Our planet is rich in resources, yet many of them, including water and especially groundwater, are often taken for granted. At the same time, groundwater accounts for almost 30% of all freshwater supply on our planet, so it’s certainly not something we should ignore – especially in areas where freshwater supply is scarce. In such areas, groundwater sustains households and industries alike, especially agriculture. The trick is not only to find it, though – we should also monitor its quality and supply, which is where satellite data comes to the rescue. But why is it important to monitor the supply and how does space tech help, exactly? Read on to find out – how are satellites being used to determine natural resources.
Importance of groundwater detecting and monitoring
Groundwater is not only a useful resource for households and agriculture; it is a strong indicator of our planet’s health – that is if assessed correctly. The top reasons for groundwater detection and monitoring include:
- Ensuring resource security because groundwater is the top freshwater source in some regions and a safety supply in areas where other sources, i.e., rivers or lakes, can dry up after seasonal droughts;
- Preventing over-extraction, often illegal, in areas where populations depend on groundwater as their chief drinking source;
- Protecting ecosystems where flora or fauna depend on groundwater supplies;
- Monitoring resource quality to prevent industrial spills or other pollutants that can harm ecosystems;
- Mitigating geological risks, especially in coastal regions where damage to groundwater supplies could result in landslides or sipping of seawater that renders groundwater supplies undrinkable, etc.
Most importantly, groundwater detection is vital for analysing the long-term effects of climate change because shifting temperature patterns can cause droughts in some areas and excessive rainfalls in others. Both could lead to a snowball effect of other climate changes – sometimes, seemingly paradoxical ones.
For example, some areas in the African savannah depend on wildfires to clean up the last-year vegetation and make room for new plants – which, in turn, will sustain local animals. A sudden increase in rainfall levels or a surfaced groundwater source could act as a stopper in the fire’s way, potentially endangering local biodiversity. Reversely, draining groundwater could intensify wildfire spread, which could have devastating consequences for local populations and regional biodiversity.
Space tech in mineral sources detecting
Even though traditional methods of finding underground water, such as physical site inspections and geological surveys, still apply, space technologies offer a series of advantages while identifying and monitoring the quality of groundwater supply.
Technically, water is not a mineral, of course — and yet, satellites use very similar remote sensing techniques for detecting groundwater and solid mineral resources. So, what is remote sensing groundwater techniques? In essence, remote sensing implies collecting various data about our planet – remotely through satellite tech. In the context of groundwater, the most common techniques include:
- Gravitational measurements of changes in our planet’s gravity, which, among other things, are affected by hidden groundwater movement. Simply put, if there’s a noticeable change in standard measurements, this could indicate the presence of a groundwater source.
- Electromagnetic surveys: advanced satellite imagery can capture an astonishing amount of data on soil moisture levels, which could also indicate the presence of groundwater sources.
- Thermal imaging: modern satellites can capture images in the infrared spectrum, which literally highlights hot spots on the surface. In turn, cooler spots are used to identify groundwater sources.
Now, let’s get more down-to-earth and move on to real-life examples. What satellite is used to detect underground water? Currently, there are two satellites designed specifically for this purpose. Launched in 2002 and 2018, NASA’s Gravity Recovery and Climate Experiment (GRACE) and its successor, GRACE Follow-On (GRACE-FO), have already transformed our approaches to groundwater detection and measurement.
So, how do the satellites measure the amount of groundwater? Both GRACE missions study variations in our planet’s gravitational field – the primary and most effective method so far. Variations in gravity distribution, especially when analyzed over time, are directly related to variations in underwater mass, allowing scientists to estimate not only where the groundwater is but also how much of it is available. Of course, this technique will not give us an accurate assessment of each cubic meter available, but it gives a surprisingly close estimate of groundwater levels and their mass.
Besides GRACE missions, a few other satellites, designed with a larger purpose of natural resource monitoring, provide contributing data that can be used to further our analysis. For example, WorldView-3 and TERRA can capture detailed images later used for mineral exploration.
Still, even this is not the limit because space tech is developing at an unprecedented pace, and Earth Observation missions are ever-more important in the context of the accelerating climate change and the growing need for sustainable use of our natural resources. This means we can count on more exciting missions from major space agencies soon, so stay tuned for more posts!
