5 min read<\/p>\n
Preparations for Next Moonwalk Simulations Underway (and Underwater)<\/h1>\n<\/div>\n<\/div>\n<\/div>\n\n\n\n![\"Watersheds](\"https:\/\/www.nasa.gov\/wp-content\/uploads\/2024\/12\/1-terra-modis-04-21-23.jpg?w=2048\")
<\/a><\/figure>\nWatersheds on the U.S. Eastern Seaboard will be among the areas most affected by underground saltwater intrusion by the year 2100 due to sea level rise and changes in groundwater supplies, according to a NASA-DOD study. NASA\u2019s Terra satellite captured this image on April 21, 2023. <\/div>\nNASA<\/div>\n<\/figcaption><\/div>\n<\/div>\n<\/div>\nIntrusion of saltwater into coastal groundwater can make water there unusable, damage ecosystems, and corrode infrastructure.<\/em><\/p>\nSeawater will infiltrate underground freshwater supplies in about three of every four coastal areas around the world by the year 2100, according to a recent study led by researchers at NASA\u2019s Jet Propulsion Laboratory in Southern California. In addition to making water in some coastal aquifers undrinkable and unusable for irrigation, these changes can harm ecosystems and corrode infrastructure.<\/p>\n
Called saltwater intrusion, the phenomenon happens below coastlines, where two masses of water naturally hold each other at bay. Rainfall on land replenishes, or recharges, fresh water in coastal aquifers (underground rock and soil that hold water), which tends to flow below ground toward the ocean. Meanwhile, seawater, backed by the pressure of the ocean, tends to push inland. Although there\u2019s some mixing in the transition zone where the two meet, the balance of opposing forces typically keeps the water fresh on one side and salty on the other.<\/p>\n
Now, two impacts of climate change are tipping the scales in favor of salt water. Spurred by planetary warming, sea level rise is causing coastlines to migrate inland and increasing the force pushing salt water landward. At the same time, slower groundwater recharge \u2014 due to less rainfall and warmer weather patterns \u2014 is weakening the force moving the underground fresh water in some areas.<\/p>\n
Worldwide Intrusion<\/strong><\/p>\n\n\n\n![\"NASA-DOD](\"https:\/\/www.nasa.gov\/wp-content\/uploads\/2024\/12\/e1-pia26491-saltwater-intrusion.jpg?w=2048\")
<\/a><\/figure>\nSaltwater intrusion will affect groundwater in about three of every four coastal aquifers around the world by the year 2100, a NASA-DOD study estimates. Saltwater can make groundwater in coastal areas undrinkable and useless for irrigation, as well as harm ecosystems and corrode infrastructure.<\/div>\nNASA\/JPL-Caltech<\/div>\n<\/figcaption><\/div>\n<\/div>\n<\/div>\nThe study<\/a>, published in Geophysical Research Letters in November, evaluated more than 60,000 coastal watersheds (land area that channels and drains all the rainfall and snowmelt from a region into a common outlet) around the world, mapping how diminished groundwater recharge and sea level rise will each contribute to saltwater intrusion while estimating what their net effect will be.<\/p>\nConsidering the two factors separately, the study\u2019s authors found that by 2100 rising sea levels alone will tend to drive saltwater inland in 82% of coastal watersheds studied. The transition zone in those places would move a relatively modest distance: no more than 656 feet (200 meters) from current positions. Vulnerable areas include low-lying regions such as Southeast Asia, the coast around the Gulf of Mexico, and much of the United States\u2019 Eastern Seaboard.\u00a0\u00a0<\/p>\n
Meanwhile, slower recharge on its own will tend to cause saltwater intrusion in 45% of the coastal watersheds studied. In these areas, the transition zone would move farther inland than it will from sea level rise \u2014 as much as three-quarters of a mile (about 1,200 meters) in some places. The regions to be most affected include the Arabian Peninsula, Western Australia, and Mexico\u2019s Baja California peninsula. In about 42% of coastal watersheds, groundwater recharge will increase, tending to push the transition zone toward the ocean and in some areas overcoming the effect of saltwater intrusion by sea level rise.<\/p>\n
