UN Population Division, Department of Economic and Social Affairs,
with support from the UN Population Fund (UNFPA)
******************************************************************* This document is being made available by the Population Information Network (POPIN) Gopher of the United Nations Population Division, Department for Economic and Social Information and Policy Analysis, in collaboration with the Population Programme Service, Sustainable Development Department, United Nations Food and Agriculture Organization. For further information, please contact: Mr. Jacques du Guerny, email: email@example.com ******************************************************************* Population and the environment: a review of issues and concepts for population programmes staff I. POPULATION AND WATER RESOURCES September 1994 FOREWORD This paper is the first in a planned series of four to six notes, designed to bring to the attention of Country Support Team Advisers (and staff of UNFPA programmes concerned) state-of-the- art information on major population-environment issues and methodological advice for dealing with such issues in the context of population policy work and population/development programmes. The purpose of each paper will be to help fellow population specialists at the regional and country level carry out (directly or through project formulation, backstopping and operation) certain tasks such as: - promote awareness of population and environment linkages and related issues, qua relevant elements in development policies; - help integrate environmental concerns and considerations in population policy analyses; - help design or carry out population-centered research in support of development policy studies; or - help design data collection and monitoring systems on population/environment issues. For this purpose, each paper will provide factual information on the environmental issue(s) under review, try to elucidate the role of population variables, propose analytical tools and examine statistical information problems where appropriate. This first paper focusses on water resources issues, which we believe to be of crucial and growing importance--indeed, likely to surpass as yet better-publicized issues such as deforestation, atmospheric pollution or soil degradation in many countries. An indication of this importance is FAO's decision to celebrate this year's World Food Day (16 October 1994) on the theme: "Water for life". Although self-contained, this paper is supplied with a "companion document", namely a special chapter of FAO's State of food and agriculture 1993 on "Water policies and agriculture", to which many references are made in the text. This paper will be first addressed to Country Support Team Directors, Advisers on Population and Development, and FAO Advisers. Suggestions for further distribution and requests from field projects will be welcome. Alain Marcoux FAO/UNFPA TSS ================================================================== CONTENTS 1. INTRODUCTION 4 2. POPULATION DYNAMICS AND DEMAND FOR WATER 5 2.1 Domestic and municipal usages 5 2.2 Agricultural usages 6 2.3 Industrial usages 8 2.4 Overall use and competition between sectors 9 3. IMPACT OF POPULATION ON WATER SUPPLY 9 3.1 Impact on surface water 9 3.2 Impact on groundwater 10 3.3 Water pollution 11 4. IMPACT OF CHANGES IN WATER SUPPLY ON POPULATION 13 4.1 Water scarcity 13 4.2 Water pollution 16 5. POPULATION-WATER LINKAGES IN A POLICY FRAMEWORK 18 5.1 Policy relevance of the linkages 18 5.2 On analyzing population-water linkages 19 5.2.1 Factors in water withdrawal 20 5.2.2 Factors in water pollution 22 5.3 Policy options 23 5.4 Knowledge base and research needs 25 5.4.1 Research topics 25 5.4.2 Indicators 27 NOTES 29 ANNEXES ================================================================== "Despite enormous expenditure [...] supplying water for food production, drinking water, fisheries and environmental protection has not kept pace with population and economic growth. The loss and degradation of rivers, lakes, wetlands and other water-dependent ecosystems around the world has been the result, along with declining human health." 1. INTRODUCTION Of all natural resources, water is the most essential. It is fundamental to all vital processes of value to mankind. It seems abundant at first sight--almost 70 percent of the earth's surface is covered with water. Yet perhaps 2 billion people live in areas with chronic water shortages. Quantitative supply and water quality problems are mounting and could constrain economic development and human well-being in general. In other words, water no longer can be taken for granted: "Ensuring that present and future generations will have adequate food and water, and concurrent maintenance of the resource base and the environment, are two of the most challenging tasks that have ever faced mankind". Populations require water for domestic and municipal usages; as an input in productive activities: agriculture, industry (including energy production) and services activities; and finally, in all usages, for the evacuation of effluents (sanitation, removing industrial wastes etc.). Demands from all these sectors are mounting and competing with one another. To understand the nature of resource use issues in this area it is necessary to keep in mind some characteristics of water supply. First of all, the seemingly abundant availability of water is misleading. Freshwater--the only usable kind, as far as human needs are concerned--is only a small fraction (2.5 percent) of the water present on our planet. Further, most of freshwater is in the form of permanent ice and snow, or of groundwater which, given its life cycle of several thousand years, must be regarded as unrenewable on a human time scale. In the end only 0.3 percent of freshwater is renewable. Runoff, however, easily compares with human needs at the global level. But "usable flow is substantially less than runoff. Water supply scarcity may become a major constraint on socio-economic development at levels of use substantially below total runoff". In addition, as with most issues, the global level has little relevance. Water supply is irregularly spread over space and often is not found where it is needed. It is also irregularly spread over time, while time constraints on water use are strong, especially for domestic uses and industry which require a basically constant supply. These natural conditions set absolute limits to human use: "Human innovative talents can make the best possible use of the water that passes through [...] a country, but technology cannot influence the rate at which water is naturally renewed from the global water circulation system". Water therefore is a finite resource: "The water cycle makes available only so much each year in a given location. That means supplies per person drop as population grows". Unlike other resources, water is mobile and necessitates catchment, transportation and storage, with related costs and efficiency problems. Ultimately water availability can be regarded as a function of the costs of delivering water at the required place and time, rather than as a physical parameter. But those costs can be high and consumers usually are reluctant to bear them because of age-old perceptions of water as a free good. Finally, water resources are vulnerable, meaning that their flow patterns and chemical properties can easily be altered by human activities and natural factors in ways which negatively affect subsequent human usages. Quality considerations are important whatever the utilization of water: industrial, agricultural and domestic usages all have their criteria of adequacy (particularly strict ones in the latter case). 