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V. Natural resource transformation and regional development planning
1. Interactions within resource systems
2. Location and design of regional development projects
3. Planning the regional spatial system and settlement pattern
4. Conclusions and implications
Transformation of natural resources for human development requires careful analysis of ecosystems within sub-national regions, because in nearly all developing countries regional resource systems and socioeconomic characteristics differ widely. National policies for resource development that do not take regional differences into consideration usually create benefits for some areas of the country at the expense of others, and produce adverse effects on those areas in which national policies are not appropriate.
The need for regional analysis and planning is becoming more widely recognized not only because regional resource systems differ from each other within developing countries, but also because within regions elements of the resource system are inextricably linked. Decisions about the design and location of development projects, such as dams and irrigation systems, can have strong impacts on regional ecosystems. Moreover, the regional pattern of human settlement is strongly affected by and, in turn, affects resource use and transformation.
1. Interactions within resource systems
The objective of any human intervention in a natural ecosystem is to direct the natural flow of energy and matter (i.e., the system's productivity or potential productivity) into forms more readily exploitable by man. Manipulation by man converts natural ecosystems into resource systems - a set of actions that, by definition, both simplifies and destabilizes the natural system. Poorly planned and ill-advised interventions may so disrupt the natural processes and functions of an ecosystem that they bring irreversible disintegration and decline to its productivity and recovery capacity in the short and medium term.
An additional and far more insidious process is the potentially destructive impact of inappropriate development policies in one element of the ecosystem on closely linked "downstream" elements. In the more densely populated parts of Southeast Asia, for example, almost any river basin, from its watershed to the inshore coastal marine water into which it debouches, provides examples of environmental and resource problems that arise from man's manipulation of closely linked ecosystems.
Relationships within and among resource systems comprise a particularly important part of regional planning for the transformation of existing resources and for the development of new ones. Such relationships can be particularly well illustrated by reference to coastal regions (see Chapter 3) and river basins in humid tropical developing countries. In such regions, interaction, incompatibility and conflict resolution in the use and transformation of renewable natural resources constitutes one of the main tasks of resource management and planning.' Interaction among resource systems, however, is a particularly complex subject for systemic investigation, and one for which a theoretical base (particularly in the tropics) is lacking. Indeed, most of the data essential for framing hypotheses are unavailable throughout the developing world.
In most cases incompatibilities and even outright conflicts in resource use have arisen because development in the lower reaches of river basins has proceeded haphazardly with little consideration of the interactions among various activities or with little regard for their impact on the biological and physical environment. Development projects have generaly been planned in isolation, with little consideration of understanding of the larger regional system of which individual resource systems and seemingly isolated activities form a part.
For the purposes of planning and managing resource development, river basins and coastal regions should always be seen as an assemblage of interacting resource systems. Planners and policy-makers must also recognize the limited nature of resources and the space available. and should always aim at maximizing compatibilities and optimizing the multiple use of resources in a region.
Regional planning is necessary, moreover, because in the absence of a policy or strictly enforced regulations on extraction rates and replanting, many Southeast Asian watersheds are subject to intense pressures from commercial and artisanal forestry and from shifting cultivation 2 Denuded slopes, exposed to intense tropical rainfall and insolation, suffer from accelerated soil erosion and landslides, and from a greatly diminished capacity to retain and gradually release water. The lost soil is rapidly transported by the unregulated waterflow to the ecologically and economically more productive lower reaches of the river basin, where floods destroy valuable investments, property and lives, and where silt, deposited in large quantities and in an unusable form, fills in reservoirs, clogs dams and irrigation systems, blocks harbours, and is deleterious to marine fisheries. The resource productivity from the formerly forested watersheds downslope to the marine fisheries is thereby disrupted and reduced basinwide. Many traditionally well-adapted techniques of ecosystem manipulation, principally shifting cultivation, have now become maladaptive as a consequence of greatly increased population and other pressures on alternative resources and other localities and thus are widely regarded as the causes of resource loss and environmental destruction, But many high technology interventions have caused and will continue to result in greater damage, particularly when their environmental impacts are combined and synergystic, as in a river basin. Poorly designed and inappropriately located large-scale dams and reservoir projects, for example, with their associated irrigation schemes, have had serious impacts on fisheries in rivers and off-shore, have increased the incidence and range of vectors of human diseases, have seriously disrupted watertables and agriculture, and in drier areas have led to major problems of soil salinization. Ironically, in the absence of up-stream controls on watershed destruction, many such water resource development projects are themselves in severe jeopardy from siltation.
