4. The availability of an adequate quantity of water, of sufficient quality, is a service provided
by ecosystems. The management of, and investment in, ecosystems is therefore essential to address water security for both people and ecosystems in terms of water scarcity, the over-abundance of water (flood risk) and its quality.
5. Accelerated investment in water-dependent ecosystems, in water infrastructure and in water
management can be expected to expedite the transition to a green economy. Modelling suggests that, under the green investment scenario, global water use can be kept within sustainable limits and all the MDGs for water achieved in 2015. With an annual investment of US$ 198 billion on average over the next forty years, water use can be made more efficient, enabling increased agricultural, biofuel and industrial production. By 2030, the number of people living in a water-stressed region is 4 per cent less than under BAU and up to 7 per cent less by 2050.
6. When investment is coupled with improvements in institutional arrangements, entitlement and allocation system, the expansion of Payments for Ecosystem Services (PES), and the improvement of water charging and finance arrangements, the amount that needs to be
invested in water can be reduced significantly. Moreover, a significant proportion of water management policies and measures in other sectors such as input subsidies are undermining opportunities to improve water management. Resolving global water supply problems is heavily dependent upon the degree to which agricultural water use can be improved. Irrigated land produces 40 per cent of the world’s food and, as populations grow, a significant proportion of this water will need to be transferred to urban, commercial and industrial uses.