2. POPULATION DYNAMICS AND DEMAND FOR WATER 2.1 Domestic and municipal usages These are the "basic" usages of drinking, food preparation, domestic hygiene and the collective usages at the community level (heating, fountains, pools etc.). Per caput levels of domestic use increase as general levels of well-being and aspirations rise; in addition demographic factors contribute heavily to shape water requirements in this sector. Population growth is a direct determinant of increases in water demand for domestic uses. Another key demographic factor is change in the geographic distribution of population, which modifies the spatial pattern of demand for domestic uses. Urbanization, in particular, through increased population density and the concentration of demand, can make the latter a serious constraint on local resources. Many third world cities are critical areas from the viewpoint of water supply (see Annex 1). Problems are especially acute when urban growth is based on the migration of rural poor rather than on economic growth. The magnitude of the requirements brought about by population growth and urbanization is revealed by the extent of unmet needs. Despite an international effort to promote the development and implementation of water and sanitation plans under the 1981-1990 International Drinking Water Supply and Sanitation Decade, progress at the end of that period still was inadequate. The number of people lacking access to clean drinking water had been reduced by one third, but still stood at more than 1.2 billion, or 23 percent of the world population. Relatively greater progress had been registered in rural areas, where the number of people in need had been reduced from 1.6 to 1 billion. But the rural population still lagged behind the urban (37 percent unserved against 18 percent). As to the number of people lacking access to adequate sanitation services, it was unchanged at 1.7 billion after ten years. More than half of the rural people were affected against 28 percent of the urban. Globally, making substantial progress on the urban and rural water supply front would require a tripling of investment over 1980s levels. The bulk of investment in water supply and sanitation so far has been directed to the urban sector and the better-off population, with persisting inequalities as a result. In principle urban concentrations should enable economies of scale, but growing numbers can be overwhelming. Human beings need only about 5 liters of water each day for cooking and drinking; according to WHO, however, good health and cleanliness require a total daily supply of about 30 liters per person (11 cubic meters per year). By comparison, regional levels of per caput withdrawal for domestic and municipal usages are estimated as follows: World ................... 52 m3/year Africa .................. 17 Asia .................... 31 North/central America ... 167 South America ........... 86 Europe .................. 92 Former USSR ............. 90 These figures refer to usage regardless of the quality of water used; the latter can be a major problem, as seen above. This being said, basic needs are sometimes abundantly covered, indicating a variable amount of wastage, particularly in developed regions. It is a fact that access to stable and easy supply--in particular water on the tap in urban settlements-- stimulates use considerably. Globally, water withdrawals for domestic and municipal usages account for a modest part of the total: 8 percent (see Annex 2). But they are growing rapidly. By 2000, withdrawals are expected to double with respect to their 1980 level and to reach 11 percent of total use (see Annex 3). Population growth, especially that which will occur in third world cities, would be responsible for a substantial part of this increase. 2.2 Agricultural usages Irrigation has been and remains of vital importance for the provision of food and employment for growing populations world- wide. In developing countries irrigated areas represent 16 percent of all cropland and provide 37 percent of the production- -implying a productivity three times as high as that of other lands. Irrigation and improved seed varieties were the basis of the "green revolution" which made most of Asia self-sufficient in food. But water requirements for irrigation are extremely high in comparison to the output: "Crops require and transpire massive amounts of water"; this makes water "the major limiting factor for world agricultural production". Depending on the crop and the location, producing one ton of cereal requires between 500 and 2000 tons of water (wet paddy being the most wasteful). Since one ton of cereal covers the annual consumption of about four persons on a world average, it can be estimated that the average consumer of irrigated cereals thus indirectly uses about 400 tons of water per year--to be compared with the few tons per caput required for domestic use. Indeed, agriculture is the major water user world-wide: around 70 percent of total withdrawals are for irrigation (Annex 2). Regional levels of water use by agriculture on a per caput basis are the following (compare with the levels of domestic use above, calculated from the same source): World ................... 444 m3/year Africa .................. 216 Asia .................... 446 North/Central America ... 912 South America ........... 282 Europe .................. 235 Former USSR ............. 832 As demand for agricultural products increases, needs for additional irrigated land and corresponding water supplies also mount. Globally, irrigated areas have increased from about 50 million hectares in 1900 to 100 million in 1950 and more than 240 million now, mostly to respond to growing third world needs. Recent projections of agricultural demand to 2010 are shown in Annex 4. The role of population growth in the projected increases in demand can be estimated from these figures, as follows: Respective shares of the growth in: per cap. population demand World 89% 11% Developed countries 100% 0% Developing countries 68% 32% Africa 97% 3% Near East 86% 14% East Asia 43% 57% South Asia 71% 29% Latin America 75% 25% FAO estimates for 130 developing countries between 1990 and 2000 indicate that providing for those requirements will require 15.2 million hectares of new irrigation development, over and above the existing 172 million hectares. In addition, more than 17 million hectares of existing irrigation schemes will need to be upgraded; small-scale water programmes and conservation actions will be needed on 10 million hectares in rainfed areas. To enable this expansion of irrigation, water withdrawals are projected to increase by about 17 percent globally. According to the projections of Annex 3, water use by agriculture is expected to grow rather slowly if compared to other usages (about one percent annually) but the additional requirements will be very large in absolute terms: twice the additional domestic requirements, and roughly equal to those of industry in the low projection for the latter sector. This will create severe competition between sectors in regions with limited water resources and a potentially growing industry. Irrigated areas will not expand again at rates comparable to that of world population growth as they did in the 1960s and 1970s. This is partly due to the ever scarcer availability of hydrologically favourable sites. These natural conditions increase the costs of irrigation development. The need to adopt preventive measures against irrigation-induced land degradation compounds this factor. This, in combination with the frequent social, health and environmental costs, has actually discouraged lending, at least for large-scale irrigation. In the medium term, population and economic growth will exert even greater pressure on water resources than on land. Africa and Asia already suffer from diminishing per caput water supplies, and many countries already are closer to their water resource limits than to their land limits. 2.3 Industrial usages Like other human activities, industrial production is dependent on water for processing, cooling and evacuation of effluents. This category of needs is rapidly increasing. Population growth contributes to that increase, although in a minor way: income growth and the diversification of needs play a bigger role in this case. Per caput water withdrawals for industrial usages are estimated as follows: World ................... 148 m3/year Africa .................. 12 Asia .................... 42 North/Central America ... 782 South America ........... 110 Europe .................. 385 Former USSR ............. 