2. Location and design of regional development projects
2.1.Water resource development projects
2.2.Dams and reservoirs
2.3.Large irrigation schemes
Regional development planning is important in transforming natural resources for human development, not only because resource systems within regions are inextricably linked, but because the location of development projects can have a fundamental impact on resource system interactions and well-being of the human population. The location of large-scale water resource development projects, dams and reservoirs, agricultural schemes, and irrigation systems, for example, change the human and natural elements of the ecosystems in ways that can either benefit or harm people living within a region. The relationships and potential impacts must be better understood and taken into account in the planning, design, location and operation of these projects. The impacts can be analyzed effectively only if planning is done at a regional level.
2.1.Water resource development projects
Freshwater is a key resource and soon may become the key resource in many developing regions. The development of freshwater resources with the multiple objective of regulating or controlling periodic or seasonal floods, providing irrigation, generating hydro-electric power, providing water for domestic consumption or for a wide range of industrial needs, is invariably a major concern of policy makers and planners in developing countries. Almost without exception, too, water resources development projects are expensive and highly visible "prestige items", and thus high on a government's list of priorities. Such projects usually have a wide range of ramifications for linked resource systems, a great many of which suffer unintended, unplanned and largely deleterious consequences as a result of poorly planned interventions in river systems, especially by large-scale dam construction, reservoir impoundment and the development of large irrigation systems in marginal areas. Massive intervention in river basins and the development of freshwater resources in tropical regions is a delicate undertaking that involves complex relationships among a myriad of interlinked social and ecological processes. If poorly conceived, planned and managed - as is usually the case given the poor knowledge of the structure and dynamics of tropical ecosystems development projects lead to severe environmental damage and resource loss, both in the regions where they are located and in linked resource systems, and therefore to severe disruptions in the social and economic processes that sustain subsistence populations. Once these disruptions occur they are difficult, if not impossible, to correct.
Hydrological cycles are usually modified by river diversion or regulation and by the extraction of groundwater. Largescale water resources development has focused principally on the construction of dams and reservoirs, the larger of which are among the main causes of ecological change directly attributable to civil engineering projects.3
Many of the mistakes made in river basin development in Africa, for example, have occurred because projects concentrated largely on reservoirs and irrigation schemes that ignored ecological considerations. In the analysis of costs and benefits of such projects, too little attention is given to secondary benefits, or to the impact on existing renewable natural resources.4
Construction of major reservoirs also displaces local inhabitants, and subjects them to considerable hardship. Construction of the Aswan High Dam required the relocation of more than 100.000 people; and because the move was inadequately planned, the World Food Programme had to rush emergency famine relief to the Nubians. Resettlement of people displaced by water development schemes has generally been troublesome. Inadequate planning, insufficient budgets, faulty implementation and tack of appreciation of technology transfer problems have all contributed to their failure. The low level of literacy and the lack of political power of the people being relocated has left them at the mercy of administrators who did not always understand their needs. In many cases those who directly benefit from such projects are usually educated elites with political power, whereas the direct social costs are absorbed by the rural poor.
2.2.Dams and reservoirs
Initially, the nutrient status of a new man-made lake depends on that of the in-flowing waters, but impoundment of a river behind a large dam leads to changes in the nutrient status of water retained in the reservoir. Usually, in young reservoirs, as the water rises behind the dam the biological productivity of the artificial lake increases as the inundated vegetation and flooded soils release nutrients into the water. Nutrient levels gradually decline later, and eventually attain a hypothesized stable state. The ratio of inflow to out-flow of impounded waters exerts a major influence on revervoir nutrient levels, an imbalance in favour of outflow lowering them. However, if such an imbalance results in drawdown, or the seasonal exposure of shallows, the excrement of herbivore grazing the seasonally exposed biota in such areas will replenish nutrient stocks during the ensuing period of high water5. Nutrient status also depends on reservoir depth and the pattern of water circulation, on the rates and quantities of nutrients released by the inundated vegetation, and on the biota colonizing the new lacustrine ecosystems. Slow turnover rates in tropical reservoirs may lead to stratification in the impounded waters, such that little vertical mixing of dissolved gases or nutrients occurs, and the lower levels become anaerobic and loaded with compounds such as hydrogen sulphide and ammonia, which are toxic to lake biota, particularly when mixed in the water column under stormy conditions. Massive downstream fish kills also occur if such waters are released from the dam. Corrosion and sulphide deposition on HEP turbines also results from the use of anaerobic lake waters with a high hydrogen sulphide content 6 Under conditions of severe deoxygenation, inundated vegetation fails to decompose rapidly, which, by interfering with artisanal gear, may hamper the adaptation of riverine fisheries to lacustrine conditions.7
Although the process is not well-understood in tropical waters, lake stratification seems to depend on altitude, shelter, depth, degree of underwater slope, and change in water temperature.
