Water use has been growing globally at more than twice the rate of population increase in the last century, and an increasing number of regions are reaching the limit at which reliable water services can be delivered. Essentially, demographic growth and economic development are putting unprecedented pressure on renewable, but finite, water resources, particularly in arid regions. By 2025, 1.8 billion people are expected to be living in countries or regions with less than 500 m3 of renewable water per year per capita, and two-thirds of the world population could be under ‘stress’ conditions (between 500 and 1000 m3 per year per capita). The situation will be exacerbated as the demands of rapidly growing urban areas place increased pressure on the quality and quantity of local water resources. In addition, environmental services and ecosystem functions are now being given explicit water allocations rather than being treated as residual users. Given the finite circulation of freshwater, and the limited opportunities for expanding arable lands, the world is facing a progressive condition of scarcity of water and land resources, which is threatening the viability of key global agricultural systems to safeguard global food security. Reconciling the competition for water among economic sectors and sustaining the productive and environmental values of these agricultural systems is now critical to avoid further shocks to the global food supply system (irrigation systems are already under pressure to produce more with less supplies of water) and to sustain the values of the already stressed environmental systems. With no gains in water productivity, average annual agricultural consumption of water could double in the next 50 years, while with reasonable increase in water productivity the global water consumption could be held down to 20 - 30%.

Therefore, increasing water productivity is imperative to coping with water scarcity while meeting rising demand for food from a growing, wealthier, and increasingly urbanized population, and responding to pressures to re-allocate water from agriculture to cities while sustainable environmental flow would have to be ensured. Targeting high water productivity reduces investment costs, because less amount of water needs to be withdrawn, and the need for additional water and land resources in agriculture. Irrigated agriculture uses about 70% of the total water withdrawal worldwide. However, the majority of large scale irrigation systems are performing well below their potential. In fact, large scale irrigation systems in several emerging and least developed countries may be characterized by an inflexible and unreliable water delivery service with significant inequities between the head and the tail-end of the systems. A number of these irrigation systems are still top-down agency-managed supply-based systems with dilapidated infrastructure, which lack meaningful participation of water users in their governance. Furthermore, although irrigation system performance and irrigation modernization has to a large extent been the focus of investments during the last two decades, expected progresses have been generally modest. The major reasons for these unsatisfactory results are related to: i) the compartmentalization of the modernization activities in either hardware or software - investments were made either in the hardware and automation or in institutional set up and participatory irrigation management - while they were needed in all of the components of an irrigation system; ii) overall lack of understanding of the modernization strategies and the concept of service oriented management; iii) limited capacity of the irrigation mangers to implement the modernization strategies and plan for improvements, iv) lack of vision for the future needs; and v) lack of understanding that regular operation and maintenance of water management systems is required and that modernization is a continuing process in the context of changing water delivery environment. To enhance the productivity of irrigated agriculture, then, a coherent strategy and a push for modernization of irrigation management is needed at the country and regional level, that addresses the past shortcomings of the investments in irrigation modernization and allows for appropriate managerial and infrastructural upgrading in a cost effective manner, while accounting for future water delivery requirements. In light of this it would be useful to investigate how many systems have been modernised in the last 10 years and to report on the achievements. Proven systematic methodologies and approaches can then be helpful in identification of investments priorities, preparation of modernization plans, and in developing national, regional, and global capacities in irrigation modernization. ‘Water productivity (WP) is the ratio of the net benefits from crop, forestry, fishery, livestock and mixed agricultural systems to the amount of water used to produce those benefits. In its broadest sense, it reflects the objectives of producing more food, income, livelihood and ecological benefits at less social and environmental cost per unit of water consumed.

