
Using Nasa airborne radar, Scientists have generated maps that reveal New Orleans and its surrounding areas are sinking at 'highly variable rates'.

The highest rates were found upriver along the Mississippi near industrial areas and in Michoud - both experienced annual drops of up to two inches.

Although the study names multiple contributing, researchers found the major culprits behind the drop in elevation were groundwater pumping and dewatering.

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Using Nasa airborne radar, Scientists generated maps that reveal New Orleans and surrounding areas are sinking at 'highly variable rates'. Although the study names multiple factors as contributors, researchers found the major culprits were groundwater pumping and dewatering. Scroll down for video Map shows ground elevation movements in Jefferson Parish, Louisiana, from June 2009 to July 2012

WHAT DO THE MAPS REVEAL? The highest rates were found upriver along the Mississippi near industrial areas and in Michoud, both regions saw annual drops of about two inches. Other notable drops in elevation were found in New Orleans' Upper and Lower 9th Ward in Metairie, where the measured ground movement could be related to water levels in the Mississippi. And an annual 1.6 inch drop was observed at Bonnet Carré Spillway east of Norco, which is the area's last line of protection against springtime river floods blowing over the levees. In the case of New Orleans, it is mostly caused by groundwater pumping and dewatering – surface water pumping to lower the water table, which eliminates standing water and soggy ground. Advertisement

Scientists at NASA's Jet Propulsion Laboratory, UCLA and the Center for GeoInformatics at Louisiana State University, Baton Rouge, collaborated on the study, which covered the period from June 2009 to July 2012.

Other notable sinking was found in New Orleans' Upper and Lower Ninth Ward in Metairie, where the measured ground movement could be related to water levels in the Mississippi.

And an annual 1.6 inch drop was observed at Bonnet Carré Spillway east of Norco, which is the area's last line of protection against springtime river floods blowing over the levees.

Experts call this drop in evaluation 'subsidence', as it is when the Earth sinks as a response to geological or man-induced causes.

In the case of New Orleans, it is mostly caused by groundwater pumping and dewatering – surface water pumping to lower the water table, which eliminates standing water and soggy ground.

Other contributing factors include withdrawal of water, oil and gas, compaction of shallow sediments, faulting, sinking of Earth's crust from the weight of deposited sediments and ongoing vertical movement of land covered by glaciers during the last ice age.

JPL scientists and lead author Cathleen Jones say the results of this research could greatly improve existing models of subsidence for the Mississippi River Delta, which could give officials the upper hand when formulating plans for future events.

'Agencies can use these data to more effectively implement actions to remediate and reverse the effects of subsidence, improving the long-term coastal resiliency and sustainability of New Orleans,' Jones said.

'The more recent land elevation change rates from this study will be used to inform flood modeling and response strategies, improving public safety.'

The maps were generated with data from Nasa's Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR).

This technology uses what is called interferometric synthetic aperture radar (InSAR), which compares radar images of Earth's surface over time to map surface deformation with centimeter-scale precision.

An annual 1.6 inch drop was observed at Bonnet Carré Spillway east of Norco, which is the area's last line of protection against springtime river floods blowing over the levees. Subsidence rates around Norco, Louisiana, and the location of flood protection levees (white). Experts call this drop in evaluation 'subsidence', which when the Earth sinks as a response to geological or man-induced causes

Scientists at NASA's Jet Propulsion Laboratory, UCLA and the Center for GeoInformatics at Louisiana State University, Baton Rouge, collaborated on the study, which covered the period from June 2009 to July 2012. The team found Norco, Upper and Lower Ninth Ward, Michoud, and Bonnet Carré Spillway in the metropolitan area of New Orleans experienced the most elevation drop in the region

Surface elevation changes from all sources were also measured, in addition to human and natural, deep seated and shallow.

UAVSAR's spatial resolution makes it ideal for measuring subsidence in New Orleans, where human-produced subsidence can be large and is often localized, said researchers.

Jones said another key advantage of this study is that UAVSAR enabled better resolution of small-scale features than previous studies.

'We were able to identify single structures or clusters of structures subsiding or deforming relative to the surrounding area,' she said.

Up-to-date GPS position information for the industrial and urban areas were provided by the Center for GeoInformatics, which helped the team develop the rate of ground movement at specific locations.

Other factors contributing to sinking include withdrawal of water, oil and gas, compaction of shallow sediments, faulting, sinking of Earth's crust from the weight of deposited sediments and ongoing vertical movement of land covered by glaciers during the last ice age. The red stars represent locations where levees breached during Hurricane Katrina -- areas that will experience problems the more they sink

This study isn't the first to reveal New Orleans' fate or other coastal regions that are said to be slowly sinking into the ocean.

Last year, a team released findings that suggest the only way to save coastal areas is to make extreme carbon cuts and shift to renewable fuel.

Scientists have already established that if we do nothing to reduce our burning of fossil fuel up to the year 2100, the planet will face sea level rise of 14-32 feet (4.3–9.9 meters), said lead author Ben Strauss, vice president for sea level and climate impacts at Climate Central.

To bring this issue home for people in the United States, the study pinpoints at-risk land where more than 20 million people reside.

Shockingly, the research found that 414 US cities already have 'lock-in' dates – and New Orleans seems to be the most at risk.

In the case of New Orleans, the sinking is mostly caused by groundwater pumping and dewatering – surface water pumping to lower the water table, which eliminates standing water and soggy ground. The map shows the location of water wells active in 2012, local industry and the Bonnet Carre Spillway. The highest subsidence forms a bowl within the refinery site to the south of the river

'Even in a best-case carbon emissions scenario, 98 percent of populated land in New Orleans would be below the future sea level,' Strauss said.

'So it's really just a question of building suitable defenses or eventually abandoning the city.'

In the past century, more than 1,880 square miles of Louisiana land has turned into open water - an area nearly the size of Delaware.

And the loss does not seem it will end anytime soon, with an estimated 17 square miles disappearing on average each year, according to the US Geological Survey.