to be learned from the cities built by the ancient civilizations of the arid zones.
National New Policy Formulation:
The policy formulation for the development of arid zones differs from one nation to another since the motivations differ.
Some of these motivations are following:
Exploitation of natural resources such as oil, gas, copper and ore.
Population growth pressure and the need for new areas for expansion, including housing needs created by urban expansion.
food production and livestock raising.
Special population problems:
Absorption of new migrants and refuges, population dis-persement in order to reorder social and economic balance, nomadic societies’ revival to ensure their survival.
Response to security and defence needs, including the development of camps for military training and weapons or materials storage.
The common necessary elements to be considered when a basic policy is to be formulated for any arid zone development are:
(a) Public involvement in such development,
(b) Long-range goals.
(c) Resource management, and
(d) Land use control.
Direct public involvement is essential in effective, efficient arid-zone development. The development of arid zones requires large investments of money, materials, and labour, especially when no infrastructure or transportation network is available. In development, public involvement is essential for the development initiation and the continuity of construction.
Resource management is an essential issue in policy formation for the arid zone, because of the limitation of these resources and in many cases, because of the strong dependency of the national economy on a single product.
Therefore, the limited basic resources, both physical and social, and the delicate environmental balance call for an effective national policy for resource management. Land, water and financial resources are most important in arid zone development and thus, require national management.
Land is one of the most important resources in the arid zones and is primarily owned by public or semi-public concerns. Most of such land is virgin, and its development necessitates a high degree of coordination because of its delicate ecosystem.
Water scarcity also presents the need for control and regulation. Financial resources, an effective tool which requires careful management, affect the implementation of all policies.
Land use policy formulation is a good opportunity to ensure successful arid zone development because most arid zone land is public, abundant, and available. The prices are relatively low. Therefore, purchase, planning and construction are relatively free from the usual financial and legal problems.
Strategy is the art of marshalling resources towards a definite goal, a system of management, or the courses of action to be taken to enact policy. Thus, strategy is the employment of means, subject to fluctuations as circumstances change, to implement the principles of the stated policy. Since strategy is sequential to policy, it deals primarily with planning and implementation. Naturally, strategy deals with future development over a lengthy period.
Despite the national or geographical uniqueness of arid zones, sonic strategies can, with different degrees of emphasis, be common to all, they are specifically concerned with: 1. Water, 2. agriculture, 3. economic development, 4. social and health issues, 5. settlement pattern, 6. site selection, 7. urban forms and 8. research strategy.
Although by definition, arid zones have limited water supplies, any one arid area may have several sources of water. In figure 30.1 the control systems, problems and solutions for various water sources are presented. The water scarcity has a direct impact on the land use pattern and therefore necessitates a comprehensive treatment of the water supply for permanent settlement.
Reliance on a single water source can bring any development to the edge of disaster in case of extreme fluctuations. In the arid region a national control agency with local and regional branches empowered by legislation to regulate all water resources, including ground and surface water. This one agency would oversee all collection, treatment, allocation, distribution, consumption, and pricing.
Arid zones can only support controlled agriculture. The need for controlled agriculture has spurred development of new production methods requiring a minimal amount of water and innovations in irrigation to improve both water conservation and crop yields.
The techniques for food production in arid zones are crop specialization and use of farming methods which require a minimum or no water. Such specialization may involve plants which are fast growing to minimize irrigation, self-fertilizing, water conserving and salt tolerant (such as sugar beets, which can use brackish water) and plants that can genetically adapt and use solar energy efficiently.
High value and high yielding crops, those without, or with a minimum of leaves and those requiring minimal space and water, are adaptable for economical food production in arid zones. Economic development
The unique form of regional distribution of population density in an arid-zone city affects all networks, infrastructure and transportation systems on the intra-settlement level by increasing construction and maintenance costs. Under such isolation, transportation of necessary goods and agricultural products to the urban centres would be costly, infrequent and time-consuming.
To ease these burdens the arid zone city should be self contained. First is diversification in the production of goods and services, including agriculture, to fulfill local needs. Second is clustering of settlements in a given arid region planned as a single economic unit.
This configuration will foster mutual reliance among the individual settlements within the cluster. Third is development of sufficient storage and refrigerating systems to reduce the frequency of outside deliveries, thus reducing dependence on long-distance imports.
The plan of an arid zone city should be implemented to have a diversified economic base to attract various demographic groups to the community. The arid zone economy should rely on industry, manufacturing, and tourism and recreation which use local talents and materials.
The acceptance of these concepts leads to the acceptance of the strategy that arid zone development must be in new urban growth centres on regional scale rather than in predominantly rural villages. Improvement of accommodations, including hotels, motels and restaurant, will support recreation and tourism as well as attract the skilled labour base needed for the manufacturing industries and for services.
Tourism can have yet another positive impact on the economy, bring foreign currency which may be needed for food and will be needed for imported goods.
Primary health services, however, need to be of good quality at the stages because of the community’s geographical isolation. Also, the demographic composition will require specialized medical facilities to be developed in addition to the formation of comprehensive health service plans to ensure proper medical treatment and prevention of health deterioration, ally, Some specialists might be required to be in residence because of the settlement’s isolation.
Settlement Pattern in Arid Zone:
It should be less dependent on water resources.
Site selection is one of the most vital processes in the success or failure of an arid city. Strategy considerations for site selection must incorporate several needs viz.,
1. Land sufficient to accommodate the planned population.
2. Water resources for daily consumption by homes, industry and services (cities featuring agricultural development will require water for irrigation).
3. Accessibility via standard transportation systems.
4. Local, resource i s to employ at least part of city’s population.
5. Comfortable climatic conditions for healthy living and working.
The lack of research and, consequently, the absence of knowledge on unique urban forms required in a stressful hot, dry climate lead many liners to transplant planning methods of urban forms from non-arid ions to arid zones without much of an attempt to make the proper adjustments.
1. The new urban form of the arid zone city should be vertical, rather than horizontal as contemporary non-arid cities are.
2. Houses and other structures should be grouped into clusters to achieve maximum shadow throughout the day. The city should be a nest of interconnected clusters.
3. Cities should be positioned to capture cool breezes and to minimize glare and solar heat reflection.
4. Water, when available, should be used to stimulate cooling and ease the harshness of the landscape.
5. Houses and public units should include an open central court to maximize shadows and ventilation.
6. A pedestrian network should be confined by buildings or trees so as to form a protective environment.
7. Large and un-shaded open spaces should be avoided by locating urban land uses near each other.
Research must now probe the impact of the development of settlements and the arid environment on each other.
The areas for research are the educational environment at all levels that is the conditions for outdoor and indoor activities of the different age groups (nursery, kindergarten, elementary and high school), social and individual entertainment, labour structure and economics.
Agricultural research should focus on helping plants to adapt the stressful climate. In addition to those areas previously mentioned, there is need to discover plants that have higher salt tolerance levels, shorter rates of maturation, drought resistance, higher heat radiation tolerance and improved grain-to-straw ratio, improvement of soil, increased fertilization, multiple cropping, and improved agricultural management, greenhouse agriculture and water resources-water desalinization etc.
The arid zones are unique in many ways, it is time that an international centre providing a specialized educational programme at the postgraduate level be developed. It should have as its primary goal the preparation of qualified planners for arid zone development.
Such a postgraduate programme can draw students with diversified backgrounds and experiences, including trained architects, engineers, urban and regional planners, economists, sociologists, geographers, environmentalists, agronomists, water and soil specialists, decision makers, public officials, and others. In addition, an interdisciplinary, international and specialized body of experts in diversified fields related to arid zones should form the teaching and research faculty.