Water, the primary resource for irrigated agriculture, is demanded by domestic, industrial, environmental and agricultural sectors within a catchment. In other words, water of varying quality is demanded by multiple sectors and in varying quantities by multiple users within a catchment. This requires trade-offs among stakeholders, based on changes to the supply of water at any particular time.
Invariably, domestic and industrial sectors have the first call on available water. These sectors largely contaminate more water than they consume, unlike agricultural sectors where water is evaporated or lost to saline aquifers. Therefore, the appropriate treatment of water used by domestic and industrial sectors will enable the reuse of water by another sector.
Environmental flows, on the other hand often improve the quality of water, and this water too may be used by another sector when necessary. In India, a study supported by IWMI on water quality remediation through irrigation infrastructure also shows that water quality improves as the distance away from a city increases. In other words, there are temporal and quality dimensions to water management in addition to the quantity dimension. By incorporating all three dimensions when allocating water, conflict among sectors can be minimized. This would not necessarily eliminate difficult, but essential, trade-offs between agricultural and environmental sectors. These trade-offs will affect a catchment’s hydrological processes and outcomes accordingly.
As water scarcity looms, the paradigm of water management should shift from fresh water for all uses and users to ‘timely supply of adequate amounts of water of acceptable quality’ to each user. This will encourage water recycling within catchments, and the use of alternative water supplies for agriculture within catchments.
About the Author:
Sanmugam Prathapar has led scientific, academic and development institutions of international stature. He has an academic background in Soil Science, Irrigation and Groundwater Hydrology. During his 25 years of post- doctoral experience he has been a Researcher, Academic, Consultant and a Development professional. He is now leading the research theme on ‘productive water use’, at IWMI, and Strategic Research Portfolio on Irrigation as a part of the CGIAR Research Program on Water, Land and Ecosystems.