All told, due to the combined effects of changes in sea level and groundwater recharge, saltwater intrusion will occur by century\u2019s end in 77% of the coastal watersheds evaluated, according to the study.<\/p>\n
Generally, lower rates of groundwater recharge are going to drive how far saltwater intrudes inland, while sea level rise will determine how widespread it is around the world. \u201cDepending on where you are and which one dominates, your management implications might change,\u201d said Kyra Adams, a groundwater scientist at JPL and the paper\u2019s lead author.\u00a0<\/p>\n
For example, if low recharge is the main reason intrusion is happening in one area, officials there might address it by protecting groundwater resources, she said. On the other hand, if the greater concern is that sea level rise will oversaturate an aquifer, officials might divert groundwater.<\/p>\n
Global Consistency<\/strong><\/p>\nCo-funded by NASA and the U.S. Department of Defense (DOD), the study is part of an effort to evaluate how sea level rise will affect the department\u2019s coastal facilities and other infrastructure. It used information on watersheds collected in HydroSHEDS, a database managed by the World Wildlife Fund that uses elevation observations from the NASA Shuttle Radar Topography Mission<\/a>. To estimate saltwater intrusion distances by 2100, the researchers used a model accounting for groundwater recharge, water table rise, fresh- and saltwater densities, and coastal migration from sea level rise, among other variables.<\/p>\nStudy coauthor Ben Hamlington, a climate scientist at JPL and a coleader of NASA\u2019s Sea Level Change Team, said that the global picture is analogous to what researchers see with coastal flooding: \u201cAs sea levels rise, there\u2019s an increased risk of flooding everywhere. With saltwater intrusion, we\u2019re seeing that sea level rise is raising the baseline risk for changes in groundwater recharge to become a serious factor.\u201d<\/p>\n
A globally consistent framework that captures localized climate impacts is crucial for countries that don\u2019t have the expertise to generate one on their own, he added.<\/p>\n
\u201cThose that have the fewest resources are the ones most affected by sea level rise and climate change,\u201d Hamlington said, \u201cso this kind of approach can go a long way.\u201d<\/p>\n
News Media Contacts<\/strong><\/p>\nAndrew Wang \/ Jane J. Lee
Jet Propulsion Laboratory, Pasadena, Calif.
626-379-6874 \/ 818-354-0307
andrew.wang@jpl.nasa.gov<\/a> \/ jane.j.lee@jpl.nasa.gov<\/a>\u00a0<\/p>\n\n\n\n\n\n\nShare<\/h2>\n<\/p><\/div>\n\n
![\"Watersheds](\"https:\/\/www.nasa.gov\/wp-content\/uploads\/2024\/12\/1-terra-modis-04-21-23.jpg\")
<\/a><\/figure>Intrusion of saltwater into coastal groundwater can make water there unusable, damage ecosystems, and corrode infrastructure.<\/em><\/p>\n Seawater will infiltrate underground freshwater supplies in about three of every four coastal areas around the world by the year 2100, according to a recent study led by researchers at NASA\u2019s Jet Propulsion Laboratory in Southern California. In addition to making water in some coastal aquifers undrinkable and unusable for irrigation, these changes can harm ecosystems and corrode infrastructure.<\/p>\n Called saltwater intrusion, the phenomenon happens below coastlines, where two masses of water naturally hold each other at bay. Rainfall on land replenishes, or recharges, fresh water in coastal aquifers (underground rock and soil that hold water), which tends to flow below ground toward the ocean. Meanwhile, seawater, backed by the pressure of the ocean, tends to push inland. Although there\u2019s some mixing in the transition zone where the two meet, the balance of opposing forces typically keeps the water fresh on one side and salty on the other.<\/p>\n Now, two impacts of climate change are tipping the scales in favor of salt water. Spurred by planetary warming, sea level rise is causing coastlines to migrate inland and increasing the force pushing salt water landward. At the same time, slower groundwater recharge \u2014 due to less rainfall and warmer weather patterns \u2014 is weakening the force moving the underground fresh water in some areas.