Water and agriculture

Transcription

1 Rural Development and Agriculture Briefing Note Water and agriculture Background According to the International Water Management Institute, 56% of global precipitation evaporates from forests, savannahs and grazing land. Another 4.5% is used in rainfed farming to produce food and animal feed. This precipitation that evaporates directly from vegetation and the soil surface is called green water. Almost 40% of precipitation does not immediately return to the atmosphere but flows into rivers, lakes, the groundwater and glaciers and is known as blue water. About 9% of this blue water is extracted from surface and groundwater sources for human activities. Of this, 70% (2,700 km³) on global average is used for agricultural irrigation to offset insufficient precipitation. In arid regions, such as the Middle East or the Sahel, that proportion can be as high as 90% or more. By contrast, extraction for drinking and domestic water is on average only about 10% and the remaining 20% is used by industry. Not only people and crops need water. Nature and its ecosystems need water in order for flora and fauna to be maintained and be able to grow. Humankind s overuse of water resources therefore also harms ecosystems and biodiversity and diminishes the ecological, economic and social functions of these systems, such as the erosion protection provided by vegetation cover, or water storage and filtering. A striking example is the Aral Sea, which dried out in the 1980s as a result of the rivers that fed it being diverted to provide water for agricul tural irrigation. The lake dried up leaving vast areas of salinised land in its place; the local fishing industry was destroyed with harsh consequences for the people working in it. Market and price trends both regional and global also affect water consumption. Higher prices for food, animal feed, fibres and fuel have made agriculture an attractive economic proposition once more in many regions. On the one hand, this opens up the possibility of funds for additional investment in water-saving technologies becoming available. On the other hand, there is a risk of increased production and agricultural land use causing higher water consumption. Water demand will continue to increase in the future. By 2050, an additional two billion people will need to be supplied with water, food and raw materials. More water will also be needed for energy generation. However, many regions will have less precipitation as a result of climate change.

2 To meet water demand in the future, it is essential that all sectors, including agriculture, make savings. Agriculture must also contribute to reducing the widening gap between its own future water demand and the needs of other sectors, while at the same time meeting the growing needs of the global population. To date, the increase in agricultural yields per unit of land was the yardstick for measuring the sector s productivity. In the future, water productivity will take on a special significance. Where we stand In light of these considerations, GIZ s position is as follows: 1. Regional water balances are essential A precise overview of regionally available water resources, how they are likely to change in future due to climate change, and current and future consumption by individual sectors is important for more efficient water management. To achieve this, we need to record and analyse the quality and ecological functions of water resources. These regional water balances form the basis for distributing water across sectors and countries as part of sustainable water management. 2. Better governance of water distribution Mounting competition for water means that better governance of water use is needed. This encompasses all policy guidance, legislation, standards and regulations on various levels that are necessary to ensure efficient and sustainable use of water in agriculture and other sectors. Functioning institutions capable of enforcing and monitoring compliance with such rules and regulations are a vital element. 3. Distributional equity is vital There is inherent potential for conflict in distribution of scarce resources. It is therefore important to ensure that distribution of water both in agriculture and between agriculture and other sectors is organised equitably. Existing power and interest constellations, but also social goals such as poverty reduction, health and the right to food, must be taken into account. The expansion of irrigated agriculture increases the value of arable land considerably, which may fuel conflicts over ownership. If water is used properly in agriculture, it can have a powerful impact on reducing poverty. The possibility of irrigating fields in a controlled way protects against lower crop yields or crop failures as a result of dry periods, droughts or floods. It is important that water management in agriculture does not focus solely on irrigation for crop production but also on the requirements and opportunities for livestock farming and aquaculture. Conflicts can arise in arid regions, for example, when flood plains that had been strategically important in providing refuge for nomadic animal herds are changed into irrigation perimeters. This may prevent the herds from gaining access to feed and drinking water. The private sector is increasingly playing a role in agriculture in partner countries as a result of direct investment in land. It is crucial to take this into account when considering the question of water use. Policy-makers must keep use of water resources in mind in cases where private investors plan to develop large areas of land.

