‘WATER SECURITY’:
WHAT DOES IT MEAN, WHAT MAY IT IMPLY?
by Bart Schultz Stefan Uhlenbrook
Discussion Draft Paper for the session on
Water Security Wednesday, 13 June 2007
Delft, The Netherlands
The pace of change in our world is speeding up, accelerating to the point where it threatens to overwhelm the management capacity of political leaders. This acceleration in history comes not only from advancing technology, but also from unprecedented world population growth, even faster economic growth, and the increasingly frequent collisions between expanding human demands and the limits of the earth’s natural systems.
Lester R. Brown, 1996
ABSTRACT
Water security involves the sustainable use and protection of water systems, the protection against water related hazards (floods and droughts), the sustainable development of water resources and the safeguarding of (access to) water functions and services for humans and the environment.
Although there is nowadays such a wealth of experience, and we have very good know how, very good technologies and high financial means, the problems with respect to water and water management are in quite some cases still enormous. The following major types of problems are discussed: water shortages, inefficient water use in irrigation and drinking water supply, inadequate sanitation, waterlogging and salinization, inadequate operation and maintenance, pollution through urban and industrial wastewater, fertilisers and pesticides, and flooding of cultivated, urban and industrial areas. In this paper a brief overview is given of certain key issues of water security, whereby mainly bio-physical and engineering aspects are addressed, issues related to water governance and capacity building are discussed in an accompanying paper. It will be illustrated what it means and what it may imply for our societies, at present and in future.
INTRODUCTION
Since more than 6,000 years man is using water to his advantage in many different ways, or protects himself against harmful effects of water in order to improve his living conditions. Tremendous successes have been obtained, but in many cases water management, flood and drought protection, drinking water supply and sanitation schemes are far from optimal, function significantly below what could be expected, or are simply absent. Other functions and uses of water like its role in ecosystems, transport, recreation, landscaping, etc. are often inadequately addressed and the connected processes are still not fully understood. Therefore, many challenges are ahead of us. It is remarkable that although there is nowadays such a wealth of experience, and we have very good know-how, the very
good technologies and high financial means, the problems in certain cases are still enormous (e.g.
Schultz, 2001). Some major types of problems are, a list that can easily be extended:
• water shortages;
• inefficient water use in irrigation and drinking water supply;
• inadequate sanitation;
• destruction of (aquatic) ecosystem;
• waterlogging and salinization;
• inadequate operation and maintenance;
• pollution through urban and industrial wastewater, fertilisers and pesticides; and
• flooding of cultivated, urban and industrial areas.
In this paper a brief overview is given of certain key issues connected to water security. It will be illustrated what it means and what it may imply in our societies, at present and in future. This paper discusses mainly bio-physical and engineering aspects; the issues connected to water governance as well as the needs for knowledge transfer and capacity building are discussed further in an accompanying keynote paper from van Hofwegen (2007; this volume).
WATER SECURITY, ITS DEFINITION
Water security involves the sustainable use and protection of water systems, the protection against water related hazards (floods and droughts), the sustainable development of water resources and the safeguarding of (access to) water functions and services for humans and the environment.
Measures to increase water security are in this context primarily concerned with human interventions in water systems and/or a wise utilization of water and water-related environmental services. These are aimed at the enhancement of the beneficial and sustainable use of water for various purposes such as water supply, irrigation, drainage, navigation, hydropower, environmental control and the protection against water related disasters such as floods and droughts. Interventions in water systems are often necessary to meet the needs of society and the environment in its widest sense and in order to be able to face the challenges of all kinds of global changes (e.g. climate change, land use change, etc.). Obviously the negative effects (e.g. environmental or socio-economic) of such interventions need to be minimised and their wider impact also for downstream water users needs to be considered. Effects of climate change and other global changes are increasingly important factors for identification of the design parameters that define the location and dimensions of hydraulic structures, water management, flood protection, drinking water supply and sanitation systems to increase water security.
One of the key-aspects is the relation water security-food security. The agricultural sector is already the largest water consumer (approximately 70% of global water supply). At present about 45%
of the global food production is realised without a water management system and 55% with either an irrigation or a drainage system. However, it is expected that global agricultural yields have to be doubled in the next 25–35 years and that about 90% of the increase would have to be realised on the existing cultivated area. This can only be achieved with a more efficient use of the water resources and a substantial improvement and extension of water management systems, in quite some regions in combination with increase in storages, either surface or sub-surface water storages (van Hofwegen and Svendsen, 2000, Schultz, et al., 2005). The problem will be enhanced if more agricultural land is used to satisfy the rapidly increasing energy demand (i.e. production of energy crops, biofuel etc.).