346 According to the forecasts of Annex 3, global requirements will increase by at least 50 percent, and perhaps 70 percent, between the 1980s and 2000. The fastest growth is expected to take place in Africa and South America, but the largest absolute increases by far will be in Asia. 2.4 Overall use and competition between sectors Total per caput withdrawal levels vary enormously, from less than 10 to more than 6,000 cubic meters per year. The lowest levels are found in poor developing countries, mainly in Africa. The highest levels are found in a few countries with high ratios of irrigated land per caput (Iraq, Pakistan and central Asian Republics of the former USSR). In the second half of this century water withdrawals increased between and 4 and 8 percent annually. Water use is still growing in the developing countries, but stabilizing in the industrial countries. As a result, global withdrawals are expected to rise at only 2 or 3 percent annually during the 1990s. Yet supply problems will keep mounting: freshwater is being extracted from some river basins at rates approaching those at which the supply is renewed and from some underground aquifers at rates exceeding natural replacement. Water demand patterns of the future will be characterized by growing competition between sectors, especially in developing countries. That competition will be particularly intense around the cities, where the demands of households, industrial plants and agriculture will inevitably put increasing stress on water (just as on land). If rural users are deprived of water resources in the process, this will accelerate migration to the cities. In the developed world, use levels are stabilizing; water- saving modalities of use and water re-use are gradually expanding as the costs of water supply and treatment are better charged to users. In developing countries the margins for increased demand are considerable, on account of rising industrial sectors, unmet domestic and municipal needs, and agriculture. 3. IMPACT OF POPULATION ON WATER SUPPLY Human populations affect water in direct and indirect ways. The former consist in modifications to the circulation of water and its quality by withdrawals, waste water disposal, river regulation etc. The latter consist in modifications of vegetation and soil cover: deforestation and compaction reduce the absorptive capacity of the soil and accelerate water runoff; this causes floods and deficits of recharge of aquifers; the loss of soil protection accelerates erosion and leaching, increasing water pollution; finally, air pollution affects the chemical properties of water through precipitations (viz. acid rains). 3.1 Impact on surface water Human activities affect levels of river runoff principally by the direct withdrawal of water, the regulation of rivers, and land uses that change the surrounding environment and affect watershed dynamics. Disturbances of water flows in turn affect the wetting of the soil, the recharge of aquifers and rivers, the quality of freshwater and the per caput availability of water. Deforestation is a major factor of changes in watershed dynamics. Forest areas tend to have more stable patterns of river runoff, because the catchment capabilities of the forest ecosystem enable a higher amount of groundwater discharge. Deforestation therefore causes significant changes in river flow patterns, with accelerated runoff and lost storage, in turn causing a higher occurrence of flooding in wet seasons and a greater likelihood of dried-up rivers in dry seasons. Population growth is an important factor (often overshadowing logging operations) in deforestation, through the needs for more cropland and wood. Examples of this are numerous. The following is a typical description: "increased runoff due to deforestation has stripped soil off slopes and deposited it downstream, where it accumulates in the beds of streams and behind the new concrete dams", resulting in reduced storage in reservoirs and unstable water supply; "silt-ridden streams begin to dry up during the dry season and flood during the rainy season". Ethiopia, "which has only 6 percent of its forest cover left, is bleeding its topsoil into rivers at the rate of 2000 tonnes per square kilometer per year". Such is the disturbance brought about by loss of forest cover that it can cause water scarcity even in places with very abundant rainfall. Damage becomes reciprocal when forests are affected by water disturbances: in the upper Indus basin in Pakistan, new irrigation canals have disrupted drainage; increased withdrawals have starved the riverain forests, in turn enhancing the chances of damaging floods. Other actions leading to land degradation (such as overexploitation or overgrazing) have analogous effects on water regimes. The diagram in Annex 5 illustrates, inter alia, such processes. Urbanization--a major demographic trend all over the world-- also has distinct effects of surface water. When streets and other impermeable surfaces replace permeable soils and vegetation, the volume, velocity and temperature of local runoff are increased, reducing the base flow of rivers during dry periods. 3.2 Impact on groundwater Because of the climatic and human-induced instability of surface water, groundwater is important for water supply security. It also is a primary resource when surface water is scarce. During the recent decades it has supplied much of the water needed for burgeoning cities as well as for irrigation development. But groundwater aquifers are replenished only slowly, and human demands often exceed the natural recharge (see Annex 6). In Tamil Nadu, heavy pumping for irrigation has caused drops in water table levels of 25-30 meters in a decade. Pumping in Beijing exceeds the annual sustainable supply by 25 percent; in northern China, with heavy agricultural, domestic and industrial demand, water tables are dropping by 1 to 4 meters per year. In the Bangladesh lowlands, the mining of groundwater for irrigation has brought about seasonal declines of the water tables; in the dry season, most village handpumps (the essential source of domestic water) go dry. Overpumping of underground aquifers can cause soil subsidence. Third world urban areas such as Bangkok, Beijing or Mexico City are affected: buildings, streets, railroads and sewage systems can be damaged. The phenomenon also occurs in rural areas (as in various areas across the southern USA). Overpumping also causes a particular type of pollution in coastal urban areas where the depletion of the aquifers fosters the intrusion of saltwater: the problem has been noted in Dakar, Jakarta, Lima, Manila and parts of Israel, Syria, the Arabian Gulf, Great Britain and western USA. 3.3 Water pollution Most human activities contribute to pollute surface and ground water, either directly (by returning dissolved effluents to water bodies) or indirectly (because waste deposited on solid ground finds its way to water bodies). Freshwater is increasingly polluted by organic nutrients, toxic metals, and agricultural and industrial chemicals, carried by industrial effluents, land use runoff, and domestic wastewater. Secondary but growing sources are the leaching from mine tailings and solid waste dumps, and atmospheric deposition of pollutants into water bodies. To the traditional concerns of pollution from organic wastes and the salinization of irrigated areas, have gradually been added those of suspended solids, heavy metals, nitrates, radioactive wastes, organic micropollutants and the acidification of lakes and streams. Too often, industrial liquid wastes are dumped in contravention of regulations, toxic and hazardous industrial and commercial wastes are disposed of in water bodies or land sites, and systems to dispose of waste water and control flooding are inadequate. It is estimated (see Annex 3) that 42 percent of the water in domestic and municipal usages is returned to the water cycle, accounting for 11 percent of total waste water. Rapid urban expansion of the recent decades "has increased the pressures on the urban environment and on surrounding regions and their natural resources. It has created immense and growing problems of air and water pollution [...] In some countries, as little as 2 percent of sewage is treated. From 30 to 50 percent of urban solid waste is left uncollected. The implications of all the above for the globe's shrinking supply of freshwater, the health of urban residents and the integrity of the globe's atmosphere are obvious". Much of the pollution arises from the rapid growth of squatter settlements on the periphery of cities--many of them springing up on low-lying land and along waterways, and their wastes flowing into urban water sources. The poor are the most affected by the deterioration of the physical and natural