The Power of Water Data

August 18, 2021
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On my office wall is the map that made me a geographer. In one of my many “what am I going to do with my life” moments in 1994, I stared at that same map, posted on my U.S. Forest Service bunkhouse wall. It is a 1993 National Geographic map with the simple title, “WATER.” I saw maps; I’m good at that. I saw water … interested. I’m going to be a hydrologist!

Clichéd as the expression may be, it is true: Water is life. The primordial ocean that first bred life still surrounds us today. Without the world ocean to absorb carbon, our planet could well resemble Venus: a lifeless rock with a toxic carbon dioxide atmosphere.

The applications of geospatial technologies to water management at all scales are as vast as the ocean itself and as dynamic as a river’s flow. In this article, I will point you to some excellent resources for exploring those applications.

The U.S. West’s historic drought

The western U.S. is in a state of severe drought. Snowpack in the mountains is at historic lows, and temperatures are at historic highs. While this means that the growing season is longer for crops, it also means there is less water for these crops. Fire season has become longer, and the fires, larger and more intense. Last night as I was writing, it was raining ash.

Although they say that in the West, “Whisky is for drinking; water is for fighting,” there has been a tremendous amount of cooperation among government agencies, agricultural organizations, environmental groups, tribes, water management districts, and many others regarding water use. Everyone knows what the problem is—there’s just not enough water.

The solution is to use water more efficiently and fairly manage supply and demand. For those interested in the details and nuances of western water politics, I recommend reading High Country News. It offers exceptional investigative journalism, and maps, spatial analysis, and infographics are a key element of many of their stories. The coverage of lead concentrations in the Coeur d’Alene Lake and floodplain in northern Idaho is just one example.

The U.S. Bureau of Reclamation, an agency of the Department of Interior, is the largest wholesaler of water in the U.S. and the second largest producer of hydroelectric power, overseeing over 600 dams and 53 power plants across 17 western states. In recent decades, GIS has played a key role in the management of these facilities as well as their upstream and downstream effects. The Lower Colorado region, for example, has some very interesting projects. Along with facilities management, mapping historic waterways using lidar and pre-digital maps, and scheduling water deliveries, the bureau also supports natural and cultural resource management, including the Multi-Species Conservation Program.


Not all water is on the surface.

As the frequency and severity of droughts escalate, people are increasingly tapping into subsurface aquifers. In the U.S., surface water is subject to numerous laws and policies, but groundwater law is left up the states. Internationally, there is less regulation.

In California, our most populous state, agriculture is an enormous sector of the economy; both people and crops rely on a steady water supply. While the state has addressed groundwater management with its Sustainable Groundwater Management Act, implementation is left to local jurisdictions. To support these efforts, the Department of Water Resources maintains a robust and user-friendly database with downloadable data and interactive maps.

At the global level, there are many efforts to monitor and locate groundwater, especially in drought-prone areas. NASA has several ongoing satellite missions that monitor groundwater as well as rising sea levels, water shifts, and climate change.

The Soil Moisture Active Passive satellite was launched in 2015 with a radar and a radiometer. The goal was to detect subsurface soil moisture with nine-meter resolution. Unfortunately, the radar became inoperable, but the radiometer is still delivering products and data, albeit with lower resolution.

Another fascinating NASA mission is GRACE, Gravity Recovery and Climate Experiment. Initially deployed for geodesy using high-resolution gravity measurements, scientists discovered that it could also be used to detect changes in aquifers. GRACE is an excellent example of the way geospatial missions can be repurposed for new applications, similar to the way GPS went from a military tool to a nearly ubiquitous application in our daily lives.


Of course, it always comes down to data.

If you are interested in free downloadable water data for your own projects, the USGS hosts and maintains the National Hydrography Database, which also includes web-based map services.

The National Oceanic and Atmospheric Administration has an amazing GeoPlatform, offering cloud-based data, AGOL maps, and apps on topics as diverse as marine debris removal, weather, storm surges, hurricane tracks, and marine aviation, among others. In the hurricane tracks map, you can enter a year, a name, or a zip code to see the tracks.

  While well-vetted, these data may be too coarse for projects at the local or regional scale. Fortunately, there are many ways to make new hydrological data. It can be as simple as citizen scientists mapping local streams with GPS, or an epic multi-year project like the sonar mapping of the bottom of Crater Lake in Oregon —which began in 1886, with 168 soundings taken with piano wire from a rowboat. I made a point feature class from the soundings on the original map, then created a surface model using various interpolation techniques. Amazingly, the surfaces were similar to the 2000 bathymetry, and the actual points were +/- 10 meters. Never discount analog technology!

Several GIS packages, including QGIS and Arc Hydro offer tools for delineation of streams and watersheds based on elevation data. The processes are iterative and can become tedious (filling in sinks, connecting “dead-end” streams, etc.) and of course the output is only as accurate as the data that goes into it, but there are ways to make it fun.

 Mapping water in the classroom

 With all of the above data sources and/or a few consumer-grade GPS units, there are great opportunities for projects in the classroom and the field. One basic exercise I use is to measure stream density by watershed. A more advanced one is to quantify intersections of streams and roads by watershed. Of course, there are many other opportunities in the field, and our favorite geographer, Dr. Joseph Kerski, offers plenty of ideas on his YouTube channel. (Does this guy ever sleep?!)

I often think of two quotes that inspire me when mapping water: In Melville’s epic classic “Moby Dick,” the narrator, Ishmael, says “Meditation and water are wedded forever.” And as Winnie the Pooh reflects, “Rivers know this: There is no hurry. We shall get there some day.”


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