HYDROLOGICAL AND WATER RESOURCES ASPECTS OF WATER SECURITY
The hydrological cycle can be divided into atmospheric, surface and subsurface water systems.
Surface water includes all water bodies, which are in direct contact with the atmosphere (i.e., streams, lakes, snow and ice as well as water in the biosphere). Subsurface water includes groundwater and water in the unsaturated zone above the groundwater table (including capillary fringe). The global reserves of water as a function of storage are shown in Table 1, and the directions of water fluxes are indicated in Figure 1. Table 1 indicates that freshwater resources are mainly stored in glaciers and permanent snow cover as well as in groundwater. The proportion of water stored in the atmosphere, soil, and in river channels is very small, and the dynamic residence times (based on mean renewable period) are short. However, because of the importance of this water for humans (including agriculture) and ecosystems, understanding the water fluxes and residence times in these different domains is of primary importance.
All the rainwater that falls on the earth and is not evaporated, transpired, or withdrawn artificially, contributes to the flow of rivers and groundwater. Dependent on different physiographic characteristics, like climate, size of the river basin, topography (slopes and other terrain parameters) as well as soil and geological parameters, the discharge of a river differs significantly in space and time.
Depending on man’s activities, the quality and quantity of water that enters the rivers differ as well.
Rivers can transport natural or artificial components; the load can differ in relation to the discharge.
Both quantity and quality of the river water will determine if it is useful for irrigation or domestic water supply.
Understanding and being able to predict of all processes of the water cycle at different spatial and temporal scales is critical for the effective management of water resources including hydrological extremes, thus it is crucial for an optimal water security. However, the large spatial and temporal variabilities that exist in water storages, fluxes, and residence times of the different components as
well as the often poorly understood interactions between the different components, make the development of hydrological and water resources models development a challenging task. This becomes more difficult when also water quality issues need to be taken into account, which is increasingly required especially when human influence is at stake.
Table 1. World water resources; renewable periods are calculated as the mean volume divided by the mean flux (from data from UNESCO, 2006).
Location Volume (103 km3)
% of total volume in hydrosphere
% of fresh water
Volume recycled annually
(km3)
Renewal period (years) Ocean
Groundwater (gravity and capillary) Predominantly fresh groundwater Soil moisture
Glaziers and permanent snow cover:
* Antarctica
* Greenland
* Arctic islands
* Mountainous regions
* Ground ice (permafrost) Water in lakes:
* Fresh
* Salt
Marshes and swamps River water
Biological water
Water in the Atmosphere
1,338,000 23,4001 10,530 16.5 24,064 21,600 2,340 83.5 40.6 300 176.4 91.0 85.4 11.5 2.12 1.12 12.9
96.5 1.7 0.76 0.001 1.47 1.56 0.17 0.006 0.003 0.022 0.013 0.007 0.006 0.0008 0.0002 0.0001 0.001
30.1 0.05 68.7 61.7 6.68 0.24 0.12 0.86 - 0.26 - 0.03 0.006 0.003 0.04
505,000 16,700
16,500
2,477
25 30 10,376
2,294 4,300
600,000
2,500 1,400
1
9,700
1,600 10,000 17
5 16 days - 8 days Total volume in the hydrosphere
Total fresh water
1,386,000 35,0029
100 2.53
- 100
1 Excluding groundwater in the Antarctic estimated at 2 million km3, including predominantly fresh water of about 1 million km3.
MAN’S INFLUENCE ON THE HYDROLOGICAL CYCLE
Within the hydrological cycle a sub-cycle of water diversion, including water consumption through irrigation and domestic water supply and drainage, exists. This branching cycle - expressing the influence of man - is exerting significant influence on the primary hydrological cycle. The direct influence of man on the hydrological cycle only concerns much less then 1% of the water resources on
earth, as can be derived from Table 1 and is illustrated in Figure 2 (Rodda and Matalas, 1987).
However, the side effects of man’s activities influence almost all accessible waters on earth and, consequently, the availability of services from water and the aquatic environment.