High nutrient levels in young reservoirs, often exacerbated by resource development around the catchment area of the lake, may cause rapid growth of aquatic macrophytes and phytoplankton populations, causing further deoxygenation of lake water. if algae populations are unstable and blooms excessive, they result in large-scale fish kills both in situ and downstream.
A major and widely discussed consequence of large dam construction is the modification of silt and turbidity loads of rivers and its impact, both in the region and downstream, on the regime of sediment erosion, transportation and deposition. Siltation and turbidity has a major impact on the life and uses of a dam and reservoir, and has major impact on downstream riverine and inshore marine fisheries as well as on agricultural systems.
The quality of watershed management in the catchment basin supplying the reservoir, and particularly the regulation of forestry and shifting cultivation, the major resource systems in tropical upland regions that cause accelerated soil erosion, is the principal factor in determining whether a dam-reservoir complex is productive and achieves its goals for its designed lifespan. Often reservoir and dam design has been based on erroneous assumptions and projections of the silt load of in-flowing streams. Excessive silt accumulation in the reservoir can alter upstream hydrological regimes and can lead to flooding, swamp formation and the alteration of watertables. It can disrupt aquatic ecosystems, with detrimental consequences for local resource systems. An unusually large influx of silt, particularly of that rich in nutrients, as a result of storm or rainy season floods in headwater areas, can trigger excessive weed and phytoplankton growth in the reservoir, leading once again to eutrophication problems as well as causing severe perturbations in the aquatic biota, which in all probability is still in the process of adjusting to lacustrine conditions.
Dams act as silt traps so that downstream waters are deprived of silt and can therefore erode their banks and the bases of man-made infrastructure and can have severe impacts on linked resource systems. In addition to affecting nutrient levels, drawdown may reduce the diversity of benthic organisms in the lake. Lake margin areas may also provide breeding sites for insect pests such as locusts.
Although few data are available, particularly for tropical regions, large artificial lakes are also known to modify local climates. The diurnal range of local air temperature may be moderated, on-and offshore breezes created, and precipitation rates and the degree of cloudiness and fogginess modified.8
Creation of artificial lakes, particularly deep ones, has resulted in seismic activity that at the Kayna dam site in India and at Kariba has attained or surpassed six on the Richter Scale.9 Although the precise nature of the geological mechanisms causing this phenomenon are not yet understood. it seems plausible that increased groundwater pressure on fissures reinforces existing stresses, thereby leading to seismic activity. Alone, the additional weight added by impounded water is not necessarily the prime cause.
Not uncommonly, river valleys contain the richest biotic assemblage within a tropical region, and large-scale impoundments of water and their associated irrigation systems may have either beneficial or deleterious impacts on the flora and fauna in the immediate area of the site. Major water development schemes may lead to the extinction of particularly localized species, create new niches for exotics, and provide the amenities for new resource systems, such as a tourist industry based on water sports and lake-shore facilities.
Migratory riperian fish species are particularly affected by dam construction and the creation of large artificial lakes, despite the provision of fish ladders and passages. Since tropical freshwaters abound in a great variety of migratory species that have distinct behavioural characteristics, dam construction will inevitably hinder some. Under the worst circumstances spawning behaviour might be so badly affected during the several seasons required for dam construction that a viable population of a particular species in a given river basin might cease to exist. Habitat changes, principally in water quality, can affect migratory fish behaviour, which is based in large part on chemoreception, such that with changes in water quality these stimuli, together with other environmental factors that guide migration routes, are eliminated.
However, creation of lacustrine conditions permits the introduction of fish species that can use the vacant niches opened up, thus permitting fisheries development and biological control of pests and weeds. But some such introductions are accidental in that water development projects enable local species to extend their ranges. Thus Tilapia nilotica, Heterotis niloticus and other species have been introduced to some Southeast Asian reservoirs in an attempt to improve productivity; more then 260 species of fish have been used to combat 35 different species of mosquitos in more than 40 countries; and the Grass carp (Ctenopharyogodon idella) is widely used to reduce infestations of water hyacinth and other aquatic macrophytes, as well as to produce animal protein for local populations.10
2.3.Large irrigation schemes
The principal aim of irrigation in rain-deficient regions is to increase soil moisture to permit satisfactory crop production in areas otherwise unsuitable for commercial agriculture. and in humid tropical regions to regulate and optimise water conditions for flooded field agriculture, particularly rice cultivation. Irrigation on a large scale has impacts on the physical and biological environment, and on human health, social systems and economic organization. Results like increased crop and livestock yields are both beneficial and essential to national development, but other repercussions of irrigation can be detrimental to regions and linked resource systems and ecosystems, as well as to human health.