Physical water productivity is defined as the ratio of agricultural output to the amount of water consumed – ‘‘more crop per drop’’ –, and economic water productivity is defined as the value derived per unit of water used and this has also been used to relate water use in agriculture to nutrition, jobs, welfare and the environment’ (Comprehensive Assessment – IWMI, 2007). With about 80-85% of the global food calories derived from crops (where 50% of the human direct food calories are provided by rice, wheat and maize only), one of the key recommendations to increase water productivity remains ‘more crop per drop’, i.e., the physical water productivity as defined above. The advantage to target the physical (rather than economical) water productivity is also in the independence from volatility of economic valuations. Similarly to land productivity, there is a large variability in water productivity between and within countries, as illustrated in the example of Figure 1;

This variability, spanning four times the minimum value, has various sources of the similar nature of those for the land productivity (e.g., economic/market induced, management or non-management related, etc.) with one of the most relevant being ‘climate’, i.e., the evaporative demand of the atmosphere and the atmospheric concentration of carbon dioxide. Each country (or sub-national though significant system) has its main crop(s) that can be taken as reference to monitor irrigated water productivity. For each of these crops, a baseline needs to be identified for benchmarking (we recommend in principle the average of a few years, e.g., 2000-05).

The weighted aggregation of the different water productivity would then represent the global water productivity for each crop (or crop category). Investigation of water productivity variability and potential (and consequently the water-productivity gap) would provide the scope for increasing water productivity and would guide the typology and affordability of intervention measures. Departing from the base-line, then, the water productivity can be monitored periodically and the slope of the interpolating line of the values over the years would indicate the % change of water productivity. There is considerable scope for improving water productivity, but not everywhere. Therefore, agricultural systems within each country may be selected for monitoring the % change of water productivity. Focusing in areas of low productivity (like in sub-Saharan Africa and South Asia) would have the advantage of both reducing the amount of additional water needed for agriculture and help to reduce poverty. In light of the requirements as outlined above it will also be necessary to preserve land for agriculture (in front of urban areas extension). This will require consistent policies, also outside the water and agriculture sector. Standard methodologies have been developed to assess water productivity at different scales (field, country, global). These will be associated to sound water accounting methodology to assess also real ‘saving’ in water use and consumption.

Typical interventions measure may relate to:

• O&M of irrigation systems (for better amount and timing control of irrigation; etc.);

•on-farm water management (to minimizing non productive consumption of water, including the use of improved varieties; etc.);

• modernization, or upgrading of existing irrigation and drainage systems, or installation of new systems where this can be viable;

• financial frameworks (to provide incentives to farmers for adoptions of best practices, and enhanced technology, including improved varieties, etc.);

• use of marginal water in non conventional agriculture (i.e. forestry);

• all of those measures that would lead to an increase of land productivity;

• countries would have to agree on a standard criteria to be adopted for water productivity analysis.

Irrigation modernization is the way forward for improving water management and water productivity in large scale irrigation networks. However, it is a long-term, continuous, and often an expensive process that must follow a systematic approach (see Figure 2) in order to avoid critical faults. In order to achieve optimal benefits from modernisation of irrigation systems it would have to be developed and implemented in conjunction with land improvement and changes in cropping patterns (high cash crops).

Main stakeholders in the modernisation processes are Governments, Irrigation and/or Drainage Agencies and farmers. This implies that these three partners would have to reach agreement on the activities, responsibilities and cost sharing in the modernisation process and the subsequent operation and maintenance costs. While the objectives of modernisation are generally improved conditions for farming and higher crop yields it may be expected that farmers share in the cost of service will increase. This can be either financially, or in kind. Appropriate cost-recovery mechanisms that include the social dimension will have to be applied. It is therefore important to have agreement among the stakeholders on such aspects preceeding to the actual implementation. Improvement of crop production systems to include appropriate crop selection and rotation, enhancement of regional and inter-regional cooperation for diversified crop production and for more crop per drop, self reliance concepts, as well as implementation of research results on high yielding and resilient crop varieties may be important to facilitate such processes.

Each individual country would have to assess the need for modernization and develop strategies that will provide basis for improvements in large-scale irrigation networks