Figure 1. Schematic sketch of the global water cycle. Water storages and fluxes are indicated by boxes and arrows (Oki and Kanae, 2006 ).
Evaporation 90%
Branching cycle Land
interchange Water vapour
Precipi- tation
Water vapour in atmosphere above land
Water vapour in atmosphere above ocean
Ocean Runoff
into ocean
Precipitation Evaporation
10%
Intake of water
Drainage Water users
Water consumption
Figure 2 Scheme of the hydrological cycle with the branching cycle, expressing the influence of man (Rodda and Matalas, 1987)
Table 2 summarizes the available water resources on different continents and presents an outlook to the water resource availability in 2025 (Shiklomanov, 1997). It is demonstrated that the resource availability will decrease everywhere while at the same time it is expected that the withdrawals and consumptions are increasing. The situation seems to be worst for Africa and Asia, in particular in the emerging and least developed countries.
Table 2 Estimated and projected volumes of available renewable water resources and water use by continent, 1990 and 2025 (Shiklomanov, 1997)
Available renewable water resources Water use
Area 109
m3/year
m3/person in 1990
m3/person in 2025
1990 with- drawal in
109 m3
1990 consump- tion in 109
m3
2025 with- drawal in
109 m3
2025 consump- tion in 109
m3 Africa
North America South America Asia
Europe Australia and Oceania
4,047 7,770 12,030 13,508 2,900 2,400
6,180 17,800 40,600 3,840 3,990 85,800
2,460 12,500 24,100 2,350 3,920 61,400
199 642 152 2,067 491 29
151 225 91 1,529 183 16
331 836 257 3,104 619 40
216 329 123 1,971 217 23
World 42,655 7,800 4,800 3,580 2,196 5,187 2,879
Figure 3 illustrates the distribution of the water scarcity index. The water scarcity index, Rws, is defined as (W–S)/Q, where W, S, and Q are the annual water withdrawal by all the sectors, the water use from desalinated water, and the annual renewable freshwater resource, respectively (Oki and Kanae, 2006). A region is usually considered highly water stressed if the water scarcity index is higher than 0.4 (e.g. Falkenmark and Rockstoem, 2004). Oki and Kanae (2006) calculated that currently 2.4 billion people live in highly water stressed areas. This number is likely to increase to 3-5 billion people in 2025, depending on the assumed scenario for the development of the future climate, economics etc.. Water stress (scarcity) is currently very high in Northern China, Central Asia, at border between India and Pakistan, the Middle East, parts of Europe and Southern and Northern Africa, Western South-America as well as in the middle and western areas of the United States. It has to be considered that the given numbers for the whole continents average over a large intra-continental variability, which is demonstrated in the global map of the water scarcity index (Figure 3). Due to population growth and the increase in water use per person, and due to the increase in the standard of living, in general the situation will become more severe (Figure 4).
Figure 3. Global distribution of the water scarcity index; the water scarcity is higher the higher the index (Oki and Kanae, 2006)
Figure 4. Current and future projections of population under high water stress under three business-as-usual scenarios. The threshold values are set to be (A) the water-crowding indicator Aw 0 Q/C G 1000 m3/year per capita, and (B) the water scarcity index Rws 0 (W – S)/Q 9 0.4, where Q, C, W, and S are renewable freshwater resources (RFWR), population, water withdrawal, and water generated by desalination, respectively. Error bars indicate the maximum and minimum population under high water stress corresponding to the RFWR projected by six climate models; climatic conditions averaged for 30 years are used for the plots at 2025 (averaged for 2010 to 2039), 2055 (averaged for 2040 to 2069), and 2075 (averaged for 2060 to 2089) (Oki and Kanae,
2006)
On the other hand, an increasing number of people is also expected to live in flood prone areas, especially in urban conglomerations. These areas are located in river valleys, deltas and coastal zones.
Floods in these areas are caused by different regions; they may be caused by excessive rainfall (urban flood generation), extreme river discharges (flooding caused by the surrounding area) - either by excessive rainfall or snowmelt - or by storm surges at near the sea.
IMPACT OF POPULATION AND POPULATION GROWTH ON WATER NEEDS AND VULNERABILITY
General
In this paper three categories of countries as indicated below have been identified, based on classifications as prepared by the leading international organisations (UN Population Reference Bureau 2005, The World Bank, 2005, and UNCTAD, 2005). Based on their considerations the three categories are (Figure 5):
− Developed countries: Most of the countries in Western and Central Europe, North America and some countries in Central and South America, the larger countries in Oceania and some countries in Asia.