environment, both the victims and unwilling agents of environmental damage. Most of the water used by industry (87 percent according to the estimates of Annex 3) is eventually returned to the water cycle, making up 47 percent of total waste water. It is often polluted by chemicals and heavy metals; often, also, its temperature is increased to the detriment of life support systems downstream. In most developing countries pollution controls, when they exist, cannot keep pace with urbanization and industrialization. "Risks from hazardous waste, even if local, are acute. In some large cities, the daily outpouring of industrial wastes into water bodies reaches millions of cubic metres". Things are better in developed countries, but even there problems exist, particularly in non-OECD countries where controls on industrial effluents are inadequate. While industries and domestic sewage are the main sources of pollution in developed countries, agriculture plays a bigger role in developing countries due to the clearing of land, the use of fertilizers and pesticides, and irrigation. The demand for range- and farmland is a major factor in deforestation. The resulting accelerated runoff in turn accelerates erosion: in fact, water erosion globally is the main source of soil degradation (accounting for 62 percent of severely or moderately degraded areas world-wide and 70 percent in Asia), and deforestation is the main cause of water erosion in 43 percent of the areas affected. Soil erosion in deforested watersheds increases water turbidity and accelerates the leaching of soil nutrients. These effects are particularly severe in tropical regions, especially during the rainy season; but other regions are not immune. Irrigation returns only a quarter of its withdrawals to the water cycle but this return flow accounts for 42 percent of total waste water. The combined increases in irrigated areas and related use of fertilizers and pesticides in developing countries have heavily polluted irrigation return flows, with significant threats to the aquatic environment as chemicals run off into streams or percolate into groundwater. Damming itself affects the quality of water downstream by reducing its nutrient contents and increasing salinity. Another typical change in land use is the destruction of wetlands, which removes natural filter mechanisms and thus allows more pollutants to reach water supplies. The livestock industry, a major water user in certain countries (e.g. Bhutan, Brazil, Lesotho, Mauritania, Namibia, Paraguay) also produces large amounts of water polluted by organic wastes. Overall, the greater part of water pollution "is due to growing populations: the direct effect of the search for protein and livelihoods, and the indirect side effects of agriculture and urbanization". Population growth (especially when compounded by urban concentration) is the source of increasing amounts of sewage that overload streams and effluent evacuation systems; third world cities cumulate the problems of industrial and domestic pollution (see Annex 7). The increase in the use of chemicals in agriculture, as well as land clearing and irrigation, are driven by the need to increase production under the pressure of population growth. 4. IMPACT OF CHANGES IN WATER SUPPLY ON POPULATION 4.1 Water scarcity Given the essential role of water in human activities, the impacts of water scarcity are potentially devastating. Those at the household level may be the most preoccupying as they regard the most essential aspects of well-being: shortages of drinking water affect nutrition and health through limited hydratation and cooking as well as constraints on hygiene. They also affect workloads, as they entail longer or more frequent trips for fetching water. Women and children typically are the most affected on both counts. At the same time water pollution is worsened, aggravating effects on human health: "Water shortages usually lead to problems of water quality since sewage, industrial effluents and agricultural and urban run-off overload the capacity of water-bodies to break down biodegradable wastes and dilute non-biodegradable ones". Unfortunately such shortages are increasingly common. Water scarcity also limits economic performance, first of all in respect of agriculture and food production. Agriculture, being a major water user, is a major victim of water scarcity when prospects for further development of the production depend on irrigation techniques. Overall economic impacts vary, depending in particular on which sectors are most affected when competition for water becomes too intense. In certain situations urban and industrial demand, being backed by greater purchasing power, has deprived agricultural users. In others, on the contrary, agricultural withdrawals have left human settlements and industries downstream short of water. The impacts can be multiple, as in the famous case of the Aral Sea: reduced river flows induced by large-scale irrigation development in the region have severely damaged all the economic activities of what once was the shores of that great water body, including the destruction of fisheries and declining agricultural yields. A method of description for the levels of competition for water has been developed from the observation of areas where both per caput supplies and resource use problems were sufficiently documented. According to this widely used model: - Population pressures under 600 persons per flow unit (P/FU; 1 FU = 1 million cubic meters) are not considered a serious issue, although water quality problems and dry season supply problems may occur. - Between 600 and 1000 P/FU, chances of more recurrent quantitative or/and qualitative supply problems increase notably; this is called the "water stress" stage. - Between 1000 and 2000 P/FU such problems are common and affect human and economic development; this is the "scarcity" stage. - 2000 P/FU is seen as the maximum population pressure that can be handled in the present state of technology and management capabilities; it has been labelled as the "water barrier". These concepts have been used to forecast levels of water scarcity in 2025 for all countries based on recent population projections and water supply estimates: - 15 countries would suffer from water stress, namely Afghanistan, Burkina Faso, Ghana, India, Korea Republic, Lebanon, Lesotho, Madagascar, Mozambique, Peru, Poland, Tanzania, Togo, Uganda and Zimbabwe. - 9 would suffer from water scarcity, namely Comoros, Cyprus, Egypt, Ethiopia, Haiti, Iran, Morocco, South Africa and Syria. - 22 countries would meet a "water barrier" before 2025, namely Algeria, Bahrain, Barbados, Burundi, Cape Verde, Djibouti, Israel, Jordan, Kenya, Kuwait, Libya, Malawi, Malta, Oman, Qatar, Rwanda, Saudi Arabia, Singapore, Somalia, Tunisia, the United Arab Emirates and Yemen. Let us give another example of use of these indicators; it refers to Africa, whose case is worth noting in this context. The water potential of the region is not particularly great: when total river runoff is related to total land area, Africa's index is only half the global value. The semi-arid areas of the continent, with their high populations in relation to water availability, are the most exposed. Regional prospects point to rapidly increasing water needs: "improved agricultural yields depend on reducing the risk of root-zone water deficiency; improved health depends on increasing household water supplies; industrial development requires ample amounts of water. In addition to this rising demand, continued population growth implies that the actual ceiling of affordable water use would decrease to half its present level in about 25 years". Annex 8 illustrates the interplay of factors responsible for this precarious situation, including rapid population growth which is typical of this region. Table 1 classifies African countries by: [a] level of water competition, i.e. the number of persons per flow unit and [b] the technological level of cultivation needed to ensure food self- sufficiency in 2025, based on FAO's classical study of potential population-supporting capacities. Table 1. Countries of Africa classified by level of water competition and level of agricultural intensification needed in 2025 for self-sufficiency. ______________________________________________________________ Technology for self-sufficiency: Low Intermed. High