Opinion

Rallying Around Our Known Unknowns: What We Don’t Know Will Hurt Us

The following will appear in the July 2012 newsletter of the AGU Hydrology Section as part of the Fellows Speak series.

Given a rare opportunity to communicate to our section, I want to focus this note on some key things that we don’t know and can’t do, rather than patting ourselves on the back too much.

Bur first…a little back-patting! For context, here’s some background on what we do in my group. First, we work to make the hydrology in climate models, like those used in the IPCC, increasingly more realistic. Second, we use satellites to explore how the water cycle, and with it, water availability, is changing.   The community that works on these issues is not large, but it is dedicated. There is no question that we should be proud of our advances over the past couple of decades.

For example, we can now simulate the water cycle with improved accuracy across multiple scales. Our computer models, from the hillslope to the GCM scale, are running at higher resolution, with greater fidelity, and are providing unprecedented insights into process interactions, while enabling new science.

Likewise, satellites are now revealing that the pace of water cycle change is greater than we thought, and not surprisingly, that the human fingerprint on our water landscape, due to water use, water management and land use change, is severe, and is global in scope.

We’re making great progress as a community. That’s for certain. However, observations from the GRACE mission, and my involvement with CUAHSI, have forced me to confront some key issues that I don’t believe that we are prepared to address.  For example: how can we expect our models to simulate the synoptic patterns of water storage changes that we see from GRACE, which are in large part human driven, if water management practices (e.g. groundwater pumping, irrigation, reservoir storage, conveyance) are not well represented in our land surface models?

In parallel, my work with CUAHSI on the Community Hydrologic Modeling Platform (CHyMP) has greatly raised my awareness of other critical unknowns on the data side.  In short, in my opinion, our nation’s hydrologic modeling assets are simply not up to the task of addressing our most pressing societal issues of food, energy, water and national security.  We are behind where we need to be, and we are falling behind other nations.

To illustrate, here are a few of what I’ve been calling the ‘unfortunate realities’ of modern hydrology.

1)    We don’t know how much fresh water we have on land. Not stored as groundwater, or surface water, as soil moisture, or as snow.  Believe it. It’s true.  Many estimates, for example, of continental scale groundwater supplies, are simply guesses based on ad hoc assumptions.  Others are reports of water storage in man-made reservoirs. It is unclear to me how we can address sustainable water management without knowing how much water is actually on and in the ground.

2)    Our knowledge of Earth’s surface and shallow subsurface, i.e. it’s water environment, including its digital representation, remains appallingly insufficient.  At the surface, we know little about the bathymetry of rivers and lakes.  We have no idea how deep our soils are, at least at the larger regional, national and global scales. While two-dimensional maps of global hydrogeology are now available, the third dimension, as well as basic aquifer parameters, remain a mystery at national and global scales.

3)    Our global monitoring system…for river discharge, for groundwater extraction, for water use…is insufficient for tracking even the most fundamental changes in water storage and availability. It doesn’t have to be that way, but for a host of political and socioeconomic reasons, it is.

To review then: we don’t really know how much water we have; we don’t have a detailed picture of our water environment; and we don’t do such a great job of measuring its storage and flows within it. How in the world have we let this happen?

I believe it’s because we haven’t rallied around core questions of societal relevance. The typical excuse that we give is that — these are not science questions. Or — these are too applied.  However, we can no longer afford the luxury of such academic arrogance.

Every single one of us works on some aspect of sustainable water management.  But let’s face facts: we simply cannot manage water sustainably until we can answer the following three questions.  How much water do we have — as snow, surface water, soil moisture and groundwater? How much do we need — for humans and for the environment?  And, how are these changing with time – with climate change and with increased understanding and adaptation? Society wants to know, we can provide the answers, and virtually all of our research fits under this broad umbrella of water sustainability.

It is time for us to move forward with core observations and models that can utilize them to predict and help prepare for the future. Getting there requires both top-down and bottom-up engagement.

From the top, commitment and focus is required at the national and state agency levels.  Vision and leadership is required at the program manager, division and directorate levels.  We must make a significant investment in the tools – namely models, observations and data products and information systems –to enable the critical science, applications and solution strategies that society demands, and that our community is capable of delivering.

From the bottom, it behooves us to rally around key societal questions including the known unknowns discussed above.  And we must recognize that it is our responsibility to communicate these key issues, in order to educate our elected officials and to motivate their support.   Other communities do it. It’s time for us to do so as well.

More broadly, our public, our teaching, our research, and our environment, will be best served if we embrace the communication challenge of elevating water issues to the level of everyday understanding.

About Jay Famiglietti

Jay Famiglietti is a Professor of Earth System Science of and Civil and Environmental Engineering at the University of California, Irvine, and the Senior Water Scientist at the NASA Jet Propulsion Laboratory at the California Institute of Technology. He and his research team use satellites and develop computer models to track changing freshwater availability and groundwater depletion around the world. Famiglietti is an active speaker, a frequent advisor to national and international government officials on water issues, and a regular contributor the National Geographic Water Currents and to the Huffington Post blogs.

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Design professional Richard Vijgen's rendering of GRACE and USGS groundwater depletion data displayed on Times Square beginning on World Water Day, March 22, 2012.

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