− Emerging countries: Most of the Eastern European countries (including Russia), most of the countries in Central and South America, most of the countries in Asia (including China, India and Indonesia), and several countries in Africa.
− Least developed countries: Most of the countries in Africa, several countries in Asia, one country in Central America and most of the smaller countries in Oceania.
From Figure 5 it can be seen that by far the majority (almost 75%) of the worlds’ population lives in the emerging countries. It can be also seen that population growth will especially take place in the least developed and emerging countries. In the developed countries almost no growth is expected anymore. In the emerging countries the standard of living is rapidly rising. However, about 1.2 billion people in the least and emerging countries are still poor (GNI less than 1 US$ per day), and out of them about 70% live in the rural area (World Bank, 2001).
In Table 3 the estimated and projected global water use by sector in 109 m3/year for 1950, 1990 and 2025 is shown (Shiklomanov, 1997). From the Tables 2 and 3 it get obvious that on a global scale the water use is only a small percentage of the resources and it seems that there is still a considerable reserve to meet the future needs. However, since the resources are to a large extent generated by the river runoff not all that water can be used. Only a certain percentage can be abstracted, the remaining has to be drained off to the sea during floods and a minimum flow to the sea has to be maintained
during other periods. On the other hand, the possible contributions from groundwater need to be considered. Table 3 also clearly demonstrates that agriculture is by far the largest water user, although the ratios are changing. Another substantial difference is that water use in agriculture generally results in a significant increase in evaporation, while the other types of water use generally result in a return flow. However, although this return flow may not result in a significant ‘loss’ of water, it may result in a significant pollution of water and a change in the hydrological regimes (e.g. water storage for hydropower generation in seasonal runoff regimes).
0 2 4 6 8 10
Million
2005 2025 2050
Year
Least Developed Countries
Emerging Countries Developed Countries
Figure 5 World population and growth in least developed countries, emerging countries and developed countries (UNDP, 2005, and International Commission on Irrigation and Drainage, 2006)
Table 3 Estimated and projected global water use by sector in 109 m3/year for 1950, 1990 and 2025 (Shiklomanov, 1997)
Item 1950 1990 2025
withdrawal consump-
tion
withdrawal consump- tion
withdrawal consump- tion Agriculture use
Industrial use Municipal use Reservoirs
1,124 182 53 6
856 14 14
2,412 681 321 164
1,907 73 53
3,162 1,106 645 275
2,377 146 81
Total 1,365 894 3,580 2,196 5,187 2,879
World population in millions
2,493 5,176 8,284
Irrigated area in 106 ha 101 243 329
Water need for agriculture
Basis for assessing agricultural water needs and realizing its appropriate management is the worlds’ population, its growth and its standard of living. Van Hofwegen and Svendsen (2000) showed the world’s population in the year 2000 and prognoses of the population in 2025 and 2050 and grouped it for developed countries, emerging countries and least developed countries separately.
Based on their findings Schultz (2001) described the possible consequences for future irrigation and drainage development. Based on data from the website of the International Commission on Irrigation and Drainage (ICID) (2006) and different other sources (i.e. FAO, 2005, UN Population Reference Bureau 2005, The World Bank, 2005, and UNCTAD, 2005) Schultz et al. (2005) presented the interactions between the standard of living, food production and development of water management.
They determined population density compared to the total area of a country and with reference to the arable land. The result for each of the continents and for the three categories of countries is shown in Table 4. With respect to this it is of importance that it is envisaged that the world population is likely to stabilize by 2050 or 2060.
Table 4 Continents and categories of countries ranked according to the population density with reference to the arable land (Schultz et al., 2005).
Continent Total area
in 106 ha
Arable land in 106 ha
Total population
in million
Population density in persons/km2 with reference to
total area arable land
Asia Africa Europe Americas Oceania
3,339 3,031 2,299 4,016 856
547 201 307 384 55
3,765 840 732 850 31
113 28 32 21 4
688 418 238 221 57
World 13,425 1,497 6,215 46 415
Developed countries Emerging countries Least developed countries
3,877 7,231 2,433
445 903 145
1,137 4,332 750
29 60 31
255 480 515
From Table 4 it can be easily observed that the Asian continent has by far the largest population and the highest population density, both with reference to the total area, as well as to the arable land. If one takes also the population growth as shown in Figure 5 into account, then it becomes clear that in the coming decades most of the activities in the field of water management to increase water security may be expected in Asia. Africa is on the second place, and the need for water management with the aim to increase the water security and food security is very obvious.