level High level level level enough not enough _______________________________________________ Competition (P/FU): < 100 Cameroon Sierra Leone Centr.Af.R. Congo Equ.Guinea Gabon Guinea Gui.Bissau Liberia 100-600 Angola Botswana Mauritania Chad Ghana Namibia Cote-d'Iv. Mali Niger Zaire Sudan Senegal Zambia Water stress Benin Ethiopia (600-1000) Burkina F. Uganda Gambia Mozambique Water scarcity Tanzania Nigeria Algeria (1000-2000) Togo Egypt Zimbabwe Lesotho Libya Morocco Somalia Water barrier Malawi Burundi (> 2000) Kenya Rwanda Tunisia ______________________________________________________________ Twenty-one countries are expected to be beyond the 600 P/FU threshold by 2025. Eleven of them (bold characters) would be in that situation already by the year 2000. In 2025 the population affected by water supply problems would thus reach 1.1 billion, or about two-thirds of the projected population of the region. Population growth "is at the heart of the problem of semi- arid development. [...] The fundamental importance of water both for habitability and for rural access to biomass for food, fodder, fuelwood and timber makes water scarcity a crucial problem in the struggle for a higher quality of life of poor rural populations [...] Migration out of the area will inevitably occur if habitability is reduced by water shortages". Admittedly, scarcity-related concepts are indicative, in view of the varying adaptive capacities of countries. In particular, the water barrier concept should not be taken literally; even if water shortage is indeed a medium-term barrier to development--especially in developing countries--there is no indication that solutions for the long term cannot be found. Rather than impending absolute physical limits, the indicator warns of steeply increasing costs of supply on account of increased investment and recurrent expenditure for water supply, treatment and/or re-use (see 5.3). It is fair to add that margins for interpretation of scarcity indices at the country level go both ways: "in the humid zones, a competition level of 600 might signal the beginning of water allocation problems. In arid conditions, the problem is more complex because of considerable seasonal variations in rainfall. The largest need for irrigation water is during the dry season when the water accessible to people can be as low as 10 percent of the annual flow. Even countries with an average competition level of only 50 [...] have considerable allocation problems during the dry season". In addition, "national figures do not reflect the stress on water resources quality in local areas exerted by rapid urbanization and industrialization". 4.2 Water pollution Water pollution can render the water unfit for various usages, from nutrition to agriculture and industry. It also can affect natural biological systems, as in the eutrophication of lakes and coastal waters or the accumulation of unsafe levels of metals and organic residues in aquatic life. The quantitative supply of water certainly can be a local issue, but in many regions the most serious problem hindering the utilization of water resources is the deterioration of water caused by pollution. Health impacts probably are the most preoccupying: the "use of polluted waters for drinking and bathing is one of the principal pathways for infection by diseases that kill millions and sicken more than a billion people each year [...] Because of their effect on human welfare and economic growth, deficient water supplies and sanitation pose the most serious environmental problems that face developing countries today". The magnitude of the problem is apparent from the information in Annex 9. Overall, "an estimated 25,000 people die every day as a result of water-related sicknesses". Water pollution problems are most serious in the urban agglomerations of developing countries, where controls on industrial emissions are not enforced and sewers, drains, let alone sewage treatment plants usually are lacking. WHO estimates that at least 600 million urban dwellers in the developing countries live in what it terms "life- and health-threatening homes and neighbourhoods". (It is worth remembering at this juncture that the urban population of developing countries, now 1.7 billion strong, is expected to grow to 4.0 billion by 2025.) Environmental health problems common to many neighbourhoods include: "pools of dirty water, which accumulate around the home because there are no drains or sewers, and house sites are contaminated with excreta; pools of waste water [which can] become a breeding ground for disease vectors; lack of drains will often mean that floods are common occurrences and these bring additional health problems". The impacts of pollution carried by water streams also include the damage done to fisheries, which are a major source of proteins in many countries. This concerns inland as well as marine fisheries, including fish nurseries in estuaries and coastal mangrove swamps. Such impacts are enhanced by the already large, and still growing, concentration of populations along sea shores and rivers around the world. The capacity of rivers to support aquatic life "is decreased when the decomposition of pollutants lowers the amount of oxygen dissolved in the water. [The effect] on fisheries may be economically important. [A sampling of] monitoring sites in the mid-1980s found that 12 percent had dissolved oxygen levels low enough to endanger fish populations. The problem was worst where rivers passed through large cities or industrial centers. In China, only five of fifteen river stretches sampled near large cities were capable of supporting fish. High-income countries have seen some improvement over the past decade. Middle-income countries have, on average, shown no change, and low-income ones show continued deterioration". The pollution of coastal waters is a factor in declining catches in many areas of the developed and developing worlds. Silt loads carried by rivers, aggravated by land development and forest destruction, alter and reduce breeding grounds, and fish are contaminated by sewage and toxic substances. In fact, pollution from industry, farms and households that daily drains into the sea imperils not only fish but the diversity of marine life. Contrary to the popular view, oil spills and other effects of shipping play a minor role in ocean pollution compared to the impacts of human activities on land; sewage contributes about half the polluting nutrients that enter the oceans worldwide, and pollution from households also causes major harm. Another widespread type of health problem is represented by the impacts of water development through vector-borne diseases. Hydrological changes brought about by dam construction and irrigation development (larger, shallower or slower water bodies) may cause significant increases in the extent and seasonal duration of the breeding sites of mosquitoes and other vectors, thereby increasing the transmission of malaria and other diseases. Similar effects derive from the random creation of water pools in third world cities, slums and industrial sites. 5. POPULATION-WATER LINKAGES IN A POLICY FRAMEWORK 5.1 Policy relevance of the linkages Population-environment linkages are a development issue: "[e]nvironment resources provide the basis for development, just as environmental factors constitute part of the improvement in the quality of life that development is meant to bring about". Because of that, environmental variables must be part of the analysis of development issues which influence population dynamics. Likewise, population variables are relevant for the analysis of environmental issues which may constrain overall development. In practice, however, this convenient dichotomy is useful only up to a point since actual issues involve both population and development variables. Two major categories of issues can be identified, namely: - Water scarcity in a general sense, i.e. actual or impending insufficiency of per caput resources, which may constrain the development of an economic base; this also constrains the well-being of the population and its very growth, mainly through poorer health, higher morbidity and mortality, and more intense out-migration than would otherwise be the case. By the same token, differential water availability contributes to shape population distribution and prospects for change in that