Coping with Competition for Water: Improving Basin Water Management and Water Productivity
In many river basins, water for domestic , agricultural or industrial use is approaching or exceeding the amount of renewable water available .The results are overbuilt basins or basin closure; where more water is used than is environmentally desirable or than is renewably available. IWMI’s Theme 1 research, “Basin Water Management” shows that the challenge for these basins is to weigh different options for water management and allocation while examining trade-offs between increased equity and productivity. Under Theme 1, IWMI contributed to the Comprehensive Assessment of Water Management in Agriculture through its research outlined in the CA Synthesis Book. Several Chapters were authored or co-authored by IWMI:
Chapter 2: Trends in water and agricultural development
Chapter 3: Looking ahead to 2050: scenarios of alternative investment approaches
Chapter 5: Policy and institutional reform: the art of the possible
Chapter 7: Pathways for increasing agricultural water productivity
Chapter 9: Reinventing Irrigation
Chapter10: Groundwater: a global assessment of scale and significance
Chapter16: River basin development and management
IWMI advocated acknowledging rainfall as the ultimate freshwater resource and identified opportunities to increase water productivity across the entire blue water- green water, rainfed-irrigated, surface-groundwater continuum. (link to diagram of water use in rainfed and irrigated agriculture) It assessed the impact of water productivity on poverty and hunger reduction. The emergence of small groundwater pumps in South Asia provides livelihoods to millions of poor farmers, but also has led to problems of resource over-exploitation. IWMI recommends increasing opportunities for off-farm livelihoods to ease population pressure on agriculture and thereby on groundwater use. IWMI also looked the significance of intersectoral water transfers and implications of climate change for water and agriculture. New water storage (in reservoirs, aquifers or as soil moisture) may be needed to abate the effects of increased rainfall variability. IWMI studied the multiple constraints faced by river basins such as expanding water supply and the cost and impact of new projects, reductions in renewable freshwater due to pollution, overdraft of aquifers and climate change. IWMI also contributed to several research reports, on river basin management, irrigation investment priorities in Southeast Asia, and the impact of food trade on global water use.
Many basins are subject to water scarcity and there are two types of water scarcity identified by IWMI: physical and economic
With increases in future world food demand, agriculture will require more land and more water. Land and water productivities have risen over the past four decades, and are expected to continue rising, particularly in areas where yields are still below potential.
The future challenge will be to manage additional water in a way that minimizes negative impacts on ecosystem services and aquatic food production while providing the necessary gains in food production and poverty reduction.
A water-food-environment policy agenda tailored to each country and region is needed.
An increase in global trade in food products and consequent flows of virtual water (water embedded in food exports) offers prospects for better national food security and the possibility of relieving water stress.
In Asia, where aquifers are being depleted through groundwater overdraft, key priorities are to develop effective direct and indirect means to regulate aggregate groundwater withdrawals, and step up investments in groundwater management including wide-scale aquifer recharge.