Water need for urban and industrial water supply and sanitation
Especially in the emerging countries we see a migration from rural to urban areas, for instance, it is expected that by 2020 more than 85% of the population of Latin America will live in urban centres. In addition, we see a rapid increase in the standard of living (and domestic water demand).
Due to this the consumption per capita as well as the need for urban and industrial water supply is rapidly increasing. For example, in the least developed countries the water use is often in the order of magnitude of 5 l/person/day, while in the developed countries it may exceed easily 100-150 l/person/day.
This increase in water use per person has also a significant impact on the required sanitation, especially in the urban areas. In general, the development of provisions for sanitation lags behind the development of urban and industrial water supply, resulting in substantial discharges of untreated wastewater with numerous impacts for the water quality and water-borne diseases. Especially in the countries of the European Union this has resulted in far reaching measures to control the pollution of surface waters. In light of this the adoption of the European Water Framework Directive may be considered as a milestone (European Commission, 2001). In the arid and semi-arid zone we see another development, being the reuse of wastewater in agriculture. This can increases the efficiency of water use (management of the local water ‘cycle’); however, various health issues are connected to this if it is not done correctly. An interesting overview of the developments with respect to this aspect was given by Huibers et al. (2005).
While domestic and industrial water supply can be provided at a substantially higher price than agricultural water supply, we often see in cases where competition develops that water is shifted from the agricultural sector to the urban and industrial sector.
Water need for other uses and their specific requirements
For specific water uses like transportation, water recreation, etc. special provisions may be required. Especially for commercial ship transport large-scale investments have been and are being made for construction, operation and maintenance with respect to river bed improvement, canalisation, harbour facilities, storm surge protection, sluices, etc. Such investments are generally justified by commercial and/or political considerations. In these cases water is not really consumed, but use of
water is being made in different ways with different requirements. Measures that are being taken to promote these types of water use may, however, have far reaching consequences for others types of water use and often the environment. This implies that decisions on such measures will have to take into account the consequences for the other types of water use as well and therefore have to be taken in an integrated way considering also environmental and socio-economic implications.
Another important use of water is hydropower. According to the data base of the International Commission on Large Dams (ICOLD) there exist about 49,000 large dams in the world and numerous small dams. Most of the reservoirs behind such dams have been developed for hydropower generation, others for irrigation, municipal, or drinking and industrial water supply, flood control, navigation, dilution of sewage water, log transport, stabilization of lake water levels, estuary improvement and supply of reservoirs. The aim of any dams is to fulfil multiple objectives. As far as water security is concerned in the development of new projects due consideration will have to be given to the environmental impacts and to the required environmental flows in the river system.
Virtual water trade – a measure to improve water security?
The concept of ‘Virtual Water Trade’ has been developed to explain how physical water scarcity in dry regions might be relaxed by importing water-intensive food or industrial goods (e.g.
Allan, 1998; Oki, et al., 2006). The original idea of virtual water trade was that food trade is virtually the trade of water because importing countries can use their own water resources for other purposes such as domestic water use. Hoekstra and Hung (2002) defined the virtual water content as the water used to produce the good. The weight of traded goods is normally a very small fraction of the weight of the water required to produce those goods, thus transporting goods is considerably easier than transporting the water itself. However, it should be noticed that the amount needed to produce the product does not necessarily reflect the amount of water, which can be saved by the virtual water import. This is due to the fact that water needs differ regionally due to differences in water use efficiency, crop yields etc..