distribution, in particular through migration. This is of particular relevance in connection with urbanization (which, as noted above, gives rise to an acute concentration of demands for water): water supply constraints must be considered when forecasting or planning for urban growth. But the relevance for intra-rural population flows and distribution should not be underrated: for instance, caution should be applied with development programmes that could cause excessive population concentration in "beneficiary" areas. - Water pollution, by affecting human health, has impacts both on work productivity and on demographic variables that determine population growth. It also affects animal health and economic activities that depend on water supply of a given quality. Overall, pollution has effects largely similar to those of scarcity (inadequate water being equivalent to lack of water), only with additional human suffering. Policy-wise, these issues can be analyzed and addressed on various scales, from the country to the village level. Certainly, population-water linkages can be considered at the national level, where broad issues arising from overall levels of use and sectoral competition can be identified (see section 4.1). This broad picture is quite insufficient, however: both on the population side and the development side, spatial distribution and location aspects are essential for the identification of problems and design of responses. Indeed, for action purposes most natural resources and environment issues simply must be dealt with at the local level. The UNCED has aptly defined three programme areas where attention to population aspects of environmental issues must be applied. Two areas are relevant at this juncture, namely: - "Formulating integrated national policies for environment and development, taking into account demographic trends and factors"; - and "Implementing integrated environment and development programmes at the local level, taking into account demographic trends and factors". National policies can set important principles and define basic criteria for evaluating issues and designing programmes. Decentralized levels of action, however, are probably more important in view of the local specificity of environmental problems. Some types of field programmes requiring attention on account of population-water linkages, either because they are heavily dependent on water resources or because they are liable to affect these in a significant manner, are the following: [i] proper attention to human health issues in policies and projects involving water use and development, in particular irrigation, water catchment and storage; [ii] proper attention to migration and urbanization factors in all forecasts made regarding water requirements, including taking into consideration different consumption patterns of households in different settings; [iii] taking into account water needs, waste production and ecosystem sustainability in formulating human settlement policies; [iv] and, of course, properly allowing for population growth in all instances. 5.2 On analyzing population-water linkages Let us see how population-water linkages can be analyzed with the help of the classical equation: I = P . c . i where I is the total environmental impact of the consumption of a given good, P is population, c is the per caput consumption of that good and i is the impact per consumption unit. The equation can be used with reference to two kinds of "impact", namely: [a] the amount of a primary resource substracted as a result of a unit consumption, or [b] the amount of pollution resulting from a unit consumption. Both are clearly relevant for water issues. 5.2.1 Factors in water withdrawal A - Domestic usages In the case of domestic water use, c corresponds to water consumption, and i to water withdrawal for domestic consumption purposes; the two variables can be regarded as equivalent for our purpose, although in all rigour withdrawals correspond to consumption plus losses. The level of c varies a lot between regions and countries (see section 2.1). It also varies among population groups within countries, the main factor of variation being the relative ease of access to water: distance to supply point, mode of supply (well, pump, fountain...) and competition at the supply point. Population dynamics determines the growth and distribution of basic needs for domestic water, rather than those of actual consumption (or "demand"). It is thus the dominant factor in developing regions, especially under arid and semi-arid areas, while progress in supply development and technology for delivery are increasingly decisive as one moves to more favourable climates and more developed regions. B - Agricultural usages Agricultural withdrawals are a function of the need for irrigation, that is--if abstraction is made of foreign trade--a function of the excess of demand for agricultural products over rainfed supply. The level of consumption of agricultural products in general, of foodstuffs, or of a particular item, can always be expressed as the product of total population times per caput consumption. Population growth has a variable part in the growth of consumption, depending on the level of per caput consumption already reached and the respective rates of growth of population on the one hand and per caput income on the other. That part can be estimated by the following calculation. Assuming that the following growth rates have been observed for a hypothetical country during a given period: Population 2.1% Per caput demand 1.0% Total demand 3.1% we shall estimate the contribution of population growth at 2.1/3.1 = 68%, and that of per caput demand at 1.0/3.1 = 32%. (An application of this calculation was given in section 2.2.) It should be noted that this calculation implicitly assumes that the two factors are independent, i.e. that the rate of population growth does not affect the rate of growth of per caput demand or vice versa. This assumption is discussed below (D). C - Industrial usages Water withdrawals for industrial usages are a function of: - total population, - per caput consumption of the various industrial products (as well as direct, private consumption of energy) and - water withdrawal required (intermediate consumption plus losses) for producing the quantity of each product (and energy) consumed on average. (There can be an I=Pci equation for every product consumed.) Population is not a major factor in the growth of industrial withdrawals: consumption levels (c) and technology (i) play the major role--as can be inferred from the sectoral projections reported earlier, which show the expected growth of industrial water use to be vastly greater than expected population growth in all regions (Annex 3). D - On the ceteris paribus assumption Hypothetical consequences of alternative courses of demographic events for the environment are often estimated on the basis of the I=Pci equation. Assuming that during a certain period the impact of a particular consumption, I, has been increased by 4 percent and P has grown by 2 percent, one might argue that "had population grown by 1 percent only, the increase in I would have--other things being equal, or ceteris paribus-- been limited to 3 percent". But, can other things be assumed to be equal? The key point in this case is: if population growth had been slower, would per caput consumption still have grown at the same rate? Per caput consumption of a given commodity # (c#) is a function of: per caput income (y); the fraction of income that is allotted to consumption expenditure (k); and the portion of consumption expenditure that is allotted to commodity # (p#): c# = y . k . p# For the sake of simplicity let us assume here that k and p# are independent from the population growth rate: this may not be quite correct, at least for k, but the assumption is acceptable because y is the major variable here. The question now boils down to that of the effect of alternative population growth rates on the growth of per caput income, and the answer does not hinge on evidence but on theoretical stances. Development theories of malthusian lineage hold that slower population growth does not translate into slower GDP growth (particularly in the short and medium run), and that it therefore enables more rapid per caput income growth. In this framework, if a hypothetical scenario