Irrigation in its broadest sense has impacts that are difficult to categorize because of the numerous and complex interactions among them, and because of the often considerable time lapse between intervention in the environment and the emergence of such undesirable phenomena as waterlogging and salinization. This hampers analysis, forecasting and remedial action.
Impacts on the hydrological regime are those first and most clearly manifested. The removal and transfer of water from a naturally occurring source leads to perturbations in hydrological systems and aquatic habitats that are manifested in the area from which the water is taken, on the irrigated land, and in the zones adjacent to both areas. Drawing irrigation water from a river causes a reduction in downstream flow, particularly during the dry season, which gives rise to changes in the sediment regime and has a major impact on habitats and biota. Removal of freshwater can lead to a deterioration of water quality by permitting the encroachment of brackish waters into the lower reaches of a river basin. Water quality also deteriorates because of pollutant-laden return flows from the irrigated land. Dams and reservoirs are an integral part of most major largescale irrigation systems; the latter reinforcing the adverse effects of the former on linked, downstream resource systems.
The hydrology of the land supplied with irrigation water is also altered. Not only is moisture made available to the layers accessible to plant roots, but also to the deeper layers through percolation. The degree of impact on the hydrology of an irrigated area depends on the general efficiency with which irrigation waters are applied. The most widespread and serious consequence of irrigation water is the change in water table levels such that salinization and waterlogging occur, together with changes in the hydrology of areas adjacent to an irrigated area, particularly when irrigated lands are situated at relatively higher elevations, or upstream.
When irrigation waters are introduced into a soil ecosystem they often bring major changes in soil structure, permeability, the cycling of nutrients, the physical and chemical removal of calcium carbonate, and the downward movement of clay particles. Changes in absorbed cations and modification to the macro- and micro-floral components of soil biology occur. The quality and quantity of organic matter also gradually changes as a result of the increased biomass of plant residues from the irrigated crops and their more rapid decomposition owing to higher levels of soil moisture. These changes in organic matter also affect soil fauna, flora, fertility, biochemistry and physical conditions. Some of the more important chemical properties of soils, like the oxidation reduction potential, for example, are also affected by irrigation and may eventually lead to such physical and biological changes in the soil as a reduction in pore space and an accompanying decline in the aerobic decomposition of organic matter. Gradually the entire soil-water-air equilibrium is altered thus leading to a possible decrease in soil fertility and crop yields."
The most widespread and serious deleterious impacts of irrigation, particularly on soils in arid and semi-arid regions, is the joint problem of salinization and water logging, which occurs if leaching and drainage are inadequate. About 7 per cent of the world's land area is detrimentally affected by salt, and an estimated 50 per cent of all irrigated lands have been damaged by secondary salinization or sodication and waterlogging. As a consequence, salt-affected soils are found on all continents. In some countries the area of land abandoned as a consequence of salinization and waterlogging is approximately equal to that newly brought under cultivation.
Major alterations in regional plant and animal life result from the implementation of large-scale irrigation schemes. The greatest change in flora and fauna as a consequence of irrigation occurs in the irrigated region itself, with the deliberate introduction of cultivated plants and domesticated animals, together with the pests they attract. In turn, the processes of cultivation and animal husbandry modify the soil and generate new life processes. The introduction of irrigation permits the cultivation of new crops in rotation which. together with increased fertilization and improved methods of tillage, raises productivity. These changed cropping practices lead to major alterations in the ecosystem. Moreover, the introduction of crops like rice or sugar that have high water requirements is accompanied by such drastic hydrological change and modification of soil processes as a rise in the groundwater table, creation of anaerobic conditions, heightened salinization potential and a deterioration of soil structure that also affect the ecosystem. Agricultural developments based on the introduction of up-grading or irrigation facilities also generally require the use of chemical fertilizers, insecticides, herbicides, and fungicides, all of which introduce toxic components into the soil system and pollute downstream waters as they are removed from the irrigated fields by percolation, thus endangering linked resource systems.
Closely related to the impact of irrigation schemes on water regime, soils and vegetation is their influence on atmospheric conditions. Even small-scale irrigation schemes have an impact on meteorological conditions over and in the irrigated area. In particular, air temperature and humidity are modified, which leads in turn to changes in the transformation of available energy into latent or sensible heat, which are reflected in a new water balance. That in turn has important consequences for water storage within the system, for the amounts of water required for irrigation, as well as for linked ecosystems and resource systems.
