With its economy based largely on agriculture, water is a critical resource for Pakistan. The country’s vast farm lands are supported by the largest contiguous irrigation system in the world – the Indus Basin Irrigation System. The system includes the Indus River and its tributaries, as well as a myriad of canals, watercourses, farm channels, and field ditches, and serves about 100 million people in the Indus region. If managed efficiently, there is enough water in the basin to support the livelihoods of those people. Water distribution and management are crucial issues.
Groundwater contributes more than 60% of the region’s surface water supplies. To manage the Indus Basin Irrigation System effectively and fairly, water resources managers must monitor how much groundwater there is, where it is, and how it is changing. Where are groundwater storage levels being recharged? Where are they being depleted through mining of water for agriculture? Those are the kinds of questions that need to be answered on a regular basis. Until recently, however, there has been no efficient way to gather this information frequently or comprehensively.
Ground-based networks have been the only method available, but such networks require a huge array of equipment and massive manpower. Pakistan’s ground-based network for just a portion of the basin took almost 8 years to complete, and provides readings only twice each year at best.
Now, however, things are ‘looking up’ for water resources management in the country. That’s because the Pakistan Council of Research in Water Resources (PCRWR), a federal agency with a mandate to provide guidance on water management for Pakistan, is ‘looking up’ to satellites orbiting the Earth. They are using data from NASA’s GRACE mission to monitor groundwater storage in the Indus Basin.
GRACE is made up of a pair of identical satellites that, together, can map tiny variations in Earth's gravity, allowing scientists to track the motions of mass around and within the globe.
What does that have to do with water?
Gravity is associated with mass. Our planet’s rocks, dirt, and other ‘solid’ objects have mass. And Earth’s copious water -- in the form of oceans, polar ice caps, snowfields, rivers, and other water bodies -- has mass too. The distribution of that mass changes much more often than does that of solid objects. Rainfall, glacial melting, the flow of water through aquifers, and the many other ways water moves around the Earth all affect the distribution of water mass on our planet. GRACE’s gravity measurements can help scientists monitor where the water is now and how it’s changing over time.
GRACE’s two satellites circle Earth in the same orbit -- one satellite 220 km (137 miles) ahead of the other. Regions of slightly stronger gravity affect the lead satellite first, pulling it slightly away from the trailing satellite. By monitoring the distance between the two with extraordinary precision (the satellites can sense a change of separation of one micron -- about 1/50th the width of a human hair), GRACE detects minute fluctuations in the gravitational field.
PCRWR is now harnessing such GRACE measurements to achieve a basin-wide view of water resources for the first time in history.
“Collecting physical data is laborious, time consuming, and costly, and it can be applied at only a limited scale,” explains PCRWR Chairman Dr. Ashraf Muhammad. “Also, that data is subject to a number of uncertainties. In contrast, GRACE-based data is readily available, free, can be applied at a large scale such as the Indus basin, and is reliable. Moreover, there are no data sharing issues as compared to traditional datasets.”
Best of all, the holistic view offered by GRACE allows PCRWR to guide and prioritize allocation of water resources cost-effectively and equitably.
PCRWR’s interest in using Earth observation tools to monitor ground water was sparked at a December 2013 workshop in Kathmandu, Nepal. The event was organized by the International Centre for Integrated Mountain Development (ICIMOD) under the framework of the NASA/USAID SERVIR-Himalaya program as part of the SERVIR Applied Sciences Team (AST) capacity building effort. It introduced 23 participants from Bangladesh, Bhutan, Pakistan, India, and Nepal, to several sensors for monitoring precipitation, surface water, cryosphere, and terrestrial water storage change. Dr. Faisal Hossain, a member of SERVIR’s AST and professor at the University of Washington, led the training, assisted by others*.
Hossain and ICIMOD also held a February 2015 training workshop in Islamabad, Pakistan, to work further with Pakistani officials, including representatives from PCRWR, interested in learning how to use information from Earth observations satellites to monitor and manage water. Next, through further collaboration led by the University of Washington with the University of Houston, Ohio State University, SERVIR, and NASA ASP Water Resources application area, PCRWR personnel were trained specifically to use data from NASA's GRACE mission to monitor groundwater storage.
“This success shows that stakeholder agencies need to be intimately involved in co-designing application tools,” says Hossain. “This kind of collaboration should be the norm rather than the exception if we scientists are to be successful in making our Earth observation data useful for the public.”
*Other resource persons (in addition to Hossain) for the workshop included Dr J Turk of NASA’s Jet Propulsion Laboratory, and Dr. C K Shum, Dr. Stephane Calmant, and Dr. Steven Tseng of Ohio State University.
The following individuals were instrumental in the current GRACE effort:
Dr. Ashraf Muhammad/Chairman of PCRWR: University of Washington counterpart to the NASA-funded capacity building and training of PCRWR staff on GRACE.
Naveed Iqbal/Assistant Director of PCRWR: Official trained for 6 months using University of Washington’s training protocols on GRACE.
Hyongki Lee/Assistant Professor at University of Houston: A lead trainer on processing and interpreting GRACE data. He visited University of Washington for a week to interact with Naveed Iqbal.
Faisal Hossain/Professor at University of Washington and SERVIR PI: Scientist who developed the capacity building and training program for PCRWR staff with support from SERVIR, NASA Water Resources, and University of Washington programs.