with slower population growth is compared with actual events (or another scenario) with faster population growth, it should be admitted that reduced population growth does not translate entirely into a reduced consumption. By contrast, the opposite view--that a slower population growth procures no gain in terms of per caput income growth-- implies that a deceleration of population growth brings about an equivalent reduction in overall consumption--and, other things being equal, in environmental impact. It must be noted that the relevance of these considerations varies from a consumption "sector" to the other. Domestic water consumption, for instance, probably is not much affected by income growth as such. As for demand for agricultural products, two situations coexist: for the part which is met through markets, the reasoning on per caput income applies; for the part which is met through own-production, it does not. 5.2.2 Factors in water pollution A - Domestic pollution Domestic water is polluted solely by human wastage. Since the level of per caput wastage is largely independent from "affluence", population growth undoubtedly is the major cause for growing emissions of polluting effluents. The impact of those emissions depends on technology, in the form of water treatment facilities. It must be noted that the efficiency of treatment systems in turn is affected by a "workload" factor, i.e. the size of population served per treatment unit. In developing countries at least, investment in such facilities is constantly running behind population growth, particularly in urban areas, leaving most of the wastage untreated (see 3.3). B - Agricultural pollution Water pollution from agricultural activities is essentially due to the use of chemicals (fertilizers and pesticides), mainly in conjunction with irrigation. It might seem plain to say that increase in that use is driven by growing demand for agricultural products (see 5.2.1-B) in the face of difficulties for extension of cultivation. This is largely true in developing regions, but fertilizer use has been known to increase also in developed regions, where such pressures are absent but economic factors may push in the same direction. The impact of population growth on the 1961-1988 increase in fertilizer use (which is different from pollution, but related to it), for major regions, has been estimated as follows: Asian centrally planned economies: 15% Developed countries: .............. 21% Far East: ......................... 22% Near East: ........................ 29% Latin America: .................... 30% Africa:.......... ................. 35% C - Industrial pollution Consistent with earlier notes on the role of population vis- a-vis economic and technical factors in this sector, the impact of population in this case in certainly weak. 5.3 Policy options Two main policy problems are posed with regard to water resources. One is to avoid major demand-supply imbalances during the "planning period" under consideration. The other is to minimize water pollution. Traditionally, the search for solutions to these problems--especially the former--has focussed on technology, much less on economic instruments and even less on population variables. In the analytical terms used earlier, minimizing total environmental impact I can conceivably lead to tackle any or a combination of the variables P, c and i: broadly speaking, the problem is to weigh the merits of population programmes, economic policies or technology policies. The options would include for instance: - slowing the growth of population or of a major consuming group (in the case of sub-national areas, the idea of diminishing population size through migration may occasionally make sense); - discouraging the consumption of the good in question, possibly through substitution; and - causing changes in the technology of production (or shifting to external supply). Admittedly, population policies will rarely be launched just to facilitate the solution of an impending environmental problem. Rather, detecting a conflict between population and supply trends in a key sector such as water may be a strong additional reason to consider such policies or to intensify them. At an elementary level, when the level of basic services (domestic supply and sanitation) is low, rapid population growth means that it will be very difficult or impossible to improve the situation rapidly. An inordinate amount of resources is needed to ensure the basic necessities to additional populations and "catch up" (i.e. provide for the unserved), leaving little or nothing to invest in progress in services. In other words, like in other areas, moderating population growth serves at least to alleviate the growth of problems; solving those problems is a matter of economic, social and technological policies. Along this line, the view has been expressed that "interventions to reduce rapid population growth may be the most expedient means of preventing further environmental degradation for one unfortunate reason: ultimate causes are extremely resistant to change"; where this is the case, population policies "can help to buy crucial time until we determine how to dismantle more ultimate causes". This assessment of the varying degrees of resistance to change, among factors of environmental problems, has also been questioned. Surely a case-by-case examination is necessary. At any rate it can be said that stabilizing population in itself has three effects, namely: - moderate the growth of demand; - moderate the growth of human waste; and - ease time and space constraints so as to facilitate a "sound development necessary to address problems of supply, inefficient irrigation and waste disposal". In various sectors, outlining and selecting among policy options is carried out through scenario analysis. A typical procedure for applying this method is: (a) Construction of a "trend scenario", illustrating the consequences of the mere continuation of existing trends. (b) Assessment of the said scenario on the basis of selected criteria and indicators; identification of potential conflicts, negative changes and required adjustments. (c) Construction of alternative scenarios, simulating the implementation of a range of possible policies to address the issues identified. (d) Comparative assessment of the alternative scenarios and choice of one of them as "target". Scenario analysis can be conducted in a variety of manners, ranging from largely qualitative analyses to the use of full- scale mathematical models of the system or sub-sector under review. In the present case, it can be applied to compare the merits of policies that address the population, consumption and technical factors in water impact issues. The issues ought to be identified both substantively (supply, scarcity; quality, pollution; ...) and geographically, i.e. in the context of specified areas. As to the merits of possible policies, they have to do both with efficiency considerations (the respective impacts of intervening variables) and with cost considerations. In effect, the debate on ways to address population pressures on the environment often has left aside the latter aspect. In its extreme version, the optimistic stand points to the theoretical possibility of technological solutions (however costly and problematic, e.g. the massive desalinization of seawater) to deny the existence of long-term issues. In reality, while sheer impossibilities may be rare, situations leading to inordinate costs for maintaining the rate of progress or even the status quo, are much more common. In sound practice, the cost and efficiency of alternative policies, including the impact of expected outcomes on the quality of life, should be considered in all cases and decisions should be based on the respective roles of the various factors in resource exhaustion and pollution and the potential impacts (versus the costs) of interventions on those factors. In this context, technical variables do not suffice to forecast outcomes and inform policies, and it is indispensable to examine the social and economic context of fundamental national or local decisions in matters of water management of technology. With regard to water resources, while one strand of thinking emphasizes the relation between physical water supply and growing human use as a constraint on development , another denies fundamental incompatibilities and places hope (albeit cautious) in the improvement of water management methods. In particular, most recent technical meetings held by water scientists or environment specialists at large do recognize population factors in water issues, but tend to focus on technical and management aspects in dealing with those issues: see Annex 10. 