Global ‘virtual water’ flows associated with major cereal trade (wheat, rice, maize, and barley) were estimated for each country where statistics were available and summarized into 16 regions (Oki et al., 2003). It was demonstrated that the Middle East, North West Africa, as well as East and South East Asia are gathering virtual water, and the sources of virtual water are North America, Oceania and Europe. Generally crop yields and water efficiencies in exporting countries are higher than in importing countries (Oki et al., 2006). Consequently, ‘real water’ in exporting countries tends to be smaller than ‘virtual water’ in importing countries. For example, 1 kilogram of soybean corresponds to 1.7 tons of ‘real water’ in the United States and 2.5 tons of ‘virtual water’ in Japan. In this sense, the virtual water trade of 1 kilogram of soybean from the United States to Japan saves 0.8 tons of global water resources. The total virtual water trade (imported virtual water) for commodities in 2000 was estimated to be approximately 1,140 km3 y-1; however, this corresponds to only 680 km3 y-1 of real
water suggesting a water saving of 460 km3 y-1 (Oki and Kanae, 2006). While the virtual water trade cannot increase the total water resource, ‘saved water’ in the importing country can be allocated to other purposes such as municipal use and environmental use. However, one has to be careful when interpreting these results since social, cultural, and environmental implications or limiting factors other than water are usually not considered. This was for example stressed by Dukhovy (2007) who stated:
“However, all authors make estimations only in terms of water, while forgetting at all about economic indicators - income derivatives, especially in processing, marketing, consumption, about economic benefits of agricultural production, the role of associated effects and the social importance of irrigated agriculture. Moreover, the water dependency index, considering virtual water is introduced in contrast to food independence. The water dependency index as it is proposed and the assessment of water deficit, based on virtual water, give a perverted idea of the possibility of national food self-sufficiency.”
Flood management and flood protection
An increasing number of the world’s population is living in flood prone areas, especially in urban areas and coastal areas. There is no indication that this trend will change in the future (Schultz, 2006). Therefore, there is an increased need for flood management and flood protection. Flood management and flood protection schemes may have to protect both rural and urban areas in flood prone zones. Generally, the central governments have their roles and responsibilities, at least for policy, legislation and the major regulation and protection works. In addition, river basin authorities, drainage agencies, local level government - provincial, municipal - and farmers may each have their roles and responsibilities. However, there are quite some differences between approaches in different countries, and it is often even not clear who is responsible for which part of the flood management, or flood protection activities, provisions and structures.
Measures with respect to flood management and flood protection are generally categorised in structural and non-structural measures. The structural measures concern: dams, dikes, storm-surge barriers, etc. In fact it concerns physical provisions to reduce the risk of flooding. Non-structural measures concern: food forecasting, flood warning, flood mapping, evacuation plans, land use zoning, etc. (Working Group on Non-structural Aspects of Flood Management, 1999 and van Duivendijk, 2005). In practice, one may expect that for a certain river basin an integrated package of flood management and flood protection measures for both rural and urban areas would have been developed and implemented as the combination of both types of measures is most effective.
Especially in lowland areas in South and East Asia one can observe a very rapid growth of cities. During the past decades mega cities like: Bangkok, Hanoi, Ho Chi Minh city, Jakarta, Manila, Osaka, Shanghai, Taipei and Wuhan have shown more or less an explosion in population growth and have transformed from cities with less than one to two million inhabitants to cities with in some cases even more than 10 million inhabitants. The increase in the value of property in these cities has been in
general even more rapid than the growth of the population suggests (Schultz, 2001).
In order to cope with the growth of these cities very often reclamation has taken place of low- lying lands in the neighbourhood of the existing urban area. From a flood protection and water management point of view this implies removal of storage area and increase in urban drainage discharges. Therefore, the development, implementation, operation, maintenance and management of integrated flood management and flood protection measures for such urbanised areas can only solve the present problems. The development and implementation of such plans is urgently required! The flooding of the city of New Orleans due to hurricane Katrina in August 2005 is an obvious proof of this statement. Also in this case the level of protection was far below the economic optimum at a level of about 1/100 per year. The costs of the measures that are being taken now after the disaster exceed by far the costs of the economic optimal flood protection measures, when such measures would have been taken before the hurricane, and the disaster would not have occurred – discussing only the related economic issues should us not let forget the environmental issues and the tragedies connected to the New Orleans and other flood disasters, which are not possible to express in a monetary way as indirect costs.
POSSIBLE FURTHER IMPACTS OF FUTURE DEVELOPMENTS
Impacts of climate change
During the past years there have been quite some debates regarding the possible impacts of climate change on for instance:
− increase in average annual rainfall and in flood generating rainfall;
− increases of dry-spells and droughts;
− rise of the sea level;
− change in river regimes; or
− impacts of the design, maintenance and functioning of water infrastructure.