<\/p>\n Worldwide Intrusion<\/strong><\/p>\n The study<\/a>, published in Geophysical Research Letters in November, evaluated more than 60,000 coastal watersheds (land area that channels and drains all the rainfall and snowmelt from a region into a common outlet) around the world, mapping how diminished groundwater recharge and sea level rise will each contribute to saltwater intrusion while estimating what their net effect will be.<\/p>\n Considering the two factors separately, the study\u2019s authors found that by 2100 rising sea levels alone will tend to drive saltwater inland in 82% of coastal watersheds studied. The transition zone in those places would move a relatively modest distance: no more than 656 feet (200 meters) from current positions. Vulnerable areas include low-lying regions such as Southeast Asia, the coast around the Gulf of Mexico, and much of the United States\u2019 Eastern Seaboard.\u00a0\u00a0<\/p>\n Meanwhile, slower recharge on its own will tend to cause saltwater intrusion in 45% of the coastal watersheds studied. In these areas, the transition zone would move farther inland than it will from sea level rise \u2014 as much as three-quarters of a mile (about 1,200 meters) in some places. The regions to be most affected include the Arabian Peninsula, Western Australia, and Mexico\u2019s Baja California peninsula. In about 42% of coastal watersheds, groundwater recharge will increase, tending to push the transition zone toward the ocean and in some areas overcoming the effect of saltwater intrusion by sea level rise.<\/p>\n All told, due to the combined effects of changes in sea level and groundwater recharge, saltwater intrusion will occur by century\u2019s end in 77% of the coastal watersheds evaluated, according to the study.<\/p>\n Generally, lower rates of groundwater recharge are going to drive how far saltwater intrudes inland, while sea level rise will determine how widespread it is around the world. \u201cDepending on where you are and which one dominates, your management implications might change,\u201d said Kyra Adams, a groundwater scientist at JPL and the paper\u2019s lead author.\u00a0<\/p>\n For example, if low recharge is the main reason intrusion is happening in one area, officials there might address it by protecting groundwater resources, she said. On the other hand, if the greater concern is that sea level rise will oversaturate an aquifer, officials might divert groundwater.<\/p>\n Global Consistency<\/strong><\/p>\n Co-funded by NASA and the U.S. Department of Defense (DOD), the study is part of an effort to evaluate how sea level rise will affect the department\u2019s coastal facilities and other infrastructure. It used information on watersheds collected in HydroSHEDS, a database managed by the World Wildlife Fund that uses elevation observations from the NASA Shuttle Radar Topography Mission<\/a>. To estimate saltwater intrusion distances by 2100, the researchers used a model accounting for groundwater recharge, water table rise, fresh- and saltwater densities, and coastal migration from sea level rise, among other variables.<\/p>\n Study coauthor Ben Hamlington, a climate scientist at JPL and a coleader of NASA\u2019s Sea Level Change Team, said that the global picture is analogous to what researchers see with coastal flooding: \u201cAs sea levels rise, there\u2019s an increased risk of flooding everywhere. With saltwater intrusion, we\u2019re seeing that sea level rise is raising the baseline risk for changes in groundwater recharge to become a serious factor.\u201d<\/p>\n A globally consistent framework that captures localized climate impacts is crucial for countries that don\u2019t have the expertise to generate one on their own, he added.<\/p>\n \u201cThose that have the fewest resources are the ones most affected by sea level rise and climate change,\u201d Hamlington said, \u201cso this kind of approach can go a long way.\u201d<\/p>\n News Media Contacts<\/strong><\/p>\n Andrew Wang \/ Jane J. Lee<\/a><\/figure>
Jet Propulsion Laboratory, Pasadena, Calif.
626-379-6874 \/ 818-354-0307
andrew.wang@jpl.nasa.gov<\/a> \/ jane.j.lee@jpl.nasa.gov<\/a>\u00a0<\/p>\nShare<\/h2>\n<\/p><\/div>\n