5.4 Knowledge base and research needs Developing a better understanding of the relationships between population dynamics, socio-economic development and water (and related life support systems), in order to anticipate and react to problems in a rational way, is an indispensable step in formulating related policies. Population and development projects could contribute to this end through their research components. 5.4.1 Research topics Let us keep following the directions of Chapter 5 of Agenda 21 and define the basic purposes of research in this area with reference to the objectives of the first programme area in that chapter (on developing additional knowledge). The said purposes would be the following (the language being adapted to the focus on population-water linkages): - To incorporate demographic trends and factors in the analysis of water resources and development issues. - To develop a better understanding of the relationships among demographic dynamics, technology, cultural behaviour, water resources and aquatic life support systems. - To assess human vulnerability in hydrologically critical areas to determine the priorities for action at all levels. Once also adapted to the context of the substantive issues at hand, the three lines of research identified in the same framework in pursuance of these objectives will read as follows: (A) Identify the interactions between demographic processes, water resources and aquatic life support systems. (B) Integrate demographic factors into the ongoing study of water resources change, to (i) study the human dimensions of such change and (ii) identify vulnerable areas. (C) Identify priority areas for action and develop strategies and programmes to mitigate the adverse impact of environmental change on human population and vice versa. In brief, one will seek a better basic information on water use patterns and the impacts of water supply problems on human populations, and applications of that information in policy- making. A research strategy could for instance include the following types of studies and address the following questions: 1. Retrospective studies, geared mainly to provide the necessary understanding of linkages between population factors, socio- economic variables and water resources dynamics: * What has been the influence of water resources and their location on rural population distribution? On urbanization? * What has been the impact of water resources development on migration and settlements? * What has been the impact of water resources development on health and household wellbeing in the areas concerned? * What have been the trends in water use by households and their determinants (affluence-habitat-supplies...)? * What have been the trends in water quailty? What are the main factors in water pollution? * What has been the impact of urbanization on local water resources, their supply and quality? * What have been the trends in water use by irrigated agriculture and industry? * Have specific areas experienced diminishing per caput supplies, growing competition, conflicts over water and the like? 2. Situation studies, i.e. cross-sectional assessments, geared mainly to identify problem areas and populations at risk and their problems: * What is the current state of water supply (quantity and quality) to households, their consumption patterns and water-related health problems? * What are the current water use patterns in irrigated agriculture? In the main industries? Do they compete locally with domestic usage? * What are the current water-related health issues? What is their prevalence? Are they on the increase or on the decline? * What population groups appear to be at disadvantage with regard to access to water, on account of their geographic location? of their socio-economic status? of other social variables? 3. Perspective studies, geared to scenario analysis and more generally to detect potential inconsistencies and explore policies. * What could be the impact of planned agricultural and industrial development projects (with specific regard to their location) on water supply for household usage? * What could that impact be on population redistribution through migration and subsequent changes in domestic demand? * What are the prospects for scarcities and other supply problems (quantitative and qualitative) at the local level? * In particular, what are the implications of urbanization trends for water competition? * Conversely, can constraints be detected that may invalidate trend projections of urbanization and limit urban population size? or the urban growth rate? * Are there areas where foreseen water supply problems are so serious that spontaneous or planned relocation of population and/or economic activities must be envisaged? * By contrast, in what areas can water problems be classified as tractable? What policies options can be recommended to deal with them? * How will population dynamics (growth, urbanization etc.) affect intersectoral and intra-sectoral competition for water? How would the conceivable alternative outcomes of that competition in turn affect population dynamics? * How might the explicit or implicit water use policies affect population dynamics? 5.4.2 Indicators A variety of indicators will obviously be needed to study water use and requirements in the relevant degree of detail--such as water use per caput, per unit or ton of industrial product, per unit of energy produced or per ton of agricultural commodity produced, per unit area, per unit value added and so on. More indices will have to be devised on an ad hoc basis. One possible approach to the exploration of potential imbalances between population and resources, for instance, is to assess the specific "carrying capacities" of relevant areas with due attention to critical resources and ecosystem sustainability. Estimates of the population which the water resources of a given area could support (under a range of assumptions regarding sectorial water use) could be used among others. The scale of investigation should be disaggregated as appropriate. On supply issues, we have seen that the area for analysis should be "relatively small [since] summation of supply over large areas obscures nonuniformity in distribution and therefore presents an overly optimistic impression of supply adequacy". Analyzing population-resources issues in the context of the watershed is a recent and useful proposal. But other issues justify similar care in selecting the study unit: for instance, health issues often are location-specific. While both rural and urban problems must be assessed and addressed, focus must be placed on urban communities in the sense that the major ones must be treated as separate "individuals". The issue of water as a general constraint on development, for want of sufficient information, so far has been approached through indices describing no more than the "density" of population relatively to water resources (the Population/Flow Unit indicator: see 4.1). Working from actual actual use levels, with some spatial disaggregation, would be a major improvement: for policy purposes, it is essential to determine which economic sectors, geographic areas or groups are at risk of water scarcity. Distributional dimensions--referring to groups within the population of a given geographic area--are extremely important. Those dimensions modify the usual risk considerations in critical ways, since unequal distribution can imply severe shortages for some groups, even though aggregate indices do not indicate overall scarcity. And they will point to problems that generally require more than technical solutions. In general, data on water resources and use still are insufficient, as underlined by the International Conference on Water and the Environment held in Dublin in 1992 and other meetings. Certainly many elements of information will have to be collected through field surveys. In many cases the classical surveys of the demographic or socio-demographic type could be extended to cover the issues covered here.