Sinking Heartland: The Startling Reason Indianapolis Is Slowly Disappearing – And What Indiana Must Do Now

When we hear about cities sinking, our minds usually drift to coastal metropolises threatened by rising sea levels – Venice, New Orleans, parts of New York. The idea of solid ground giving way beneath a major urban center in the American heartland, far from oceanic tides or the Great Lakes’ vast expanse, seems almost counterintuitive. Yet, according to startling new research, that’s precisely what’s happening. Indianapolis, the capital of Indiana, a city over a three-hour drive from even the state’s small Lake Michigan border, is among the U.S. cities most extensively affected by land subsidence, with 98% of its area slowly but surely sinking.  

This unsettling revelation comes from a study published Thursday, May 8th, in the journal Nature Cities, led by researchers from Columbia University and Virginia Tech. They mapped ground movement across America’s 28 most populous cities and found that all of them are compressing to some degree, like a gradually deflating air mattress. For 25 of these cities, including Indianapolis, significant sinking is occurring across two-thirds of their land, impacting an estimated 34 million people nationwide. While the movement is slow – millimeters per year – its cumulative effects over decades pose a serious threat to buildings, roads, and rail lines, and can exacerbate flooding.  

The Science Behind Our Sinking Cities: The Dominant Role of Water Use

So, why is this happening, especially in an inland city like Indianapolis? The primary culprit, responsible for an estimated 80% of the sinkage across the studied cities, is groundwater pumping. The ground beneath our urban centers isn’t solid rock down to the Earth’s core. It consists of layers of sediment, including aquifers – underground layers of water-bearing permeable rock or materials like gravel and sand. Water fills the porous spaces within these aquifers, helping to support the weight of the land and structures above.

However, as cities grow and demand for water increases for drinking, industry, and agriculture, we pump vast quantities of water out of these underground reservoirs. When water is removed and not adequately replenished, the spaces between sediment grains can compress under the immense pressure from above – the weight of buildings, infrastructure, and even the soil itself. The land, quite literally, sinks.

While other factors contribute to subsidence in various regions – the slow settling of land responding to the melt of Ice Age glaciers (glacial isostatic adjustment) along the East Coast and Great Lakes, the sheer weight of massive skyscrapers in New York, or tectonic activity in the Pacific Northwest – the overarching driver identified in this comprehensive study is our relentless extraction of groundwater. And as lead study author Leonard Ohenhen points out, “The usage of groundwater is not going to decline… that may be the only available resource for a particular region or city.”

Indianapolis Underfoot: A Silent, Spreading Challenge

For residents of Indianapolis and other similarly affected inland cities (Chicago, Dallas, Columbus, Detroit, Denver, Houston, and Fort Worth were also in the 98% affected category), this news might come as a particular shock. Without the immediate visual of an encroaching ocean, the threat can seem less tangible. Yet, the risks are very real.

Sinking land, even by a few millimeters a year, can destabilize infrastructure over time. Roads can crack, railway lines can warp, and building foundations can be compromised. This is especially true when subsidence occurs unevenly across a small area – a phenomenon known as differential subsidence. The study found that across the 28 cities, some 29,000 buildings are at risk due to this precarious, destabilized ground. Cities like San Antonio, for instance, face a high risk of damage for 1 in 45 buildings. Furthermore, sinking land changes natural drainage patterns, which can trap stormwater for longer periods and significantly worsen flooding during heavy rain events, even far from any coast.  

Solutions Exist: A Call for Urgent Action from Indiana’s Leaders

The researchers emphasize that their findings are not meant to create panic. The slow rate of subsidence provides a window – if utilized wisely – for communities and their leaders to prepare and mitigate the effects. “We should start talking about those solutions right now,” Ohenhen urges.

Proven strategies exist. One of the most effective is the implementation of aquifer recharge systems. These systems collect water from rain, floods, rivers, or even treated wastewater and actively return it to underground aquifers, helping to replenish them and stabilize the land. Such systems are already successfully slowing and even pausing subsidence in places like California’s Coachella and Santa Clara Valleys, as well as internationally in Spain and Beijing.

Beyond direct intervention, detailed mapping of ground movement and a thorough understanding of local geological conditions and water usage patterns are crucial. This data, as researcher Pejman Tahmasebi (not involved in the study) noted, “can aid in designing policies,” leading to better groundwater management plans and improved urban planning that proactively curbs damage and protects lives.

This is where state leaders, including those in Indiana, must step up – now. The reality is that the problem “is always only going to increase as we progress into the future” if ignored. It is incumbent upon Indiana’s legislators and the Governor’s office to:

1. Acknowledge and Investigate: Treat this new data with the seriousness it deserves. Commission Indiana-specific studies to understand the precise local drivers, rates, and risk areas for subsidence across Indianapolis and other potentially affected urban centers in the state.
2. Develop a Comprehensive Water Management Strategy: Given that groundwater extraction is the primary culprit, a forward-thinking plan for sustainable groundwater use, conservation, and aquifer recharge is paramount.
3. Integrate Subsidence into Urban Planning and Infrastructure Development: Future building codes, infrastructure projects, and land-use planning must account for the reality of sinking land to ensure long-term resilience.
4. Fund Solutions: Proactively allocate resources for implementing mitigation strategies, including the exploration and potential development of aquifer recharge projects where feasible.

Ignoring this issue because it’s slow-moving, or because its primary cause is tied to a resource as vital as water, is not an option. The long-term costs of damaged infrastructure, increased flood risk, and potential threats to public safety will far outweigh the investment needed for proactive solutions. The current leadership in Indiana, regardless of political affiliation or any perceived “unfriendliness” towards such scientific warnings, has a fundamental responsibility to address this clear and present, albeit slow-moving, danger to the state’s largest city and its inhabitants.

The ground beneath our feet may be shifting, but our resolve to protect our communities must remain firm. For Indianapolis and countless other cities, the time to act on the science of subsidence is not when buildings start to visibly crack or floods become unmanageable – it’s now, while there’s still time to build a more stable and resilient future.