Large-scale irrigation schemes can have major and direct effects, either positive or negative, on human health through alterations of local and regional hydrological systems, as well as indirect effects as a consequence of changed sociological and economic conditions. The main positive consequences include improved hygiene, better nutrition, and increase in personal income, the latter enabling the purchase of medicines and other health needs. Although most of the increased water supply made available by water development projects is used for economically productive purposes, some of the additional water can be used to satisfy domestic needs for potable water and for personal and community hygiene. Malnutrition is a common phenomenon in most developing countries. The increased quantities and diversity of foodstuffs available from irrigated areas can lead to improved health conditions through higher nutritional levels. However, for economic and cultural reasons, dietary habits are notoriously slow to change, particularly if the consumption of unfamiliar foodstuffs is required. If higher incomes result from the increased agricultural productivity of the irrigated land, cash becomes available for the purchase of medicines and specialized health care, improvement of living quarters and for personal and community hygiene. This assumes, however, that the necessary materials are available and that these innovations, too, are culturally acceptable.
On the other hand, irrigation systems can also have catastrophic consequences for human health if they serve to introduce or spread more widely diseases either previously unknown or unimportant in the newly irrigated area. Freshwater can transmit many epidemic diseases, functioning as both a transfer medium and as a favourable habitat for the multiplication of vectors and disease pathogens.
Modern irrigated agriculture requires the application of many types of chemicals to the crops and soil. Irrigation runoff becomes either contaminated or polluted, and if the chemicals have been wrongly applied. directly toxic to plants and to the animals and humans who drink the water.
More serious, however, are infectious diseases such as cholera, typhoid fever, bacillary or amoebic dysentery, infectious hepatitis and poliomyelitis that can be directly transmitted by irrigation water used for domestic consumption. Hitherto such diseases were present in the limited areas served by contaminated wells, springs and pools, but with the spread of irrigation systems they have become more widely distributed. Whereas inexpensive measures can be taken to protect wells or springs the protection of irrigation canals and reservoirs is both more costly and difficult. Moreover. with the increased density of human settlement occasioned by an irrigation scheme, outbreaks of these diseases are more likely to reach epidemic proportions.
Other diseases are spread from infected to healthy persons by vectors or intermediate hosts present in water. This class of disease includes malaria, schistosomiases, plasmodium, filarioses, dracunlosis, onchocercosis, among many others, whose pathological effects can be cumulative. The best known and most serious are malaria and schistosomiases.
A major factor leading to changes in the social system is that new irrigation schemes are generally established by the central government, which establishes certain conditions and regulations for participants concerning land and water use, crops and cropping systems and the like. Other changes in the social system result from improved economic conditions as a consequence of increased agricultural productivity and intensified contacts with the outside world.
Adopting modern, irrigated agriculture requires discarding old work habits. All methods of work have to be changed. More labour is demanded by the diversified and intensified cropping systems, because multiple cropping is possible under irrigation. The quality of work must be improved because investment in modern agricultural inputs is high and small mistakes or apparently minor acts of negligence can result in major losses. Higher levels of collaboration and cooperation among farmers are also demanded, as well as between the farmers and the various outside agencies responsible for providing essential inputs and for marketing the agricultural products. This creates a need to establish institutions such as farmers' co-operatives. Concomitant with changes of agricultural technique is a reorientation of the farmers' value system; indeed, without alterations to the traditional rural value system, modern irrigated agricultural systems will be relatively unsuccessful. New skills and knowledge must be acquired and appreciated, and the quality of work valued, particularly since it directly affects family income. Of particular importance in irrigated agriculture is understanding the need for precise timing, measuring and weighing of inputs.
Settling on a new irrigation scheme also demands changes in the living habits of traditional populations. This represents a major change: the physical environment is completely unfamiliar, and the arrangement of villages, houses and neighbours is new. New social structures and patterns of leadership emerge; there is less leisure time and significant alteration of working and sleeping habits as well as in social and recreational customs. Improved family incomes lead to changes in household economies as well as in personal and family aspirations and goals.
The adoption of irrigated farming generally results in more diverse and intense cropping patterns, the use of modern agricultural technologies and the application of the economic concepts demanded by commercial agriculture oriented to markets outside the local community. Theoretically, increases in farm incomes as a consequence of adopting irrigated agriculture makes possible continuous improvement in farming business, living conditions, and the education of children, which together reinforce the process of change.
Because the introduction of development projects such as irrigation schemes tends to bring about these fundamental changes in the natural environment and social structure of a region, the economic, spatial and resource components of development policies must be considered together. Especially important is the role of human settlement patterns on the direction and pace of regional economic development and the use and transformation of natural resources within a region, particularly in marginal areas.
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