3 4. Seeing technology as part of a bigger picture Water-saving technologies are available in agriculture as they are in all other sectors. The use of sprinklers, drip irrigation or subsurface irrigation, for example, uses far less water per unit produced than commonly used methods of surface irrigation. But use of efficient technology is still not sufficiently widespread. However, more extensive use of technical possibilities alone is not sufficient to harness the full potential for saving water. Alongside watersaving technologies, regulatory requirements relating to the development, protection and distribution of scarce water resources must be considered, in particular how they might be used to create incentives to use water efficiently. Distribution of water to the various sectors must focus more on the cost/benefit aspect, including impact on the environment. Our recommended action The areas listed below are good starting points for international cooperation activities to promote more sustainable use of water. 1. Record and analyse water availability Sustainable water management in agriculture requires detailed knowledge of the extent of existing water resources and how they are likely to develop. Achieving that relies on better data on water availability and consumption by the different sectors than has been available to date. Data recording and analysis must take account of changes caused by climate change. The level of water consumption in different sectors of industry and society must be transparent and up for discussion. One good way is to use what is known as a water footprint, which records the specific amount of water used to produce goods and services of all kinds. The advantages and disadvantages of using fossil groundwater resources, especially in arid regions, must be made known. Seawater desalination options must be included. This primarily offers possibilities for supplying towns and tourist centres in coastal areas but is still very energy-intensive. 2. Improve and manage water use efficiency It is important to improve water use efficiency in agriculture, as well as in other sectors. Top priority here is to reduce water losses and increase water productivity. Water retention in soils or reservoirs makes it possible to increase water availability and improve supply security, which is also important in terms of adaptation to climate change. There are three broad approaches towards achieving greater efficiency. One is to modernise the technology of irrigation systems both operational ones and those in need of rehabilitation. Another approach is to improve the way the water reaches the crops on the field. The focus there is on water-saving technologies, first and foremost drip irrigation, which however often poses a problem in terms of inadequate water quality as a result of dirt particles. The third approach is to increase water charges, which are often very low, in order to increase the incentive to save water and ensure infrastructure is maintained properly. Accurate surveys of water availability, demand, consumption and losses are needed. That kind of analysis should also take into account the water needed for ecosystems to function.

4 There are numerous technical options for improving water efficiency both in rainfed and irrigated farming: physical or biological erosion protection to increase infiltration, water-conserving soil cultivation methods, reducing evaporation by better ground cover, building small reservoir systems or larger reservoir structures. Large dam projects, on the other hand, are often controversial due to their social and environmental impact, which makes it difficult to implement them. From the point of view of individual irrigation operations, improvements in channelling water using an efficient distribution system are important. Optimising the timing and amount of water dispensed is also an important factor, as is selecting seed varieties that have shorter growing times and therefore consume less water. If used properly, water-saving technologies, especially drip irrigation, make it possible to reduce the amount of water extracted to supply a particular crop. But that does not necessarily lower the water consumption of an individual farm because a farmer may continue to extract the same amount of water and either increase the amount of cropland or produce crops that have a higher water demand. As the problem of water scarcity worsens, it is becoming more important to exploit unused precipitation runoff and what are known as marginal water resources, such as municipal waste water, drainage and brackish water. 3. Work towards integrated solutions The challenge is to move away from considering agricultural water management in terms of individual farms or irrigation systems. To meet the various demands on resources, ideas need to be based on higher-level regional plans and objectives and resource management goals in water catchment areas.an integrated land and water resource management (ILWRM) approach relies on detailed recording and analysis of existing land and water resources and their current and proposed future use. ILWRM takes the use demands of various sectors in the individual water catchment areas into account and seeks to reconcile them. It consolidates land and water management aspects, integrating them at local, regional and national level. The coherence of land and water law is particularly important here. 4. Enforcing water prices requires a strong political will and strong institutions Introducing and enforcing water prices based on the amount of water extracted helps saving water in agriculture. However, the possibilities for implementing that kind of scheme in developing countries are often overestimated. On the one hand, installing and checking water meters in small farmers irrigation systems entails considerable technical and organisational difficulties. Secondly, enforcing economically appropriate water prices and organising their collection requires a high level of institutional capacity and political will. A more promising option for small farm irrigation is often to make use of local self-management mechanisms that are based on social control and mutual responsibility for communally used resources.

5 Prices for production inputs that are linked to irrigation can also have an influence on water consumption. In some regions of India, subsidised fuel for irrigation pumps is one of the causes of overuse of groundwater and the associated lowering of the water table. A lack of transparency around water distribution and use, combined with the inefficiency that results, fosters corruption in water distribution. Improving transparency and accountability in irrigation system management can bring about significant water savings. 5. Take cross-sector action and carry out reforms Water efficiency cannot be achieved by more economical use of water in agriculture alone. Significant savings can also be achieved outside the agriculture and water sector. A reduction in global population growth could also help to curb the rise in water demand. An estimated 20 30% of food produced is not used as food, but is lost during production, storage and processing or is thrown away by consumers. Wasting food also means wasting the water and land that has been used to produce it. The same applies to wasting farmed feedstocks for industry. The import and export of agricultural goods determines water use. Trade in agricultural goods transfers water to other regions. This virtual water is the water used to produce the traded goods. Thus, for example, exporting soya for animal feed from arid regions of Latin America to Northern Europe equates to exporting virtual water from arid regions to water-rich regions. Since the boundaries of water catchment areas often cross national borders, it is essential to negotiate and regulate water distribution not merely between sectors but also between countries in order to avoid conflicts. All these issues need to be looked at from a cross-sector perspective and addressed with cross-sector action. International development cooperation can help with the necessary negotiation processes and work towards coherency across the various sectoral policies in order to achieve more sustainable use of water resources. Contact Dr Dieter Nill E Dieter.Nill@giz.de T I Published by Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH Registered Offices Bonn und Eschborn Dag-Hammarskjöld-Weg Eschborn T F E info@giz.de I Division Rural Development and Agriculture / May 2015