IAH TDM - Understanding the Sustainability of Global Water Resources

Bridget R. Scanlon - Use of Satellites, Global Modeling, and Monitoring to Assess Sustainability of Global Water Resources

Bureau of Economic Geology, Jackson School of Geosciences, The University of Texas at Austin

Managing global water resources is becoming increasingly challenging with growing irrigation water demand and intensifying climate extremes. Our analysis of global water storage trends benefits from advances in remote sensing, especially GRACE satellite data, global and regional modeling, and expanding monitoring networks.

GRACE satellite data show declining, stable, and rising trends in total water storage over the past two decades in various regions globally. The causes of water storage variability are primarily linked to human drivers, particularly irrigation, and climate extremes, especially droughts and floods. GRACE satellites show large-scale water storage depletion over the past two decades in NW India, Middle East, N Africa, and SW US. Groundwater monitoring and regional modeling provide longer-term context over the past century, showing rising water storage in NW India, central Pakistan and the NW US, and declining water storage in parts of the US High Plains and US Central Valley. Areas of stable or rising water storage show potential for irrigation expansion, including many parts of Africa and humid E US. Water resource resilience can be increased by conjunctively managing surface water and groundwater and storing water in surface and subsurface reservoirs from wet climate cycles for use during droughts. Examples of conjunctive surface water and groundwater management include combining canal irrigation and groundwater irrigation in NW India and SW US. Inefficient surface water irrigation during wet periods can be used to recharge depleted aquifers for use during droughts, as in the SW US and using managed aquifer recharge.

A diverse portfolio of water management solutions, in tandem with managing groundwater and surface water as a single resource, can help address human and ecosystem needs while building a resilient water system. The visual power of GRACE satellite data has helped communicate water storage variability to the public and influence water policy in many regions, including India and the US.

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