As far as the increase in drought is concerned, this may imply that rainfed agriculture will become more vulnerable and that water availability for irrigation may become even more at risk in the arid and semi arid zones. All the other developments may increase the risk of flooding in particular of lowland areas. However, although such developments occur, it is expected that the possible changes in design standards for water management and flood protection schemes due to the impacts of climate change are generally in the order of magnitude of 10 - 30% over the forthcoming 100 year. It seems that at least the more developed world could deal with the associated costs, even if they will be significant in the coming decades. Locally there are exceptions that can have more far reaching consequences, for example when drainage by gravity would have to be replaced by drainage by
pumping, or drastic impacts of climate change in particularly sensitive areas. Therefore, the effects of climate change seem generally such that in the modernization of water management and flood protection schemes - which normally takes place every 25 to 50 years - the impacts of such changes can be accommodated (Schultz, 2002, 2006). But, it will have its price for the societies in developed countries and even more difficult to deal with in the emerging and least developed countries.
Impacts of future population growth and urbanisation
If we look at the increase in population and increase in value of public and private property - houses, buildings, infrastructure, public facilities, public and private property - in lowland, flood prone areas, then such increases are much more significant than the possible direct impacts of climate change which augment the problem. Therefore, compared to the issue of climate change, these value increases would have to dominate significantly decision-making on water management and flood protection measures. So far this has generally not been the case, but the understanding that these processes would indeed have to play a major role is rapidly growing and not only the issue of structural measures for flood protection, but the much broader approach to flood management is getting increasing attention.
This was recently clearly shown in the 21st ICID European Regional Conference in Frankfurt an der Oder (German National ICID Committee, 2005), the 3rd International Symposium on Flood Defence (van Alphen et al., 2005) and the 19th Congress of ICID (Schultz, 2005).
Impacts of increased bioenergy production on farm land
The future uptake of the renewable energy source bioenergy (i.e. bio-fuels, bio-diesel) in the developed world and in countries in transition is enormous. The US Department of Energy would like to substitute 30% of their transportation fuel by biofuel, similar increases are expected for the European Union, some countries (e.g. Sweden) would like to become widely independent from fossil fuel for transportation purposes. The advantages of the renewable energy source are manifold: security of supply, low net greenhouse gas and other emissions (sulfur, particulates etc.), economic and strategic advantages. Intensive agriculture (incl. modern breeding, monocultures, and transgenic techniques) could result in achievements greater than those of the Green Revolution in food crops.
Currently, many research efforts in this field concentrate mainly on technical and engineering aspects.
However, important environmental (incl. hydrological regimes, biodiversity, water quality etc.) and socio-economic (incl. food prizes) effects of large-scale bioenergy production are poorly understood and they can not be quantified reliably with existing models – the impacts on hydrological processes and water systems are crucial in this regard. The interactions between water security-food, food- security and energy-security for sustainable development are not fully understood and its impacts on water system need to be investigated in an integrated way.
CLOSING REMARKS
The emerging and the least developed countries are in particular confronted with the need to significantly increase their food supply in the coming decades. These countries can only do this by increasing their local production, may be in combination with increased imports, where inescapable.
As far as water management is concerned this will have to result in more efficient systems and, consequently, in significant improvements of existing irrigation and drainage systems in these countries through modernisation in combination with increased stakeholder involvement. In addition, new systems will have to be installed in areas where so far agricultural production is achieved without a water management system, or in new land reclamations (Schultz et al., 2005).
As long as population growth, increases in standards of living, urbanisation and industrialisation in lowland areas goes on, increasingly flood management and flood protection provisions will be required. Additional complications with respect to this are created by the effects of global changes (e.g. climate change, land use changes) and land subsidence, which occur in many of the lowland areas. Such processes make these areas increasingly vulnerable. Maybe this will result in the need to abandon such areas or change the agricultural use (e.g. extensive pasture land?) in the medium or long term future. If this would become an actual problem in a certain area there will be an urgent need for timely and complicated measures with various implications at different levels (Schultz, 2006).
For the symposium discussion some guiding questions are, which are complemented through the paper of van Hofwegen (2007, same issue):
- What are the impacts of climate change in comparison to other global/regional changes for water security?
- What are the impacts of large-scale bioenergy production for water security and food security?
- What are the most promising technical vs. non-technical measures to increase water security in the future?
- What are needs for capacity enhancement to improve water security in a changing world?
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